Fundamentals of Neurosurgery. A Guide for Clinicians and Medical Students 9783030176488, 9783030176495

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Fundamentals of Neurosurgery A Guide for Clinicians and Medical Students Andrei Fernandes Joaquim Enrico Ghizoni Helder Tedeschi Mauro Augusto Tostes Ferreira  Editors

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Andrei Fernandes Joaquim Enrico Ghizoni • Helder Tedeschi Mauro Augusto Tostes Ferreira Editors

Fundamentals of Neurosurgery A Guide for Clinicians and Medical Students

Editors Andrei Fernandes Joaquim Department of Neurology Neurosurgery Division University of Campinas (UNICAMP) Campinas, São Paulo Brazil Helder Tedeschi Department of Neurology Neurosurgery Division University of Campinas (UNICAMP) Campinas, São Paulo Brazil

Enrico Ghizoni Department of Neurology Neurosurgery Division University of Campinas (UNICAMP) Campinas, São Paulo Brazil Mauro Augusto Tostes Ferreira Federal University of Minas Gerais Belo Horizonte, Minas Gerais Brazil

ISBN 978-3-030-17648-8    ISBN 978-3-030-17649-5 (eBook) https://doi.org/10.1007/978-3-030-17649-5 © Springer Nature Switzerland AG 2019 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Foreword

Dr. Joaquim is to be congratulated for assembling a roster of star clinicians who have provided a readable and easy-to-understand introduction to the art of neurosurgery. These authors represent the best of a range of training and treatment centers at institutions around the world. The topic of Fundamentals of Neurosurgery is aptly introduced by chapters that review the application of neuroanatomy to clinical practice and give an overview of basic neuroimaging and neurological examination techniques. Subsequent chapters address specific neurological conditions affecting the brain (e.g., intracranial hypertension, traumatic brain injury, subarachnoid hemorrhage, stroke, hydrocephalus, and brain tumors) and spine (e.g., spinal trauma, spinal dysraphism, and degenerative spine disease). In addition to providing insights on the medical management of these conditions, the text includes chapters that discuss brain tumors specific to adults or children, that examine brain death, that touch on the social and economic burdens of misdiagnosis, and that consider the remaining frontiers which neurosurgeons will face in the future. It is critical for both medical students and allied physicians alike to have a broad-­ based reference text such as this one that provides them with basic management guidelines and exposes them to up-to-date neurosurgical care techniques. This book no doubt not only will serve as a reference resource for clinicians but will also inspire medical students to consider a career in the neurosciences. Robert F. Spetzler Department of Neurosurgery Barrow Neurological Institute St. Joseph’s Hospital and Medical Center Phoenix, AZ, USA

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Preface

Neurosurgery textbooks have contributed to the lack of interest for the specialty as they used to be packed with astonishingly complex anatomical pictures and with a myriad of terms that have made the area a forbidding territory for many students. Although, unlike neurosurgeons, the nonspecialists will probably never be directly involved in the surgical procedures or in the therapeutic decisions, they certainly need to be thoroughly informed about the newest treatment recommendations and the science and evidence that are behind them. With that in mind, the authors have chosen to make neurosurgery more practical and thus more available to those in search for information on the subject. Each chapter of this book has the intention to bring a comprehensive, state-of-­ the-art, and consistently formatted text on the recommendations for the management of a particular neurosurgical condition. The apprehensions of the students about the complexity of neurosurgery are put to ease with a concise and yet complete description of the essentials of the neurosurgical practice that is both easy to grasp and readily applicable. Inviting acknowledged experts in the various areas to contribute to the chapters has certainly enhanced the quality of the text and reinforced our belief that readers would benefit from different opinions. This new textbook was designed to provide a practical and in-depth reference that gives the reader an easy guide to the therapeutic options of the commonest problems in neurosurgery, serving as a constant companion for the daily clinical practice. Helder Tedeschi Department of Neurology, Neurosurgery Division University of Campinas (UNICAMP) Campinas, SP, Brazil

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Acknowledgments

We thank all the contributing authors of this manuscript.

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Contents

1 Neuroanatomy Applied to Clinical Practice��������������������������������������������   1 Mauro A. T. Ferreira 2 Basic Neuroimaging ����������������������������������������������������������������������������������  25 Caio Fiuza Ferreira and Marcos Marins 3 The Basic Neurological Examination ������������������������������������������������������  37 Mauro A. T. Ferreira 4 Intracranial Hypertension������������������������������������������������������������������������  51 Vânia Graner Silva Pinto, Alexandre Guimarães de Almeida Barros, and Antonio Luis Eiras Falcão 5 Traumatic Brain Injury Overview and Practice Parameters����������������  61 James W. Bales and Louis J. Kim 6 Spinal Trauma��������������������������������������������������������������������������������������������  81 Otávio Turolo da Silva, Andrei Fernandes Joaquim, Alexander R. Vaccaro, and Richard H. Rothman 7 Thoracolumbar Spine Trauma ����������������������������������������������������������������  95 Eugene Warnick, Sheena Amin, Mayan Lendner, Joseph S. Butler, and Alexander R. Vaccaro 8 Subarachnoid Hemorrhage���������������������������������������������������������������������� 111 Joshua S. Catapano and Michael T. Lawton 9 Neurosurgery for Ischemic and Hemorrhagic Stroke���������������������������� 129 Thomas J. Sorenson, Enrico Giordan, and Giuseppe Lanzino 10 Hydrocephalus Basic Concepts and Initial Management���������������������� 147 Fernando Campos Gomes Pinto and Francisco Del Rosario Matos Ureña 11 Tethered Cord Syndrome�������������������������������������������������������������������������� 161 Enrico Ghizoni, João Paulo Sant’Ana Santos de Souza, and Dominic N. P. Thompson

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12 Craniosynostosis���������������������������������������������������������������������������������������� 177 Enrico Ghizoni, Cássio Eduardo Raposo do Amaral, and Rafael Denadai 13 Management of Low Back Pain���������������������������������������������������������������� 191 Otávio Turolo da Silva, Andrei Fernandes Joaquim, and Alpesh A. Patel 14 Peripheral Nerve Surgery������������������������������������������������������������������������� 201 Roberto S. Martins and Mario G. Siqueira 15 Degenerative Lumbar Spine Disease�������������������������������������������������������� 211 Andrei Fernandes Joaquim, Otávio Turolo da Silva, Barlas Benkli, and Ronald A. Lehman Jr 16 Degenerative Cervical Spine Disease�������������������������������������������������������� 221 Andrei Fernandes Joaquim, Otávio Turolo da Silva, John Rhee, and K. Daniel Riew 17 Brain Tumors in Adults ���������������������������������������������������������������������������� 231 Victor Leal de Vasconcelos, Marcelo Gomes Cordeiro Valadares, and Helder Tedeschi 18 Brain Tumors in Children ������������������������������������������������������������������������ 241 Enrico Ghizoni, Carolina Ribeiro Marques Naccarato, and Roger Neves Mathias 19 Determination of and Difficulties with Brain Death������������������������������ 263 James W. Bales and Louis J. Kim 20 The Frontiers of Neurosurgery ���������������������������������������������������������������� 279 Mauro A. T. Ferreira Index�������������������������������������������������������������������������������������������������������������������� 293

Contributors

Sheena Amin  Drexel University College of Medicine, Philadelphia, NJ, USA James  W.  Bales  Department of Neurosurgery, Harborview Medical Center, University of Washington, Seattle, WA, USA Barlas Benkli  Department of Neurology, UT Health, Houston, TX, USA Joseph  S.  Butler  National Spinal Injuries Unit, Department of Trauma & Orthopaedic Surgery, Mater Misericordiae University Hospital, Dublin, Ireland Joshua S. Catapano  Department of Neurosurgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA Otávio  Turolo  da Silva  Department of Neurology, Neurosurgery Division, University of Campinas (UNICAMP), Campinas, SP, Brazil Alexandre  Guimarães  de Almeida  Barros  Faculty of Medical Sciences, State University of Campinas (UNICAMP), São Paulo, Brazil Victor Leal de Vasconcelos  Division of Neurosurgery - Department of Neurology, University of Campinas, Campinas, SP, Brazil Rafael  Denadai  Institute of Plastic and Craniofacial Surgery, SOBRAPAR Hospital, Campinas, SP, Brazil Cássio Eduardo Raposo do Amaral  Institute of Plastic and Craniofacial Surgery, SOBRAPAR Hospital, Campinas, SP, Brazil Antonio  Luis  Eiras  Falcão  Faculty of Medical Sciences, State University of Campinas (UNICAMP), São Paulo, Brazil Caio Fiuza Ferreira  Vera Cruz Hospital/Centro Radiológico Campinas e Clínica de Diagnóstico por Imagem de Salvador, Campinas, SP, Brazil Mauro  A.  T.  Ferreira  Department of Anatomy and Radiology, University Hospital, Belo Horizonte, MG, Brazil Enrico Ghizoni  Department of Neurology, Neurosurgery Division, University of Campinas (UNICAMP), Campinas, SP, Brazil

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Enrico Giordan  Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA Fernando Campos Gomes Pinto  Group of Cerebral Hydrodynamics, Division of Functional Neurosurgery, Institute of Psychiatry, Hospital das Clínicas, University of São Paulo, SP, Brazil Andrei  Fernandes  Joaquim  Department of Neurology, Neurosurgery Division, University of Campinas (UNICAMP), Campinas, SP, Brazil Louis  J.  Kim  Department of Neurosurgery, Harborview Medical Center, University of Washington, Seattle, WA, USA Giuseppe  Lanzino  Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA Department of Radiology, Mayo Clinic, Rochester, MN, USA Michael T. Lawton  Department of Neurosurgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA Ronald A. Lehman Jr.  Department of Orthopedic Surgery, The Daniel and Jane Och Spine Hospital- NewYork-Presbyterian/The Allen Hospital, New York, NY, USA Mayan Lendner  Rothman Orthopaedic Institute, Philadelphia, PA, USA Marcos  Marins  Vera Cruz Hospital/Centro Radiológico Campinas, Pontifical Catholic University of Campinas, Campinas, SP, Brazil Roberto S. Martins  Peripheral Nerve Surgery Unit, Department of Neurosurgery, Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil Roger  Neves  Mathias  Department of Neurology, University of Campinas, Campinas, SP, Brazil Carolina  Ribeiro  Marques  Naccarato  Department of Radiology, Hospital Boldrini, Campinas, SP, Brazil Alpesh  A.  Patel  Department of Orthopaedic Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA John  Rhee  Department of Orthopaedic Surgery and Neurosurgery, Emory University, Atlanta, GA, USA K. Daniel Riew  Department of Orthopedic Surgery, Daniel and Jane Och Spine Hospital – New York Presbyterian Hospital, New York, NY, USA Richard  H.  Rothman  Sidney Kimmel Medical Center at Thomas Jefferson University, Rothman Institute, Philadelphia, PA, USA João Paulo Sant’Ana Santos de Souza  Laboratory of Neuroimaging, Department of Neurology, University of Campinas, São Paulo, Brazil

Contributors

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Vânia  Graner  Silva  Pinto  Faculty of Medical Sciences, State University of Campinas (UNICAMP), São Paulo, Brazil Mario G. Siqueira  Peripheral Nerve Surgery Unit, Department of Neurosurgery, Institute of Psychiatry, University of São Paulo Medical School, SP, Brazil Thomas J. Sorenson  Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA School of Medicine, University of Minnesota, Minneapolis, MN, USA Helder Tedeschi  Department of Neurology, Neurosurgery Division, University of Campinas (UNICAMP), Campinas, SP, Brazil Dominic  N.  P.  Thompson  Department of Neurosurgery, Great Ormond Street Hospital for Children, London, England Francisco Del Rosario Matos Ureña  Group of Cerebral Hydrodynamics, Division of Functional Neurosurgery, Institute of Psychiatry, Hospital das Clínicas, University of São Paulo, SP, Brazil Alexander  R.  Vaccaro  Department of Orthopaedic Surgery and Neurosurgery, Rothman Institute at Thomas Jefferson University, Philadelphia, PA, USA Marcelo Gomes Cordeiro Valadares  Division of Neurosurgery – Department of Neurology, University of Campinas, Campinas, SP, Brazil Eugene Warnick  Thomas Jefferson University, Philadelphia, PA, USA

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Neuroanatomy Applied to Clinical Practice Mauro A. T. Ferreira

Introduction Unlike other human organs such as the lung, the liver, the pancreas, and so on, where morphological and functional units tend to repeat themselves regardless of its location on a given organ, the brain is composed of multiple, different, complex, and interconnected neural systems and pathways, each one located in different areas of the brain. This is important because lesions occurring on any given area of the brain may cause different neurological deficits, allowing, thus, a more or less precise topographical diagnosis. The central nervous system (CNS) is composed of a very complex network of neurons, with numerous connections, some of those remaining unknown to this date. The cutting edge of this knowledge is knowing how exactly each neuron communicates with other neurons in the brain (connectome), but this is out of the scope of this chapter. The so-called Brodmann areas (after German anatomist Korbinian Brodmann, 1868–1918) are cortical areas with specific cortical cytoarchitectural features of neurons, as well as cell laminar organization, which differs from one area to the other, as they have been studied using Nissl method of cell staining. The brain has been mapped into 52 different areas, according to his original work, published in 1909. Although a matter of debate, the vast majority of neuroanatomy textbooks mention Brodmann areas as cortical functional reference areas. In theory, the different Brodmann areas represent different cortical areas responsible for different brain functions. Brodmann areas don’t apply to the cerebellum. The main Brodmann areas are presented herein (Fig. 1.1). The knowledge of all Brodmann areas is absolutely unnecessary. Besides establishing these cortical areas, Brodmann studied the comparative anatomy of 52 different animal species.

M. A. T. Ferreira (*) Department of Anatomy and Radiology, University Hospital, Belo Horizonte, Minas Gerais, Brazil © Springer Nature Switzerland AG 2019 A. F. Joaquim et al. (eds.), Fundamentals of Neurosurgery, https://doi.org/10.1007/978-3-030-17649-5_1

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Fig. 1.1  Brodmann’ areas; this picture depicts the different cortical areas involving information processing of the brain. Each one has its function and is composed of different circuitries inside the central nervous system (http://thebrain.mcgill.ca/flash/capsules/outil_jaune05.html) (internet picture)

The macroscopic and the surgical microscopic anatomies of the brain have been well studied by several authors, but a monumental work, put together by Dr. Albert L. Rhoton Jr. and his fellows, over a 40-year period at the University of Florida, FL, is worth mentioning, and its reading is indicated for those interested in studying this subject in further detail. This work includes the white matter fiber dissection techniques, as proposed by Klingler in 1902, where specific and individual neural systems are dissected, and its anatomical relationships with other systems are presented. This is key to understanding and planning surgical approaches in order to avoid damage. The socalled tractography, or diffusion tensor imaging (DTI) technique, available to most

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neurosurgeons, is a magnetic resonance imaging (MRI) technique that shows these pathways, in both normal and pathological situations. This is particularly important when pathological conditions like tumors, arteriovenous malformations, or any neurological condition that may require surgery, is located close to eloquent brain areas. The DTI-MRI may show displacement or involvement of such fibers by the disease, allowing, thus, a safer surgical planning and execution.

Objective This chapter intends to present the basic neuroanatomy and the location of the so-­ called “eloquent” areas. “Eloquent” areas are responsible for the perception of vision, primary motor and sensory functions, speech, some association areas of the brain, and the dominant side of memory. Lesion to these areas may cause gross neurological deficits, and any given disfunction of these systems should prompt immediate action to elucidate any possible aggression to the brain. After the basic neuroanatomy is presented, a brief comment on the clinical picture of dysfunction of the different regions is presented. One key phenomenon concerning the brain hemispheres, almost as a rule, is the fact that lesion to one hemisphere causes deficit to the opposite side of the body. This is different from “dominance,” when a given area, like speech and language processing, causes a global deficit.

The Central Nervous System The central nervous system (CNS) comprises all neural tissue inside the cranial cavity and the vertebral canal. The encephalon locates, and it is completely encased by the cranium, and the spinal cord extends down to the level of the first lumbar vertebrae in adults. The spinal cord is also involved completely by the bony vertebral canal. The cranial nerves have its origins inside the cranial cavity, and the peripheral nerves are, for the most part, extensions of spinal cord neurons that convey impulses that arrive at (afferent) or leave the central nervous system (efferent). Afferent and efferent stimuli are processed in the CNS, at various levels, and involve a variable number of neurons. They may become conscious or unconscious. There are no ganglia at the CNS, and, by definition, a group of neurons (gray matter) inside the CNS is called a nucleus. In the spinal cord and at the brainstem, the gray matter is located inside the white matter, while in the cerebellum and the brain, the gray matter (neurons) is located outside the white matter, the so-called cerebellar and cerebral cortex, respectively. As a simplification, the encephalon comprises the brain, the midbrain (thalamus and hypothalamus), the cerebellum (or “small brain”), the brainstem (midbrain, pons, and the medulla), the ventricular system, and the cranial nerves, intracranial arteries, and veins. For its importance, it is completely involved by bone. The cranium is divided into two parts: the neurocranium (comprises the bones related to the encephalon) and the viscerocranium (comprises all other cranial bones including the facial bones or facial skeleton). All the encephalon and spinal cord (thus, the CNS) are covered by three membranes: (1) the dura mater, located and attached to the inner surface of the

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neurocranium; (2) the arachnoid membrane, which lies between the dura mater and the pia mater. It has a trabeculated aspect; it contains the cerebrospinal fluid (CSF) that circulates around the CNS, being produced at the choroid plexus of the ventricles, and it is absorbed by the arachnoid villi, along the superior sagittal sinus (“Pacchioni” villi). The intracranial arteries run in the subarachnoid space; (3) pia mater: a very thin membrane underneath the arachnoid and adherent to the surface of the CNS. It shapes the gyri and the sulci. The cerebral veins run attached to the pia mater, although they may cross the surface of two of more gyri. So, as for intracranial vessels, arteries and veins are located inside different anatomical compartments, or spaces, the subarachnoid space and the pia mater, respectively. The brain is the largest part of the central nervous system (CNS). It is comprised of the right and the left hemispheres, including the cerebral cortex, the underlying white matter, the deep white matter, the basal ganglia, and the ventricular system. The corpus callosum unites the right and the left hemispheres. The brain, the midbrain, the lateral and third ventricles, and the first and second cranial nerves (optic and olfactory nerves, respectively) are located in the supratentorial space, above the tentorium, and lie in relationship with the cranial vault. The cerebellum, the brainstem, the cranial nerves III to XII, the mesencephalic aqueduct, and the fourth ventricles are located in the infratentorial space, a much smaller space than the supratentorial space, and lie in close relationship with the posterior aspect of the temporal and occipital bones. These structures are mentioned to belong to the posterior cranial fossa. Its clinical importance relies on the fact that the infratentorial space, or the posterior cranial fossa, is more vulnerable to mass effect lesions, and if it occurs, the brainstem may be damaged, eventually leading the patient to death. The encephalon communicates with the cord at the most inferior aspect of the occipital bone, where a large bony opening, the foramen magnum, divides the inferior part of the medulla oblongata from the uppermost aspect of the cervical cord.

Morphological Aspects of the Encephalon or Telencephalon The Brain The cerebral hemispheres will be referred to as the brain. The brain has six lobes according to Ribas. This division is in accordance with the Terminologia Anatomica, as established in 1989. It is divided into frontal, temporal, parietal, occipital, insular, and limbic lobes. For the sake of simplification, the central lobe will be included in the convexity of the frontal and parietal lobes, respectively. The reader has referred to the work of Ribas and Frigeri who have described the anatomy of the central lobe, but this is rather more of a functional division of the brain than a morphological one. For the same reason, the limbic lobe will be included in the other lobes, since the limbic lobe correlates with the limbic system; however, the limbic system extends far beyond the limits of the limbic lobe. The limbic system is a complex matter that deserves special attention elsewhere. When looking at the lateral surface of the brain, one can observe the frontal lobe, the parietal lobe, the temporal lobe, and the occipital lobe. The recognition of the two most important morphological accidents, the identification of the lateral sulcus

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and the central sulcus, is key to understanding how to identify the other sulci and gyri. The lateral sulcus is present in the embryo at week 17, and the central sulcus is present at week 21. They are the earliest sulci that become apparent in the lateral surface of the brain, and they induce the formation of the adjacent sulci and gyri. The lateral sulcus runs anteroposterior and separates the frontal and temporal lobes, above it and below it, respectively. Furthermore, the lateral sulcus is always continuous. The direction of the sulci and the gyri in the frontal and the temporal lobe is grossly horizontal, from anterior to posterior. For a complete study of the human brain’s sulci patterns, we refer the reader to the book by Ono, Kubik, and Abernathey. The intraoperative recognition of all brain sulci and gyri is impossible, but their main morphology patterns are mandatory.

 he Frontal Lobe T Lateral surface: the frontal lobe has three gyri and two sulci that tend to run horizontally in an antero-posterior direction. There is, however, a change in the direction of the gyri and sulci as we proceed posteriorly. They tend to be more vertically oriented (Fig.  1.2). Indeed, the superior frontal gyrus ends at a point where it causes an impression on the precentral sulcus, causing a posterior curve on the precentral sulcus and the precentral gyrus. The middle frontal sulcus always communicates (via a bridging gyri) with the precentral gyrus, thus interrupting the precentral gyrus. By definition, the precentral sulcus is interrupted in 100% of times (arrowhead Fig. 1.2). This is an important information because the precentral sulcus, the precentral gyrus, the central sulcus, the postcentral gyrus, the postcentral sulcus, and the postcentral gyrus have a somewhat similar morphology. Between the precentral sulcus and the central sulcus lies the precentral gyrus, an eloquent area that is responsible for

Fig. 1.2  Lateral surface of the brain. The frontal lobe is limited by the central sulcus (yellow paper), by the superomedial margin of the brain, by the anterior infero-lateral margin (black arch), and by the lateral sulcus. Notice the horizontal direction of the frontal and the temporal sulci and gyri. The middle frontal sulcus always interrupts the precentral gyrus. Note: F1 – superior frontal gyrus; 1 – superior frontal sulcus; F2 – middle frontal gyrus; 2 – inferior frontal sulcus; F3 – inferior frontal gyrus; T1 – superior temporal gyrus; 3 – superior temporal sulcus; T2 – middle temporal gyrus; 4 – inferior temporal sulcus; T3 – inferior temporal gyrus; : communication between middle frontal; gyrus and precentral gyrus; ★: precentral gyrus; Yellow paper: central sulcus; ●: postcentral sulcus

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contralateral body movement (initiation of conscious movement; Brodmann area 4). Although the morphology of the precentral sulcus and the central sulcus is similar, they can be safely differentiated by the following tips: 1 . The precentral sulcus is interrupted in 100% of the cases. 2. The central sulcus is continuous in almost 100% of the cases (92%). 3. The central sulcus almost never reaches the lateral sulcus inferiorly, and it ends at an inferior frontoparietal gyrus (Rolando’s). The base of the frontal lobe corresponds to an area that overlies the optic plates of the frontal bones. It has a superiorly directed convexity, and it has two sulci and five gyri. The orbital sulcus is an “H”-shaped sulcus and limits four gyri: the anterior orbital gyrus, the posterior orbital gyrus, the lateral orbital gyrus, and the medial orbital gyrus. The gyrus rectus locates between the olfactory sulci (covered by the olfactory tract) (Fig. 1.3). On the medial surface: the frontal lobe has its representation at the medial surface of the brain as well. It extends from the gyrus rectus, in the floor or the interhemispheric fissure, to an area below the rostrum of the corpus callosum, anteriorly and superiorly toward the superomedial border, and then, posteriorly, outside the cingulate gyrus (Fig. 1.4). The frontal lobe is the largest lobe, both from the lateral and the medial surface of the brain. The superior frontal gyrus extends medially, in the superomedial border, and will remain the superior frontal gyrus in the medial surface of the brain. On the medial aspect of the frontal lobes, a central lobe is present, and it encompasses

Fig. 1.3  The basal view of the right frontal lobe: the base of the frontal lobe sits on the orbital plate of the frontal lobe. It has the frontal sulcus with an “H” morphology. It limits the lateral frontal gyrus, the medial frontal gyrus, the anterior frontal gyrus, and the posterior frontal gyrus. The olfactory sulcus divides the medial frontal sulcus from the gyrus rectus. Its view is partially obstructed by the olfactory tract. ●: orbital sulcus; LOG: lateral orbital girus; MOS: medial orbital gyrus; AOS: anterior orbital gyrus; POS: posterior orbital gyrus; T, olfactory tract; GR, gyrus rectus; TP, temporal pole

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Fig. 1.4  The medial aspect of the hemisphere is exposed. The corpus callosum has an inverted “c” shape, as does the sulcus of the corpus callosum, the cingulate gyrus, and the cingulate sulcus. Even the superior frontal sulcus presents a similar display. Notice that the marginal ramus of the cingulate gyrus describes a small notch pointing forward to the central sulcus, highlighted by the yellow markings. The paracentral lobule lies within the paracentral and the marginal ramus of the cingulate gyrus, related to the splenium and the body of the corpus callosum, respectively. CC corpus callosum: 1 – rostrum, 2 – genu, 3 – body, 4 – splenium; ● – sulcus of the corpus callosum; CG – cingulate gyrus; ★ – cingulate sulcus; arrowheads – paracentral ramus of the cingulate sulcus; green paper – marginal ramus of cingulate gyrus; SFS – superior frontal sulcus

the sensory and motor areas (Brodmann areas 4 and 5 and 1, 2, and 3). This lobe is located between two rami of the cingulate gyrus. The corpus callosum, the floor of the interhemispheric fissure, has an inverted “C-shaped” morphology that determines the morphology of the sulci and the gyri on the medial surface. The corpus callosum has a rostrum, a knee, a body, and a splenium. The cingulate gyrus encircles the corpus callosum, and it is located between the callosal sulcus and the cingulate sulcus. The callosal sulcus is continuous in 100% of the times. The cingulate gyrus branches off into various rami, two of which must be identified. The first is the marginal ramus of the cingulate gyrus, which reaches the superomedial border of the hemisphere and causes an impression directed anteriorly. Its importance relies on the fact that it points to the central sulcus located anterior to its impression on the superomedial margin of the hemisphere. To identify with certainty, the ending of this sulcus is in line with the splenium of the corpus callosum. On the other hand, the paracentral sulcus arises in the midportion of the body of the corpus callosum. The central lobule on the medial surface contains motor and sensorial cortex, and it is limited anteriorly by the paracentral sulcus, posteriorly by the marginal ramus of the cingulate sulcus, and inferiorly by the cingulate sulcus (Fig. 1.4). The cingulate gyrus ends as the isthmus of the cingulum, just below the splenium of the corpus callosum. Posterior to the isthmus, the anterior portion of the parieto-­occipital sulcus may be identified, and as an anterior continuation of the “cingulate belt,” the parahippocampal gyrus arises. The anterior most aspect of the lateral ventricles, the frontal horns, and the anterior part of the body of the lateral ventricles lies deep in relation to the frontal lobe, and it is separated from its counterpart by the septum pellucidum.

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The frontal lobe is extremely important for planning and executing contralateral movements. It is, indeed, considered a “motor” lobe, since it can be divided into a primary motor area (the precentral gyrus), the premotor area (the cortex located immediately anterior to the primary motor area), and the supplementary motor area (cortical areas located in the medial surface of the hemisphere, immediately anterior to the primary motor cortex). The conscious movement is initiated at the motor cortex, but they have to be planned. The premotor area (Brodmann 6) is responsible for planning and executing movements, especially its sequence. The prefrontal area (Brodmann 6, 8 and 9–12, 32, 45, 47) is located in the medial surface of the hemisphere, and it is an important association area, and one of its functions is the so-­ called executive function, which means the ability to practice and monitor a series of actions in order to achieve a certain goal. It is related to planning and organization, as well as motivation. It is also related to personality flexibility, problem solving and rewarding. Another important function of the prefrontal area refers to the frontal ocular fields, located in the middle frontal gyrus (area 6). It controls movement of the eyes toward the contralateral side. Extensive lesions to this area cause the eyes to deviate to the same side of the lesion. Epilepsy causes the opposite effect. The anterior portion of the inferior frontal gyrus on the left side is also particularly important (mainly the pars triangularis and the pars opercularis), since it represents the cortical area responsible for uttering words (the so-called Broca’s area; areas 44 and 45) (Fig. 1.5). Almost as a rule, with a few exceptions, the left

Fig. 1.5  Lateral view of the left hemisphere. The lateral or Sylvian fissure has three main rami; a posterior, which usually ends in a bifurcation; a superior; and an anterior. The superior and the anterior rami divide the inferior frontal gyrus into an orbital part, a triangular part, and an opercular part. The triangular and the opercular portions are responsible for the expression of words and naming objects, the so-called Broca’s area, on the left side. The center for perceiving language is located in the left posterior temporal lobe, on the left side (Wernicke’s area). Red sphere – stem of the lateral fissure; Yellow line – superior ramus of lateral fissure; White line – anterior ramus of lateral fissure; Dotted red line – bifurcation of posterior ramus of lateral fissure; Black circle – Broca’s area; Green line – Wernicke’s area; 1 – pars orbitalis; 2 – pars triangularis; 4 – pars opercularis; 41 and 42 – primary auditory cortex

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hemisphere is responsible for most language and communication processes, both for right-handed individuals and for left-handed ones. Rarely, lesion to the right anterior inferior frontal gyrus may cause dysphasia. Extensive lesions to the frontal lobes may cause major behavioral changes. It may cause humor instability, compulsive crying, laughter, or fury. There may be irritability and euphoria, along with lack of initiative and spontaneity. There is also apathy, indifference, and decreased spontaneous speech and social interaction.

The Temporal Lobe Lateral surface: the temporal lobe has two sulci and three gyri (Fig. 1.3). Its tip dives into the temporal fossa on the middle fossa floor. The superior temporal gyrus lies between the lateral sulcus and the superior temporal sulcus. The inferior temporal gyrus lies below the inferior temporal sulcus, and it turns medially to continue as the inferior temporal sulcus in the basal surface of the brain. These gyri and sulci extend posteriorly and it limits posteriorly to the lateral temporoparietal line, an artificial line drawn from the preoccipital notch, in the infero-lateral border of the hemisphere, to the impression of the parieto-occipital sulcus (well seen in the medial surface) in the superomedial border of the hemisphere. Basal surface: the temporal lobe has a large representation on the basal surface of the brain. When viewed from below, the inferior temporal gyrus is the most lateral structure, until it meets the occipitotemporal sulcus. The occipitotemporal gyrus lies between the occipitotemporal sulcus and the collateral sulcus (this gyrus is also known as the fusiform gyrus). Medial to the collateral sulcus, the parahippocampal gyrus is found, and it folds over itself anteriorly to form the uncus and extends posteriorly until the isthmus of the cingulate gyrus, below the splenium of the corpus callosum (Fig. 1.6). All these sulci and gyri are separated from the occipital lobe by the basal temporoparietal line that unites the preoccipital notch to the impression of the parieto-occipital sulcus as seen from an inferior perspective. Medial surface: the temporal lobe is represented by the parahippocampal gyrus and the uncus anteriorly. The uncus has a triangular shape with its apex directed medially, toward the anterior part of the midbrain (Fig. 1.6). The hippocampus lies in the uncus, and the amygdaloid nucleus is located just above the hippocampus. The uncus separates itself from the lateral and basal temporal lobe by the rhinal sulcus. An anterior, inferior, and lateral extension of the ventricular system, the temporal horn, lies within the temporal lobe. The temporal lobe has important wholes in an array of mental functions. The primary auditory cortex (areas 41 and 42) is located in the superior temporal lobe, precisely at the anterior temporal transverse gyrus (Heschl’s) (Fig. 1.6). Although hearing has bilateral representation, some degree of differentiation and sound discrimination may be observed in unilateral lesions. Stimulus to peri-cortical areas may elicit hearing, visual, and olfactory hallucinations. Particularly important for musicians, temporal lobe lesions may affect the ability to perceive music pace and rhythm. The temporal lobe has a cavity that is an anterior extension of the atrium of the lateral ventricles. Surrounding the anterior part of the temporal horn, the Meyer’s loop (a bundle of visual fibers from the corpus callosum that turns anterolateral,

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Fig. 1.6  The basal and medial temporal lobes are illustrated. At the base of the brain, the temporal lobe has the major representation among all lobes. Notice that the parietal lobe doesn’t have any representation. The sulci and gyri are disposed as follows, from lateral to medial: Inferior temporal gyrus, Occipitotemporal sulcus, Occipitotemporal or fusiform gyrus, Collateral sulcus, Uncus (triangular shape), Parahippocampal gyrus

anterior to the ventricular cavity, toward the lateral wall of the temporal horn; it arises at the lateral geniculate body in route to the calcarine sulcus) is found, and limiting the temporal horn laterally lies the inferior fibers of the geniculocalcarine tract. Lesion to these fibers may cause a visual deficit located in the contralateral superior external visual field. The hippocampus is also located at the uncus of the temporal lobe and is responsible for learning and memory (areas 26, 27, and 28). Acute lesion to the dominant hippocampus may cause severe memory deficits, including retention of any new information and loss of acquired memory. Memento, 2000, starring Guy Pearce, is an interesting and striking movie depicting the clinical picture of anterograde memory loss. The posterior and superior temporal lobe bears the cortical area that interprets words, especially on the left side, and whose lesion may cause a severe neurological deficit called sensory dysphasia (areas 42 and 22). The patient is unable to discriminate words, as if he hears a completely different language, with its consequent lack of meaning and understanding of spoken words (Wernicke’s area) (Fig. 1.5). One of the most impressive experimental findings ever, as far as behavior is concerned, the Klüver-Bucy syndrome, has been found in monkeys submitted to bilateral temporal lobe resection. Its full developed symptoms and signs are rare in humans. The syndrome is characterized by apathy, hypersexuality, tendency to recognize objects by putting them in the mouth, memory loss, bulimia, and visual agnosia. Interestingly, Hreniuc reported on a case of a 71-year-old man who had an

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ischemic stroke on the right side and developed a Klüver-Bucy-like syndrome. The amygdala, the hippocampus, and the medial temporal lobe play an important whole in the limbic system, thus in behavior and emotions. Neurobehavioral research is underway to try to elucidate the limbic system circuitry and its clinical manifestations of how emotions and behavior manifest in a normal and abnormal range of mental status.

 he Parietal Lobe T The parietal lobe is located posterior to the frontal lobe, superior to the temporal lobe, and anterior to the occipital lobe. Its limits are superiorly the superomedial border of the hemisphere, anteriorly the central sulcus, inferiorly the temporo-­ occipital line, and posteriorly the lateral temporoparietal line that limits the occipital lobe located posteriorly (Fig. 1.7). The parietal lobe has the following features: –– It has the primary sensory cortex (the postcentral gyrus, areas 1, 2, and 3), where various sensory stimuli are processed and become conscious. –– It is divided into two parietal lobules, superior and inferior, respectively, in relation to the intraparietal sulcus. The inferior intraparietal sulcus encompasses the supramarginal and the angular gyri. They correspond externally to the most prominent part of the parietal bone: the parietal prominence. Both the superior and the inferior parietal lobules are association cortical areas.

Fig. 1.7  The parietal lobe: the parietal lobe is located above the temporal lobe and anterior to the occipital lobe (dashed black lines). It is divided into a superior and inferior parietal lobules, by the intraparietal sulcus, an arched sulcus (arched curved black line) that tend to meet the postcentral sulcus (straight red line). The inferior parietal lobule is an eloquent area and is formed by two gyri. The first, the supramarginal gyrus (rounded red dashed area, approximately), is located by identifying and following the superior temporal sulcus (arrows). The angular gyrus is located by following the superior temporal sulcus that tends to bifurcate or trifurcate. The angular gyrus (rounded dashed yellow area, approximately) has an inverted “m” shape or a “ʊ” shape. SupmG – supramarginal gyrus; AG – angular gyrus

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The postcentral gyrus is limited anteriorly by the central sulcus and posteriorly by the postcentral sulcus. The intraparietal sulcus initiates at the intraparietal point, located 7.0  cm anterior to the lambda and 5.0  cm off the midline, usually at the midpoint of the postcentral sulcus, and may be continuous posteriorly as the intraparietal sulcus, or it may have a separate origin. The supramarginal gyrus (area 40) and the angular gyrus (area 41) may have different morphologies, but its identification is relatively simple. The supramarginal gyrus is a natural continuation of the superior temporal gyrus. It encircles the posterior part of the lateral fissure that usually ends in a superior and an inferior ramus, the first being more prominent, thus, the name supramarginal or the gyrus that follows the ending, especially superiorly, of the lateral sulcus. The angular gyrus is found by following the superior temporal sulcus. It ends at the inferior parietal lobule as a bifurcation or as a trifurcation. Thus, the angular gyrus has an omega shape, or an “M-letter” shape, clearly different from the supramarginal gyrus (Fig. 1.7). The intraparietal sulcus is arched superiorly, and posteriorly, it usually ends at the occipital lobe. The inferior parietal lobule is usually larger than the superior (Fig. 1.7). There is no representation of the parietal lobe at the base of the brain. On the medial surface of the brain, the parietal lobe is represented mainly by a quadrangular lobe called the precuneus. Its superior limit is the superomedial margin of the hemisphere; anteriorly, by the marginal ramus of the cingulate gyrus; posteriorly by the parieto-occipital sulcus; and inferiorly, by the cingulate gyrus. It usually has a sulcus, the subparietal sulcus, an “H-like” sulcus that does not divide the precuneus into other sulci and gyri. Just anterior to the marginal ramus of the cingulate sulcus, an impression of the central sulcus directed posteriorly is seen. Between these sulci, the postcentral gyrus is located (Fig. 1.8). The parietal lobes are primarily association lobes. They locate close to occipital and the posterior temporal lobe. They also receive important input from the thalamus. The main functions of the parietal lobes are sensory reception, correlation, analysis, synthesis, integration, interpretation, and elaboration of primary sensory impulses from the thalamus. The clinical compromise to the left parietal lobule may cause the so-called Gerstmann’s syndrome: (1) acalculia; (2) agraphia; (3) digital agnosia, or the difficulty to name the fingers of the hand; and (4) disorientations to right and left sides. On the right hemisphere, an inferior parietal lobule lesion may cause various forms and intensities of apraxia, hemineglect, and anosognosia, or failure to recognize deficits or limiting condition. Usually, patients do not recognize contralateral paralysis. This condition may be accompanied by asomatognosia, a form of hemineglect in which patients deny ownership to their limbs.

 he Occipital Lobes T The occipital lobes are located posterior to the parietal and the temporal lobes. They have a somewhat pyramidal shape with its apex forming the occipital pole. The

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Fig. 1.8  Representation of the parietal lobe in the medial brain surface (precuneus). The precuneus is limited by the marginal ramus of the cingulate gyrus anteriorly, the cingulate sulcus inferiorly, and the parieto-occipital sulcus posteriorly. Its superior limit is the superior-medial border of the hemisphere. Just posterior and inferior to the precuneus lies the cuneus, an edged shaped region of the medial part of the occipital lobe. Its main structure is the calcarine sulcus, where the primary visual cortex is located (Brodmann 17)

occipital lobe is basically related to vision. We herein present the different surfaces of the occipital lobe with emphasis on its medial surface, where the visual area is located (Fig. 1.8). The nuances of the occipital lobe sulci and gyri in the convexity are well discussed elsewhere. On the lateral surface of the brain, the occipital lobe extends from the preoccipital notch to the tip of the occipital pole, in the infero-lateral surface of the brain. Its superior limit is the impression of the parieto-occipital sulcus on the lateral surface. The anterior limit is the artificial line that extends from the preoccipital notch to the impression of the parieto-occipital notch, the lateral temporoparietal line. Another artificial line, drawn in the basal or inferior surface of the occipital lobe, extends from the very same anatomic landmarks as aforementioned, separating the occipital lobe from the anteriorly located temporal lobe (Fig. 1.7). This arbitrary division is the basal temporoparietal line. The occipital lobe sits on the tentorium, a dural fold that demarcates the supra and infra, or the anterior and middle, from the posterior cranial fossa, respectively. On the medial surface, the occipital lobe has an edged-­like morphology that is called the cuneus. The cuneus extends from the parieto-­occipital sulcus anteriorly and superiorly to the calcarine sulcus posteriorly and inferiorly (Fig. 1.8). These are deep sulci, and the primary visual area rests on the lips of the calcarine sulcus (Brodmann 17). The inferior lip of the calcarine sulcus is the lingual gyrus (or the lingula) that extends anteriorly, below the

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splenium and isthmus of the cingulate gyrus to continue anteriorly and medially as the parahippocampal gyrus. Important to notice is the fact that there is no visual representation on the anterior aspect of the parieto-occipital sulcus; however, when the parieto-occipital sulcus meets the calcarine sulcus, the primary visual cortex is present. The calcarine sulcus is a deep sulcus, and as so, it causes a morphological accident in the medial wall of the ventricular atrium, the calcar avis. There may be a variable posterior extension of the ventricular system that, when present inside the occipital lobe, is called the occipital horn of the ventricle. The variable occipital horn is devoid of choroid plexus. Another interesting feature of the occipital lobe is the fact that it doesn’t drain venous blood into the superior sagittal sinus. Rather, it drains to the tentorium inferiorly, medially toward the vein of Galen, via the medial occipital vein, and toward the junction of the transverse and sigmoid sinus, in the so-called vein of Labbè, or the inferior anastomotic vein, that unites the superficial Sylvian vein to the dural sinuses. The occipital lobes are primarily related to vision. Fibers originating in both retinas reach the calcarine sulcus, on both sides. The primary visual area, or Brodmann area 17, sits on the superior and inferior lips of the calcarine sulcus and at its depths as well. This represents a very particular area called the striate cortex. There is a thin granular cortex with its fourth cortical layer relatively thick. It represents the external prominent band of Baillarger (Gennari line or striae that may be visible with the naked eyes). The striate cortex is able to distinguish colors, shapes, motion, and illumination. The parastriate region and the peristriate areas (Brodmann 18 and 19, respectively) are responsible for the visual association area, vital to object recognition and identification. Lesion to the striate area and peristriate area may result in different degrees of visual damage (visual field amputation) or cortical blindness (the patient cannot process conscious input from the retinas nor distinguish an object). However, patients with cortical blindness may prevent themselves from dangerous situations and somehow identify obstacles when they ambulate. Various studies on the subcortical visual pathways are currently underway.

 he Insular Lobes T The insula, or Island of Reil (Johann C. Reil, German anatomist 1759–1813, has first called the insula as Reil’s fingers and Reil’s Islands), may be considered an atypical lobe, either by its morphology, consisting of only one layer of mesocortex, or by its function, yet widely discussed. It has been included in the current official international anatomical nomenclature in 1998, during the publication of the Terminologia Anatomica. The insular lobe represents 2% of the human cortex, and it is entirely hidden in the depths of the lateral fissure. Its view is hampered by the frontal and temporal opercula, respectively. It has a grossly inverted pyramidal shape, and it is surrounded by a limiting sulcus (divided into the superior limiting sulcus, anterior limiting sulcus, and the inferior limiting sulcus). It is further divided by the insular central sulcus, into an anterior insular lobe and a posterior insular lobe. The anterior insular lobe is composed of a variable number of anterior short insular sulci and gyri

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Fig. 1.9  The insular lobe. The frontoparietal and the temporal opercula have been removed to expose the insula. It is surrounded by the anterior (black continuous line), by the superior (red dotted line), and the inferior limiting sulcus of the insula (★). The insula is divided by a central sulcus of the insula (●). The central sulcus of the insula has a morphology that “follows” inferiorly the central sulcus of the brain. The anterior insular lobe (AIL) has its short sulci and gyri, and the posterior insular lobe (PIL) usually has one sulcus and two gyri. The inferior limiting sulcus has been opened to show the temporal horn of the lateral ventricle. The head of the hippocampus and the choroid plexus can be seen. The M1 and the M2 segments of the middle cerebral artery overlie the insular cortex

(usually 3–5 gyri). The posterior insular lobe has two or three long insular gyri and usually two insular sulci. Interestingly, the insular central sulcus follows the same inferior, as like if it was an inferior continuation of the central sulcus of the hemisphere (Fig. 1.9). Inferiorly, it has an apex, a prominent lateral bulge that coincides with the fusion, or the origin of the short insular gyri. Inferior and medial to the apex, the limen insula is a convex structure located lateral to the anterior perforated substance, medial to the deep Sylvian fissure, superior to the rhinal sulcus, and anterior and superior part of the uncus. The uncinate fasciculus lies deep to the limen insula. The interested reader is referred to the paper by Ribas. The insula is the lateral limit of the basal ganglia. Its insular limiting sulcus, if opened, gives access to the lateral ventricles: the junction of the anterior and superior limiting sulcus points to the frontal horn of the ventricle; the junction of the superior and inferior sulcus points to the ventricular atrium. The opening of the inferior limiting sulcus exposes the temporal horn of the ventricle. The middle cerebral artery runs in the surface of the insula, and its rami draw the anterior, superior, and posterior portions of the basal ganglia, in the so-called Sylvian triangle. This is useful when evaluating vascular lesions and defining if it lies in the basal ganglia or outside it. From lateral to medial, the structures found in the basal ganglia are the insular cortex, the extreme capsule, the claustrum, the external capsule, the lentiform nucleus, the internal capsule, the head of the caudate nucleus anteriorly, and the thalamus posteriorly.

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As for the insular functions, numerous integrative wholes may the related to the insula, such as speech production, pain perception, and processing of social emotions. Other possible insular functions, as well as the detailed histological architecture of the insular cortex, are well discussed in a review by Nieuwenhuys. Pathologies involving the insula are usually ischemic strokes and low-grade gliomas. As for the insular gliomas the typical clinical presentation is epilepsy that usually resolves with proper tumor resection.

 he Limbic Lobe T The limbic lobe, as described by Broca (Paul Broca, 1824–1880, French anatomist, surgeon, and anthropologist), has a “C” shape, as seen on the medial surface of the hemispheres, and it does not represent all the structures currently known as the limbic system. The limbic system is a far more complex structure or “concept” that involves feelings and behavior and includes other subcortical areas. It is composed of the paraterminal gyrus and the subcallosal area (Brodmann 25), below the rostrum of the corpus callosum, the cingulate gyrus, the parahippocampal gyrus, the dentate gyrus, the subiculum on the parahippocampal gyrus, and the hippocampus. The cingulate gyrus is described in item 1.1.

The Diencephalon The diencephalon lies deep and inferior in relation to the cerebral hemispheres. It has a cavity corresponding to the third ventricle. The lateral ventricles communicate with the third ventricle through the interventricular foramina, or foramen of Monro, and with the fourth ventricle via the mesencephalic aqueduct. Its anterior limit is called the lamina terminalis, the superior limit is the fornix, the posterior limit is the pineal gland (epithalamus), and the inferior limit is the floor of the third ventricle, with the supraoptic recess (related to optic chiasm), the infundibular recess (related to the hypophyseal infundibulum), the tuber cinereum, and the mammillary bodies. The anterior part of the posterior perforated substance is also related to the floor of the third ventricle. The lateral limits of the third ventricle are the two most important components of the diencephalon: the thalamus and the hypothalamus. The hypothalamic sulcus, which extends from the foramen of Monro to the mesencephalic aqueduct, separates the thalamus above it, from the hypothalamus below it. The hypothalamus is a small area that bears various nuclei and has a number of neural connections with the midbrain, the limbic system, and the cerebellum. It controls all the endocrine functions, and it regulates the anterior hypophysis via the porto-­ hypothalamic vascular system. It is believed to play a major whole in the limbic system. The thalamus is an ovoid mass of gray matter that plays a major whole in receiving sensory information from the body and activating a large area of the cerebral cortex. Some sensory information becomes conscious, while others are processed in the thalamus and remain in the subcortical level.

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The Basal Nuclei The basal nuclei are masses of gray matter located inside the subcortical white matter. They are disposed around the lateral ventricles (Figs.  1.10 and 1.11). These nuclei are the caudate nucleus, lentiform (putamen and globus pallidus), claustrum, amygdaloid body, subthalamic nucleus, and the olfactory tuberculum. The caudate and the lentiform nucleus form the striatum. The basal nuclei, according to phylogenetical criteria, may be divided into neostriatum, or striatum; paleostriatum or pallidum, with the two divisions of the globus pallidus; and the archystriatum, composed of the amygdaloid nucleus. The nucleus accumbens, the olfactory tubercle, and the ventral part of the caudate and the putamen are called the ventral striatum. The basal ganglia have complex connections, and they are involved mainly in movement control. Various patterns of movement disorders are due to dysfunction of the basal nuclei, but this discussion is without the scope of this chapter. Some of these nuclei are also involved in behavior regulation, with intricate connection with the limbic system.

Fig. 1.10  The basal nuclei. This picture shows an axial cut through the left basal ganglia. The head of the caudate (1) nucleus and the thalamus (2) lies in contact with the lateral ventricles medially and the internal capsule laterally (3). The internal capsule (3) lies between the head of the caudate anteriorly and the thalamus posteriorly. Lateral to the internal capsule, a biconvex structure can be seen, the lentiform nucleus. The lentiform nucleus is the union of the globus pallidus medially and the putamen laterally (5). Lateral to the putamen, and in this sequence, the external capsule (6), the claustrum (7), the extreme capsule (8), and the insular cortex (9) are shown. The basal nuclei are an “ovoid” mass that has an anterior narrowing, the anterior isthmus, and a posterior one (dotted lines. Notice the close relationship of the basal nuclei and the lateral ventricle. The yellow area corresponds to the anterior transverse temporal gyrus, or Heschl’s gyrus, the primary cortical hearing area. The purple area corresponds to the superior lip of the calcarine sulcus, part of the primary visual area. ★ – central sulcus of the insula. The different parts of the lateral ventricles are also shown)

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Fig. 1.11  The left basal ganglia have been further dissected to show its anatomical display. The thalamus is most posterior nucleus (1). The head of the caudate nucleus lies in close relationship with the frontal horn of the lateral ventricles. The internal capsule is an extremely complex structure that surrounds the lentiform nucleus (3). The lentiform nucleus is composed of the globus pallidus and the putamen. It has five segments: (1) (★) the anterior portion; 2 ( ) the genu that has a close relationship with the interventricular foramen; (3) (●) the posterior part, between the thalamus and the lentiform nucleus. Both the genu and the posterior part contain motor fibers, and care should be taken to avoid any lesions to this area; (4) ( ) retrolenticular fibers, located posterior to the lentiform nucleus; and (5) (■) infralenticular fibers, located inferior to the lentiform nucleus. The ventricular system has been opened. The interventricular foramen has been pointed out. The atrium of the lateral ventricle (7) lies lateral to the frontal horn and the body of the lateral ventricles. It has an anterior projection, the temporal horn of the ventricles, and a variable temporal horn, almost non-existent in this specimen. The hippocampus lies within the temporal. Its head (6), its body (6′), and its tail (6″) are shown. The amygdala lies just superior to the hippocampus (5). The tail of the caudate nucleus has a connection with the head of the hippocampus

The Cerebellum The cerebellum lies within the boundaries of the posterior cranial fossa, below the tentorium. In fact, the tentorium is the superior limit of the cerebellum; its anterior limits are the brainstem and the posterior surfaces of the petrous temporal bone; and its posterior limits are the occipital bones (squama of the occipital bone). The cerebellum (or “the small brain”) has three surfaces: the superior surface that lies below the tent; the petrosal surface that lies posterior to the petrous bone; and the suboccipital surface that lies anterior to the convex occipital bone. The cerebellar sulci and gyri are thinner when compared with the brain. They are called cerebellar folia (the Latin plural of folium, or “leaf”). However, deep fissure allows for division of the cerebellum into different vermian parts or lobes, as we refer to the vermis located at midline, or to the cerebellar hemispheres, lateral to the vermis on both sides. In its superior surface (tentorial surface), the cerebellar vermis is a prominent midline structure, with the bilateral hemispheres located laterally. The vermis is divided into

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a culmen, a declive, and a folium (a portion of the vermis constituted by only one leaf). The corresponding cerebellar hemispheres are the quadrangular lobe, the simple lobe, and the superior semilunar lobe (in relation to the culmen, declive, and folium, respectively). These three lobes are separated by the primary fissure and the postclival fissure. The superior surface of the cerebellum connects with the brainstem via the superior cerebellar peduncle. A deep fissure, or cleft, the cerebello-­ mesencephalic fissure, hides the central cerebellar lobule and the wings of the central lobule. The lingula sits in the anterior aspect of the central lobule, and it is attached to the superior medullary vellum, the superior limit of the roof of the fourth ventricle. For meticulous dissections of the cerebellum and the posterior fossa, the interested reader is referred to the work of Rhoton. In the suboccipital surface, and for embryological reasons, the vermis seems retracted from the cerebellar hemispheres. The parts of the vermis in this surface are the tuber, the pyramid, and the uvula. The corresponding cerebellar hemispheres, in this order, are the inferior semilunar lobule, the semilunar lobule, and the biventral lobule. They are separated from each other, from superior to inferior, by the prepyramidal fissure, and by the prebiventral fissure. The paired tonsils are the most inferior part of the cerebellum, and they lie lateral to the pyramid. On its medial surface, the foramen of Magendie (the inferior opening of the fourth ventricle) opens into the cisterna magna. Between the tonsils and a small part of the biventral lobule, a deep fissure of cleft extends upward, and when exposed, it shows the opening of the fourth ventricle, the tela choroidea (the tela and the choroid plexus of the fourth ventricle), the inferior cerebellar peduncle, and the inferior medullary vellum (the inferior limit of the roof of the fourth ventricle. This deep cleft is called the cerebello-­ medullary fissure, a space that is frequently explored by neurosurgeons. The third surface is called the petrosal surface since it sits posterior to the petrous bone. A relatively shallow cleft is observed, the so-called cerebello-pontine fissure, which tends to hide the middle cerebellar peduncle. The corresponding parts of the tentorial and the suboccipital parts of the cerebellum are represented in the superior and the inferior lips of this fissure, respectively. The middle cerebellar peduncle is a natural continuation of the pons, but anatomically, it separated itself from the pons, by a line that extends from the emergency of the fifth cranial to the seventh cranial nerves in the ventral aspect of the brainstem (see Fig. 1.12). Bonstan provides an overview of the neural circuitry connecting the cerebellum, the basal ganglia, and the cerebral cortex.

The Brainstem The brainstem is an exquisite complex area that sits on the anterior part of the posterior cranial fossa. It is a compact structure where numerous nuclei are located and different fiber tracts go up, and down, or cross from one side to the other. It has also regions of somewhat scattered and some compact neurons extending throughout the brainstem, the so-called reticular substance, which cannot be precisely located. The brainstem consists of the midbrain, the pons, and the medulla oblongata (Fig. 1.12).

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Fig. 1.12  An overview of the brainstem and the cerebellum. Anterior view  – the brainstem is divided into the mesencephalon, the pons, and the medulla. All cranial nerves exit the brainstem except for the optic and the olfactory nerves. III – oculomotor nerve; IV – trochlear nerve; V – trigeminal nerve; VI – abducens nerve; VII and VIII – vestibulocochlear nerve; IX, X, and XI – glossopharyngeal, vagus, and spinal accessory nerves; XII  – hypoglossal nerve; MCP  – middle cerebellar peduncle

The upper midbrain has three parts: the tectum is located posterior to the mesencephalic aqueduct and composed of the superior and inferior colliculus; the tegmentum lies ventral to the aqueduct that connects the third to the fourth ventricles and bears various nuclei, the most important are the red nucleus, the substantia nigra, and the nuclei of the trochlear and the oculomotor nerves, the fourth and third cranial nerves, respectively. The paired trochlear nerve leaves the midbrain just off the midline, below the inferior colliculus. It is the only cranial nerve that arises at the posterior surface of the brainstem. The ventral tegmentum corresponds to the cerebral peduncles or the crura cerebri. The oculomotor nerve leaves the anterior brainstem in the medial mesencephalic sulcus, below the posterior perforated substance. The loss of neurons in the pars compacta of the substantia nigra causes Parkinson’s disease. The midbrain connects itself to the cerebellum via the superior cerebellar peduncle. The pons is located inferior to the midbrain (Fig. 1.12). It has an anterior bulging and it is opened posteriorly, corresponding to the cavity of the fourth ventricle. The pons carries fibers from the encephalon to the cerebellum and has a wide connection to the thalamus. The fifth cranial nerve arises from the anterolateral and superior part of the pons, just medial to the middle cerebellar peduncle. Posteriorly, in the floor of the fourth ventricle, fibers of the seventh cranial nerve loop around the abducens nerve nucleus, causing the so-called facial colliculus in the floor of the fourth ventricle. The abducens nerve (sixth cranial nerve) leaves the brainstem usually 2–3 mm off midline at the pontomedullary sulcus, which separates the pons and the medulla. The vestibulocochlear nerve (seventh cranial nerve) leaves the sulcus in its most lateral aspect, just above the cerebellar flocculus. This anatomical relationship has important topographical orientation to the neurosurgeon. The pons connects itself to the cerebellum via the middle cerebellar peduncle (Fig. 1.12).

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The medulla oblongata is the lower and the smallest part of the brainstem. It has a ventral part and opens posteriorly into the fourth ventricle. On its anterior surface, the medulla oblongata has a median longitudinal fissure. Lateral to this sulcus lies both pyramids, a place where the corticospinal tract descends. Lateral to the pyramids, the anterolateral sulcus is anterior to an “olive-like” prominence, the olives. The retro-olivary area lies between the anterior and the posterolateral medullary sulcus. The glossopharyngeal nerve (ninth cranial nerve) arises at the junction of the pontomedullary sulcus and the posterolateral medullary sulcus. It lies just below the flocculus and anterior to the choroid plexus of the fourth ventricle. It points to the opening of the foramen of Luschka or the lateral openings of the fourth ventricle (Fig.  1.12). The tenth cranial nerve (the vagus nerve) arises in the posterolateral medullary sulcus, below the ninth. The accessory part of the spinal accessory nerve (eleventh nerve) arises just below the tenth cranial nerve. The hypoglossal nerve arises at the anterolateral medullary sulcus, just lateral to the pyramids, and medial to the olives. The lower part of the fourth ventricle is located below the stria medullaris. Below the stria, some triangular areas may be identified on both sides of the dorsal median sulcus. From superior to inferior there are the vestibular area, the hypoglossal trigone, and the vagus trigone. The obex locates just where the gracile and cuneate fascicles separate as the gracile and cuneate tubercles, respectively. The obex is the posterior wall of the median opening of the fourth ventricle or the foramen of Magendie. A more detailed description of the cranial nerves and its functions is provided in Chap. 3 (The Basic Neurological Examination).

Vascularization The arterial blood supply to the encephalon comes from both internal carotid arteries (ICA) and from both vertebral arteries. The internal carotid arteries arise in the neck, as the common carotid bifurcates into the ICA and the external carotid artery. The ICA does not branch off in the neck. Inside the cranial cavity, the ICA branches into the ophthalmic artery, the posterior communicating artery, and the anterior choroidal artery and bifurcates below the anterior perforated substance, into the anterior end middle cerebral arteries. The anterior cerebral arteries irrigate the anterior two-­ thirds of the medial surface of the brain. The middle cerebral artery irrigates two-­ thirds of the cerebral hemispheres, and occlusion of the main trunk of the middle cerebral artery may cause the so-called malignant infarction that may require a wide decompressive craniectomy, as a lifesaving procedure. There are, however, numerous anastomoses between the internal and the external carotid arteries. The vertebral arteries ascend in the neck inside the foramen transversarium of the first six cervical vertebrae. Inside the cranium, they join at the pons, to form the basilar artery. Before joining in the basilar artery, the vertebral artery gives off the posterior inferior cerebellar artery, to irrigate the suboccipital surface of the cerebellum. The first branch of the basilar artery is the anterior inferior cerebellar artery, which irrigates the petrosal surface of the cerebellum. The tentorial surface is

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irrigated by the second branch of the basilar artery, the superior cerebellar artery. The basilar artery ends up at a bifurcation where the paired posterior cerebral arteries arise. These vessels irrigate the base and the medial surface of the temporal lobe, the occipital lobe, and a part of the precuneus. The basilar artery apex and the proximal posterior cerebral arteries send perforators to the posterior perforating substance. The detailed anatomy of the anterior circulation of the brain is presented by Ferreira. At the base of the brain, the anterior right and the left arterial circulation may communicate via the anterior communicating artery, and the anterior and the posterior circulations (from the ICA and from Vertebral) may communicate through the posterior communicating artery. These communications are referred as to the Willis’ circle (the anastomotic arterial circle of the brain). As for the venous drainage, two-fifths of the brain are drained by a superficial venous system, from the cortical and subcortical areas to the dural sinuses. The remaining of the brain drains into the deep venous system, through the internal cerebral and the veins of Rosenthal. These veins, along with others, drain into the great vein of Galen and then to the straight sinus. The interested reader is referred to the detailed venous drainage of the brain, as shown by the work of Ferreira.

Suggested Readings and References 1. Gabbay DM, Thagard P, Woods J, editors. Handbook of the philosophy of science. Philosophy of psychology and cognitive science. Oxford, UK: Elsevier. p. 146–7. 2. Rhoton AL. In: The Congress of Neurological Surgeons, editor. Cranial anatomy and surgical approaches. Shaumburg: Lippincott/Willimas & Wilkins; 2003. 3. Matshushima T, Richard Lister J, Matsushima K, de Oliveira E, Timurkaynak E, Peace D, Kobayashi S. The history of Rhoton’s lab. Neurosurg Rev. 2019;42(1):73–83. https://doi. org/10.1007/s10143-017-0902-4. 4. Ludwig E, Klinger J. Atlas cerebri humani. Basel: S. Karger (German); 1956. 5. Costa Leite C, Castilho M, editors. Diffusion weighted and diffusion tensor imaging. A clinical guide. New York: Thieme Medical Publishers; 2016. 6. Moore KL. The head – Chapter 7. In: Moore KL, Dalley AF, AMR A, editors. Clinically oriented anatomy. 7th ed. Baltimore: Wolters-Kluwer/Lippincott Williams & Wilkins; 2014. p. 993–1170. 7. Ribas GC. The cerebral sulci and gyri. Neurosurg Focus. 2010;28(2):E2, 1–24. 8. Frigeri T, Paglioli E, de Oliveira E, Rhoton AL Jr. Microsurgical anatomy of the central lobe. J Neurosurg. 2015;122(3):483–98. 9. Nishikuni K, Ribas GC. Study of fetal and postnatal morphological development of the brain sulci. J Neurosurg Pediatr. 2013;11:1–11. 10. Ono M, Kubik S, Abernathey CD, editors. Atlas of the cerebral sulci. New York: Georg Thieme Verlag/Thieme Medical Publishers, Inc.; 1990. 11. Gray´s Anatomy. Nervous system. In: Williams PL, Bannister LH, Berry MM, et al., editors. Gray’s anatomy. International student edition. 38th ed. New York: Churcill Livingstone, Pearson Professional Limited; 1995. p. 901–1398. 12. De Jong-The Neurological Examination. Functions of the cerebral cortex and regional cerebral diagnosis. In: Campbell WW, editor. DeJong’s the neurological examination. 7th ed. Philadelphia: Lippincott Williams & Wilkins, a Woters Kluwer business; 2013. p. 65–74. 13. Lanska DJ. The Klüver-Bucy syndrome. Front Neurol Neurosci. 2018;41:77–89.

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14. Hreniuc NC, NeamŢu C, Sferdian MF, et  al. Clinical manifestations and morphological changes in one case with post-stroke Klüver-Bucy syndrome. Romanian J Morphol Embryol. 2017;58(2):665–9. 15. Alves RV, Ribas GC, Párraga RG, et al. The occipital lobe convexity sulci and gyri. J Neurosurg. 2012;116:1014–23. 16. Federative Committee on Anatomical Terminology. Terminologia Anatomica: International anatomical terminology. Stuttgart: Georg Thieme Verlag (Portuguese); 1989. 17. Nieuwenhuys R. The insular cortex: a review. Chapter 7. In: Elsevier, editor. Progress in brain research, vol. 195; 2012. p. 123–63. 18. Bostan AC, Dum RP, Strick PL. Functional anatomy of basal ganglia circuits with the cerebral cortex and the cerebellum. Prog Neurol Surg. 2018;33:50–61. 19. Schunke M, Schulte E, Schumacher U, editors. Prometheus LernAtlas der Anatomie. Kopf, Hals, und Neuroanatomie. Stuttgard: Georg Thieme Verlag KG. 20. Ferreira MAT, Tedeschi H, de Oliveira E, et al. Microsurgical anatomy of the anterior cerebral circulation. In: Le Roux P, Winn R, Newell DW, editors. Management of cerebral aneurysms. Philadelphia: Saunders; 2004. 21. Ferreira M. Cranial venous anatomy. In: Spetzler RF, MYS K, Nakaji P, editors. Neurovascular surgery. 2nd ed. New York: Thieme Medical Publishers; 2015. p. 71–88.

2

Basic Neuroimaging Caio Fiuza Ferreira and Marcos Marins

Imaging techniques have rapidly advanced both technologically and in availability over the last few decades, becoming essential in patient care. Computed tomography (CT) and magnetic resonance imaging (MRI) now more than ever play an important role in investigating central nervous system (CNS) anatomy and pathologies. Our goal is to guide you through the basic concepts of these imaging modalities, how to interpret common findings, and potential pitfalls.

Computed Tomography Computed tomography technology was a huge imaging cornerstone, enabling radiology from going from 2D to 3D. This became possible because CT scanners use ionizing radiation (x-rays), the same as conventional x-ray machines, but instead of producing images in a single plane, the x-ray tube revolves around the patient acquiring information from every angle. The x-rays interact with the area being studied, and the results are stored in the detector. This information is then digitally processed and displayed using a grayscale, which is based on tissue density. The images are then reviewed by an experienced professional who analyses them both qualitatively and quantitatively, the latter through Hounsfield units (HU) (Table 2.1). CT scanner generations rapidly escalated, with an increase in the number of detectors (multidetector computed tomography  – MDCT) and processing power,

C. F. Ferreira Vera Cruz Hospital/Centro Radiológico Campinas e Clínica de Diagnóstico por Imagem de Salvador, Campinas, São Paulo, Brazil M. Marins (*) Vera Cruz Hospital/Centro Radiológico Campinas, Pontifical Catholic University of Campinas, Campinas, São Paulo, Brazil © Springer Nature Switzerland AG 2019 A. F. Joaquim et al. (eds.), Fundamentals of Neurosurgery, https://doi.org/10.1007/978-3-030-17649-5_2

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26 Table 2.1  Examples of different tissue densities using Hounsfield units

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C. F. Ferreira and M. Marins Material Air Lung Fat Water Blood Muscle Bone

Hounsfield unit −1000 −500 to −200 −200 to −50 0 25 25 to 40 200 to 1000

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Fig. 2.1 (a) Axial view NECT shows bilateral frontoparietal subdural hematoma with multiple stages of hemoglobin degradation. (b) Coronal view of NECT showing frontal epidural hematoma with slight compression of the encephalic parenchyma

with huge improvements regarding axial resolution, multiplanar reconstruction capabilities, and acquisition time. CT scans are faster, cheaper, and more available than MRI scans, which led them the imaging modality of choice in the emergency room (ER). CT has a special role in trauma patients, widely used in order to detect and analyze cranial, facial, and spine fractures, as well as intraventricular, intra-, and extra-­ axial hemorrhages and diffuse axonal injury (DAI). Non-enhanced computed tomography (NECT) has a central role in the management of patients with suspected stroke, to demonstrate the absence of hemorrhage and increase the safety of thromboembolic treatment. Although CT scans are less capable than MRIs in detecting acute brain ischemia, these findings may still be present in 50–60% of patients with stroke (Fig. 2.1). Contrast-enhanced computed tomography (CECT) uses iodinated contrast media, and it is prescribed when there is a need to study brain vessels and areas of blood-brain-barrier (BBB) disruption, such as tumoral lesions. It is possible to manipulate the grayscale through post processing of the images in order to demonstrate small differences of contrast between two adjacent tissues. This process is known as “windowing.” There are also reference window options

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Fig. 2.2  Metopic craniosynostosis: (a) Bone window axial imaging demonstrating triangular appearance of the frontal bone. (b) MIP reconstruction showing premature fusion of the metopic suture, with adjacent sclerosis. (c) 3D volume rendering showing trigonocephaly

that are standardly used to highlight different structures within the body, as bone, soft tissue, brain, and lungs. CT volumetric acquisition allows multiplanar image reconstructions and the creation of 3D images with techniques as volume rendering (VR) techniques and maximum intensity projection (MIP). Both techniques are particularly useful in demonstrating fractures, in craniosynostosis, and in therapeutic planning and prosthetics. Recently, 3D printing has also gained uses involving CT scans, in order to build custom-fit prosthetics or to create models for planning and testing surgical procedures (Fig. 2.2).

Magnetic Resonance Imaging (MRI) Unlike CT, MRI scanners don’t use ionizing radiation. The MRI scanner creates a powerful magnetic field around the patient. A radio-frequency coil (antenna) is positioned on the patient’s area of interest, which sends information back and forth to the scanner through radiofrequency (RF) pulses. These pulses align the protons of the molecules of the patient’s body, and when they return to their regular spin, they emit energy back to the antenna, which is then translated into the signal that it processed into the image that we see. There are two basic MRI sequences, spin echo (SE) and gradient echo (GRE), and they are used accordingly in order to better access a specific tissue composition. Determining tissue composition is one of the MRIs’ main functions. Parameters called T1 and T2 are obtained through different combinations assessing repetition time (TR) and echo time (TE) of the RF pulses and are responsible for determining tissue contrast. A third parameter beyond TR and TE is the inversion time (TI), which is used to suppress a specific signal range from determined tissue. Examples are the fluid attenuation inversion recovery (FLAIR) sequence, suppression of cerebrospinal fluid, and short tau inversion recovery (STIR) sequence – suppression of fat.

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Fig. 2.3 (a) Sagittal T1 midline imaging showing normal anatomy. (b) Ectopic posterior pituitary: Sagittal T1 midline imaging showing absent posterior pituitary bright spot. A hyperintensity oval imaging corresponding to ectopic posterior pituitary lobe is observed at the median eminence (floor of the third ventricle). (c) Dysgenesis of the corpus callosum and pericallosal lipoma: Sagittal T1 midline imaging showing hypogenesis of the isthmus and splenium of the corpus callosum associated with a small lipoma

We will now show the main sequences used to acquire a basic brain MRI scan, their importance, and how to interpret them. Brain MRI protocols may vary between imaging centers, and main disease being studied.

T1 T1 is one of the most anatomical sequences. It’s commonly acquired using a sagittal plane and is largely useful for the evaluation of the anatomical structures of the sagittal midline, as well as the brain’s sulci and gyri. One of the ways to recognize you are facing a T1 sequence is to look at the signal intensity of the white matter, which will be hyperintense (white) in relation to the gray matter that has intermediate signal (gray); also note that the cerebrospinal fluid is hypointense. It is important to remember specific structures and findings that have a high signal, such as the neurohypophysis, cystic lesions with high protein content, and blood degradation by-products. T1 is the sequence that best shows contrast enhancement (Fig. 2.3).

T2 Like T1, T2 is also of the utmost importance. It’s mainly used because of the high signal displayed on liquids, therefore brain lesions with high fluid content and edema will have high signal. Small lesions located in the posterior fossa and deep gray matter will be better evaluated on T2 than with FLAIR. T2 has great importance when analyzing tumors because signal intensity correlates with their nuclear-­ cytoplasmic ratio (NC ratio), so tumors with a high NC ratio, such as gliomas, have

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Table 2.2  Intracranial blood/hemorrhage – different stages and its characteristics according to the degradation phase Phase Hyperacute Acute (1 to 2 days) Early subacute (2 to 7 days) Late subacute (7 to 14–28 days) Chronic (>14 days)

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Blood degradation Intracellular oxyhemoglobin Intracellular deoxyhemoglobin

T1 Isointense Isointense

T2 Hyperintense Hypointense

Intracellular methemoglobin

Hyperintense

Hypointense

Extracellular methemoglobin

Hyperintense

Hyperintense

Intracellular hemosiderin

Iso- and hypointense

Hypointense

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Fig. 2.4 (a) Sagittal T1 showing extensive hemorrhagic temporal lobe lesion with blood content in the methemoglobin phase in a patient with an AVM. (b and c) Transverse sinus thrombosis: Axial T1 sequence showing small area of high signal in the left transverse sinus. Axial postcontrast T1 sequence confirming obstruction of the sinus

higher signal intensity and tumors with low NC ratio, such as lymphomas and medulloblastomas primitive neuroectodermal tumors (PNETS), have lower signal. Rapid fluid and vascular flow creates areas of signal loss called “flow voids.” Flow voids are useful to infer arterial anatomy and arterial occlusion/subocclusion where the “flow void” is absent. The phase in which blood is being degraded alters its signal characteristics, as shown in Table 2.2 and Fig. 2.4.

FLAIR The Cerebrospinal fluid (CSF’s) high signal may mask adjacent lesions that are also T2 bright. As mentioned before, FLAIR is basically a T2 sequence with the CSF suppressed, increasing its sensibility to detect white and gray matter lesions. Like T2, FLAIR is very helpful in evaluating edema and white matter

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Fig. 2.5  Multiple sclerosis: (a) Axial FLAIR image showing multiple high signal lesions located in the periventricular and subcortical white matter, with perivenular orientation. (b) Sagittal FLAIR image showing lesions perpendicular to the corpus callosum, known as “Dawson fingers”

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Fig. 2.6  Subacute infarcts: (a) Axial FLAIR and (b) DWI showing multiple cerebellar subacute infarcts. (c) These lesions enhance on T1 postcontrast images

lesions. This sequence is also one of the key components of any brain scan (Figs. 2.5 and 2.6).

Fat Suppression Fat has high signal both on standard T1 and T2 sequences, posing challenges in evaluating contrast enhancement on T1 and liquids on T2. This created an urge to designing different fat suppression techniques that can be used coupled with the sequences previously described. Combining regular sequences with fat suppression is also useful to demonstrate fat content in lesions such as lipomas and other fat containing lesions.

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a

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Fig. 2.7  Paraclinoid meningioma: (a) T2 coronal image showing low signal lesion involving the right internal carotid artery. (b) Postcontrast T1 axial images showing marked enhancement of the lesion

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Fig. 2.8  Examples of blood content on T2∗ images: (a) Cerebral amyloid angiopathy showing multiple subcortical small “black” lesions. (b) Diffuse axonal injury showing foci of low-intensity signal and susceptibility artifact in a typical distribution, mainly on the right frontal lobe

T1 Postcontrast (Gadolinium) Gadolinium (Gd)-based contrast agents (GBCAs) are the most commonly used agents on MRI. A volume that typically ranges from 5 to 15 ml is injected intravenously. The GBCAs have high signal on T1; therefore contrast patterns and vascular studies use this sequence postcontrast as well. Contrast enhancement results from disruption of the BBB such as by ischemia, infection, and tumors. Contrast patterns are maintained longer with GBCAs than its iodinated counterpart in CT, allowing for postcontrast sequences to be obtained after a longer amount of time. Postcontrast

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volumetric whole brain acquisitions commonly being obtained in order to plan procedures and to use in neuronavigation software (Fig. 2.7).

Advanced Sequences Susceptibility Sensitive Sequence (T2∗, SWI) These sequences serve best in evaluating hemoglobin degradation by-products and calcifications. The first sequence designed for this purpose was the T2∗, which further led to the creation of susceptibility weighted imaging (SWI), which has a higher accuracy. These sequences are great for evaluating DAI, cavernomas, hemorrhages, and calcifications (Fig. 2.8).

DWI and DTI Diffusion weighted imaging (DWI) detects the random Brownian motion of water molecules within tissues. When there are factors slowing down this movement (popularly described as restriction), the signal increases. DWI was a huge breakthrough in MRI, playing a vital role in evaluating the acute phase of ischemia (cytotoxic edema). Later on, researchers noted that many other lesions also showed signal increase, such as epidermoid cysts, lymphomas, and medulloblastomas PNETS (because of its high cellularity) (Fig. 2.9). Beyond the qualitative analysis (restriction, facilitation, or neither), DWI also enables quantitative analysis through the apparent diffusion coefficient (ADC) values. These values are also processed and used to build the ADC map, which is more visually appealing. Pitfall  – DWI is weighted in T2; therefore high signal must always correlate with low signal on the ADC map in order to correctly correlate this increase as true restriction. This “false” restriction is known as “T2 shine through.”

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Fig. 2.9  Examples of DWI restriction: (a) DWI showing area of acute ischemia of the vascular territory of middle cerebral artery (MCA) branches. (b) Pyogenic abscess on the right parietal lobe with central area of restricted diffusion. (c) Epidermoid cyst of the right PCA

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Fig. 2.10 (a) Postcontrast T1 image showing enhancing intra-axial tumoral lesion in left frontal lobes deep white matter. (b) Fractional anisotropy (FA) color map showing reduced FA values on the corona radiata this side. (c) 3D fiber tractography (FT) showing reduced fibers through the corona radiata and corticospinal tract

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Fig. 2.11  Left fronto-insular low-grade astrocytoma. (a) Postcontrast T1 image showing no enhancement. (b) Axial FT (directionally encoded color map) showing displacement of the superior longitudinal fascicle, with no signs suggestive of destruction. (c and d) 3D FT confirming the previous finding

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Fig. 2.12  Glioblastoma: (a) Postcontrast T1 shows peripheral and irregular enhancement of the lesion, associated with central necrosis. (b) ASL perfusion showing increase of the CBF values in the solid component of the lesion. (c and d) Multivoxel spectroscopy demonstrating increase of choline levels and decrease in NAA levels in the solid component of the lesion

Diffusion tensor imaging (DTI) is a technique that uses anisotropic diffusion to estimate the axonal (white matter) organization of the brain. Fiber tractography (FT) uses this information to create a 3D model of the neural tracts (Figs. 2.10 and 2.11).

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MR Perfusion-Weighted Imaging There are two main perfusion techniques currently employed to evaluate ischemia and tumors. The first one is dynamic susceptibility contrast (DSC) MR perfusion, which is a T2∗ contrast-based sequence, capable of determining parameters such as cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) in order to assess the vascular bed. The second type is arterial spin labeling (ASL), which was introduced more recently and has the advantage of still determining CBF without contrast injection (Fig. 2.12).

Spectroscopy MR spectroscopy (MRS) is a technique used to detect and quantify the concentration of specific metabolites within a specific tissue. Different TE values (35  ms, 144 ms, and 288 ms), single or multivoxel, are different parameters that can be used to employ this technique. The brain metabolites that are commonly seen on the MR spectrum are: • Creatine (Cr): resonates at 3.0 ppm – It provides a measure of energy stores. • Choline (Cho): resonates at 3.2 ppm – It is a measure of increased cellular turnover and is elevated in tumors and inflammatory processes. • N-Acetylaspartate (NAA): resonates at 2.0 – It is a neuronal marker and decreases with any disease that adversely affects neuronal integrity. • Lipids/lactate (Lip/Lac): resonates at 0.9–1.3 ppm – It is a marker of anaerobic metabolism (infeccions) and also elevated in necrotic areas. • Myoinositol (mI): resonates at 3.5 ppm – It plays an important role in osmoregulation and is elevated in low-grade astrocytomas, for example. a

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Fig. 2.13  Examples of FIESTA/CISS sequence: (a) Aqueduct stenosis: Sagittal image showing focal narrowing of the cerebral aqueduct. (b) Neurocysticercosis of the fourth ventricle: Sagittal image showing cystic lesion with well-defined borders inside the fourth ventricle. (c) Sagittal image showing third ventriculostomy through discontinuity of the third ventricle’s floor

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 teady-State Gradient Echo Acquisition for CSF S Cisternography (FIESTA, CISS) Currently the sequence of choice for CSF is cisternography for visualizing cranial nerves at the skull base. It is acquired volumetrically, has high spatial resolution, and allows multiplanar reconstructions. Liquid (particularly CSF) is bright on this sequence and provides great contrast with adjacent structures, making it ideal to evaluate CSF drainage pathways, cysts, the inner ear, and cranial nerves. The best way to describe this sequence is to think of searching for a single piece of hair inside a glass of water (Fig. 2.13).

MR Angiography MR angiography (MRA) is an alternative to CT angiography and conventional angiography, with the benefits of eliminating the need for iodinated contrast media and ionizing radiation, in order to study vascular structures. While initial techniques, such as TRICKS and FLUORO, required GBCA injections, other techniques such as time of flight (TOF) angiography and phase-contrast angiography make it possible to also acquire high-resolution images without GBCAs (Fig. 2.14). a

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Fig. 2.14 (a) Coronal MIP MRA showing right MCA aneurism. (b) 3D MRA volume rendering of the aneurism. (c) 3D CTA volume rendering of the aneurism

3

The Basic Neurological Examination Mauro A. T. Ferreira

Introduction Although the thorough and time-consuming neurological examination may be ­performed by the neurologist and the neurosurgeon in specific conditions, identification of neurological dysfunction or deficit may be identified expeditiously and easily by the general practitioner. Because the central nervous system (CNS) is a complex of numerous neural pathways, responsible, each one, for a known neural function, lesions and damage to a specific pathway may be identified, and a topographical diagnosis may be performed. Besides the topographical diagnosis, an etiological and a syndromic diagnosis may be performed as well. Differential diagnosis in neurology and neurosurgery provides the ultimate understanding of neurological diseases, as well as its pathology, pathophysiology, incidence, and typical clinical presentation and clinical course. Textbooks are available for the detailed neurological examination, but its nuances and details are not within the scope of this chapter. The interested reader, may, however, become more familiar with the subject. We refer the interested reader to study the peripheral nervous system elsewhere, since it is another chapter of the neurological examination.

Objective This chapter intends to present a brief and concise stepwise sequence of the ­different aspects of the neurological examination, in order to rapidly identify neurological dysfunction and deficit. This may allow prompt communication with the neurologist and/or neurosurgeon, and prevent treatment delay with

M. A. T. Ferreira (*) Department of Anatomy and Radiology, University Hospital, Belo Horizonte, Minas Gerais, Brazil © Springer Nature Switzerland AG 2019 A. F. Joaquim et al. (eds.), Fundamentals of Neurosurgery, https://doi.org/10.1007/978-3-030-17649-5_3

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eventual further, and non-necessary, neurological deterioration. For instance, in stroke patients, “time is brain,” since every minute after ischemia means loss of millions of neurons.

Rationale for Diagnosis in Neurology/Neurosurgery As a guide to follow, neurological deficits may present themselves in four different timeframes: 1. Acute onset: acute onset usually points out to a vascular lesion, either by the lack of blood supply to a specific vessel, therefore causing brain death, or due to vessel rupture, leading to hemorrhage (the latter is usually a more dramatic event, more often than not causing loss of consciousness, and eventually dysautonomia); trauma, with few exceptions that tend to develop neurological dysfunction or deficits at the scene, in a super-acute fashion; and metabolic conditions such as specific poisoning and hypoglycemia which may lead to neurological deficits and altered states of consciousness very quickly. 2. Subacute onset: in this case scenario, the finding of neurological deficits may be due to various pathologies such as brain tumors, some neurological infections and granulomas, hydrocephalus (not all patients with hydrocephalus), a variety of mass effect lesions, and autoimmune diseases of the central nervous system. The hallmark of these conditions is the progressive and gradual worsening of a given neurological dysfunction of deficit. If associated with headache, increased intracranial pressure must be ruled out. 3. Chronic onset: the chronic onset and development of a given neurological disease is usually due to degenerative diseases such as dementia and Parkinson’s disease, specific poisoning agents, slow growing tumors such as, but not always, meningiomas, and some autoimmune diseases. 4. Fluctuating neurological symptoms: fluctuating symptoms may occur in diseases like multiple sclerosis, but one should keep in mind that multiple sclerosis, as other organic or “true” neurological diseases, causes residual deficits after a major event, until another one develops. There is, tough, a stepwise overall worsening of the neurological condition. Worth noticing is the fact that “positive neurological symptoms,” such as paresthesia, numbness, and tingling, especially in a young individual, especially if bilateral, should raise the suspicion of a psychological/psychiatric disease or malingering. A typical case is the general anxiety disorder causing perioral tingling or bilateral hand numbness. In such cases, the objective neurological examination is normal. It is interesting to notice that brain diseases cause contralateral symptoms, while cerebellar dysfunction reflects dysfunction at the same side of symptoms and signs. Cranial nerves manifest dysfunction on the same side. Some neural functions are ipsilateral when the spinal cord is involved, while others manifest symptoms contralateral (like the Brown-Sèquard syndrome). Almost as a rule, language function is

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located in the left hemisphere, or the “dominant hemisphere,” both in right-handed and in left-handed individuals.

The Neurological Examination “Eloquent” Brain Areas Unlike other human organs, where a certain morpho-functional unit tends to repeat itself regardless of its position inside the organ (like the lung, the liver, the pancreas, etc.), the brain is a unique and complex network of different neuronal systems. Consequently, lesions to the frontal lobe cause symptoms different from lesions to the occipital lobe. Even a lesion of the right and left frontal or parietal lobes may cause different symptoms. The so-called Brodmann’s brain areas refer to various numbered cortical areas and their hole in executing a given neural function. This concept of brain areas has been criticized by some and has been replaced by a better understanding of “neural systems” or “neural pathways.” The so-called eloquent areas refer to areas that, if damaged, may cause major neurological deficits, and major impact in quality of life, with severe consequences. They are as follows: 1 . The precentral gyrus, which causes contralateral hemiplegia. 2. The postcentral gyrus in which lesions may cause inability to process sensory input to the CNS. 3. The anterior part of the left inferior frontal gyrus (pars triangularis and pars opercularis) which may prevent the patient’s ability to utter words, even though word discrimination remains intact (Broca’s area/conduction aphasia); 4. Left posterior temporal lobe lesion which causes incapacity to understand words (Wernicke’s area/sensory aphasia), although the ability to speak remains intact. 5. The calcarine sulcus and adjacent gyri, located in the inner or medial surface of the occipital lobes which are responsible for recognition of visual input. Lesion to this area may cause “cortical blindness.” There are, however, subcortical and unconscious visual pathways that may help the patient to protect himself and even perform some tasks. This is the matter of current clinical research. 6. Right and left supramarginal and angular gyri located in the inferior parietal lobule. Lesion to the left parietal lobule causes the Gerstmann’s syndrome (inability to differentiate right and left, agraphia, acalculia, and inability to identify the fingers of the hand), while extensive lesion to the right parietal lobule causes incapacity to recognize the right half of the body, a hemineglect syndrome. The patient does not recognize his arm, even though he moves the limb unintendedly. Both parietal lobes are association and integration areas, as it is the area of convergence of multiple neural pathways. 7. The left hippocampus, one of the main components of the memory system, whose lesion causes severe memory loss, both anterograde (usually severe) and also retrograde.

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These are highly functionally developed areas, and there is special concern when a tumor is located or involves such areas. The other “non-eloquent areas” (maybe an inappropriate definition) are important (especially when the neurological examination seems normal, and a neuropsychological examination show major damage or various small positive findings), but damage to these areas is “compatible” with an acceptable quality of life. It obviously depends on the patient’s ­previous occupation.

Consciousness and Cognition Patients may be fully alert, cooperative, and oriented, or he/she may be disoriented, somnolent, confuse, or disoriented. Although it has been originally conceived to assess impaired level of consciousness in head trauma patients, almost 40 years ago, the Glasgow Coma Scale (GCS) is widely used to evaluate coma and consciousness in neurological patients with a variety of conditions. The GCS score varies from 3 to 15, where 3 means the patient has no response to any stimuli and 15 represents a fully alert and cooperative patient. The GCS is presented in the context of brain injury elsewhere, but it is important to emphasize it relies on verbal, motor, and ocular response to stimuli. The knowledge and its application, especially in the emergency room, are mandatory to every doctor. According to this scale, a GCS 15 means the patient is awake and oriented, obeys commands, and keeps the eyes opened during examination. The GCS underwent minor modifications in 2014. It is important for neurological follow-up, as its score may change quickly. Although the definition of coma is complex, the vast majority of comatose patients present a GCS ≤ 8, and this is of utmost importance because these patients are unable to protect airway. Pediatric patients are evaluated with a modified GCS scale. Another useful tool to assess cognitive function is the Mini-Mental Status Examination (MMSE). It is used to evaluate the cognitive status of a given subject. It usually does not take more than 5 minutes to be completed, and it assesses attention and calculation, recall, language, ability to follow simple commands, orientation, and registration (repeating names). It is particularly useful as a screening tool to identify cognitive disorders such as dementia. The scores obtained must be correlated with the patient’s level of education. The score varies from 0 to 30 points, the latter meaning the patient has no cognitive deficit. It is also important to follow improvement/impairment of any given therapeutic action on such patients. This scale does not intend to diagnose etiology but the degree of cognitive impairment. Abnormality of the MMSE should prompt further investigation. The MMSE is particularly important for doctors managing old patients, and a sheet containing the questionnaire of the MMSE must be available, as well as serial follow-up examination should be performed.

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Gait and Balance Gait is the ability to ambulate properly and perform real-time modifications to keep balance and body control. Axial balance is the ability to keep the axis of the body steady and perform adjustments as the body changes its position in relation to space. Gait and balance involve multiple neural pathways, but its disorders usually point out to cerebellar diseases such as strokes and tumors, particularly those affecting the cerebellar vermis or the middle cerebellar peduncle. Failure of coordination of muscle activity during movement is called ataxia. Altered proprioception as in diseases affecting the posterior spinal cord function (as in the subacute combined degeneration of the cord due to the lack of B12 vitamin and as in the tabes dorsalis, a late manifestation of neurosyphilis), motor deficits, and vestibular system malfunction (like labyrinthitis) should also be considered when evaluating gait ataxia. Ataxia may compromise gait and balance and may result in limb movement incoordination when the cerebellar hemisphere is compromised. Ataxia due to the lack of proprioception is called sensory ataxia. A common cause of gait ataxia is alcohol abuse. To evaluate gait and balance ask the patient to stand up with the feet together. Ask him to look forward and then close the eyes. If the cerebellum is compromised, there will be oscillation in the body, from one side to the other, of forward-­ backward. Closing the eyes does not impair the exam if the cerebellum is involved, but causes the patient to be more unstable of tend to fall in sensory ataxia (Romberg’s sign). Balance testing may be tested by asking the patient to stand on one foot. It is still tested by asking the patient to walk straight ahead. Cerebellar ataxia causes the patient to present with oscillations, a wide-based gait, and reeling (“drunk-like” gait). This pattern will remain similar with the eyes opened or closed, but will worsen considerably in sensory ataxia (lack of proprioception). The ability to perform fine movements, with hesitation, fragmentation of movement, and intentional tremor may occur in the arms and legs if the cerebellar hemisphere is compromised.

Muscular Examination Conscious muscle activity, and the initiative to start a movement, is possible due to the corticospinal tact (pyramidal tract) that arises at the precentral gyrus and ends at the motoneurons of the anterior horn of the spinal cord. In its down course, this tract is regulated by various other tracts (unconscious). They modulate movement. They are called the extrapyramidal system, as these fibers do not cross over the midline at the pyramid, on the ventral surface of the medulla. The extrapyramidal system is more a concept than an anatomical structure, as they include the basal ganglia and all its highly complex connections. Their disorders are referred to as “movement disorders”. Interestingly, the motor system is largely modulated by the extrapyramidal system, via fibers that project directly inferiorly, but movement is also regulated by fibers not related to the basal ganglia like the rubrospinal, vestibulospinal,

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olivospinal, and reticulospinal tracts. Although not connected to the basal ganglia, these fibers are “extrapyramidal,” in the sense they regulate movement and they extend to the spinal cord without crossing over the pyramids. Other than the concept of the pyramidal and extrapyramidal motor systems, the understanding of the superior motor and inferior motor neuron syndromes is mandatory. In the first, a given lesion is located above the level of the last motor neuronal synapsis, and its symptoms result in spastic paralysis syndrome that include (1) increased muscle tonus, (2) hyperreflexia, (3) spasticity, (4) light to moderate muscle wasting, and (5) the Babinski sign (extension of the hallux when the plant is stimulated). The inferior motor neuron syndrome is due to lesions of the motoneurons of the spinal cord or at the nuclei of the cranial nerves and causes a flaccid paralysis syndrome. It is also the case for peripheral nerve diseases. It includes the following: (1) decreased muscular tonus, (2) loss of osteotendinous reflexes (deep muscle reflexes), (3) severe muscle wasting, and (4) lack of Babinski sign. These findings are important to explain the differences of a paralysis caused by a stroke and a spinal cord injury (upper and lower motor neuron syndrome, respectively), for example. Muscular activity is dependent and regulated by numerous neural circuits. However, gross movement disorders are easily identified. As for motor strength, it can be quickly evaluated using a grading system ranging from 0 to 5 as follows and according to the Medical Research Council (MRC) Scale for Muscle Strength: 0, no movement; 1, only muscle fiber contraction may be visible or palpated; 2, movement may occur if gravity is abolished, like flexion of the forearm at the elbow when the examiner holds the elbow in a horizontal plane position; 3, movement is observed at a given body joint without the need for help; 4, there is movement against some resistance placed by the examiner; and 5, normal muscle strength. One can move vigorously against full resistance placed by the examiner. It is important to compare muscle strength on both sides for the same muscular groups. Muscles are also evaluated by its tonus. Muscle tonus or the residual muscle tension is defined as the continuous and passive partial contraction of the muscles or the muscle’s resistance to passive stretch during resting state (when there is no voluntary movement). Muscle tonus helps maintaining body posture. The exam consists of passively stretching a given joint to evaluate muscle resistance. One must also compare one side to the other. Increased tonus may be seen in lesions of the corticospinal tract, and generally in extrapyramidal disorders like parkinsonism (with its typical cogwheel tonus) and other conditions as well, and decreased tonus is seen in inferior motor neuron syndrome. The reader is referred to specific literature for a comprehensive overview on this topic. The causes of hypotonia and hypertonia are too large to be included in this chapter. Spasticity usually refers to hypertonia and paralysis, with hyperreflexia. On the other hand, flaccid paralysis refers to hypotonia, paralysis, and decreased or absent muscle reflexes. The muscle reflexes may be separated into superficial and deep muscle reflexes. The superficial reflexes consist in a cutaneous stimulus that causes muscular contraction. The cremasteric reflex consists of gently touching the inner upper thigh with contraction of the cremasteric muscle. The umbilical reflexes consist on

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touching the skin over the abdominal wall and observing a deviation of the umbilicus toward the stimulus site. One of the most well-known signs in neurology is the cutaneous-plantar reflex, a response of the hallux, in flexion or extension when a non-cutting object is applied to the plant. In the later situation (extension), the Babinski sign becomes present, and it means a lesion to the superior motor neuron exists. Again, it is important to compare the two sides. Absence or hyperactivity on both sides may be a normal finding. The deep muscle reflex consists of an input into the CNS, and is processed in the spinal cord, by suddenly stretching a muscle tendon with a hard rubber hammer. This is a monosynaptic reflex. The output consists of muscle contraction and movement. The osteotendinous reflexes usually tested are the triceps, biceps, patellar, and the ankle jerk reflexes (Achilles reflex). Testing is bilateral, and its importance lies in the fact they may locate the level of a given spinal cord lesion. Deep muscle reflexes are also described for its intensity. A commonly used scale is as follows: 1, no movement is elicited; 2, movement is elicited; 3, a vigorous movement is perceived; 4, temporary clonus (an oscillation of a body part when the joint in suddenly stretched by the examiners hand); and 5, permanent clonus, similar to the above, but the oscillation is continuous as long as the stimulus persists.

Sensory Evaluation There are several types of sensory inputs in the human body, such as pain, temperature, light touch, gross touch, body positioning, kinesthesia, muscle tonus, and so on. Most of the sensory inputs are unconscious. For instance, the autonomic nervous system, carrying sensation from viscera, metabolic control, heart rate, respiration, and so on, is entirely unconscious. Patients are usually tested for touch and pain. Apply gentle touch over the skin surface of the face, neck, thorax, and abdomen at midline, and over the skin of the shoulders, arms, forearms, the hands, thigh, legs, and feet bilaterally. Always compare to two sides. Ask the patient to keep the eyes closed. Do the same thing with a somewhat dull needle to test for pain and light touch. If a sensory loss is present, an altered neurological examination will reveal it. If a sensory loss is suspected, repeat the sensory examination carefully, starting from a skin area where sensation is judged normal, proceeding to the site of suspected loss of sensation. Because sensation is a subjective measure, neurological examination may change, from time to time, from examiners, because of patient’s anxiety or fear, or even by examiner techniques. Again, comparison of one side to the other is of utmost importance.

Pupil Examination The pupil is the black spot in the eye that is surrounded by the iris that contains the muscles that regulate the pupil’s diameter. It represents the anterior opening of the eyeball. The pupils are responsive to light, and fine adjustments as to the amount of

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light allowed into the retina is regulated, in a real-time fashion, by the iris (smooth cell muscles, known as intrinsic eye muscles, or iris muscles) muscles, that constrict (pupillary constrictor and pupillary sphincter muscles) and dilate the pupil (iris dilator muscle). The pupils are usually the same size in a given moment. Its diameter varies from 2.0 to 6.0 mm, but in daylight exposure, it usually ranges from 3.0 to 4.0 mm. Some patients may have congenital different pupil diameters. As a matter of fact, a difference in pupil diameter of 1 mm or less is present in 15 to 20% of cases. To be noticed, the pupils must differ 0.25 mm or more. Pupils react to light. In order to react, light must be perceived by the optic nerves, and constriction may be performed by the oculomotor nerve (third cranial nerve, see below). Different pupil diameter is known as anisocoria. The smooth muscle present in the iris is particularly sensitive to metabolic diseases, endogenous and exogenous toxic agents, and may show abnormalities involving the optic and oculomotor nerve. As a simplification, the pupils may be of normal size, may be abnormally small (≤2.0 mm = miosis), or may be abnormally dilated (mydriasis). Unilateral mydriasis, especially if unresponsive to light may be due to oculomotor nerve palsy. It should be studied carefully. The oculomotor nerve is also responsible for innervation of four of the six extraocular muscles, and the levator palpebrae superioris muscle. Thus, unilateral mydriasis (non-reactive to light), associated with eye deviation and ptosis (levator palpebrae superioris muscle palsy) indicate oculomotor nerve palsy, usually due to compression. In such cases, no response to light stimulus will be observed. The oculomotor nerve has a long intracranial course, and it is vulnerable to various types of compression. Aneurysms and tumors may cause compression of the third nerve. In the context of head trauma, the mydriasis should be regarded as an emergency, since the swollen brain or any other hematoma or brain contusion may compress the third nerve, indicating brainstem compression and risk of death. In the case of a tentorial herniation, contralateral hemiplegia will be found. A computed tomography scan should be performed immediately and the neurosurgeon should be communicated. Important causes of bilateral miosis are neurosyphilis, diabetes, levodopa use, and alcohol abuse. Very small pupils (punctiform pupils) in a comatose patient may indicate severe brainstem damage, particularly the pons. On the other hand, mydriasis in a comatose patient indicates midbrain lesion, post-cardiac-arrest status, and terminal life status. Atropine, hyoscyamine, scopolamine, cocaine, and amphetamine may cause mydriasis. On the other hand, fentanyl, heroin, methadone, risperidone, quetiapine, haloperidol, acetylcholine, ondansetron, mirtazapine, organophosphates, and pilocarpine cause miosis. Barbiturate intoxication (thiopental, pentobarbital, phenobarbital) and benzodiazepines also may cause miosis. The reader is referred to comprehensive reviews on neurotoxicology/brainstem damage/ herniation syndromes causing coma with miosis and mydriasis.

Coma Coma has been mentioned briefly in this chapter, but the author recommends the reading of a textbook dedicated to this subject, as well as to specific neurology textbooks.

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Cranial Nerves There are 12 paired cranial nerves that distinguish from spinal nerves by carrying special sense fibers, absent in spinal nerves. The special senses fibers of vision, olfaction, tasting, balance, and hearing are carried in the cranial nerves. A summary listing the cranial nerves and its main functions are presented below. The anatomy of the cranial nerves is elegantly depicted by Rhoton: • Cranial nerve I: olfactory nerve. The paired olfactory nerve is located in the superior one third of the nasal cavity; their neurons traverse the cribriform plate of the ethmoid bone to synapse at the ganglion of the olfactory nerve. It is responsible for the sense of smell, and it is intimately connected to the limbic system. Clinical examination of this nerve is difficult since they are paired, and smell discrimination is not yet well understood. • Cranial nerve II: optic nerves. The optic nerves are prolongations of visual cells present in the retina. It perceives light, shapes, depth, and colors. The two superimposed visual fields allow for stereoscopic vision. Vision may be tested for visual fields integrity, and for visual accuracy. By sitting in front of the patient, the examiner may ask he or she to look him in the eyes and keep their eyes fixed while the examiner shows his fingers in different positions and ask the patient if they are moving or how many fingers the examiner is showing. The confrontation campimetry is a triage test that compares the examiner’s visual field to the patient’s field. Any abnormality should prompt a computed visual field examination. As for accuracy, or the ability to differentiate two points, is usually tested by the Snellen card. The patient is asked to read letters at a distance of 20 feet away from the patient. The ability to read letters that are 1 inch tall at 20 feet distance is considered normal. The patient gets a record of 20/20, meaning normal vision. Subnormal vision should prompt further evaluation. • Cranial nerve III: oculomotornerve. The oculomotor nerve is responsible for carrying sympathetic and parasympathetic fibers to the intrinsic muscle fibers (iris muscles) and for the innervation of four of the six extraocular muscles (the six extraocular muscles allow for the nine cardinal eye gaze directions possible); the superior rectus, the medial rectus, the inferior rectus, and the inferior oblique muscle. It innervates the levator palpabrae superioris muscle. By innervating the ciliary ganglion, it controls the size of the pupil. • Cranial nerve IV: trochlear nerve. It innervates the superior oblique muscle (one of the extraocular muscles). • Cranial nerve V: the trigeminal nerve receives its name because it has three different divisions: the ophthalmic division, the maxillary, and the mandibular division. The nerve is responsible for somatic sensation of the paranasal sinuses, the eye, the nasal cavity, the oral cavity, the superior and inferior teeth with their corresponding gum, the general sensation of the two anterior thirds of the tongue, the inner surface of the vestibule of the mouth, and the skin over the face, and over the front. It is also responsible for mastication muscles (temporalis, masseter, medial, and lateral pterygoid muscles, as well as the temporomandibular joint). It may be tested by gently touching the skin over the surface of the face

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and the front, and observing muscle movement, symmetry, and jaw strength of the temporalis and masseter muscles. The other muscles cannot be directly examined since they are located deep in relation to the mandible. Light touch in the eye may be tested by gently applying loose cotton over the eye surface when the patient is looking away from the examiner. The response to this reflex is blinking of both eyes. • Cranial nerve VI: the abducens nerves. It is responsible for eye abduction or lateral deviation of the eye. It innervates the lateral rectus muscle. Ask the patient to look to the extreme side to the right and to the left. Inability to move the eyes to the right and to the left extreme lateral gaze points out to abducens nerve palsy. • Cranial nerve VII: the facial nerves. Despite the fact that the facial nerve is responsible for some sensitivity like the taste of the anterior two thirds of the tongue and cutaneous sensory impulses from the external auditory meatus, and a region back of the ear, the facial nerve is essentially a motor nerve that is responsible for facial motricity or the muscles responsible for expression of emotions/ facial expressions. Therefore, it can be easily tested by asking the patient to frown, close his eyes, move his mouth to both sides, and smile. If only the mouth is affected and the forehead/eyes are spared, it represents central facial nerve palsy. If the whole hemiface is affected, a peripheral lesion is present, the most common cause being idiopathic (Bell’s palsy). This paralysis usually has a good prognosis for complete recovery, and the human papiloma virus complex seems to be involved in the process. • Cranial nerve VIII: the vestibulocochlear (vestibular and cochlear) nerves. Most of the vestibulocochlear nerve is examined during the balance exam. Hearing can be examined using a tuning fork (and the so-called Rinne and Weber testing may be applied). To perform the Weber’s test, strike the tuning fork against your knee or elbow, and then place the base of the tuning fork in the front of the patient, high, at midline. Then ask the patient if he can hear the sound louder in one ear than the other and if so, hearing is best in what side? If the patient’s hearing is normal he will perceive hearing in the midline, and on both ears. The sound will not shift into one side or the other. However, deviation of the sound into one side may reveal hearing deficit (Weber’s sign), that can be conductive (the sound does not reach the internal ear) or sensory/neural (the sound is not well perceived in the affected inner ear). If the patient has conductive hearing loss, he hears better in the affected ear. It happens because the vibration of the tuning fork is better conducted in solid media (bone) than in the air. If he has sensorineural hearing loss, hearing will be better in the non-affected ear. The Rinne’s test aims to compare air conduction with bone conduction, on both ears separately. It complements Weber’s test. First explain the test and then begin by striking the tuning fork against your knee or elbow. Then, hold the tuning fork in one hand and place its base against the patient’s mastoid process. Hold it in place for at least 2–3 seconds, allowing the patient to appreciate the intensity of the sound. Then, promptly position the fork with its vibrating tips about 1 cm close to the external auditory meatus. Leave it there for a few seconds before taking the tuning fork away from the ear. Finally, ask the patient in what position the sound was better heard. If the

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patient has normal hearing, he will hear the air waves louder than the bone. If he has conductive hearing loss, the test is called positive and he will hear bone vibration louder than the air. In somatosensory loss, both air and bone vibration sounds are compromised. • Cranial nerves IX and X (glossopharyngeal and the vagus nerves). The IXth and the Xth cranial nerves are both situated close to each other inside the skull base and are both responsible for the motor and sensitivity innervation of the pharynx and the larynx. In order to check its integrity, it’s necessary to rule out dysphagia (difficulty or inability to swallow). The Xth cranial nerve lesion can also cause dysphonia. In the physical examination, we ask the patient to open his mouth and say “ahhh.” His palatine uvula will move to the normal side due to the normal contraction of the soft palate on the normal side. Dysphasia is, itself, a sign of pharyngeal dysfunction (glossopharyngeal dysfunction), and dysphonia/hoarseness may be a sign of vagus nerve dysfunction, the latter, a sign of unilateral palsy of the recurrent laryngeal nerve, a branch of the vagus nerve in the neck. • Cranial nerve XI: spinal-accessory nerve. The XIth nerve is a motor nerve that is responsible for the innervation of the sternocleidomastoid muscle and the superior part of the trapezius muscle. The sternocleidomastoid muscle is tested by asking the patient to turn his head against the examiner’s resistance, and the trapezius is tested by asking the patient to raise his shoulder (as if “trying to touch the ears with the shoulders”). • Cranial nerve XII. Hypoglossal nerve. The XII nerve is a motor nerve, responsible for the tongue muscles. It should be tested by asking the patient to exteriorize the tongue. If the patient has a XII nerve injury, the tongue will be shifted to the affected side. There is usually marked muscle atrophy of the tongue in the affected side.

Conclusion This chapter has shown that a comprehensive neurological examination is feasible and can be performed by every physician. Further information on the various topics has been provided. However, for the sake of clinical practice, some tips are presented here: –– If the examiner asks the patient to pronounce the number 33; tell where he is and what date it is; raise both arms and keep them extended for a few seconds; stand up over 1 feet and the other; and walk a straight line correctly, a major neurological event can be ruled out. –– Be acquainted with the Glasgow Coma Scale. A GCS score of ≤8 mandates orotracheal intubation and ventilatory support. An IV line should be obtained, and hypertonic glucose, preceded by thiamine, should be administered. –– Confusion and any altered state of consciousness along with bilateral mydriasis should raise suspicion of intoxication or drug abuse.

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–– An oculomotor palsy accompanied by contralateral motor deficit should prompt a computed tomography (CT) scan if the patient is not comatose. If the GCS score is ≤8, the ABCDEs, according to the Advanced Trauma Life Support (ATLS) manual, should be followed. –– Saddle anesthesia (anesthesia in the upper thigh, genitals, and intergluteal sulcus), urinary dysfunction (usually retention), and difficulty walking (the cauda equina syndrome) should raise the possibility of an acute lumbosacral compression, especially in the presence of low back pain. An immediate neurosurgical evaluation should be performed. –– The sudden onset of a neurological deficit, with relatively preserved level of consciousness, especially in patients with risk factors for cardiovascular and cerebrovascular disease should raise suspicion of an ischemic stroke; if a sudden onset of neurological deficit is followed by loss of consciousness, an intracranial bleeding should be suspected. In both situations, and after the vital signs are stable, and airway and breathing are secured, a CT scan should be performed immediately. –– If an ischemic stroke is suspected, and a CT scan shows hypodense areas, immediate therapeutic measures should be started. A neurologist, a neurosurgeon, or an interventional neuroradiologist should be contacted in order to evaluate the best medical management, invasive or not. –– The neurological examination does not obviate the need to perform a thorough clinical evaluation. For example, hypoglycemia may mimic a number of neurological signs and symptoms; urinary tract infection in elderly patients may be the cause of acute confusion and disorientation; and hysteria may trick even the expert examiner. –– Fever should raise the case for an infectious disease, but may be due to CNS blood outside vessels, raised intracranial pressure, and so on. –– In the event of head trauma associated with any neurological deficit, an immediate CT scan is mandatory. –– If any neurological abnormality on the neurological examination is found, a CT scan should be performed as soon as possible. As a matter of fact, the CT scan may be considered part of the neurological work-up.

Suggested Readings and References 1. Baehr M, Frotscher M.  Duus’ topical diagnosis in neurology: anatomy, physiology, signs, symptoms. 5th ed. New York: Thieme; 2012. 2. Alberstone CD, Benzel EC, Najm IM, Steinmetz MP, editors. Anatomic basis of neurologic examination. New York: Thieme Medical Publishers; 2009. 3. Tsementzis SA.  Differential diagnosis in neurology and neurosurgery. A clinician’s pocket guide. New York: Thieme; 2000. 4. Campbell WW.  De Jong-the neurological examination. 7th ed. Philadelphia: Lippincott Wilams & Wilkins, a Wolker Kluwer business; 2013. 5. Hopper AH, Samuels MA, Klein JP, editors. Adams and Victor’s principles of neurology. 10th ed. New York: McGraw-Hill Education; 2014.

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6. Russel SM.  Examination of peripheral nerve injuries. An anatomical approach. New  York: Thieme Medical Publishers; 2006. 7. Teasdale G, Jennet G.  Assessment of coma and impaired consciousness. A practical scale. Lancet. 1974;2:81–4. 8. Teasdale G, Allen D, Brennan P, McElhinney E, Mackinnon L. The Glasgow Coma Scale: an update after 40 years. Nurs Times. 2014;110:12–6. 9. American College of Surgeons, editor. ATLS student course manual. Advanced trauma life support. 9th ed. Chicago: St. Clair Street; 2009. 10. Chung CY, Chen CL, Cheng PT, See LC, Tang SF, Wong AM. Critical score of Glasgow Coma Scale for pediatric traumatic brain injury. Pediatr Neurol. 2006;34(5):379–87. 11. Posner JB, Saper CB, Schiff ND, Posner F.  Examination of the comatose patient-pupillary responses. In: Posner JB, Saper CB, Schiff ND, Posner F, editors. Plum and Posner’s diagnosis of stupor and coma. 4th ed. New York: Oxford University Press; 2007. p. 54–60. 12. Folstein MF, Folstein SE, McHugh PR. Mini-mental status. A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12(3):189–98. 13. De Jong Neurological Examination. Gait and station (Chapter 44). In: Cambell WW, editor. DeJong’s the neurological examination. 7th ed. Philadelphia: Lippincott Williams & Wilkins; 2014. 14. De Jong Neurological Examination. The extrapyramidal level (Chapter 26). In: Cambell WW, editor. DeJong’s the neurological examination. 7th ed. Philadelphia: Lippincott Williams & Wilkins; 2014.. 15. The Jong Neurological Examination. Muscle tone (Chapter 28). In: Cambell WW, editor. DeJong’s the neurological examination. 7th ed. Philadelphia: Lippincott Williams & Wilkins; 2014. 16. Patten J.  The pupils and their reactions. In: Neurological differential diagnosis. 2nd ed. London: Springer-Verlag London Ltd.; 1996. p. 6–15. 17. Greenberg MS. Chapter 12. Coma. In: Handbook of neurosurgery. 7th ed. New York: Thieme Medical Publishers; 2010. p. 279–88. 18. Greenberg MS.  Chapter 11. Neurotoxicology. In: Handbook of neurosurgery. 7th ed. New York: Thieme Medical Publishers; 2010. p. 237–78. 19. Posner JB, Saper CB, Schiff ND, Posner F, editors. Plum and Posner’s diagnosis of stupor and coma. 4th ed. New York: Oxford University Press; 2007. 20. Tarulli A. Coma. Chapter 2. In: Neurology. A clinician’s approach. 2nd ed. Cham: Springer International Publishing; 2016. p. 26–7. 21. Principles of Neurolgy Victor and Adams. Coma and related disorders of consciousness. In: Hopper AH, Samuels MA, Klein JP, editors. Adams and Victor’s principles of neurology. 10th ed. New York: McGraw-Hill Education; 2014. p. 357–82. 22. The Jong Neurological Examination. Cranial nerves-section D (Chapters 11–21). In: Cambell WW, editor. DeJong’s the neurological examination. 7th ed. Philadelphia: Lippincott Williams & Wilkins; 2014. 23. Summary of cranial nerves. In: Moore KL, Dalley AF, Agur AMR, editors. Clinically oriented anatomy. 7th ed. Baltimore: Wolters-Kluwer/Lippincott Williams & Wilkins, 2014; p. 1261–1290.

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Intracranial Hypertension Vânia Graner Silva Pinto, Alexandre Guimarães de Almeida Barros, and Antonio Luis Eiras Falcão

Definition Intracranial pressure (ICP) is defined as the pressure inside the intracranial compartment exerted by its contents. The ICP values vary with age, body, position, and clinical conditions. Its normal range is about 7–15 mmHg in a supine healthy adult. Values higher than 20–22 mmHg are considered as an elevated ICP.

Background Intracranial hypertension results from central nervous system injuries. Traumatic brain injury, ischemia, or mass lesions may increase ICP through different mechanisms. Elevated ICP increases mortality and morbidity leading to devastating neurological damage. Therefore, it requires prompt recognition to successful management. Studies have shown an association between severity and duration of intracranial hypertension with worse patients’ outcome. Thus, judicious use of invasive monitoring and treatment directed to reduce ICP and reverse its underlying cause are the cornerstones of management.

Pathophysiology Once the sutures and fontanelles are closed, the brain and other intracranial ­components become walled in a bone structure that permits no further expansion. The cranial compartment holds together brain tissue, blood, and

V. G. S. Pinto · A. G. de Almeida Barros · A. L. E. Falcão (*) Faculty of Medical Sciences, State University of Campinas (UNICAMP), São Paulo, Brazil © Springer Nature Switzerland AG 2019 A. F. Joaquim et al. (eds.), Fundamentals of Neurosurgery, https://doi.org/10.1007/978-3-030-17649-5_4

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cerebrospinal fluid (CSF). Brain parenchyma represents 80% of intracranial content and is almost incompressible. Blood and CSF encompass 10% each and have their volumes nearly constant. There is around 150  mL of blood in the cranial compartment of a 70  kg adult. CSF is produced at a rate of approximately 400  mL/ day by the choroid plexus. It flows through the ventricular system and subarachnoid space and is finally absorbed by arachnoid granulations into the venous sinus. Blood and CSF have an essential role in buffering rises of intracranial pressure. The ICP is a function of volume and compliance of each of the intracranial components and the cranial bone structure. In other words, if there is an intracranial expansive process, it must be accommodated by reductions in the volume of intracranial elements or the pressure inside the cranial compartment will raise. This relation is known as the Monro-Kellie doctrine (Fig. 4.1). In acute scenarios, intracranial volume increases are immediately compensated by CSF displacement and a reduction of cerebral blood volume. As this new setting chronify, brain parenchymal changes accommodate part of the volume variation through reductions of extracellular water, neurons, and glial cells. Different stages may be distinguished in the intracranial pressure-volume curve (Fig. 4.1). The first part of the curve represents a state of high compliance where the intracranial volume rises have mild effects over ICP. During this stage, CSF and cerebral blood are displaced to compensate for the volume change. As volume continues to increase, a second stage may develop. At this point, volume accommodation capacity of intracranial components is near maximum. The pressurevolume curve begins to turn upward indicating a reduction in compliance and imminet decompensation. At the final stage, the system is overwhelmed, and even small changes in intracranial volume may lead to very pronounced rises in ICP.

Fig. 4.2  Idealized curves of CBF at varying levels of systemic BP in normotensive and hypertensive subjects. A rightward shift in autoregulation is shown for a patient with chronic hypertension. (Adapted from Strandgaard et al. [9])

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Elevated ICP may lead to brain damage in different ways. Two mechanisms are well-described: cerebral perfusion pressure reductions and mechanical distortion with herniation of brain tissue. Cerebral blood flow (CBF) is driven by cerebral perfusion pressure (CPP) which results from the difference between mean arterial pressure, usually measured at the level of external auditory meatus, and ICP. Studies have shown that CBF is also regulated by cerebrovascular resistance (CVR) which is under the influence of brain metabolism, arterial blood pressure, blood pH, and PaCO2 and PaO2 levels. This relationship is known as CVR autoregulation and maintains CBF at a relatively constant level over a wide range of CPP (50–100  mmHg). CVR’s autoregulation may become dysfunctional in pathologic states, letting brain tissue to be strongly reliant on CPP. Noteworthy, the set-point for autoregulation may be different in patients with chronic hypertension. This note is important because reductions of blood pressure within the normal range may produce ischemic symptoms in those patients (Fig. 4.2). As ICP rises, CPP decreases and CBF is reduced to critical levels which predispose an already injured brain to ischemic lesions. According to this, hypotension may also decrease CPP and lead to secondary injury. Therefore, arterial pressure should be closely monitored, and shock states promptly reversed. Folds of dura mater divide the cranial vault into different compartments. Cerebellar tentorium separates the cranial bone structure in supra and infra-tentorial compartments while the cerebral falx splits the supra-tentorial compartment in the median plane, confining cerebral hemispheres on each side. The cranial vault has an exit through the foramen magnum, where the posterior fossa (infra-tentorial compartment) communicates with the spinal cord space. As ICP increases, pressure gradients may be created between different cerebral compartments and brain tissue displaced, resulting in herniation syndromes.

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Several conditions might cause acute ICP rises, e.g., intracranial mass lesions (tumor, hematoma), cerebral edema (acute hypoxicischemic encephalopathy, large cerebral infarction, severe traumatic brain injury), increased CSF production (choroid plexus papilloma), decreased CSF absorption (arachnoid granulation adhesions after bacterial meningitis), obstructive hydrocephalus, obstruction of venous outflow (venous sinus thrombosis, jugular vein compression, neck surgery), and idiopathic intracranial hypertension (pseudotumor cerebri). Therefore, it is important to promptly recognize elevated ICP associated with these conditions as delaying diagnosis may result in catastrophic consequences.

Physical Examination and Clinical Features The clinical examination may be used for diagnosis and monitoring of patients at risk or with increased intracranial pressure. However, as diagnostic accuracy of signs and symptoms is limited, they may be unreliable. Neurologic assessment should be attended after the initial resuscitation of the patient. The cause of increased ICP may be evident as in cases of traumatic brain injury or following a middle cerebral artery stroke. In other scenarios, antecedent symptoms (vomiting, fever, double vision, coagulopathy) and comorbidities (liver failure) may help in developing a diagnosis. Glasgow Coma Scale objectively assesses arousal. Therefore, patients with increased ICP originating global ischemia or imminent herniation with compression of midbrain reticular formation may lose points. Also, pupils and eye movements may be distorted in herniation syndromes. Anisocoria with one dilated and non-­reactive pupil suggests compression of the third nerve while bilaterally dilated and non-reactive pupils point to severe midbrain damage. Focal symptoms may be caused by local effects of mass lesions or herniation. More global symptoms include nausea or vomiting and complaints of headache. The presence of Cushing’s triad or response (hypertension, bradycardia, and respiratory pattern irregularity) is a warning sign that warrants prompt intervention. Papilledema is a late sign of elevated ICP.  Nevertheless, it should be assessed on initial evaluation as its presence or absence (along with its sudden appearance in the context of previous absence) may provide useful information regarding the time course. Herniation syndromes result from pressure gradients that develop between two regions of the cranial vault. Common herniation locations include subfalcine, central, uncal, and cerebellar tonsils (Fig. 4.3). Central herniation occurs when ICP rises symmetrically in both hemispheres. Asymmetric compression may cause herniation of ipsilateral cingulate gyrus under the falx or transtentorial uncal herniation. Posterior fossa increased ICP may result in downward herniation of cerebellar tonsil through foramen magnum or upward compression of midbrain.

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Central herniation

Falcine herniation Midline shift

Fig. 4.3  A schematic drawing to illustrate the different herniation syndromes seen with mass effect. (a) symetric and (b) asymetric ICP rises. (Adapted from Plum and Posner [3])

Additional Work-Up and Monitoring Neuroimaging  Non-contrast computed tomography (CT) of the head is often obtained immediately when acutely elevated intracranial pressure is suspected. CT scan may reveal signs of reduced intracranial compliance and elevated ICP such as the absence of basal cisterns, sulcus and subarachnoid space effacement, third or fourth ventricle compression, and midline shift (mass effect). It may also disclose the reason for elevated ICP as stroke, hydrocephaly, and mass lesions. Direct ICP Monitoring  Continuous ICP monitoring is the only reliable way of monitoring CPP. A direct ventricular or intraparenchymal catheter is a commonly used ICP monitoring system, with the former considered the gold standard. Disadvantages include the risk of hemorrhages, infections, and the invasive nature of the procedure. The ICP is not a static value and exhibits cyclic variations based on the superimposed effects of cardiac contraction, respiration, and intracranial compliance. ICP wave pattern brings interesting clinical information and was described by Lundberg and colleagues in 1960. Pathological A waves are abrupt, marked elevations of ICP (50–100 mmHg) that last for minutes to hours. It is related to the loss of intracranial compliance and imminent decompensation of cerebrovascular autoregulatory mechanisms. B waves are of moderate magnitude while C waves are of low magnitude. Both are of short duration, and their pathologic significance is uncertain. ICP waveform transduces pulsations resulting from arterial blood pressure. The first

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Fig. 4.4  ICP wave second peak (P2) increases in amplitude as compliance decreases. Images at the bottom are representative CT scans of different stages of intracranial hypertension. (Adapted from Jon Perez-Barcena et al. [6])

peak (P1) is the percussive wave and reflects systolic peak pressure transmitted from vasculature and choroid plexus to the cerebral ventricles. The second peak (P2), often called the tidal wave, reflects the accommodation of systolic volume by intracranial elements. It generally increases in amplitude as compliance decreases and herald’s imminent loss of cerebrovascular autoregulation when its peak exceeds that of P1. The third peak (P3) is related to the aortic valve closure and dicrotic notch (Fig. 4.4). Noteworthy, indexes like the cerebral vascular reactivity index and the correlation coefficient between mean pulse amplitude and mean ICP pressure (PRx) may be used in multimodal monitoring to evaluate autoregulation of cerebrovascular bed.

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Neurosonology  Transcranial Doppler ultrasonography (TCD) can be used to follow the velocity of blood flow in the basal intracranial arteries. Based on the features of waveforms, it is possible to estimate ICP. Unfortunately, TDC is not accurate to provide a non-invasive alternative to ICP monitoring. The correlation coefficient between mean pulse amplitude and mean cerebral blood vessel velocity in the middle cerebral artery (Mx) can also be used in multimodal monitoring to evaluate the autoregulation of cerebrovascular bed.

Treatment Management of neurocritical patients aims a CPP value between 60 and 70 mm Hg. Noteworthy, whether 60 or 70 mmHg is the optimal CPP threshold is unclear and may depend upon the autoregulatory status of the patient. ICP should be treated if it exceeds 20–22  mmHg because values above this level are associated with increased mortality.

General Management 1. Keep patient’s head in a neutral position, with the bed head elevated to 30 degrees to promote venous drainage. 2. Maintenance of normothermia at 36–37 °C using antipyretics and cooling blankets, surface cooling, or intravascular devices (fever increases CBF and canelevate ICP by increasing the volume of blood in the cranial vault). 3. Glucose control: keep blood glucose between 140 and 180 mg/dL. 4. Serum Na between 145 and 155  mmol/L; serum osmolality less than 320 mOsm/kg. 5. Maintain hematocrit levels of 30–33% and hemoglobin levels of 8–10 g/dL. 6. Oxygen saturation above 96% and PaO2 between 80 mm Hg and 120 mm Hg. 7. Airway protection and normocapnia: Intubation should be done quickly in cases of airway compromise, and ventilation set to a carbon dioxide pressure (pCO2) of 35–40 mmHg. Prophylactic hyperventilation is discouraged based on studies showing tissue ischemia below a PaCO2 of 30 mmHg. 8. Normovolemia and normotension: Large shifts in blood pressure should be minimized, with care taken to avoid hypotension. Maintain systolic blood pressure at or above 100 mmHg for patients 50–69 years old or at 110 mmHg or above for others. Curiously, although it seems that lower BP would result in lower ICP, hypotension can induce reactive vasodilation and elevations in ICP. These thresholds may be tailored to maintain target CPP. Use of noradrenaline may be considered. Hypertension should be treated when CPP >120 mmHg and/or ICP >20 mmHg. 9. Optimization of analgesia decreases ICP by reducing metabolic demand, ventilator asynchrony, venous congestion, and the sympathetic responses of hypertension and tachycardia.

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10. Phenytoin may be used prophylactically in certain circumstances, once seizures are accompanied by increases in both ICP and tissue oxygen demand. The overall benefit must be weight against the complications associated with such treatment. 11. Consider repeat cranial CT to rule out worsening or new intracranial lesions that may require surgical evacuation.

First Level Measures 1. CSF drainage: CSF should be removed at a rate of approximately 1–2 mL/minute, for 2–3 minutes at a time, with intervals of 2–3 minutes, until a satisfactory ICP level has been achieved (ICP 70 years), long-term corticosteroid use, and trauma history.

Diagnosis Physical Examination The initial examination includes gait evaluation, sitting posture, and skin inspection. The muscles of the posterior spine should be palpated in order to determine trigger points of pain. The neurological exam is the most important component of the assessment of patients with low back pain. Muscle strength must be examined in detail, using muscular strength opposition. The tests should include hip flexion (L2), knee extension (L3), ankle dorsiflexion (L4), thumb extension (L5), and foot flexion (S1) (Table  13.2). The muscular strength degree is then classified from 0 to 5 (Table 13.3). Sensory can be divided in the same way as dermatomes as well the tendon reflexes. Special attention must be given to perineal and perirectal sensation as well as volitional rectal contraction in patients with a clinical concern for an acute cauda Table 13.2 Correlation between nerve root and its innervated muscle

Nerve root L2 L3 L4 L5 S1

Muscle Hip flexion Knee extension Ankle dorsiflexion Thumb extension Foot flexion

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Table 13.3  Muscular strength gradation Grade 0 1 2 3 4 5

Muscular strength No movement, no contraction Contraction, but no movement Movement is present but the limb does not overcome gravity Strength to overcome gravity, but no resistance to opposition forces Some resistance to opposing force Full strength

equine syndrome. These cases are considered a neurological emergency, requiring imaging immediately and surgical treatment in most cases. Specific maneuvers could help with differential diagnosis though none are specific or definitive. Lasègue signal is positive when the sciatica pain is evoked with straight leg raised more than 45°, with the patient laid on the bed. This signal is result of neural stretching in intervertebral foramen as the result of compression. Other maneuver that can help is Patrick’s sign, in this maneuver the patient in the bed, with the flexion leg do an external rotation, the leg pain will be generated due to hip problem, not to neural compression, because of knee flexion the roots are not stretched in this maneuver.

Radiologic Assessment The majority of patients with acute low back pain will not require imaging evaluation. The benign and limited course of most cases and absence of “red flags” are sufficient to treat pain without further evaluation. In the setting of “red flags” and the suspicion of secondary disease, advanced imaging assessment is mandatory. MRI imaging of the spine is the most sensible and specific radiological modality to evaluate low back pain, allowing a good visualization of the neural elements, ligaments, and also the vertebral and intervertebral discs very well. Plain radiographs are widely used as they are inexpensive and widely available, allowing the identification of spinal fractures and also some spinal tumors. CT scan is the best imaging modality for spinal fractures but does not visualize the neural elements and soft tissues like MRI.

Laboratory Assessment As a general point of view, laboratory exams are not useful for low back pain evaluation. However, they are important to rule out differential diagnosis, especially in the setting of red flags. Blood cell count, blood sample culture, and inflammatory activity markers are very useful in diagnosing low back pain secondary to infection or inflammatory disease. Finally, laboratorial exams are also important to rule out other causes of low back pain, such as urine evaluation for nephrolithiasis or pyelonephritis and serum amylase to diagnosis pancreatitis (Table 13.4).

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Table 13.4  Potential differential diagnoses of low back pain and their main characteristics Nephrolithiasis/pyelonephritis Abdominal aortic aneurysm Pancreatitis/stomach and gallbladder disease Pelvic disease Hip disease

Dysuria, Giordano’s sign, genital and perineum pain Pulsatile abdominal mass Food-related pain, vomiting, pain that runs into the middle back Vaginal discharge, perineum discomfort, sexual pain Restriction hip movement, pain that increases with hip rotation movement

Management of Acute Low Back Pain General Aspects Routine bed rest should be avoided as it is associated with clinical worsening. The patient should return to normal activity as soon as the pain decreases. Patients should be advised about avoiding physical activities that require excessive muscular strength or lifting weight. The intensity and frequency of pain must be evaluated as well as assessment of psychological disease secondary to the disease. The benign and transitory course of acute low back should be emphasized, and patients should be oriented about further evaluation with image with pain persist or there are new additional signs and symptoms.

Pharmacological Treatment Common analgesics, such as acetaminophen, and nonsteroidal anti-inflammatory drugs (NSAIDs) are recommended as first-line medication for pain relief. These medications are generally enough for the majority of cases. Muscle relaxants, preferentially nonbenzodiazepinic, can be used together with analgesics and NSAIDs. However, in elderly patients, these medications may result in falls because of dizziness. Opioids can be used in patients with severe pain, but care must be taken due to their risk of tolerance and addiction. Due to their unfavorable side effects profile, opioids should be avoided in the management of acute low back pain.

Nonpharmacological Treatment Some restriction of high impact or high load physical activity should be initiated in most people to prevent an aggravation of symptoms. Muscle stretching and strengthening exercises are the recommended to avoid recurrence of pain, but weight lifting, excessive repetitive activities, and contact sports are not recommended. Aerobic exercises are also recommended as soon as the pain disappears. Practical changes of lifestyle should be recommended. The main recommendations are weight loss, smoking cessation, and physical activities. These recommendations may decrease the risk of recurrence and chronic low back pain.

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Other Treatment Modalities Other treatment modalities are still debated, but they can be used in refractory cases. No convincing evidence suggests a benefit of heat over ice treatment and, as such, topical modalities can be based on patient’s response to treatment. Brace prescription is also controversial. Some studies suggest that long-term use may result in muscular weakness, leading to brace dependency and increasing chronic back pain. Other studies shown that brace prescription may have some benefit in acute pain. However, braces are not routinely recommended. Acupuncture and chiropractics may result in some relief, but they are not first-line treatment and the evidence of their benefits is unclear.

Management of Chronic Low Back Pain General Aspects The degree of disability leads to a wide range of clinical presentation. General management is similar to acute pain, including education, rehabilitation, and pharmacological treatment. However, the focus should be centered on nonpharmacological management. Approaching psychosocial comorbidities are of paramount importance, such as depression, psychological problems, work satisfaction, family disruption, drug abuse, and alcoholism. A multidisciplinary approach is mandatory.

Pharmacological Treatment NSAID drugs are prescribed for pain relief in chronic pain, but their side effects are more evident in the longer use. Acetaminophen and muscle relaxants are also prescribed for pain control. Specific medication for chronic pain such as tricyclic antidepressants and neuromodulators (gabapentin/pregabalin) may result in some pain control, but there is no high level of evidence for their use. Opioids should be avoided in chronic pain due to development of tolerance and risk of addiction. Usually the benefit of opioids is only for short term; they lose their efficacy in the long-term use (tolerance) and have an unfavorable side effect profile, including a higher risk of sudden death. Corticoid injections are not recommended for non-specific chronic low back pain, even acute or chronic. In patients with nonspecific chronic low back pain, surgical interventions are restricted to a minority of the cases, and may include facet joint blocks, facet joint denervation, and also spinal fusion, when there is concomitant degenerative disc disease. The results of surgery for chronic low back pain are out of the scope of this chapter, but surgery is the last resource in referral centers for a minority of the patients with persistent and incapacitating pain.

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Nonpharmacological Treatment Other treatment modalities are described in the literature, with scarce evidence of their real effectively. They include manual therapy, acupuncture, massage, mild exercises, yoga, Tai-Chi, stretching therapy, behavior and cognitive therapy, physiotherapy, and hydrotherapy interventions. Physical exercises are strongly recommended and they should be performed preferentially with professional supervision.

Outcomes Smoking, age over 45  years, neurologic impairment, stress, and depression are related to poor control of low back pain. Glotle et al. evaluated 123 patients with acute lumbar pain, and 24% of these patients did not recover in 3 months, leading to chronic pain. Most of the patients will recover from pain in 1 month; however, about 2/3 of these patients will have another episode of acute pain within a 1-year period.

Pearls and Important Messages –– Identification of “red flags” is useful for differentiating primary and secondary low back pain. –– Acute low back pain has generally a benign and transient course. –– Imaging usually is not necessary for acute low back pain without the presence of “red flags.” –– Bed rest is only recommended initially acute low back pain, after some improvement the patient should be most active possible. –– Chronic low back pain is usually associated with depression, smoking, and obesity, as well as psychological issues. –– Social and psychological impact can be determinant of treatment success, especially in chronic low back pain. –– Opioid medications should be avoided in the treatment of acute or chronic low back pain.

Conclusions Low back pain is one of the most common symptoms that leads to medical care. The course is benign and short in the majority of the cases, but identifying underlying diseases is of paramount importance. Emergency doctors must be alert to signs and symptoms of secondary diseases and further investigation. For nonspecific low back pain, medical treatment with common analgesics and NSAIDs is sufficient to treat the pain in the majority of the cases.

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Suggested Readings and References 1. Carey TS, Garrett J, Jackman A, McLaughlin C, Fryer J, Smucker DR.  The outcomes and costs of care for acute low back pain among patients seen by primary care practitioners, chiropractors, and orthopedic surgeons. The North Carolina Back Pain Project. N Engl J Med. 1995;333(14):913–7. https://doi.org/10.1056/NEJM199510053331406. 2. Casazza BA.  Diagnosis and treatment of acute low back pain. Am Fam Physician. 2012;85(4):343–50. 3. Chou R, Qaseem A, Owens DK, Shekelle P, Clinical Guidelines Committee of the American College of Physicians. Diagnostic imaging for low back pain: advice for high-value health care from the American College of Physicians. Ann Intern Med. 2011;154(3):181–9. https://doi. org/10.7326/0003-4819-154-3-201102010-00008. 4. Cifuentes M, Webster B, Genevay S, Pransky G. The course of opioid prescribing for a new episode of disabling low back pain: opioid features and dose escalation. Pain. 2010;151(1):22– 9. https://doi.org/10.1016/j.pain.2010.04.012. 5. Dagenais S, Tricco AC, Haldeman S. Synthesis of recommendations for the assessment and management of low back pain from recent clinical practice guidelines. Spine J. 2010;10(6):514– 29. https://doi.org/10.1016/j.spinee.2010.03.032. 6. Deyo RA, Tsui-Wu YJ.  Descriptive epidemiology of low-back pain and its related medical care in the United States. Spine. 1987;12(3):264–8. 7. Enthoven WT, Roelofs PD, Deyo RA, van Tulder MW, Koes BW.  Non-steroidal anti-­ inflammatory drugs for chronic low back pain. Cochrane Database Syst Rev. 2016;2:CD012087. https://doi.org/10.1002/14651858.CD012087. 8. Eskin B, Shih RD, Fiesseler FW, Walsh BW, Allegra JR, Silverman ME, Cochrane DG, Stuhlmiller DF, Hung OL, Troncoso A, Calello DP.  Prednisone for emergency department low back pain: a randomized controlled trial. J Emerg Med. 2014;47(1):65–70. https://doi. org/10.1016/j.jemermed.2014.02.010. 9. French SD, Cameron M, Walker BF, Reggars JW, Esterman AJ. Superficial heat or cold for low back pain. Cochrane Database Syst Rev. 2006;1:CD004750. https://doi.org/10.1002/14651858. CD004750.pub2. 10. Grotle M, Brox JI, Veierod MB, Glomsrod B, Lonn JH, Vollestad NK.  Clinical course and prognostic factors in acute low back pain: patients consulting primary care for the first time. Spine. 2005;30(8):976–82. 11. Henschke N, Maher CG, Refshauge KM, Herbert RD, Cumming RG, Bleasel J, York J, Das A, McAuley JH. Prevalence of and screening for serious spinal pathology in patients presenting to primary care settings with acute low back pain. Arthritis Rheum. 2009;60(10):3072–80. https://doi.org/10.1002/art.24853. 12. Heuch I, Foss IS. Acute low back usually resolves quickly but persistent low back pain often persists. J Physiother. 2013;59(2):127. https://doi.org/10.1016/S1836-9553(13)70166-8. 13. McGirt MJ, Parker SL, Hilibrand A, Mummaneni P, Glassman SD, Devin CJ, Asher AL. Lumbar surgery in the elderly provides significant health benefit in the US Health Care System: patient-reported outcomes in 4370 patients from the N2QOD registry. Neurosurgery. 2015;77(Suppl 4):S125–35. https://doi.org/10.1227/NEU.0000000000000952. 14. Pengel LH, Herbert RD, Maher CG, Refshauge KM. Acute low back pain: systematic review of its prognosis. BMJ. 2003;327(7410):323. https://doi.org/10.1136/bmj.327.7410.323. 15. Punnett L, Pruss-Utun A, Nelson DI, Fingerhut MA, Leigh J, Tak S, Phillips S. Estimating the global burden of low back pain attributable to combined occupational exposures. Am J Ind Med. 2005;48(6):459–69. https://doi.org/10.1002/ajim.20232. 16. Rasmussen-Barr E, Held U, Grooten WJ, Roelofs PD, Koes BW, van Tulder MW, Wertli MM.  Non-steroidal anti-inflammatory drugs for sciatica. Cochrane Database Syst Rev. 2016;10:CD012382. https://doi.org/10.1002/14651858.CD012382.

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17. Roelofs PD, Deyo RA, Koes BW, Scholten RJ, van Tulder MW (2008) Non-steroidal anti-­ inflammatory drugs for low back pain. Cochrane Database Syst Rev (1):CD000396. doi:https:// doi.org/10.1002/14651858.CD000396.pub3 18. Shamji MF, Mroz T, Hsu W, Chutkan N.  Management of degenerative lumbar spinal stenosis in the elderly. Neurosurgery. 2015;77(Suppl 4):S68–74. https://doi.org/10.1227/ NEU.0000000000000943. 19. van Tulder MW, Touray T, Furlan AD, Solway S, Bouter LM.  Muscle relaxants for non-­ specific low back pain. Cochrane Database Syst Rev. 2003;2:CD004252. https://doi. org/10.1002/14651858.CD004252. 20. Zarghooni K, Beyer F, Siewe J, Eysel P. The orthotic treatment of acute and chronic disease of the cervical and lumbar spine. Deutsches Arzteblatt Int. 2013;110(44):737–42. https://doi. org/10.3238/arztebl.2013.0737.

Peripheral Nerve Surgery

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Roberto S. Martins and Mario G. Siqueira

Definition Peripheral nerves are specialized structures related to neural transmission that connect the brain and spinal cord to the whole body. The peripheral nerve surgery aims to repair these structures that can be damaged by different etiological factors.

Background Considering that nerves are present in the entire body, it is not difficult to understand that these structures can often be injured. Recent data show that about 5% of patients admitted to trauma treatment units present peripheral nerve damage. Peripheral nerve injury causes weakness, loss of sensation, and pain, and their involvement has a significant influence on the patient’s quality of life. Although some milder lesions may recover spontaneously, more severe injuries usually require surgical treatment. The main factor related to the response to surgical treatment is the time between injury and surgery, which makes fundamental the correct diagnosis of these lesions.

Etiology Peripheral nerves can be injured by various causes including trauma, entrapment syndromes, and tumors. Peripheral nerve injury due to sustained external pressure is often reported in patients admitted to a general medical service. Acute ischemia is the mechanism of injury involved when a nerve is compressed against an osseous

R. S. Martins (*) · M. G. Siqueira Peripheral Nerve Surgery Unit, Department of Neurosurgery, Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil © Springer Nature Switzerland AG 2019 A. F. Joaquim et al. (eds.), Fundamentals of Neurosurgery, https://doi.org/10.1007/978-3-030-17649-5_14

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or ligamentous structure. One example is the so-called Saturday night palsy, where an individual, generally under the effects of alcohol or drugs, sleeps for hours in the same position, thereby compressing the lateral aspect of his or her arm, affecting the radial nerve. Another example is peroneal lesions in patients who have endured prolonged anesthesia in a lateral position, with weight on their knee. Traumatic peripheral nerve injuries can be open or closed. For traumatic injury, the main etiological factors are as follows: sharp nerve injury, gunshot wounds, traction injury, and others uncommon etiologies. Sharp nerve injury (injury resulting from clean nerve cut) may be produced by knife, glass, scalpel, shovel, which g­ enerally are caused by open wounds and are associated with nerve section (neurotmesis – see ­classification). In gunshot wounds, the projectile causes generally an indirect injury, by transmission of kinetic energy or heat. These lesions are considered closed injury because they generally do not produce extensive tissue exposure, and the nerve remains in continuity. It can produce either neurapraxia, axonotmesis, or a combined lesion (see classification). Peripheral nerves are relatively resistant to stretch, due to their extensive connective tissue network, but they can be injured if traction is sufficient to compromise tissue integrity. This is the main mechanism in brachial plexus injuries or in knee joint subluxation with traction of the peroneal nerve. Injury by injection, heat, radiation and electrical trauma are unusual etiologies that may injure the peripheral nerves. Injection injuries most commonly involve the sciatic nerve as it passes through the buttock or the axillary nerve in the shoulder. The degree of compromise depends upon factors like the volume injected, the type of drug, the presence of oily solvents, and, especially, the location of the injection. Heat, radiation, and electrical injuries can cause diffuse and extensive nerve damage. Initial management generally is expectant, and refractory cases in which surgical exploration and reconstruction are carried out usually are not accompanied by good functional results.

Epidemiology (Classification) Acute peripheral nerve injuries are one of the complications of trauma affecting extremities, present in 3–10% of patients, depending on its mechanisms. These traumatic injuries are a significant cause of physical disability that affect mainly young adults at working age. On the other hand, entrapment syndromes more frequently affect middle-aged patients. Seddon’s classification is most commonly used to grade the peripheral nerve injury (Fig. 14.1). In this classification, (1) neurapraxia is the mildest form of injury, resulting from focal demyelination conduction blockade. The patient has severe motor loss, but the sensitivity is relatively preserved. Spontaneous recovery will occur in days or weeks (2) Axonotmesis is a more severe degree of injury than neurapraxia, since there is a rupture of axons, but with preservation of the endoneurial tubes and its basal lamina. Spontaneous recovery is still possible, provided that the distance from the lesion to the terminal organs is not too great. The recovery is slow, because under optimum conditions the regenerating axons will grow at a speed of approximately 1 mm per day (3) Neurotmesis is the most severe degree of injury, where both the axons and the supporting connective tissue are disrupted. In this type of injury there is no possibility of spontaneous recovery.

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Epineurium Perineurium Endoneurium

Axon Myelin sheath Normal

Neurapraxia

Axonotmesis

Neurotmesis

Fig. 14.1  Schematic drawing of a normal nerve fiber and the grades of nerve injury according to Seddon’s classification. (Reproduced with permission from: Martins et al. [13]) Table 14.1  Comparison between main findings in Seddon’s and Sunderland’s classification of peripheral nerve injury Seddon Neurapraxia Axonotmesis Neurotmesis

Sunderland I II III IV V

Findings Segmental demyelination Segmental demyelination + damage to the axon Grade II findings + damage to the endoneurial tubes Grade III findings + damage to the perineurium Only the epineurium was preserved Complete nerve section

Peripheral nerve injury may also be classified according to Sunderland’s scale in which two additional degrees of injury were added (Table  14.1). Sunderland’s fourth grade injury is a lesion involving the axon, endoneurium, and perineurium, and fibrosis within the lesion area prevents axonal regeneration. There’s no spontaneous recovery. Sunderland’s fifth grade injury involves the axon, endoneurium, perineurium, and the more external epineurium with entire nerve section.

Physical Examination The detailed clinical history and thorough physical examination of the compromised limb, with careful graduation of sensory and motor impairments, is fundamental in the management of any peripheral nerve injury. This evaluation generally allows, with the aid of electrophysiological studies, an accurate diagnosis of the location and extent of the lesion. The simple observation of the patient’s limbs with consequent deformities can already provide important information regarding the

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lesion. Clinical examination should include the testing of muscle strength of all muscles innervated by the injured nerve and testing of all modes of sensory function, especially of the area supplied exclusively by a specific nerve (autonomic zone of innervation). In addition to establishing whether the functional loss distal to the lesion is complete or incomplete, this initial clinical evaluation is useful as a point of comparison for subsequent examinations. When the percussion of a nerve, distal to the point of injury, causes paresthesias (Tinel’s sign), it can be generally concluded that some sensory axons are continuous, crossing the point of injury. If over time this signal is obtained more distal to the initial point, it is assumed that there is evidence of continuous sensory regeneration towards the distal stump. However, a positive Tinel’s sign implies only the occurrence of regeneration of fine fibers, and nothing informs the examiner about the quantity and possible quality of the new fibers, including the motor one. On the other hand, a complete neural interruption is strongly suggested by the absence of a distal sensitive response (negative Tinel’s sign) after an adequate period of time for the regeneration of fine fibers (4–6 weeks). Thus, a negative Tinel’s sign has greater validity in clinical evaluation than a positive sign. The return of sweating in an autonomous zone means regeneration of sympathetic nerve fibers. This return may precede the sensory or motor return for weeks or months as the autonomous fibers regenerate faster. However, the return of sweating does not necessarily mean that there will be a return of sensory and motor functions. True sensory recovery is also a useful signal, especially when it occurs in autonomous zones, regions where the overlap of innervation of adjacent nerves is minimal. However, this assessment also does not ensure a subsequent motor recovery. A series of provocative signs are described for evaluation of entrapment syndromes. In general, these signs are resulted from increased pressure in the tunnel or region where the nerve is compressed, reproducing positive symptoms (tingling or numbness) in the nerve-related innervation area. The Phalen maneuver (obtained with forced flexion of the wrist) and Durkan’s test (performed by pressure of the examiner’s thumb over the median nerve in the wrist for a period of 30 seconds) are described for examination of carpal tunnel syndrome, for example.

Additional Work-Up Electromyoneurography The main subsidiary test used in the assessment of a peripheral nerve lesion is electromyoneurography (ENMG). This examination should be performed 2–3  weeks after the injury, since before that period Wallerian degeneration (degeneration of axons and endoneurial tubes) distal to the lesion has not been completed and false results may occur. With ENMG it is possible to document the extent of denervation and confirm the distribution pattern related to nerve injury. The ENMG can provide evidence of regeneration weeks or months before any voluntary motor function can

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be detected; however, this examination should be a complement to the clinical examination and, as such, needs to be evaluated in conjunction therewith.

Entrapment Syndromes Due to their prevalence, the knowledge of the main entrapment syndromes is important to the general practitioner. Predisposing factors such as repeated trauma, hyperthyroidism, diabetes mellitus, acute renal failure, acromegaly, inflammatory rheumatic diseases, and other metabolic abnormalities can be identified in some cases. Many entrapment syndromes are described, but the most important are carpal tunnel syndrome and ulnar nerve compression at the elbow. Carpal tunnel syndrome (CTS) is the most common compressive neuropathy, affecting the median nerve in its passage through the carpal tunnel in the wrist. The symptoms (tingling, paresthesia, and pain) are usually intermittent, affecting the palmar aspect of the first three fingers and the distal palmar region. These symptoms usually worsen during sleep hours and typically improve when the hands are shaken. Compression of the ulnar nerve at the elbow is the second most common entrapment syndrome. The symptoms usually set in an insidious way. Unlike CTS, pain is not a prominent symptom. The patient usually presents with tingling and numbness in the palmar and dorsal aspects of the fifth and the medial half of the fourth fingers, in addition to the dorsal and palmar aspects of the medial region of the hand and wrist. There may be motor deficit and atrophy of the intrinsic hand muscles in cases where compression has been more prolonged.

Treatment Entrapment Syndromes When there is mild neurological impairment the initial treatment may be conservative based basically on periodic joint immobilization, such as, for example, using of splint for nocturnal wrist mobilization in CTS. The purpose of the treatment is to avoid definitive lesions, and for this reason, when the surgical treatment is indicated, this should be carried out as soon as possible. Surgical treatment is primarily indicated when there is significant sensory deficit (loss of protective sensitivity in the hand, for example) or motor deficit and/ or muscle atrophy. Basically the surgery consists of widening the osteo-fibrous channel through the section of ligaments or anatomical structures involved in reducing the​​tunnel that contains the nerve (Fig. 14.2). Endoscopy may be a treatment option especially in CTS. Less often, neurectomies are indicated in specific cases (such as in meralgia paresthetica or compression of the femoral cutaneous nerve of the thigh or in the compression of the intermetatarsal plantar nerve or Morton’s neuroma).

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Fig. 14.2 Intraoperative view of median nerve decompression at the left wrist. Note the edges of the flexor retinaculum (∗) after its section allowing visualization of the median nerve (MN). TE thenar eminence

Peripheral Nerve Traumatic Injury The goals of surgical intervention in traumatic injuries of peripheral nerves are as follows: (1) confirm and define the diagnosis; (2) restore nerve continuity; (3) remove any agent by compressing, distorting, or invading the nerve, which may prevent regeneration axonal; (4) provide conditions for axonal regeneration and functional recovery; and (5) relieve pain. The indication for surgery depends on whether the lesion is opened or closed and the time elapsed since the injury. Surgery is indicated early when the lesion is opened, affecting the nerve route, and there is complete neurological deficit. In closed lesions, since there is less possibility of nerve section, an expectant treatment has been recommended due to the possibility of spontaneous recovery. In these cases surgery is usually indicated 3 months after injury. In cases of open lesions and complete nerve section there are two possible situations. Sharp instruments like knives or scalps may acts as causative factors resulting in section with sharp nerve stumps (Fig. 14.3). The repair should be done promptly, if possible within the first three days after injury. Usually the direct coaptation of the nerve ends can be performed with an end-to-end tension free suture. In specific cases, blunt stumps (associated with significant inflammatory process, heterogeneous aspect, and contusion) may be identified during surgery (Fig. 14.4). The repair should not be performed immediately because the inflammatory process that takes place at the nerve ends and extends for up to 3 weeks after injury. In these cases, the repair should be done within the first 3 days after injury. At the second and definitive surgery, the fibrous tissue must be resected by trimming the nerve ends with a scalpel blade until viable fascicles have been exposed. Table 14.2 summarizes the timing of surgery for traumatic injury to peripheral nerves (“Rule of Three”) (Table 14.2).

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Fig. 14.3 Intraoperative view of the ulnar nerve approach at the left wrist. Note the blunt stumps showing regular aspect without significant inflammatory process. L lateral side, P proximal

Fig. 14.4 Intraoperative view of the radial nerve approach at the left elbow. Note the blunt stumps showing significant inflammatory process, heterogeneous aspect, and contusion. L lateral side, P proximal

Table 14.2  The timing of surgery for traumatic injury to peripheral nerves Timing Within 3 days 3 weeks 3 months

Injury Open injuries with nerve section + clean and sharp nerve ends Open injuries with nerve section + blunt/bruised nerve endsa Closed injuriesb, c

Blunt or rugged nerve stumps, associated with significant inflammatory process and contusion b Exceptions to the rule: when there is concomitant vascular injury susceptible to surgery c Gunshot wounds with nerve injury are closed injuries; exception: when there is concomitant vascular injury susceptible to surgery

a

The time elapsed since the injury is another important factor in determining the surgical treatment since there is an ideal period for surgery indication. Due to the trophic changes occurring in the target organs after denervation, motor recovery after 1 year after injury is unlikely and surgery from this period is not recommended.

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Fig. 14.5  Radial nerve reconstruction by using sural nerve grafts (∗). DS distal stump, PS proximal stump

Basically two techniques may be used to reestablish the continuity of an injured peripheral nerve: end-to-end neurorrhaphy (direct neurorrhaphy) and graft reconstruction. Direct neurorrhaphy without interposition of grafts is only possible if approximation of the nerve stumps resulting in tension-free repair, otherwise there will be fibrosis in the repair area and hindrance of axonal progression and regeneration. When direct neurorrhaphy is not possible the continuity of the nerve is restored by using nerve grafts. The nerves used as grafts are usually taken from the patient himself (autologous grafts) and the most used for this purpose is the sural nerve (Fig. 14.5).

Outcome For traumatic injuries, the results of the treatment, regardless of surgeon’s skill and experience, are related to the nerve involved, the level of the injury, the age of the patient, the mechanism of the injury, the distance between nerve stumps, and the period between injury and repair. Considering the upper limb, results from radial nerve repair have been related as better than median nerve repair, whereas the results of median nerve repair have been reported as better compared to those of the ulnar nerve. At the lower limb, surgical treatment of tibial and femoral nerve injury presents better results than peroneal nerve. The need for rehabilitation, which includes pre- and postoperative physical and occupational therapy, is of the utmost importance for a useful recovery, since reinnervation will not produce any return of function due to pain and reduced joint mobility due to proliferation of fibrous tissue.

Suggested Readings and References 1. Ashworth NL. Carpal tunnel syndrome. Am Fam Physician. 2016;15(94):830–1. 2. Assmus H, Antoniadis G, Bischoff C. Carpal and cubital tunnel and other, rarer nerve compression syndromes. Dtsch Arztebl Int. 2015;112(1-2):14–25. 3. Boone S, Gelberman RH, Calfee RP. The management of cubital tunnel syndrome. J Hand Surg [Am]. 2015;40(9):1897–904.

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4. Campbell WW.  Evaluation and management of peripheral nerve injury. Clin Neurophysiol. 2008;119:1951–65. 5. Dvali L, Mackinnon S. The role of microsurgery in nerve repair and nerve grafting. Hand Clin. 2007;23:73–81. 6. Grant GA, Goodkin R, Kliot M.  Evaluation and surgical management of peripheral nerve problems. Neurosurgery. 1999;44:825–40. 7. Houschyar KS, Momeni A, Pyles MN, Cha JY, Maan ZN, Duscher D, et al. The role of current techniques and concepts in peripheral nerve repair. Plast Surg Int. 2016;2016:4175293. 8. Isaacs J. Treatment of acute peripheral nerve injuries: current concepts. J Hand Surg [Am]. 2010;35:491–7. 9. Kline DG, Hackett ER, May PR. Evaluation of nerve injuries by evoked potentials and electromyography. J Neurosurg. 1969;31:128–36. 10. Kline D.  Physiological and clinical factors contributing to the timing of nerve repair. Clin Neurosurg. 1977;24:425–55. 11. Kretchmer T, Antoniades G, Braun V, Rath SA, Richter HP. Evaluation of iatrogenic lesions in 722 surgically treated cases of peripheral nerve trauma. J Neurosurg. 2001;94:905–12. 12. Li R, Liu Z, Pan Y, Chen L, Zhang Z, Lu L. Peripheral nerve injuries treatment: a systematic review. Cell Biochem Biophys. 2014;68(3):449–54. 13. Martins RS, Bastos D, Siqueira MG, Heise CO, Teixeira MJ. Traumatic injuries of peripheral nerves: a review with emphasis on surgical indication. Arq Neuropsiquiatr. 2013;71(10):811–4. 14. Menorca RMG, Fussell TS, Elfar JC. Nerve physiology: mechanisms of injury and recovery. Hand Clin. 2013;29(3):317–30. 15. Rasulic L. Current concept in adult peripheral nerve and brachial plexus surgery. J Brachial Plex Peripher Nerve Inj. 2017;12(1):e7–e14. 16. Robinson LR. Traumatic injury to peripheral nerve. Muscle Nerve. 2000;23:863–73. 17. Sachanandani NF, Pothula A, Tung TH. Nerve gaps. Plast Reconstr Surg. 2014;133:313–9.

Degenerative Lumbar Spine Disease

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Andrei Fernandes Joaquim, Otávio Turolo da Silva, Barlas Benkli, and Ronald A. Lehman Jr

Definition With aging, the intervertebral discs, the facet joints, and the spinal ligaments of the spine degenerate and suffer changes that may result, in some patients, in significant complaints. These clinical manifestations of degeneration of the lumbar spine are known as lumbar degenerative disease (LDD). The most common presentations of LDD are low back pain, lumbar disc herniation (LDH), and lumbar stenosis (LS) (with or without spine instability or deformity that affects different age groups). Spondylosis is the term related to the degenerative changes that occur in the spine with aging, in all its segments. It is a descriptive term once the majority of the population will have spondylosis but will not present any clinical symptoms. The estimated prevalence of degenerative changes in the intervertebral disc in asymptomatic individuals is 37% in the second decade of life but increases to 96% in the eighth decade of life. The prevalence of disc protrusion also increases with aging, from 29% (20s) to 43% (80s). These findings suggest that a large number of patients have degenerative changes in the lumbar spine without symptoms. The high number of patients without clinical symptoms emphasizes the importance of correlating radiological findings with clinical signs and symptoms.

A. F. Joaquim (*) · O. T. da Silva Department of Neurology, Neurosurgery Division, University of Campinas (UNICAMP), Campinas, SP, Brazil B. Benkli Department of Neurology, UT Health, Houston, TX, USA R. A. Lehman Jr Department of Orthopedic Surgery, The Daniel and Jane Och Spine Hospital- NewYork-­ Presbyterian/The Allen Hospital, New York, NY, USA e-mail: [email protected] © Springer Nature Switzerland AG 2019 A. F. Joaquim et al. (eds.), Fundamentals of Neurosurgery, https://doi.org/10.1007/978-3-030-17649-5_15

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Background There is no direct arterial supply to the intervertebral disks. The disks consist of an outer annulus, also known as annulus fibrosus (predominantly composed of fibrous connective tissue) and an inner nucleus, the nucleus pulposus (which is mainly responsible for absorbing impact). With aging and repetitive injuries, the water content decreases, leading to disc tears, herniation, loss of height, and calcification. Due to subsequent overloading of other spinal elements, these changes also result in secondary spinal pathologies, such as osteophyte formation, facet joint degeneration, hypertrophy of facets and ligaments, spondylolisthesis, as well as ligamentous buckling and infolding. These degenerative changes may result in clinical signs and symptoms. The great variability in clinical presentations, varying from a mild and intermittent back pain to a severe and refractory radicular pain with spinal deformity, depends on the degree and severity of the degenerative process, as well as individual factors, such as the presence of coexisting vertebral anomalies, other systemic diseases, comorbidities, etc.

Etiology The etiology of lumbar degenerative disease (LDD) is multifactorial. These factors are normal aging, genetic tendency (probably one of the most important factors), congenital malformations (i.e., congenital canal stenosis, midline closure defects, pars interarticularis defects), trauma, and acute disc herniation, among others. External factors may worsen or exacerbate symptoms, such as heavy work (weightlifting, twisting and bending activities, vibration activities, etc.), obesity, smoking, sedentary lifestyle, social and economic factors, job satisfaction, depression and other mood disorders, etc.

Epidemiology Low back pain is one of the most common causes of work absence and seeking emergency care in the world. The cause for complaints is generally non-specific and mainly attributed to sustained muscle spasm or non-specific degenerative changes. It is estimated that about 13 million physician visits are due to chronic low back pain each year. Symptomatic lumbar disc herniation occurs in about 1–3% of the population, having a higher prevalence among people aged 30–50  years, with a male/female ratio of 2 (Jordon et al). In the vast majority of the cases it affects the L4-L5 or L5-S1 levels (approximately 95% of the cases); on the other hand, herniations in the upper lumbar levels are more common in elderly patients. In 90% of the cases, symptoms disappear in up to 6 weeks and only a minority of the patients will require surgical treatment.

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In older patients, lumbar stenosis is more common than an isolated disc herniation. Of note, lumbar stenosis is the most common cause of spinal surgery in patients in their 60s. Lumbar stenosis is associated with ligamentous and facet joint hypertrophy; in some cases, spondylolisthesis, loss of lumbar lordosis, and scoliosis can also be seen.

Clinical and Radiological Diagnosis Low back pain is defined as a pain in the posterior lumbar region restricted to the area between the rib cages and the buttocks. It is acute when lasting less than 6 weeks. Low back pain secondary to degenerative diseases is usually chronic, with periods of acute exacerbation. With time, the degree and intensity of low back pain increase, especially after some specific activities, such as weightlifting and bending or twisting the lumbar spine. Pain worsening with flexion suggests that disc disease is more prominent, whereas pain that exacerbates with lumbar extension may be secondary to posterior foraminal stenosis, decreasing the diameter of the lumbar foramen and compressing the nerve roots. With time, the nerve roots leaving spinal canal are compressed by disc herniation (protrusion or extrusion), osteophyte formation, or spine instability/deformity, resulting in radicular pain (also known as radiculopathy). Radiculopathy may occur in a single nerve root, with typical irradiation to the cutaneous territory of innervation (dermatome), or may involve multiple nerve roots, either unilaterally or bilaterally. Radicular syndrome is characterized by sensory, motor, and/or sphincter function disturbances. Atypical presentation may occur without a classic pain trajectory. Pain may be selflimited but generally worsens with time, as the degenerative process continues. In younger adults, the clinical presentation is generally due to disc herniation, where a specific lumbar nerve root is compressed by the soft content of the disc (with aging, the water content of the disc decreases which consequently decreases the chances of a disc herniation). Lumbar disc herniation commonly affects L4-L5 or L5-S1 discs, resulting in compression of the nerve roots that compose the sciatic nerve. The typical pain irradiates from the lower back to the posterior portion of the thigh, calf, and the foot. The most typical clinical syndromes of lumbar disc herniation are presented in Table 15.1. Of note, generally disc herniations are located posterolaterally, compressing the nerve root that emerges the level below; the reason for that is that the herniated disc mostly does not compress the nerve root corresponding to the level of disc herniation, since this root generally leaves the foramen just above the correspondent disc, eg., a posterolateral disc herniation of L4-L5 generally compresses the root of L5, that exits through the foramen of L5-S1. In older patients, disc herniation is not so common, since the water content of the discs decreases. As the degenerative process progresses, in more severe cases, central canal stenosis occurs, resulting in neurogenic claudication (NC). This syndrome is characterized by leg or thigh pain exacerbated by walking (claudication) or lumbar extension (causing ischemia of the nerve roots) and decreases with lumbar

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Table 15.1  Clinical characteristics of main lumbosacral radicular syndromes Most common site Involved of the disc nerve root herniation L3 L2-3

L4

L3-4

L5

L4-5

S1

L5-S1

Pain territory Anterior portion of the thigh to the knee Medial portion of the leg

Sensory changes Motor weakness Medial region Quadriceps, iliopsoas, hip adductors of the thigh and knee

Medial portion of the leg Lateral portion Lateral portion of the of the thigh leg, dorsum of and leg, dorsum of the the foot and first toe foot Sole and Posterior lateral portion portion of thigh, calf, and of the foot, 4th and 5th heel toes

Anterior tibialis, quadriceps, hip adductors Toe muscles (flexion and extension), ankle dorsiflexion, hip abductors

Involved reflex Patellar Adductor Patellar Posterior tibialis

Gastrocnemius, biceps Achilles reflexes femoris, gluteus maximus, toe flexors

Adapted from Tarulli and Raynor [23]

a

b

Fig. 15.1  A sagittal (a) and axial (b) lumbar spine MRI T2 sequence showing a disc herniation at L5-S1 with nerve root compression

flexion (that increases the lumbar canal) or rest. Of note, although NC is not rare, central stenosis most commonly courses with lumbar radiculopathy. Finally, spinal deformity may also occur as a degenerative process, due to asymmetric degeneration of the spinal elements and the effects of body weight on lumbar spine. The normal alignment is generally lost, resulting in lumbar kyphosis, and scoliosis as well as lumbar spondylolisthesis (loss of the congruence between two adjacent vertebral body, in a coronal or sagittal plane) (Figs. 15.1 and 15.2).

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Fig. 15.2  A sagittal lumbar spine MRI T2 sequence showing compression of the spinal canal at L12, L23, and L34 and also a listhesis at L45. These degenerative changes result in spinal stenosis

Radiological Diagnosis of Lumbar Degenerative Disease The diagnosis of LDD is generally clinically made, but radiological evaluation is important to rule out differential diagnoses, especially in the setting of red flags. These red flags are presented on patients’ medical history, such as previous history of cancer, rapid and recent weight loss, urinary changes (retention or incontinence), chronic use of corticosteroids or immunosuppressants, severe osteoporosis, extremes of ages, and previous surgeries, and in the physical examination such as leg weakness, sphincter disturbances, or cauda equina syndrome. Additionally, in patients without red flags but with persistent pain (longer than 3 months) refractory to medication and nonsurgical measures (as seen below), radiological evaluation is necessary. The main radiological modalities used for evaluation of LDD are plain radiographs, computed tomography (CT) scan, and magnetic resonance (MR). Plain radiographs  they are extremely useful for evaluation of the spine alignment (local, in the lumbar spine, or entire spine alignment), evaluating fractures and listhesis (as seen in lateral lumbar flexion and extension radiographs that may diagnose dynamic changes). They can also be used for diagnosing osteophytes, facet arthritis, bone spurs, and disc changes such as loss of height.

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MRI  MRI is the best imaging modality for diagnosing disc herniation or root compression, as well as ruling out differential diagnoses, such as tumors, discitis, inflammatory diseases, etc. MRI can characterize properly the process of disc degeneration, end plate changes, ligamentous edema, and facet arthritis, among many other degenerative radiological findings. CT scan  CT scan is sensitive and specific for diagnosing fractures, as well as visualizing osteophytes, foraminal stenosis due to bone spurs, spondylolisthesis, etc. CT scan may also visualize disc herniations and rule out differential diagnoses, but it is less precise than MRI. It can be useful for surgical planning, when instrumentation is necessary to reconstruct the spine, such as when there is scoliosis or spondylolisthesis. CT scan with myelography is important in the diagnosis of nerve root compression in patients with contraindication to MR studies (such as those with peacemakers) or for those who underwent a previous lumbar instrumented fusion (that may result in artifacts on MR images).

Additional Work-Up Evaluation Electromyography and nerve conduction studies may be useful to rule out differential diagnoses, such as peripheral neuropathy or myopathies, as well as to document an evident radiculopathy. Laboratory exams are only used for differential diagnosis and are not routinely used.

Treatment Treatment modalities may be grouped according to the main clinical presentation of LDD. For didactical purposes, we divided the treatment modalities in three groups of clinical syndromes of LDD: 1 . Axial chronic back pain 2. Lumbar disc herniation 3. Lumbar stenosis

Axial chronic back pain Treatment of chronic low back pain is based on the results of initial physical rehabilitation, since most of the time it may decrease the degree of patient’s pain and disability, increasing both muscle strength and flexibility. Education and orientation about potential causes of pain worsening is an integral part of treatment. Patient should be recommended to avoid repetitive activities, weightlifting, and long sitting periods. Patients should be advised to adopt dietary changes to prevent weight gain and to quit smoking.

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Initial pharmacological treatment is based on analgesic prescription. The most commonly used drugs are acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs). They are first-line drugs. Muscle relaxants are also potentially useful, but care should be taken especially in older patients, because they may result in drowsiness and falls. In some cases, opioids are also prescribed, but this class of medication may result in addiction and tolerance over time. Facet joint blocks, as well as disc injections of corticosteroids, may be used in refractory cases. Finally, in carefully selected cases, surgical treatment may be considered if a source of pain, such as severe and focal disc degeneration, is suspected.

Lumbar disc herniation Nonsurgical treatment is recommended in the vast majority of patients, since the pain is generally self-limited with a benign disease course in more than 90% of the cases. Nonsurgical treatment consists of pain medications, especially analgesics and NSAIDs, as well as muscle relaxants. Spinal injections of corticosteroids in the affected nerve root may also result in some pain relief. Physical therapy is also recommended for relieving some muscle spasm and help in the treatment of pain. Absolute rest is not recommended. Surgical treatment, which consists of removal of the disc herniation and decompression of the affected nerve root, is recommended when nonsurgical treatment is not able to control the pain after at least 6 weeks or in the setting of persistent or progressive muscular weakness. Surgery has an acceptable absolute indication in patients with cauda equine syndrome due to massive disc herniation. Surgery for treating lumbar disc herniation may be done using a posterior lumbar midline incision, with or without magnification (microscope or loupes), or using an endoscope. The choice of one technique over another depends on surgeon’s preference and the characteristics of disc herniation.

Lumbar stenosis Nonsurgical treatment is recommended in patients with mild symptoms, generally without motor weakness and with good functional capacity. In patients with moderate or severe symptoms, such as those with functional limitation, refractory pain, and a good correlation between radiological findings and patients’ symptoms, surgical treatment is well accepted. Surgery may improve pain, function, and quality of life. Nonsurgical treatment consists of establishing a physical rehabilitation program and advising the patient about healthy habits, weight loss, and avoiding a sedentary life style. Pain medication is considered, such as analgesics and NSAIDs, as well as other medications for chronic neuropathic pain, such as amitriptyline, nortriptyline, and gabapentin. Spinal injections of corticosteroids to affected nerve roots may also result in some pain relief, at least temporarily.

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Surgical treatment consists of decompressing the affected nerve roots. However, the procedure depends of the radiological findings of each patient: some patients may require reconstructive procedures when lumbar stenosis is associated with spinal deformity, to reestablish spinal alignment, improving final outcomes. Additionally, an instrumented fusion may be necessary when there is spinal instability concomitant to stenosis, such as in those patients with a mobile spondylolisthesis.

Pearls and Important Messages Lumbar degenerative disease may affect the majority of population, generally with low back pain and radiculopathy. Almost all patients have radiological evidences of spinal degeneration, but only a few present with symptoms, and even less patients need a surgical procedure. However, lumbar disc herniation and lumbar stenosis are probably the most common surgeries performed to treat spine diseases in the world. Lumbar disc herniation generally occurs in younger adults affecting L4-L5 and L5-S1 levels in most of the cases, whereas lumbar stenosis affects older patients. Axial lumbar pain is generally managed with physical rehabilitation and adoption of a healthy lifestyle. Pain medication may be used. Surgery is rarely performed for treating axial low back pain. Lumbar radiculopathy secondary to disc herniation generally has a benign course, with symptomatic recovery in days or weeks with nonsurgical treatment. Surgery is indicated for those patients with severe pain refractory to medication and to other nonsurgical measures and for those with progressive neurological deficits or cauda equina syndrome. Lumbar stenosis may require surgery in patients with refractory pain, functional limitation, or muscle weakness. Surgical treatment is based on decompressing the nerve roots, but, in some cases with spinal deformity, it is necessary to reconstruct the lumbar spine to reestablish spinal alignment. Identifying red flags of more severe diseases, ruling out differential diagnoses, and referring patients with important symptoms for specialist evaluation are mandatory to improve patients’ final outcome.

Suggested Readings and References 1. Amundsen T, Weber H, Nordal HJ, Magnaes B, Abdelnoor M, Lilleas F.  Lumbar spinal stenosis: conservative or surgical management?: A prospective 10-year study. Spine. 2000;25(11):1424–35; discussion 1435-1426 2. Boden SD, Davis DO, Dina TS, Patronas NJ, Wiesel SW. Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am. 1990;72(3):403–8. 3. Brinjikji W, Luetmer PH, Comstock B, Bresnahan BW, Chen LE, Deyo RA, Halabi S, Turner JA, Avins AL, James K, Wald JT, Kallmes DF, Jarvik JG. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015;36(4):811–6. https://doi.org/10.3174/ajnr.A4173.

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4. Brox JI, Reikeras O, Nygaard O, Sorensen R, Indahl A, Holm I, Keller A, Ingebrigtsen T, Grundnes O, Lange JE, Friis A. Lumbar instrumented fusion compared with cognitive intervention and exercises in patients with chronic back pain after previous surgery for disc herniation: a prospective randomized controlled study. Pain. 2006;122(1–2):145–55. https://doi. org/10.1016/j.pain.2006.01.027. 5. Brox JI, Sorensen R, Friis A, Nygaard O, Indahl A, Keller A, Ingebrigtsen T, Eriksen HR, Holm I, Koller AK, Riise R, Reikeras O. Randomized clinical trial of lumbar instrumented fusion and cognitive intervention and exercises in patients with chronic low back pain and disc degeneration. Spine. 2003;28(17):1913–21. https://doi.org/10.1097/01.BRS.0000083234.62751.7A. 6. Ciol MA, Deyo RA, Howell E, Kreif S. An assessment of surgery for spinal stenosis: time trends, geographic variations, complications, and reoperations. J Am Geriatr Soc. 1996;44(3):285–90. 7. de Graaf I, Prak A, Bierma-Zeinstra S, Thomas S, Peul W, Koes B. Diagnosis of lumbar spinal stenosis: a systematic review of the accuracy of diagnostic tests. Spine. 2006;31(10):1168–76. https://doi.org/10.1097/01.brs.0000216463.32136.7b. 8. Deyo RA, Ciol MA, Cherkin DC, Loeser JD, Bigos SJ.  Lumbar spinal fusion. A cohort study of complications, reoperations, and resource use in the Medicare population. Spine. 1993;18(11):1463–70. 9. Deyo RA, Gray DT, Kreuter W, Mirza S, Martin BI. United States trends in lumbar fusion surgery for degenerative conditions. Spine. 2005;30(12):1441–5; discussion 1446-1447 10. Deyo RA, Mirza SK, Martin BI, Kreuter W, Goodman DC, Jarvik JG. Trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults. JAMA. 2010;303(13):1259–65. https://doi.org/10.1001/jama.2010.338. 11. Epstein NE, Maldonado VC, Cusick JF.  Symptomatic lumbar spinal stenosis. Surg Neurol. 1998;50(1):3–10. 12. Fairbank J, Frost H, Wilson-MacDonald J, Yu LM, Barker K, Collins R, Spine Stabilisation Trial G. Randomised controlled trial to compare surgical stabilisation of the lumbar spine with an intensive rehabilitation programme for patients with chronic low back pain: the MRC spine stabilisation trial. BMJ. 2005;330(7502):1233. https://doi.org/10.1136/bmj.38441.620417.8F. 13. Gibson JN, Waddell G. Surgery for degenerative lumbar spondylosis. Cochrane Database Syst Rev. 2005;4:CD001352. https://doi.org/10.1002/14651858.CD001352.pub3. 14. Haig AJ, Tong HC, Yamakawa KS, Parres C, Quint DJ, Chiodo A, Miner JA, Phalke VC, Hoff JT, Geisser ME.  Predictors of pain and function in persons with spinal stenosis, low back pain, and no back pain. Spine. 2006;31(25):2950–7. https://doi.org/10.1097/01. brs.0000247791.97032.1e. 15. Joaquim AF, Sansur CA, Hamilton DK, Shaffrey CI. Degenerative lumbar stenosis: update. Arq Neuropsiquiatr. 2009;67(2B):553–8. 16. Jordan J, Konstantinou K, O’Dowd J. Herniated lumbar disc. BMJ Clin Evid. 2011;2011:1118. Published online 2011 Jun 28. 17. Kalichman L, Li L, Kim DH, Guermazi A, Berkin V, O'Donnell CJ, Hoffmann U, Cole R, Hunter DJ. Facet joint osteoarthritis and low back pain in the community-based population. Spine. 2008;33(23):2560–5. https://doi.org/10.1097/BRS.0b013e318184ef95. 18. Malmivaara A, Slatis P, Heliovaara M, Sainio P, Kinnunen H, Kankare J, Dalin-Hirvonen N, Seitsalo S, Herno A, Kortekangas P, Niinimaki T, Ronty H, Tallroth K, Turunen V, Knekt P, Harkanen T, Hurri H, Finnish Lumbar Spinal Research Group. Surgical or nonoperative treatment for lumbar spinal stenosis? A randomized controlled trial. Spine. 2007;32(1):1–8. https:// doi.org/10.1097/01.brs.0000251014.81875.6d. 19. Martin CR, Gruszczynski AT, Braunsfurth HA, Fallatah SM, O'Neil J, Wai EK.  The surgical management of degenerative lumbar spondylolisthesis: a systematic review. Spine. 2007;32(16):1791–8. https://doi.org/10.1097/BRS.0b013e3180bc219e. 20. Osterman H, Seitsalo S, Karppinen J, Malmivaara A.  Effectiveness of microdiscectomy for lumbar disc herniation: a randomized controlled trial with 2 years of follow-up. Spine. 2006;31(21):2409–14. https://doi.org/10.1097/01.brs.0000239178.08796.52. 21. Peul WC, van Houwelingen HC, van den Hout WB, Brand R, Eekhof JA, Tans JT, Thomeer RT, Koes BW, Leiden-The Hague Spine Intervention Prognostic Study Group. Surgery versus

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prolonged conservative treatment for sciatica. N Engl J Med. 2007;356(22):2245–56. https:// doi.org/10.1056/NEJMoa064039. 22. Stokes IA, Frymoyer JW. Segmental motion and instability. Spine. 1987;12(7):688–91. 23. Tarulli AW, Raynor EM. Lumbosacral radiculopathy. Neurol Clin. 2007;25(2):387–405. 24. Vaccaro AR, Garfin SR.  Degenerative lumbar spondylolisthesis with spinal stenosis, a prospective study comparing decompression with decompression and intertransverse process arthrodesis: a critical analysis. Spine. 1997;22(4):368–9. 25. Weinstein JN, Lurie JD, Tosteson TD, Hanscom B, Tosteson AN, Blood EA, Birkmeyer NJ, Hilibrand AS, Herkowitz H, Cammisa FP, Albert TJ, Emery SE, Lenke LG, Abdu WA, Longley M, Errico TJ, Hu SS. Surgical versus nonsurgical treatment for lumbar degenerative spondylolisthesis. N Engl J Med. 2007;356(22):2257–70. https://doi.org/10.1056/NEJMoa070302.

Degenerative Cervical Spine Disease

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Andrei Fernandes Joaquim, Otávio Turolo da Silva, John Rhee, and K. Daniel Riew

Definition Degenerative spinal disease refers to signs and symptoms secondary to changes that occur when the elements of the spine degenerates, such as the discs, facets, and ligaments. It occurs at all spine levels (cervical, thoracic, and lumbar spine). Spondylosis is a broad term used to refer to degenerative changes that occur through the years – a descriptive term instead of a clinical diagnosis, since patients with spondylosis may not have clinical symptoms. Of note, spondylosis is ubiquitous with aging, but a relatively small proportion of people will have significant clinical symptoms.

Background The intervertebral discs do not have a direct blood supply. Degeneration of these structures occurs naturally during life. The pathophysiology of degenerative changes is similar in the entire spine: the normal disc has an outer annulus composed mainly of type 1 collagen and an inner nucleus, which is composed primarily of type 2 collagen. With aging, the disc water content decreases, resulting in loss of height, tears, herniation, and even calcification, as well as a cascade of secondary events, such as compensatory osteophytes, facet joint degeneration with hypertrophy, and even

A. F. Joaquim (*) · O. T. da Silva Department of Neurology, Neurosurgery Division, University of Campinas (UNICAMP), Campinas, SP, Brazil J. Rhee Department of Orthopaedic Surgery and Neurosurgery, Emory University, Atlanta, GA, USA K. D. Riew Department of Orthopedic Surgery, Daniel and Jane Och Spine Hospital – New York Presbyterian Hospital, New York, NY, USA © Springer Nature Switzerland AG 2019 A. F. Joaquim et al. (eds.), Fundamentals of Neurosurgery, https://doi.org/10.1007/978-3-030-17649-5_16

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instability, as well as buckling and infolding of the ligamentum flavum. All these changes may result in clinical symptoms and signs that may be divided into three main clinical presentations: 1 . Cervical axial pain 2. Cervical radiculopathy 3. Cervical myelopathy The degree and severity of the degenerative process, as well as specific individual characteristics (such as congenital canal stenosis, vertebral anomalies, spinal trauma, systemic diseases, etc.), result in a large variability of clinical presentations.

Etiology The etiology of cervical spondylosis (CS) is mainly attributed to degeneration itself. However, we can group the types of symptomatic cervical spondylosis according to the following etiologies: disc herniation (a soft or a hard disc herniation), facet arthrosis, congenital (patients with congenital spinal stenosis and minor degenerative changes may result in symptoms), post-traumatic (induced by spinal trauma, even one with low energy mechanism, increasing the chances of neurological deficits), and ossification of the posterior longitudinal ligament (OPLL). OPLL is commonly seen as an ossification behind the vertebral bodies and its extent is better visualized on a sagittal CT scan.

Epidemiology The incidence of CS increases with age, with some MR studies based on population findings reporting that almost 100% of people over the age of 40 will have some degree of disc degeneration. CS is the most common cause of spinal cord dysfunction in patients older than 55 years. In young adults, spinal cord dysfunction is less common, except in the setting of spinal trauma. Studies report that 51–67% of adults may experience neck and arm pain at some point in life. The incidence of cervical radiculopathy reported in some population studies is about 3.5 cases per 1000 people. Finally, the incidence is similar in men and women, but some authors report that women had higher degrees of disability compared to men. About 2% of all US hospital admissions are secondary to CS. The important fact is that a small subset of the population will have significant axial neck pain, and an even smaller minority will present with cervical radiculopathy or myelopathy requiring surgical treatment. Only 1% to 2% of patients with symptomatic CS will need surgical management, as non-operative treatment is sufficient in the majority of patients.

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Clinical and Radiological Diagnosis The diagnosis of cervical degenerative disease is based on the presence of clinical symptoms and signs, most commonly confirmed with radiological imaging. Herein we present signs and symptoms according to the three main forms of clinical presentation:

Cervical Axial Pain Cervical pain associated with spondylosis is usually episodic, with some periods of exacerbation, generally improving over some days/weeks and exacerbated with mechanical factors, such as motion or position. The cause of pain is not well understood, but it may be attributed to the discs, muscles, greater occipital nerve, and also the facet joints. Pain generally worsens with motion, usually with neck extension. It can be centrally located or radiating to one side, over the shoulder, trapezius or interscapular region. Especially important is pain that exacerbates with rotation in elderly patients – typically without worsening with motion in flexion or in extension – which may be due to severe osteoarthrosis of the atlantoaxial joint. Cervical pain that wakes the patient up during the night, as well as pain associated with cervical swelling or systemic signs (such as fever, weight loss, night sweats, etc.), may be associated with spinal tumor or spinal infection.

Cervical Radiculopathy Anatomically, cervical roots exit above their corresponding pedicles: C6 nerve roots exist just above the pedicle of C6 (between C5 and C6 vertebra), except C8 that exits the spine above the T1 pedicle (between C7 and T1 vertebra, since there are only seven cervical vertebrae in the majority of patients). The T1 nerve root exits between the T1 and T2 vertebrae. Cervical radiculopathy is characterized radiating symptoms in the distribution of the affected nerve root. Symptoms and signs may include sensory, motor, and/or reflex compromise, sometimes in a classical dermatomal distribution or in an atypical presentation due to the large variation in anatomical patterns. Fortunately, the majority of patients with cervical radiculopathy have a self-limited course of symptoms, which allows nonsurgical treatment in more than 95% of the cases. Neck pain, which is often associated with radiculopathy, is generally unilateral and ipsilateral to the radicular symptoms. In Table 16.1, we present the characteristics of the main cervical root compression syndromes. C6 and C7 are the most commonly involved nerve roots, and C2, C3, C4, C8, and T1 are less commonly involved. Of note, the typical presentation of cervical root involvement, as presented in Table 16.1, is not always present, with some presentations being nonspecific, such as interscapular or trapezial pain or occipital headaches. Less commonly, neck pain radiating to the shoulder, without compromising the arms, may be found. With high cervical

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Table 16.1  Cervical radiculopathy – typical characteristics according to the involved root Root Clinical presentation C2 Posterior occipital pain C3 Posterior occipital pain, retro-orbital and temple pain C4 Posterior auricular, temple pain C5 Lateral upper arm pain C6 Pain in the shoulder down to the radial forearm C7 Pain in the interscapular area, shoulder, down the dorsal forearm, axilla, chest C8 Pain in the shoulder, interscapular area, ulnar forearm T1 Pain in the shoulder, interscapular area, ulnar forearm

Motor function – – – Deltoid, biceps, grip Biceps, wrist extension, supination, grip Triceps, wrist flexion, finger extensors, grip Grip, all intrinsic hand muscles Grip, all intrinsic hand muscles

Deep tendon reflex – – – Biceps Brachioradialis Triceps – –

radiculopathy from C3 or C4 root compression, one can get pain that radiates unilaterally behind the ear and into the retro-orbital (C3) or the retro-auricular (C4) region. With C5 impingement, shoulder pain is common. The typical C6 radiculopathy causes pain down into the forearm. With C7 radiculopathy, a common finding is pain over the triceps, into the dorsal forearm, in the axilla and in the chest region. Not unsurprisingly, it is often mistaken for angina. The physical exam is critical to making the diagnosis of cervical radiculopathy. But it must be kept in mind that anatomical variations are common; myotomes and especially dermatomes are highly variable and therefore cannot be relied upon to determine the pathologic level in many cases. Sensory exam to test light touch and pin prick is performed. We also test the following motor groups: shoulder abductors (C5), internal (C6 - T1) and external rotators (C5,6), elbow flexors (C5,6) and extensors (C7), forearm supinators (C6) and pronators (C5 – T1), wrist flexors (C7) and extensors (C6), fingers flexors (C8  - grip strength using a dynamometer) and extensors and strength in the median nerve innervated intrinsic hand muscles (C8, T1: opponens, abductor policis brevis and flexor policis brevis). Provocative tests may exacerbate symptoms of root compression in the cervical spine. The Spurling test is commonly used, consisting of maximal extension of the neck followed by rotation to the involved pain site – this maneuver exacerbates nerve root compression, narrowing the foramen and may reproduce patient symptoms. Provocative tests of the shoulder, elbow and wrists are important to help in differentiating cervical radiculopathy from peripheral nerve entrapment syndromes, brachial plexopathy, thoracic outlet syndrome, and tendinopathies of the shoulder, elbow and wrist. More rarely, and generally associated with other typical syndromes, differential diagnosis may include pain from coronary disease referred to the arm, usually associated with chest pain or respiratory discomfort (Figs. 16.1 and 16.2).

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b

Narrowed disc spaces

Herniated disc

Decreased height of vertebral bodies Bone spurs

Fig. 16.1 (a) This sagittal cervical MRI T2 sequence shows a disc herniation at C6–C7. (b) Illustrative schematic drawing of degenerative disease at the cervical spine: bone spurs, decreased disc, and vertebral body height and narrowed disc spaces

a

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Fig. 16.2  Cervical sagittal MRI T2 sequence of two different patients: (a) cervical spinal cord compression due to disc protrusions and ligament flavum hypertrophy, with a preserved cervical spine lordosis, and (b) cervical kyphosis associated to a narrowed cervical spine canal due to misalignment of vertebral body and signs of instability

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Cervical Myelopathy The clinical course of cervical myelopathy is variable, but typically is not acute. The most common clinical course is a stepwise progression with variable periods of quiescence followed by short periods of deterioration. Patients with mild cervical myelopathy (pathologic reflexes with minimal loss of manual dexterity or gait disturbance) may remain stable for years and so careful observation is not unreasonable. Unfortunately, the data on what happens to these patients after several decades remains unclear. With more severe myelopathy, symptoms rarely improve in the long-term without surgical treatment. Non-surgical treatment may have a role in treating the neck pain component of symptoms, especially in patients with mild myelopathy or who are not candidates for a surgical procedure. Unfortunately, despite surgical treatment and spinal cord decompression, some patients may still worsen. The most common complaints are numbness of the arms and hands, weakness, gait disturbance, neck and arm pain, coordination difficulties, loss of dexterity, neck stiffness and, finally, sphincter disturbances, in the most severe cases. On physical examination, patients may have long-tract signs, such as Babinski’s, Hoffmann’s hyperreflexia and clonus. Making things more difficult, all of these signs may be present in individuals without myelopathy and conversely, many patients with myelopathy do not exhibit any of these signs. Different clinical scales to grade the degree of severity of CM are found in the spine literature. Basically, patients may range from those with only mild symptoms, being able to walk and work without any assistance, to those who are severely compromised, bedridden and requiring full assistance.

Radiological Diagnosis of Cervical Degenerative Disease Although the diagnosis is based on clinical findings and patients’ complaints, radiological investigation is necessary for confirmation and to rule out the other causes in the differential diagnosis. For cervical axial pain and early cervical radiculopathy, without signs and symptoms of spinal cord involvement, radiological evaluation may be postponed, since the vast majority of patients will have improvement of symptoms in a few weeks. Imaging can then be obtained in those who fail to improve or present with significant neurologic deficits. The main imaging modalities used for diagnosis of cervical degenerative disease are: plain radiographs, CT scan and MR. Plain radiographs are useful for assessing the spinal alignment, excluding fractures and instabilities (especially in patients with previous trauma history) and also for assessing for the presence of osteophytes, facet hypertrophy and bone spurs. Discs may demonstrate loss of height on the lateral view, and foraminal stenosis may be seen on oblique views. The AP view demonstrates the presence of uncinate hypertrophy, which may result in root compression. MR is the study of choice to identify spinal canal stenosis and/ or nerve root

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compression, cord signal change and to rule out differential diagnoses, such as spinal tumors, inflammatory diseases. MR may also demonstrate disc herniations and their exact location and is important for surgical planning. MR can also identify discs and facets that are autofused. Finally, CT scan is important to evaluate bony pathology, such as ossification of the spinal elements, facet arthrosis, and bony foraminal stenosis, and to confirm areas of autofusion. Although the CT is inferior to MR in visualizing the spinal cord, it is especially useful for evaluation of spinal fractures. In patients with contraindication to MR, CT myelography may help to identify spinal compression.

Additional Work-Up Evaluation Nerve conduction studies/electromyography: these exams are poor in demonstrating myelopathy but may show evidence of cervical radiculopathy, even though the physiological level may not correspond to the anatomical level of compression. In other words, their utility in actually diagnosing symptomatic cervical root levels may be limited. These exams are especially useful for ruling out differential diagnoses, especially compressive peripheral neuropathies, Parsonage-Turner syndrome, and motor neuron diseases, such as amyotrophic lateral sclerosis.

Treatment The initial treatment of cervical axial neck pain and/or cervical radiculopathy is generally based on nonsurgical measures, since the majority of patients will have clinical improvement with a favorable outcome. An optimal nonsurgical regimen has not been clearly established, but many regimens have been described and proposed with successful results, such as physical therapy, traction, and short-term immobilization of the neck with a cervical brace (which may diminish inflammation and decrease muscle spasms), among others. Medical management of the acute pain includes nonsteroidal anti-inflammatory drugs, steroids, and analgesics. Gabapentin and pregabalin are anti-epileptic medications that are widely used off label to treat nerve pain and are often efficacious for radicular pain. In selected cases, narcotic analgesics may be used, but extreme caution should be taken to avoid addiction and tolerance, weaning off as soon as possible. Muscle relaxants are also associated with some pain relief, but may increase the incidence of falls, especially in older patients. Cervical steroid injections guided by fluoroscopy may help to improve symptoms and also to identify the source of the pain. In chronic pain syndromes, prescription of antidepressants and anticonvulsants are associated with some pain relief, even though the evidence for their use in cervical radiculopathy is low. The most commonly used medications used in this category are amitriptyline and gabapentin.

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Surgical Treatment Cervical radiculopathy – surgery is indicated for patients with severe or progressive neurological deficits. For muscle weakness we recommend urgent surgery for patients with loss of antigravity strength. For 3–4 out of 5 muscle strength, we recommend trying non-operative treatment for 6–12 weeks for weakness of the deltoid, biceps, and triceps and no more than 6  weeks for intrinsic hand muscles. This is because the loss of intrinsic hand muscles is rapid and devastating for most patients. Recovery is also very slow because the nerve may have to regenerate from the cervical spine all the way down to the hand. For numbness, we recommend surgery for patients with constant of near-constant numbness in an area that would be bothersome to the patient if it became permanent. For pain, we recommend surgery when the patient has tried all non-operative treatment options that they can tolerate and are unable to tolerate the pain. Classic literature recommends at least six weeks of nonsurgical management of pain prior to surgery. We typically recommend waiting at least 3 months, if the patient can tolerate the pain. Surgical treatment for cervical radiculopathy consists of decompressing the affected nerve root, which can be performed either by an anterior or a posterior cervical spine approach. Since most of the pathologies are anterior to the cord (osteophytes, disc herniation, bone spurs), anterior cervical discectomy and fusion is generally the most common surgical procedure to treat cervical radiculopathy. More recently, for selected patients, such as those without severe degenerative changes, without segmental instability, and with soft disc herniation, cervical arthroplasty may be performed. This procedure is also performed by an anterior cervical approach, potentially preserving motion of the index level treated. Finally, posterior foraminotomy is another option for certain patients with cervical radiculopathy, in which dorsal enlargement of the neuroforamen is performed in order to relieve nerve root compression. Cervical degenerative myelopathy – surgical treatment is usually the procedure of choice for patients with moderate to severe disability, since evidence for non-­ operative treatment as a primary modality for myelopathy is lacking. For mild cases, although some authors recommend nonsurgical treatment or observation, better surgical results may be obtained for patients with early symptoms, before severe structural injury to the spinal cord occurs. Surgical treatment for myelopathy may be also performed by an anterior cervical approach (discectomy, removing the disc; corpectomy, removing the vertebral body; and arthroplasty, adding a mobile device in the disc placed in selected cases) or a posterior spine procedure to decompress the spine (a laminectomy that consists in removal of the lamina, with or without fusion, or a laminoplasty that consists in expanding the spinal canal). Many variables are involved in the choice of the best surgical treatment, such as the number of levels involved, site of spinal cord compression, previous surgeries, instability, alignment, the presence/absence of neck pain, etc. The choice of approach depends on specific patient radiological characteristics, as well as surgeon experience and preference.

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Pearls and Important Messages Although cervical spondylosis is ubiquitous with aging, symptomatic cervical radiculopathy or myelopathy is much less common. Many people have degenerative radiographic changes without significant clinical symptoms  – these patients can generally be observed. Cervical axial pain is generally managed nonsurgically. Surgery is rarely performed to treat isolated axial neck pain in the absence of radiculopathy, myelopathy, or deformity. Cervical radiculopathy generally has a benign course, with improvement in days to weeks in the majority of patients. Surgery is reserved for those patients with severe pain refractory to medication and nonsurgical measures or those with progressive, significant neurological deficits. Cervical myelopathy due to spondylotic changes is the most common cause of spinal cord dysfunction in older adults. It is generally treated surgically, especially in those with progressive worsening. Recognizing signs and symptoms of severity are important for early referral of these patients for specific care, since surgical treatment may be necessary in some patients to improve or at least maintain neurological function.

Suggested Readings and References 1. Alafifi T, Kern R, Fehlings M. Clinical and MRI predictors of outcome after surgical intervention for cervical spondylotic myelopathy. J Neuroimaging. 2007;17(4):315–22. https://doi. org/10.1111/j.1552-6569.2007.00119.x. 2. Benzel EC, Lancon J, Kesterson L, Hadden T.  Cervical laminectomy and dentate ligament section for cervical spondylotic myelopathy. J Spinal Disord. 1991;4(3):286–95. 3. Fehlings MG, Barry S, Kopjar B, Yoon ST, Arnold P, Massicotte EM, Vaccaro A, Brodke DS, Shaffrey C, Smith JS, Woodard E, Banco RJ, Chapman J, Janssen M, Bono C, Sasso R, Dekutoski M, Gokaslan ZL.  Anterior versus posterior surgical approaches to treat cervical spondylotic myelopathy: outcomes of the prospective multicenter AOSpine North America CSM study in 264 patients. Spine. 2013;38(26):2247–52. https://doi.org/10.1097/ BRS.0000000000000047. 4. Fehlings MG, Wilson JR, Kopjar B, Yoon ST, Arnold PM, Massicotte EM, Vaccaro AR, Brodke DS, Shaffrey CI, Smith JS, Woodard EJ, Banco RJ, Chapman JR, Janssen ME, Bono CM, Sasso RC, Dekutoski MB, Gokaslan ZL. Efficacy and safety of surgical decompression in patients with cervical spondylotic myelopathy: results of the AOSpine North America prospective multi-center study. J Bone Joint Surg Am. 2013;95(18):1651–8. https://doi.org/10.2106/ JBJS.L.00589. 5. Fouyas IP, Statham PF, Sandercock PA. Cochrane review on the role of surgery in cervical spondylotic radiculomyelopathy. Spine. 2002;27(7):736–47. 6. Gandhoke G, Wu JC, Rowland NC, Meyer SA, Gupta C, Mummaneni PV. Anterior corpectomy versus posterior laminoplasty: is the risk of postoperative C-5 palsy different? Neurosurg Focus. 2011;31(4):E12. https://doi.org/10.3171/2011.8.FOCUS11156. 7. Grob D. Surgery in the degenerative cervical spine. Spine. 1998;23(24):2674–83. 8. Harrop JS, Naroji S, Maltenfort M, Anderson DG, Albert T, Ratliff JK, Ponnappan RK, Rihn JA, Smith HE, Hilibrand A, Sharan AD, Vaccaro A. Cervical myelopathy: a clinical and radiographic evaluation and correlation to cervical spondylotic myelopathy. Spine. 2010;35(6):620– 4. https://doi.org/10.1097/BRS.0b013e3181b723af.

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9. Joaquim AF, Appenzeller S.  Cervical spine involvement in rheumatoid arthritis--a systematic review. Autoimmun Rev. 2014;13(12):1195–202. https://doi.org/10.1016/j. autrev.2014.08.014. 10. Joaquim AF, Cheng I, Patel AA. Postoperative spinal deformity after treatment of intracanal spine lesions. Spine J. 2012;12(11):1067–74. https://doi.org/10.1016/j.spinee.2012.09.054. 11. Joaquim AF, Ghizoni E, Anderle DV, Oliveira E, Tedeschi H. Axis instrumentation: surgical results. Arq Neuropsiquiatr. 2012;70(11):857–63. 12. Kadanka Z, Bednarik J, Novotny O, Urbanek I, Dusek L. Cervical spondylotic myelopathy: conservative versus surgical treatment after 10 years. Eur Spine J. 2011;20(9):1533–8. https:// doi.org/10.1007/s00586-011-1811-9. 13. Kaminsky SB, Clark CR, Traynelis VC. Operative treatment of cervical spondylotic myelopathy and radiculopathy. A comparison of laminectomy and laminoplasty at five year average follow-up. Iowa Orthop J. 2004;24:95–105. 14. Kato S, Oshima Y, Oka H, Chikuda H, Takeshita Y, Miyoshi K, Kawamura N, Masuda K, Kunogi J, Okazaki R, Azuma S, Hara N, Tanaka S, Takeshita K. Comparison of the Japanese Orthopaedic Association (JOA) score and modified JOA (mJOA) score for the assessment of cervical myelopathy: a multicenter observational study. PLoS One. 2015;10(4):e0123022. https://doi.org/10.1371/journal.pone.0123022. 15. LaRocca H. Cervical spondylotic myelopathy: natural history. Spine. 1988;13(7):854–5. 16. Law MD Jr, Bernhardt M, White AA 3rd. Cervical spondylotic myelopathy: a review of surgical indications and decision making. Yale J Biol Med. 1993;66(3):165–77. 17. Macdonald RL, Fehlings MG, Tator CH, Lozano A, Fleming JR, Gentili F, Bernstein M, Wallace MC, Tasker RR. Multilevel anterior cervical corpectomy and fibular allograft fusion for cervical myelopathy. J Neurosurg. 1997;86(6):990–7. https://doi.org/10.3171/jns.1997.86.6.0990. 18. Matz PG, Anderson PA, Holly LT, Groff MW, Heary RF, Kaiser MG, Mummaneni PV, Ryken TC, Choudhri TF, Vresilovic EJ, Resnick DK, Joint Section on Disorders of the S, Peripheral Nerves of the American Association of Neurological S, Congress of Neurological S. The natural history of cervical spondylotic myelopathy. J Neurosurg Spine. 2009;11(2):104–11. https:// doi.org/10.3171/2009.1.SPINE08716. 19. Nouri A, Martin AR, Mikulis D, Fehlings MG. Magnetic resonance imaging assessment of degenerative cervical myelopathy: a review of structural changes and measurement techniques. Neurosurg Focus. 2016;40(6):E5. https://doi.org/10.3171/2016.3.FOCUS1667. 20. Nurick S. The natural history and the results of surgical treatment of the spinal cord disorder associated with cervical spondylosis. Brain. 1972;95(1):101–8. 21. Nurick S. The pathogenesis of the spinal cord disorder associated with cervical spondylosis. Brain. 1972;95(1):87–100. 22. Patel AA, Spiker WR, Daubs M, Brodke DS, Cannon-Albright LA.  Evidence of an inherited predisposition for cervical spondylotic myelopathy. Spine. 2012;37(1):26–9. https://doi. org/10.1097/BRS.0b013e3182102ede. 23. Satomi K, Nishu Y, Kohno T, Hirabayashi K.  Long-term follow-up studies of open-door expansive laminoplasty for cervical stenotic myelopathy. Spine. 1994;19(5):507–10. 24. Tetreault LA, Kopjar B, Vaccaro A, Yoon ST, Arnold PM, Massicotte EM, Fehlings MG. A clinical prediction model to determine outcomes in patients with cervical spondylotic myelopathy undergoing surgical treatment: data from the prospective, multi-center AOSpine North America study. J Bone Joint Surg Am. 2013;95(18):1659–66. https://doi.org/10.2106/JBJS.L.01323. 25. Wilson JR, Fehlings MG, Kalsi-Ryan S, Shamji MF, Tetreault LA, Rhee JM, Chapman JR. Diagnosis, heritability, and outcome assessment in cervical myelopathy: a consensus statement. Spine. 2013;38(22 Suppl 1):S76–7. https://doi.org/10.1097/BRS.0b013e3182a7f4bf. 26. Wilson JR, Patel AA, Brodt ED, Dettori JR, Brodke DS, Fehlings MG. Genetics and heritability of cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament: results of a systematic review. Spine. 2013;38(22 Suppl 1):S123–46. https://doi.org/10.1097/ BRS.0b013e3182a7f478. 27. Wilson JR, Tetreault LA, Kim J, Shamji MF, Harrop JS, Mroz T, Cho S, Fehlings MG. State of the art in degenerative cervical myelopathy: an update on current clinical evidence. Neurosurgery. 2017;80(3S):S33–45. https://doi.org/10.1093/neuros/nyw083.

Brain Tumors in Adults

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Victor Leal de Vasconcelos, Marcelo Gomes Cordeiro Valadares, and Helder Tedeschi

Epidemiology, Classification, and Diagnosis of Brain Tumors Brain tumors are a group of potentially morbid neoplasms that arise from the constituent cells of the brain (primary tumors) or from systemic tumors that have spread to the brain (brain metastases). The clinical manifestations of brain tumors are usually related to the anatomical structures of the region of the brain involved. The World Health Organization (WHO) has classified brain tumors in a variety of types according to their histologic and molecular characteristics. Currently, the diagnosis and response to treatment is basically evaluated by magnetic resonance imaging (MRI). This chapter deals with the epidemiology, classification, neuroimaging evaluation, and management of brain tumors.

Epidemiology Brain tumors account for approximately 2% of all cancers. According to the Central Brain Tumor Registry of the United States (CBTRUS), the overall average annual age-adjusted incidence for primary brain and central nervous system (CNS) tumors was 21.42 per 100,000 (2007–2011). Data from 2009 to 2013 from the CBTRUS from incident brain and other CNS tumors shows 68% (n = 250,211) nonmalignant

V. L. de Vasconcelos · M. G. C. Valadares (*) · H. Tedeschi Division of Neurosurgery - Department of Neurology, University of Campinas, Campinas, SP, Brazil e-mail: [email protected]

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Fig. 17.1  Gioblastoma multiforme. (a) Axial postcontrast T1 – weighted image shows an heterogeneous, irregular, enhancing tumoral mass centered within the right frontal lobe, surrounding by edema with mass effect. (b) Axial T2 – weighted hyperintese image showing the same lesion

and 32% (n = 117,906) malignant tumors. The most common primary brain tumor is the nonmalignant meningioma representing 36.2% of all tumor types, followed by the nonmalignant pituitary tumors (15.9%). The most common malignant primary brain tumor is the glioblastoma, accounting for 14.9% of all central nervous system tumors (Fig. 17.1). Around 10% to 15% of patients who have cancer will present with a brain metastasis during the course of their illnesses. Brain metastases are 10 times more prevalent than primary brain tumors. Carcinomas from the lungs, breasts, kidney, and colon and rectum, along with melanomas, are the commonest tumors responsible for metastases to the brain in adults. In children metastases usually originate from sarcomas, neuroblastomas, and germ cell tumors. Brain tumors have marked differences in incidence among different age groups. They are the most common cancer site among children younger than 14 years with 5.47 cases per 100,000 population, the third most common in adolescents and young adults (15–39 years) with 10.71 per 100,000 and only the ninth most common cancer site in adults aged 40+ years. Mortality data follows a similar pattern. Brain and CNS tumors are the most lethal cause of cancer in those aged 0–14 years with an average annual age-adjusted mortality of 0.70 per 100,000. The most common cause of death in general in this group is perinatal complications (19.86 per 100,000). In adolescents and young adults, mortality rate is 0.95 per 100,000 (accidents are the most common cause of death in this group). In people older than 40 years brain CNS tumors have a mortality of 8.89 per 100,000 whereas heart attack kills 397.40 people every 100,000.

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Gender differences are also a feature in the epidemiology of brain tumors. There is a female predominance in the overall incidence among all types of primary brain tumors almost reaching 1.4:1. This is due to a higher incidence of nonmalignant tumors in females (64.2% compared to 35.8% in males), whereas malignant tumors were diagnosed more frequently in males (55.2% compared to 44.8% in females). Gliomas are more frequent in males, and meningiomas (usually nonmalignant) are more frequent in females. Figure 17.2 illustrates a low-grade glioma and Fig. 17.3 a meningioma. The incidence of meningiomas, pituitary tumors, and craniopharyngiomas is significantly higher in Afro descendants than in whites and other race groups, and the incidence rates of gliomas are two or more times greater in whites than in Afro descendants. There is no strong evidence of geographically related risk factors. Genetic factors, otherwise, are in some cases strongly associated with tumors and usually present with very rare gene or chromosomal abnormalities (i.e., tuberous sclerosis, neurofibromatosis types 1 and 2, Li–Fraumeni cancer family syndrome, von Hippel–Lindau syndrome, Turcot syndrome, etc.). Infections play a minor role a

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Fig. 17.2  Low grade glioma. (a) Axial T2  – weighted and (b) axial fluid-attenuated inversion recovery (FLAIR) revealing a cortical and subcortical expansive lesion of the left frontal lobe (c) intraoperative view. Resection was performed with the patient awaken according to functional boundaries identified at cortical and subcortical zones (number tags)

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Fig. 17.3  Meningioma. (a) Axial postcontrast T1- weighted image depict homogeneos, regular, enhancing mass centered within the left occipital lobe, with mass effect and without surrounding edema. (b) Sagital T1 precontrast and (c) coronal T2 – weighted hyperintese image

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in CNS tumor development. HIV has been shown to increase the risk of CNS lymphoma. Other virus and parasites failed to show solid evidence of relationship with CNS tumors. Occupational and industrial hazards could not been proved as causal factors for the development of brain and CNS tumors. To date no strong relationship between head trauma and brain tumors has been shown. Therapeutic ionizing radiation (radiotherapy) is also strongly associated with the development of intracranial tumors. Prophylactic CNS radiation for acute lymphoblastic leukemia and even low-dose radiation used for treatment of tinea capitis have been associated with meningiomas, nerve sheath tumors, and gliomas. Cellular telephones, radio, and electromagnetic fields in general have been studied but not been proved to be associated with an increased risk of CNS tumors.

Classification The most used reference classification for brain and CNS tumors was published by the World Health Organization (WHO) in 2016 (Table 17.1). In this classification, brain and CNS tumors were divided into 17 groups with a total of more than 150 different subtypes. Every subtype has a different spectrum of clinical manifestations, prognosis, and treatments. This last review of the WHO classification was considered a major update. For the first time, molecular parameters were included to be used together with the classic histological elements. This change advanced towards the knowledge that tumor heterogeneity is not present only between different histology and locations but also within the same histology with important clinical and therapeutic consequences.

WHO Grading of Tumors of the Central Nervous System Tumor grading uses histological and genetic features found on tissue samples obtained from biopsies or surgical removal to assign numbers from I to IV according to the potential of malignancy in a specific tumor (Table 17.1). Grade I lesions are tumors of a low proliferative potential. If these tumors grow in areas where Table 17.1  WHO grading of tumors of the central nervous system Who grade I

II III IV

Histological definition Circumscribed, well differentiated Benign phenotype Low infiltrative potential Potentially curative surgery Moderate cellularity No anaplasia and low mitotic index Generally infiltrative Intense cellularity and anaplasia Very high mitotic index Very infiltrative Similar to grade III but with vascular proliferation or necrosis Rapid progression

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surgery can be performed safely there is a potential for cure after surgical resection alone. Grade II lesions also have low proliferative activity but are infiltrative and often recur after surgical removal. Some grade II entities tend to progress to higher grades of malignancy due to the cumulative mutations that happen during cell division. Grade III lesions have clear histological evidence of malignancy and most tumors in this group receive chemoradiation therapy. Grade IV lesions are the most malignant group. These tumors hold enormous mitotic activity and are necrosis-­ prone and often associated with rapid progression and recurrence after surgery and a fatal outcome.

Clinical Presentation Brain tumors may cause clinical manifestations due to the local mass effect, perilesional edema, local brain invasion, and increased intracranial pressure. The signs and symptoms are determined by the localization and function of the normal brain tissue involved and may be divided into focal and generalized neurological manifestations. Among primary tumors, the most common symptoms are progressive neurological functional loss (68%), with motor weakness being the most common focal complaint, headache (54%), and seizures (26%). Generalized manifestations: • Headache is a common complaint and estimates range between 33% and 71% of brain tumor patients. The pattern of early morning pain is the classic manifestation, although it is uncommon and may be associated with other conditions such as obstructive sleep apnea and chronic obstructive pulmonary disease. Bifrontal localization may be present, and it can be localized on the same side of the tumor. Most frequently, brain tumor headache is associated with visual impairment, nausea, papilledema, seizures, and other focal neurological signs, as well as a change in a preexisting headache. These comorbid symptoms represent “red flags” and require further investigation (Table  17.2). Brain tumor headache is more frequently described as a dull and aching rather than a pulsating pain, which mimics tension-type headaches (69%–88%) more than any other. It tends to be worse at night and may awake the patient, which is thought to be due to the Table 17.2  Signs requiring further investigation Focal neurological symptoms other than visual or sensory aura Headaches not resembling any of the primary headaches Headaches associated with nausea/vomiting in patients without migraine Sudden onset headache or persistent headache associated with no family history of migraine Persistent headaches associated with substantial episodes of confusion, disorientation, or emesis Papilledema, diplopia, blurred vision Hemicrania associated with contralateral neurological symptoms Headaches that have changed in character/quality Headaches that awaken the patient repeatedly from sleep or occur immediately on waking Rapid onset of headache after strenuous exercise

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increase of PCO2, a potent vasodilator, during sleep. Valsalva maneuvers and change in body position is frequently associated with reports of worsening of the headache. Considering primary tumors, headache was the more frequently reported symptom (75% to 80%) in those tumors likely to produce ventricular obstruction and hydrocephalus (germinomas, hemangioblastomas, ependymomas, and medulloblastomas). When categorized by tumor location, headache was most often observed in cases of cerebellar tumors (70%), where obstructive hydrocephalus is more likely to occur. Seizures are a common symptom of patients with brain tumors. Seizures are an added burden with a negative impact on quality of life, affecting independence and activities of daily living, such as work and driving. It is particularly common with slow-growing gliomas, with meningiomas located in the convexity of the brain, and with metastatic brain tumors. Among patients with primary tumors, it is more common in low-grade gliomas. In a review of 1028 patients with primary tumors, the prevalence of seizures was 49%, 69%, and 85% among patients with glioblastoma, anaplastic glioma, and low-grade glioma, respectively. Seizures may be present at the time of the diagnosis or develop subsequently. In focal seizures, clinical presentation is dependent on the tumor location. Patients with occipital lobe tumors may present symptoms associated with visual disturbances, behavioral changes are common in temporal lobe lesions, and motor signs such as tonic–clonic movements involving the extremities are typical in frontal lobe tumors. Although patients may present either with generalized or focal seizures, any seizure focus can cause a generalized manifestation. When categorized by tumor location, seizures were most frequently connected with frontal lobe tumors (36%). Cognitive dysfunction is a significant issue in patients with newly diagnosed brain tumors, even when in good neurological condition, and before surgical resection or any other treatment modalities are initiated. Patients usually complain of low energy, fatigue, and an urge to sleep. Memory problems and mood and personality changes are commonly presented. It may affect the patient’s social and professional abilities and ultimately may lead to a loss of self-­sufficiency and quality of life. In addition, neurocognitive dysfunction may affect the patient’s decision to pursue therapy. As far as neurosurgical oncology technology improves in extent of tumor resection, progression-free survival, and overall survival, neurocognitive dysfunction becomes more relevant. Signs and symptoms due to increased intracranial pressure (ICP): Nausea and vomiting are usually caused by increased ICP at the area postrema, located at the inferior end of the floor of the fourth ventricle, in the medulla oblongata, usually occurring in the context of minimal systemic complaints, associated with other neurological symptoms, and may be subtle or in association with abrupt change of body position. When related to hydrocephalus, it is commonly presented in association with headache, gait disturbance, vertigo, and papilledema.

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Focal symptoms: • Aphasia can happen when the lesion is adjacent to the speech areas, usually located in the frontal and parietal lobes of the dominant hemisphere. It may result from an infiltration by the tumor or displacement by mass effect or edema. This symptom is not restricted to vocalization and may be confused with manifestation of dementia or psychiatric disorders. Among patients with subacute psychosis without preceding manifestations, further investigation is mandatory in order to rule out neurological causes. • Muscle weakness is the most frequent focal symptom. May be subtle or slowly progressive. It can originate from direct tumor invasion or may be caused by edema near the motor cortex or its descending fibers. A response to dexamethasone usually means that the weakness is caused by edema. Transient weakness may represent a postictal state, such as in Todd’s paralysis. Among primary tumors, progressive neurological functional loss was most frequent in cases of invasive and destructive GBM (78%), and, when categorized by tumor location, progressive functional loss was associated mostly with parietal lobe tumors (75%), where so many cognitive and performance functions reside. • Sensory loss may result from damage to the primary sensory cortex. The type of deficit depends on the specific location of the tumor. Vision impairment, spatial orientation, and lack of coordination are examples of sensory loss manifestations. These sensory deficits usually do not respect dermatome distribution.

Management A thorough evaluation of the patient’s medical history, neurological examination, and diagnostic neuroimaging is fundamental for the proper management of a patient with a brain tumor. Based upon the area of the brain involved, specific tests such as visual fields evaluation or hearing tests may be necessary. Lumbar puncture could be helpful in determining the spread of certain tumors from the brain to the spinal cord or to diagnose tumors that secrete substances that can be measured in the cerebrospinal fluid. It is important to note that lumbar punctures should only be performed after neuroimaging studies have not shown any signs of increased intracranial pressure. Diagnostic Neuroimaging  The diagnostic neuroimaging and specific treatment of brain lesions is dependent on the etiology of the tumor. Although neuroradiology imaging cannot definitively establish the specific histology, it is the major diagnostic modality in the evaluation of brain tumors. Several imaging modalities can be helpful when performing the initial work-up. Magnetic resonance imaging (MRI) is specially helpful in localizing the tumor and the surrounding structures. Gadoliniumenhanced imaging may provide additional information that suggests the specific tumor type. In addition, with recent advances in structural and functional brain imaging techniques, with quantitative cellular, hemodynamic, and metabolic data,

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physicians can determine the tumor’s biologic activity and can get critical information for preoperative planning. Complementary techniques of MRI are also used to assess the effects of treatment, differentiate tumor recurrence from radiation necrosis, and determine tumor progression. Computed tomography has been largely replaced by MRI but is still helpful to detect bone or vascular involvement, in patients for whom MRI is contraindicated or in an emergency situation, when the images need to be quickly obtained. Clinical Management  Steroids have been widely used in cancer therapy and are particularly beneficial in brain cancer patients with significant peritumoral edema and associated neurological deficits. The efficacy of steroids in reducing the tumor-­ associated edema has been well demonstrated. Approximately 70% of patients with cerebral metastases symptomatically improve after starting with steroids. Administration of steroids 1–2 days prior to an elective surgical procedure has the potential to reduce edema formation and to improve clinical condition by the time of the craniotomy. The use of steroids is also associated with potentially serious side effects such as gastrointestinal bleeding, myopathy, osteoporosis infections, and neuropsychiatric manifestations. Dexamethasone has become the drug of choice in neurooncology, in part owing to its long half-life, low mineralocorticoid activity, and a relatively low tendency to induce psychosis. Typically, large doses of 10–20  mg of dexamethasone are given intravenously at initial presentation of patients with acute neurological symptoms secondary to a brain tumor surrounded by vasogenic edema. Antiepileptic Drugs  Up to 60% of people with brain tumors may present with seizures or may have a seizure for the first time after diagnosis or neurosurgery. Seizures are a potentially devastating complication of resection of brain tumors, often worsening existing neurological deficits, producing new deficits, and prolonging the length of hospitalization. Nevertheless, there is no unequivocal evidence that patients with brain tumors without seizure history can benefit from the clinical epileptic prophylaxis in comparison to placebo, and thus, antiepileptic drugs should not be routinely recommended. The clinical decision to initiate medication should be based on both the risk of seizure occurrence and the risk of the medication and its toxic effects. Surgical Management  The presumption of diagnosis through indirect methods such as neuroimaging studies cannot be done without the correct determination of a tumor’s type and grade through a biopsy or surgery. Adequate pathologic examination of the tissue sample can confirm the histological type and grade of the tumor, guide the correct treatment, and with the recent studies on molecular biology, can also help predict response to treatment and prognosis. When the tumor is surgically accessible, the surgeon usually attempts to safely remove all of the abnormal tissue. Maximal resection is standard for primary glial tumors as a more extensive resection is associated with improved survival.

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When the lesion is small, deeply located, or situated in areas where it cannot be safely approached or removed, the surgeon can perform a guided stereotactic biopsy. Stereotactic biopsies are usually recommended for CNS lymphomas as surgical resection does not influence survival. The management of patients with metastatic disease to the brain is primarily based on the number and location of the lesions and on the patients’ neurological status. When a metastasis to the brain is suspected the rest of the body should be screened in search of the primary tumor. Usually, the resection of a brain metastasis is done when there is a single lesion and the surgeon wants to ameliorate the patients’ symptoms due to the lesion.

Suggested Readings and References 1. Anderson SW, Damasio H, Damasio AR. A neural basis for collecting behaviour in humans. Brain. 2005;128(Pt 1):201–12. Epub 2004 Nov 17 2. Bell BA, Smith MA, Kean DM, McGhee CN, MacDonald HL, Miller JD, Barnett GH, Tocher JL, Douglas RH, Best JJ.  Brain water measured by magnetic resonance imaging. Correlation with direct estimation and changes after mannitol and dexamethasone. Lancet. 1987;1(8524):66–9. 3. Berleur MP, Cordier S. The role of chemical, physical, or viral exposures and health factors in neurocarcinogenesis: implications for epidemiologic studies of brain tumors. Cancer Causes Control. 1995;6(3):240–56. 4. Bernstein M, Berger MS. Neuro-oncology. The essentials. 2nd ed. New York: Thieme Medical Publishers, Inc; 2008. 5. Coble JB, Dosemeci M, Stewart PA, et al. Occupational exposure to magnetic fields and the risk of brain tumors. NeuroOncol. 2009;11(3):242–9. https://doi.org/10.1215/15228517-2009-002. 6. Forsyth PA, Posner JB.  Headaches in patients with brain tumors: a study of 111 patients. Neurology. 1993 Sep;43(9):1678–83. 7. French LA, Galicich JH. The use of steroids for control of cerebral edema. Clin Neurosurg. 1964;10:212–23. 8. Goffaux P, Fortin D.  Brain tumor headaches: from bedside to bench. Neurosurgery. 2010;67(2):459–66. https://doi.org/10.1227/01.NEU.0000372092.96124.E6. 9. Jacobs AH, Kracht LW, Gossmann A, Rüger MA, Thomas AV, Thiel A, Herholz K. Imaging in neurooncology. NeuroRx. 2005;2(2):333–47. Review 10. Keane JR.  Neurologic symptoms mistaken for gastrointestinal disease. Neurology. 1998;50:1189. 11. Kong X, Guan J, Yang Y, Li Y, Ma W, Wang R. A meta-analysis: do prophylactic antiepileptic drugs in patients with brain tumors decrease the incidence of seizures? Clin Neurol Neurosurg. 2015;134:98–103. https://doi.org/10.1016/j.clineuro.2015.04.010. Epub 2015 Apr 18 12. Little MP, Rajaraman P, Curtis RE, et al. Mobile phone use and glioma risk: comparison of epidemiological study results with incidence trends in the United States. BMJ. 2012;344:e1147. 13. Loghin M, Levin VA.  Headache related to brain tumors. Curr Treat Options Neurol. 2006;8(1):21–32. 14. Lote K, Stenwig AE, Skullerud K, Hirschberg H. Prevalence and prognostic significance of epilepsy in patients with gliomas. Eur J Cancer. 1998;34(1):98–102. 15. Louis DN, Ohgaki H, Wiestler OD, Cavenee WK. WHO classification of tumours of the central nervous system. 4th ed. Revised, Vol. 1. Lyon: IARC; 2016. 16. M K, Vecht CJ. Seizure characteristics and prognostic factors of gliomas. Epilepsia. 2013;54 Suppl 9:12–7. https://doi.org/10.1111/epi.12437.

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17. Mahaley MS Jr, Mettlin C, Natarajan N, Laws ER Jr, Peace BB. National survey of patterns of care for brain-tumor patients. J Neurosurg. 1989;71(6):826–36. 18. Miller JD, Leech P. Effects of mannitol and steroid therapy on intracranial volume-pressure relationships in patients. J Neurosurg. 1975;42(3):274–81. 19. Moots PL, Maciunas RJ, Eisert DR, Parker RA, Laporte K, Abou-Khalil B.  The course of seizure disorders in patients with malignant gliomas. Arch Neurol. 1995;52(7):717–24. 20. Ostrom QT, Gittleman H, Farah P, et al. CBTRUS statistical report: primary brain and central nervous system tumors diagnosed in the United States in 2006–2010. Neuro-Oncology. 2013;15(Suppl 2):ii1–ii56. https://doi.org/10.1093/neuonc/not151. 21. Rasmussen BK, Jensen R, Schroll M, Olesen J. Epidemiology of headache in a general population--a prevalence study. J Clin Epidemiol. 1991;44(11):1147–57. 22. Ryken TC, McDermott M, Robinson PD, Ammirati M, Andrews DW, Asher AL, Burri SH, Cobbs CS, Gaspar LE, Kondziolka D, Linskey ME, Loeffler JS, Mehta MP, Mikkelsen T, Olson JJ, Paleologos NA, Patchell RA, Kalkanis SN.  The role of steroids in the management of brain metastases: a systematic review and evidence-based clinical practice guideline. J Neuro-Oncol. 2010;96(1):103–14. https://doi.org/10.1007/s11060-009-0057-4. Epub 2009 Dec 3. Review. 23. Tucha O, Smely C, Preier M, Lange KW. Cognitive deficits before treatment among patients with brain tumors. Neurosurgery. 2000;47(2):324–33; discussion 333-4 24. Vázquez-Barquero A, Ibáñez FJ, Herrera S, Izquierdo JM, Berciano J, Pascual J.  Isolated headache as the presenting clinical manifestation of intracranial tumors: a prospective study. Cephalalgia. 1994;14(4):270–2. 25. Vecht CJ, van Breemen M.  Optimizing therapy of seizures in patients with brain tumors. Neurology. 2006;67(12 Suppl 4):S10–3.

Brain Tumors in Children

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Enrico Ghizoni, Carolina Ribeiro Marques Naccarato, and Roger Neves Mathias

Epidemiology Central nervous system (CNS) tumors have a high incidence during childhood followed by an exponential growth from second decade through the seventh decade of life. CNS tumors represent the second most common neoplasm in the pediatric population, only behind leukemias that are the most frequent tumors in children under 15 years old. The most frequent CNS tumors in the pediatric population are midline neoplasms (pontine and hypothalamic gliomas and craniopharyngiomas), posterior fossa tumors, and embryonal tumors (Table  18.1). Approximately, 50–60% of these tumors have their initial growth in the posterior fossa. CNS tumors in newborns (0–36 months old) are rare and have a more aggressive clinical presentation, with early symptoms and signs when compared with the ones in older children. They predominate in the supratentorial compartment. They represent a treatment challenge due to the low age and immature CNS of these patients (Table 18.2).

Clinical Presentation and Diagnosis Clinical presentation depends on age and tumor location. Many of the signs and symptoms are present in common pathologies like gastroenteritis, migraine, and behavioral disorders and can cause misdiagnoses. Only 40% of the children present E. Ghizoni (*) Department of Neurology, Neurosurgery Division, University of Campinas (UNICAMP), Campinas, SP, Brazil C. R. M. Naccarato Department of Radiology, Hospital Boldrini, Campinas, SP, Brazil R. N. Mathias Department of Neurology, University of Campinas, Campinas, SP, Brazil © Springer Nature Switzerland AG 2019 A. F. Joaquim et al. (eds.), Fundamentals of Neurosurgery, https://doi.org/10.1007/978-3-030-17649-5_18

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Table 18.1  CNS tumor incidence in children older than 3 years

CNS tumors in Children Medulloblastoma Astrocytoma Glioblastoma Ependymoma Craniopharyngioma

Incidence 16–29% 13–22% 4–20% 6–17% 6–13%

Table 18.2  CNS tumor incidence in children younger than 3 years

CNS tumors in newborns Astrocytoma Medulloblastoma Ependymoma Supratentorial PNET Atypical teratoid rhabdoid

Incidence 30% 16% 12,6% 4,6% 4,4%

Table 18.3  Main signs and symptoms of CNS tumors during childhood

Children of all ages Headache – 33% Nausea and vomiting – 32% Gait abnormality – 27% Papilledema – 13% Seizures – 13%

Children younger than 4 years Macrocephaly – 41% Nausea and vomiting – 30% Irritability – 24% Lethargy – 21% Gait abnormality – 19%

with classic signs and symptoms of intrinsic intracranial hypertension (ICH) as morning headache with vomiting and papilloedema. The main signs and symptoms are listed in Table 18.3.

 reatment and Prognosis of the Most Common Pediatric T Tumors Primitive Neuroectoderm Tumors (PNETs) PNETs are the most common tumors of the pediatric population, and despite the histological similarity, they present distinct epigenetics, which allows them to be divided into distinct entities (medulloblastomas, supratentorial PNETs, pineoblastomas).

Medulloblastomas Medulloblastomas represent 16–29% of all tumors in the pediatric group, affecting 1 in every 14,000 children up to the age of 15. Histologically it is a small, rounded bluish cell that originates in the cerebellum and is prone to spread through the central nervous system (CNS). Medulloblastomas can be divided into distinct groups according to their histological characteristics: classic; desmoplastic, and anaplastic. However, the molecular expression of these tumors allows the division into four distinct groups (genetically, demographically, clinically, and with different prognoses): Sonic Hedgehog group (SHH); Wingless group (WNT); group 3; and group 4. The WNT group presents the best prognosis

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with survival of up to 90% in 5 years, and group 3 presents the worst prognosis of 40–60% in 5 years, while the SHH and group 4 present a prognosis of 75% in 5 years. Clinical presentation is related to the presence of an expansive lesion in the posterior fossa, with signs of ICH due to obstructive hydrocephalus (headache, vomiting, lethargy, motor and cognitive deterioration). The main diagnostic exam is MRI of the skull and it is mandatory to perform a staging MRI of the entire neuraxis. Ependymoma and pilocytic astrocytoma should be considered as differential diagnoses. In computed tomography (CT), classic medulloblastoma typically presents as a well-defined and spontaneously hyperdense tumor. In MRI, they present hyposignal in T1 and T2 sequences compared to the cortex. Due to their high cellularity and high nucleus-cytoplasm ratio, these lesions also present hypersignal in the diffusion sequence (DWI) and low signal in the apparent diffusion coefficient (ADC) maps, characterizing restriction to the diffusion of water molecules. Following intravenous administration of gadolinium, there is usually homogeneous impregnation of variable intensity. Calcifications and cysts are also described; however, the presence of intratumoral hemorrhage is very uncommon. Proton spectroscopy with short echo time shows a significant peak of taurine, which is characteristic of medulloblastomas (Naa), which correlates with loss or neuronal dysfunction and increase of choline peaks (Cho), due to cell membrane turnover/cellularity and lactate (Lac), which is a necrosis marker/anaerobiosis (Fig. 18.1). CSF dissemination is the most common form of metastasis and is best a

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Fig. 18.1  Classical medulloblastoma: expansive lesion inside the fourth ventricle, in intimate contact with the cerebellar vermis and cerebellar hemispheres, isosignal to the cortex in T1 (a), T2 (b), and FLAIR (c), without areas of hemorrhage or calcification in the T2 ∗ (d) sequence, with diffusion restriction (e) and heterogeneous impregnation by the paramagnetic agent (f)

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Fig. 18.2  Medulloblastoma classic (continuation): sagittal T1 (g), sagittal T2 (h), sagittal T1 with suppression of post-gadolinium (i, j) fat, and axial T1 post-gadolinium without fat saturation (k) and with fat saturation (l, m), demonstrating diffuse impregnation of the leptomeningeal plane mainly in the posterior aspect of the thoracic marrow and adjacent to the medullary cone, with gross nodular areas compatible with cerebrospinal fluid dissemination

evaluated by contrast magnetic resonance imaging. Vermicular cistern, basilar cistern, subependymal region of the lateral ventricles and anterior cranial fossa are the most common intracranial sites. Drop metastases may present as a faint leptomeningeal impregnation, or as foci of extramedullary and intradural impregnation and occasionally intradural. The thoracic region and the caudal portion of the dural sac are the most involved locations (Fig. 18.2). Treatment begins with surgery aiming to reduce ICH, provide material for tumor analysis and achieve the widest possible tumor resection as the initial step. Whenever possible, the patient is subjected directly to resection of the tumor for clearance of the fourth ventricle and resolution of hydrocephalus and ICH. But in more severe cases, signs and symptoms of decompensate ICH, an external ventricular device can be placed and tumor operation postponed until the patient shows improvement of good clinical conditions. In our facility all patients are operated in ventral decubitus in the Concorde position in an attempt to position the fourth ventricle as more

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perpendicular to the ground as possible. We perform a suboccipital craniotomy with wide opening of foramen magnum laterally; the C1 arch is removed depending on how far caudally the tumor extends and the need for turning the microscope vision cranially. In order to preserve cerebellar vermis and prevent cerebellar mutism, the fourth ventricle and tumor are accessed via the telovelar pathway. After surgery, disease staging is evaluated through CSF analysis, neuraxis MRI, and tumor residue. Patients are classified into two groups: intermediate risk and high risk. Patients with residual tumor over 1.5  cm2 and/or metastatic disease at diagnosis (CSF or MRI) are classified as high risk. Patients classified as intermediate risk may undergo a multiple chemotherapy regimen and a dose of reduced spinal-­cranial radiotherapy(24 Gy), with an average survival of 80% over 5 years, while patients classified as high risk receive a higher dose of spinal-cranial radiotherapy (36  Gy) associated with a boost in the tumor bed of 54Gy followed by chemotherapy, with an average survival of 60% in 5 years. In contrast to the good overall survival, especially in intermediate-risk patients, survivors face several treatment-related problems that impair their quality of life: neuropsychological disorders, neuroendocrine disorders, growth deficit, and ototoxicity. Children younger than 3 years are a separate group due to the high risk of neuraxial irradiation and severe neuropsychological sequelae, making radiotherapy prohibitive in this age group. The treatment is based on the use of multiple chemotherapeutic agents, with several protocols in progress, with a survival rate of 52–58% in intermediate-risk patients. With the great advances in molecular signaling and epigenetics of medulloblastoma knowledge, target therapies are being developed to provide more effective treatments with lower morbidity of patients, hopefully in the early future.

Atypical Teratoid Rhabdoid Atypical teratoid rhabdoid tumor is a rare CNS embryonal tumor typically seen in young children ( 200 mmHg.    Reduce ventilation frequency to 10 breaths per minute to eucapnia.   Reduce positive end-expiratory pressure (PEEP) to 5 cm H2O (oxygen desaturation with decreasing PEEP may suggest difficulty with apnea testing).   If pulse oximetry oxygen saturation remains >95%, obtain a baseline blood gas (partial pressure of oxygen [PaO2],PaCO2, pH, bicarbonate, base excess).    Disconnect the patient from the ventilator.   Preserve oxygenation (e.g., place an insufflation catheter through the endotracheal tube and close to the level of the carina and deliver 100% O2 at 6 L/min).   Look closely for respiratory movements for 8–10 minutes. Respiration is defined as abdominal or chest excursions and may include a brief gasp.    Abort if systolic blood pressure decreases to 30 days to 18 years) is recommended. Assessments in neonates and infants should preferably be performed by pediatric specialists with critical care training. The first examination determines the child has met the accepted neurologic examination criteria for brain death. The second examination confirms brain death based on an unchanged and irreversible condition. When ancillary studies are used, a second clinical examination and apnea test should be performed and components that can be completed must remain consistent with brain death. In this instance, the observation interval may be shortened and the second neurologic examination and apnea test (or all components that are able to be completed safely) can be performed at any time thereafter.

Conclusions Understanding brain death is an important aspect of the care provided to patients. This is particularly true in surgical or intensive care situations. This chapter provided a brief synopsis of the steps in brain death determination and the caveats that remain. One aspect we did not discuss is how patients and families react to the “diagnosis” of brain death. It is important to remember that even with all of the modalities we have available to us as practitioners it is our interaction with patients that remains our most crucial tool. While undertaking the unenviable task of determining brain death one must remain compassionate and understanding. In doing so we can provide care to our patients and their families even in the most trying of times.

Suggested Readings and References 1. Guidelines for the determination of death. Report of the medical consultants on the diagnosis of death to the President’s Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research. JAMA. 1981;246(19):2184–6.

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2. Ibsen B. Treatment of respiratory complications in poliomyelitis; the anesthetist’s viewpoint. Dan Med Bull. 1954;1(1):9–12. 3. Woolmer R. The management of respiratory insufficiency. Anaesthesia. 1956;11(4):281–8. 4. Mollaret P, Goulon M.  The depassed coma (preliminary memoir). Rev Neurol (Paris). 1959;101:3–15. 5. Wertheimer P, Jouvet M, Descotes J. Diagnosis of death of the nervous system in comas with respiratory arrest treated by artificial respiration. Presse Med. 1959;67(3):87–8. 6. Settergren G. Brain death: an important paradigm shift in the 20th century. Acta Anaesthesiol Scand. 2003;47(9):1053–8. 7. A definition of irreversible coma. Report of the Ad Hoc Committee of the Harvard Medical School to Examine the Definition of Brain Death. JAMA. 1968;205(6):337–40. 8. Diagnosis of brain death. Statement issued by the honorary secretary of the Conference of Medical Royal Colleges and their Faculties in the United Kingdom on 11 October 1976. Br Med J. 1976;2(6045):1187–8. 9. Practice parameters for determining brain death in adults (summary statement). The Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 1995;45(5):1012–4. 10. Wijdicks EFM, Varelas PN, Gronseth GS, Greer DM.  American Academy of Neurology. Evidence-based guideline update: determining brain death in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2010;74(23):1911–8. 11. Shemie SD, Hornby L, Baker A, et al. The International Guidelines for Determination of Death phase 1 participants, in collaboration with the World Health Organization. International guideline development for the determination of death. Intensive Care Med. 2014;40(6):788–79. 12. Haupt WF, Rudolf J.  European brain death codes: a comparison of national guidelines. J Neurol. 1999;246(6):432–7. 13. Citerio G, Crippa IA, Bronco A, Vargiolu A, Smith M. Variability in brain death determination in Europe: looking for a solution. Neurocrit Care. 2014;21(3):376–82. 14. Plum F, Posner JB. The diagnosis of stupor and coma. Philadelphia: Davis; 1966. 15. Bauer G, Gerstenbrand F, Rumpl E.  Variables of the locked-in syndrome. J Neurol. 1979;221(2):77–91. 16. Carroll WM, Mastaglia FL. ‘Locked-in coma’ in postinfective polyneuropathy. Arch Neurol. 1979;36(1):46–7. 17. Marti-Masso JF, Sufirez J, Lopez de Munain A, Carrera N. Clinical signs of brain death simulated by Guillain-Barre syndrome. J Neurol Sci. 1993;120(1):115–7. 18. Milanovic R, Husedzinovic S, Bradic N. Induced hypothermia after cardiopulmonary resuscitation: possible adverse effects. Signa Vitae. 2007;2(1):15–7. 19. Danzl DF, Pozos RS. Accidental hypothermia. N Engl J Med. 1994;331(26):1756–60. 20. Gilbert M, Busund R, Skagseth A, Nilsen PA, Solbo JP. Resuscitation from accidental hypothermia of 13.7 degrees C with circulatory arrest. Lancet. 2000;355(9201):375–6. 21. Wijdicks EF. The diagnosis of brain death. N Engl J Med. 2001;344(16):1215–21. 22. Wijdicks EF, Smith WS. Brain death in children: why does it have to be so complicated? Ann Neurol. 2012;71(4):442. 23. Wijdicks EF. Brain death worldwide: accepted fact but no global consensus in diagnostic criteria. Neurology. 2002;58(1):20–5. 24. Virginia statute, section 54–1-2972; 1997. 25. Florida statute annotated, section 382.009; 1997. 26. New Jersey statute annotated, 26–6A-5, suppl. 1994; 1987. 27. New York Compilation Codes Regulations, Rules 7 REGS, title 10, section 400.16 (d), (e)(3). 28. Sprung CL, Cohen SL, Sjokvist P, Ethicus Study Group, et al. End-of-life practices in European intensive care units: the Ethicus Study. JAMA. 2003;290(6):790–7. 29. Smilevitch P, Lonjaret L, Fourcade O, Greeraerts T. Apnea test for brain death determination in a patient on extracorporeal membrane oxygenation. Neurocrit Care. 2013;19(2):215. 30. Yee AH, Mandrekar J, Rabinstein AA, Wijdicks EFM. Predictors of apnea test failure during brain death determination. Neurocrit Care. 2010;12(3):352–5.

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31. Greer DM, Varelas PN, Haque S, Wijdicks EF. Variability of brain death determination guidelines in leading US neurologic institutions. Neurology. 2008;70(4):284–9. 32. Shappell CN, Frank JI, Husari K, Sanchez M, Goldenberg F, Ardelt A. Practice variability in brain death determination: a call to action. Neurology. 2013;81(23):2009–14. 33. Brierley JB, Graham DI, Adams JH, Simpsom JA.  Neocortical death after cardiac arrest. A clinical, neurophysiological, and neuropathological report of two cases. Lancet. 1971;2(7724):560–5. 34. Busl KM, Greer DM. Pitfalls in the diagnosis of brain death. Neurocrit Care. 2009;11(2):276–87. 35. Siminoff LA, Burant C, Youngner SJ. Death and organ procurement: public beliefs and attitudes. Kennedy Inst Ethics J. 2004;14(3):217–34. 36. Pribram HF.  Angiographic appearances in acute intracranial hypertension. Neurology. 1961;11:10–21. 37. Riishede J, Ethelberg S.  Angiographic changes in sudden and severe herniation of brain stem through tentorial incisure; report of five cases. AMA Arch Neurol Psychiatry. 1953;70(3):399–409. 38. Flowers WM Jr, Patel BR. Radionuclide angiography as a confirmatory test for brain death: a review of 229 studies in 219 patients. South Med J. 1997;90(11):1091–6. 39. Bradac GB, Simon RS. Angiography in brain death. Neuroradiology. 1974;7(1):25–8. 40. Braum M, Ducrocq X, Huot JC, Audibert G, Anxionnat R, Picard L. Intravenous angiography in brain death: report of 140 patients. Neuroradiology. 1997;39(6):400–5. 41. Kramer AH, Roberts DJ. Computed tomography angiography in the diagnosis of brain death: a systematic review and meta-analysis. Neurocrit Care. 2014;21(3):539–50. 42. Taylor T, Dineen RA, Gardiner DC, Buss CH, Howatson A, Pace NL. Computed tomography (CT) angiography for confirmation of the clinical diagnosis of brain death. Cochrane Database Syst Rev. 2014;(3):CD009694. 43. Greer DM, Strozyk D, Schwamm LH. False positive CT angiography in brain death. Neurocrit Care. 2009;11(2):272–5. 44. Goodman JM, Mishkin FS, Dyken M. Determination of brain death by isotope angiography. JAMA. 1969;209(12):1869–72. 45. Sinha P, Conrad GR.  Scintigraphic confirmation of brain death. Semin Nucl Med. 2012;42(1):27–32. 46. Mishkin FS, Dyken ML. Increased early radionuclide activity in the nasopharyngeal area in patients with internal carotid artery obstruction: “hot nose”. Radiology. 1970;96(1):77–80. 47. Joffe AR, Lequier L, Cave D.  Specificity of radionuclide brain blood flow testing in brain death: case report and review. J Intensive Care Med. 2010;25(1):53–64. 48. Yoneda S, Nishimoto A, Nukada T, Kuriyama Y, Katsurada K. To-and-fro movement and external escape of carotid arterial blood in brain death cases. A Doppler ultrasonic study. Stroke. 1974;5(6):707–13. 49. de Freitas GR, André C. Sensitivity of transcranial Doppler for confirming brain death: a prospective study of 270 cases. Acta Neurol Scand. 2006;113(6):426–32. 50. Matsumura A, Meguro K, Tsurushima H, et al. Magnetic resonance imaging of brain death. Neurol Med Chir (Tokyo). 1996;36(3):166–71. 51. Wagner W. Scalp, earlobe and nasopharyngeal recordings of the median nerve somatosensory evoked P14 potential in coma and brain death. Detailed latency and amplitude analysis in 181 patients. Brain. 1996;119(Pt 5):1507–21. 52. Ruiz-López MJ, Martínez de Azagra A, Serrano A, Casado-Flores J. Brain death and evoked potentials in pediatric patients. Crit Care Med. 1999;27(2):412–6. 53. Sandroni C, Cariou A, Cavallaro F, et  al. Prognostication in comatose survivors of cardiac arrest: an advisory statement from the European Resuscitation Council and the European Society of Intensive Care Medicine. Intensive Care Med. 2014;40(12):1816–31. 54. Nakagawa TA, Ashwal S, Mathur M, Mysore M. Guidelines for the determination of brain death in infants and children: an update of the 1987 task force recommendations. Pediatrics. 2011;128(3):e720–40.

The Frontiers of Neurosurgery

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Mauro A. T. Ferreira

Introduction Neurosurgery is a relatively new surgical specialty. William S.  Halsted (1852– 1922) is considered by many as the “father” of modern surgery. Harvey Cushing (1869–1939), one of Halsted’s disciples, published a paper entitled The Special Field of Neurological Surgery at the Bulletin of the Johns Hopkins Hospital (16:77–87, 1905.). Although relatively “young,” the neurological surgery has experienced a phenomenal development, including impressive technological improvement, anatomical knowledge, basic science research, and the development of major neurological surgery centers around the world. In fact, the exponential increase in neurosurgery knowledge, has made it to become one of the most difficult fields in surgery, and arguably, in the entire medical practice. The neurosurgical training in the United States of America and Europe are described by Burkhardt et al. The need to develop laboratory work for 1 or 2 years is well emphasized. It requires, thus, a subset of individual characteristics necessary to become a neurosurgeon.

Frontiers of Neurosurgery: Neurosurgeon’s Profile Neurosurgery is usually sought by top medical students that usually make their decisions of becoming neurosurgeons early in medical school, or of even before it. As medical students, future neurosurgeons are usually involved in multiple activities, including research. For the most part they achieve high grades, and not

M. A. T. Ferreira (*) Department of Anatomy and Radiology, University Hospital- Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil © Springer Nature Switzerland AG 2019 A. F. Joaquim et al. (eds.), Fundamentals of Neurosurgery, https://doi.org/10.1007/978-3-030-17649-5_20

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uncommonly, they are overachievers. As residents, the future neurosurgeons endure countless sleepless hours, study countless hours, cope with complex cases, deals with competition, and the sense of loneliness, and are regularly evaluated for their performance. The basic training lasts from 5 to 7 years. It entails resilience, abdication, sheer will power, sacrifice, self-overcoming, passion, dedication, and compassion and humbleness to patient care.

Frontiers of Neurosurgery: Technology Neurological Surgery has experienced immense technological improvements that made its practice safer to the patient and more comfortable for the surgeon. As we’re living the fourth industrial revolution that, according to Klaus Schwab (Founder and Executive Chairman of the World Economic Forum), neurosurgery seems to be developing alongside with this revolution. According to the author, the artificial intelligence, robotics, fast Internet, independent vehicles, 3D printing, nanotechnology, biotechnology, and storage of energy and quantic computation are all features of such a revolution. It differs from the others for its speed, amplitude and depth. The interaction between physics, digital, and biological domains is observed. Some of these concepts will be shown in the appropriate sections below. Navigation devices have been developed and may be integrated to the surgeon’s microscope. The “Brain Suite” has all available resources integrated into an operating room: state-of-the-art microscope, neuronavigation, intraoperative magnetic resonance (MR) imaging, a display of MR images on its various modalities (functional MRi, diffusion tensor MRi, etc.), intraoperative angiography, intraoperative indocyanine green angiography (ICG), electrophysiological monitoring, temporary cardiac standstill with adenosine IV administration, smaller surgical corridors, and so on. Unfortunately, this technology is costly and is not available to everyone. It is conceivable, in the near future, the use of virtual reality to foresee the surgical steps of a given surgery. Tridimensional models, based on the patient’s radiological exams, may be constructed and viewed through augmented reality glasses, or holograms, in an interactive fashion. Thus, surgical planning, lesion location, patient’s anatomy details, and possible difficulties may be anticipated. This kind of technology should be pursued, and it may be of great help for beginners. Tridimensional imaging manipulation is a possible tool in the near future. As for virtual reality, especially for neurosurgical training, it is not very realistic at this point in time, to consider reliable models, since haptic feedback is so far away of becoming a reality. The neurosurgeon deals with soft tissue, bones, the brain, several tumors of different consistencies, in such a way that only practice and experience may bring excellence. Microneurosurgery is a fine art. Gmeiner, however, presents a brain aneurysm simulator with haptic feedback.

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Frontiers of Neurosurgery: Neuroanatomy Neuroanatomy is a key knowledge to perform neurosurgery. The more one knows, the safer it will be during surgery. The monumental work put together by Dr. Albert L. Rhoton Jr., over a 40-year period at the University of Florida, is worth mentioning. It would be fair to say his work and the work of his fellows has led to the full understanding of the microsurgical anatomy of the various brain areas, skull base, brain vessels, and the fiber dissection technique, as first proposed by Klingler in 1902. A beautiful work of presenting stereoscopic images of fiber dissection technique, and comparing it to the diffusion tensor technique magnetic resonance imaging (DTIMRI) has been performed. As a matter of fact, there is little left to be learned with this kind of anatomy. The reader is referred to appreciate this outstanding work published on, in a CNS (Congress of Neurological Surgeons, USA) book. It has led to a great surge of complex skull base surgery in the 1990s and then, with the wide use of less invasive surgical approaches, the use of radiosurgery, and now with the wide use of the endoscope, This anatomy, although invaluable, has led surgeons to be more straight forward. There has been a wide use of the endoscope recently. All of a sudden, every single pathology became amenable to endoscopic treatment. Considered “less invasive to the brain,” it may be “maximally invasive to the nose and paranasal sinuses.” Medium- to long-term results are still to be evaluated. The cerebrospinal fluid fistula has become a trivial complication, instead of a life-threatening complication. Some say the endoscopic removal of craniopharyngiomas, for example, is the treatment of choice, but the log term results are yet not shown pending. It seems time is necessary to adequate the endoscope to its full capability, not crossing the line of classical and safer skull base approaches. This tecchnique is, however, replacing some of the classical neurosurgical approaches. The new challenge of the anatomy lies in the cellular level and it concerns how neurons communicate with each other, both from the anatomical point of view, and from the physiological point of view. The Human Connectome Project has been launched in July 2009, and it is sponsored by 16 components of the National Institutes of Health. Connectomics is the study of the relationship of a given part of the brain to its surrounding areas, or more broadly, it may refer to the full organization of a given organism’s nervous system, or part of it. Brain mapping using the functional MRI (fMRI) is the main tool to study these relationships. Brain mapping of normal human young individuals have been performed. There have been great advancements in understanding brain connectivity, as well as disruption of neural pathways causing clinical disorders. Figure  20.1 shows a diffuse tensor image of a normal brain, with its exceptional complexity. The image has been retrieved from the Human Connectome Project (HCP) web page, an open access site (www.humanconnectomeproject.org/gallery/). For instance, Tang has published a probabilistic atlas of the human brainstem using the fMRI, where the relationship of 23 tracts has been established. The HCP was first elaborated to try to understand conditions like dementias, such as

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Fig. 20.1  Diffuse tensor image (DTI) magnetic resonance showing the various brain tracts and its complex relationships

Alzheimer’s disease, behavioral disturbances like major depression, schizophrenia, sleep disorders, and epilepsy. It is far known that although treatment of these diseases has greatly developed in the past, the physiopathology remained obscure. In fact, Whelan et al. have published the ENIGMA study, a multicenter analysis (24 research centers in 14 countries) that compared various brain areas in epileptic and non-epileptic patients. It is the largest epilepsy image study to date. They conclude epilepsy syndromes may represent a network disorder, indicating that certain epilepsy disorders involve a more widespread structural compromise than previously thought. Hopefully, more neurological disorders will have their physiopathology discovered, and a comprehensive individual-based treatment can be delivered. These highly sophisticated brain maps, with various pathways may enable the neurosurgeon to perform safer surgical approaches to delicate or eloquent brain areas. As the magnetic resonance imaging advances, by adding new research resources, or increasing its magnetic field, a better understanding of the overlying diseases will eventually become possible. The issue of increasing MRI (≥7,0 T), from the traditional 1,5 to 3,0 T field, is well addressed by Vu.

Frontiers of Neurosurgery: Functional Surgery Functional neurosurgery has also developed into a sophisticated science that has changed its paradigms. From lesioning certain known areas of the central nervous system, the deep brain stimulation (DBS) changed this reality to closed circuit stimulation. A deeper understanding of the functional neuroanatomy, the mechanical development of pulse generator, as well as pulse frequency, and patient selection have played a major whole in DBS development. DBS has become an established treatment for medically refractory movement disorders such as Parkinson’s disease, essential tremor and dystonia. The safety to treat the Tourette syndrome has been established. As a matter of fact, Lozano et al. have studied the publications regarding Parkinson’s disease surgery in the past century. They have identified 8000

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papers, half of which are BDS procedures. They have noticed, however, that the number of papers on DBS procedures has plateaued, maybe an indicator that emerging procedures may compete with DBS in the future. Bari et al. have called attention to a recent approval of magnetic resonance-guided focused ultrasound (MRgFUS) for the treatment of essential tremor. It heralds the potential resurgence in lesion creation as a viable alternative to DBS in selected cases. DBS have reached situations where medical therapy consistently failed. Elias et al. performed a literature review of the maladaptive syndrome after ischemic stroke and found that multiple targets may be used to improve pain, dystonia, dyskinesias, tremor, and even hemiparesis. It is known that biomarkers precede clinical presentation of Alzheimer’s disease. Memory improvement and surgery safety in mild or high probability Alzheimer’s disease patients has been established (ADvance trial). The authors have targeted the bilateral fornix. Eating disorders, supranuclear palsies, freezing of gait, are already conditions to be treated with DBS in selected cases. Better target selection and pathophysiology understanding will probably establish the optimum whole of functional neurosurgery for these conditions as well as others. Interestingly, Lisarraga et al. have published the molecular imaging of movement disorders. It’s worth mentioning the pioneering, and intensive research that has been performed in Toronto, Canada, by Prof. Andres Lozano. It seems certain that a better understanding of microanatomy, neuromodulation, technological improvement, and improved patient selection, as well the proper understanding of neurophysiology, will improve results and include other pathological conditions within the scope of functional neurosurgery.

Frontiers of Neurosurgery: Neurovascular Surgery Neurovascular surgery has suffered a major paradigm shift from surgery to endovascular procedures, such as coiling, coiling and stenting, and more recently flow diversion devices. There have been unsolved problems as far as coiling, and coiling and stenting are concerned. A number of studies have shown that mortality and morbidity are lower than microsurgery, but the recurrence rate is higher in the first group. The flow diverters, however, introduce another concept of excluding aneurysms from the circulation, as well as arterial dissections, and stenosis (angioplasty plus flow diverters). Based on the reduction of blood flow, it induces thrombosis of a given lesion, and re-establishes blood flow into areas of dissection, for example, in situations that are difficult to surgery. Roughly 70% of brain aneurysms are treated endovascularly in the United States today, while 30% are treated surgically. It creates, though a problem to think about. The learning curve for endovascular procedures seems to be steep when compared to surgery. There will always be lesions not amenable to endovascular treatment alone, such as arteriovenous malformations, probably one of the most challenging lesions in neurosurgery. Some other cases will require complex revascularization procedures. So, if the current neurosurgery resident is more prone to endovascular procedures, how and who will be treating the complex vascular lesions in the near future? The endovascular

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industry is pushing hard and putting a great amount of money into research, while the simple Sylvian fissure dissection seems a difficult task to the average neurosurgery resident. There are dozens of endovascular devices being evaluated by the Food and Drug Administration (FDA), in Washington, DC, USA, as of today (Dr. Cristopher Loftus, personal communication, December 2017). Flow diverters may be used in large vessels, and the near future will show its real efficacy, and longterm results. Surgical expertise and excellence in vascular neurosurgery, as measured by the numbers achieved by giants like Drake, Spetzler, Evandro de Oliveira, Michael Lawton, and others will be virtually impossible to reach (Dr. Robert F. Spetzler and Dr. Michael Lawton have operated on almost 11,000 aneurysm cases). Worth mentioning is the Barrow Ruptured Aneurysm Trial (BRAT), when the authors analyzed only saccular aneurysms. This prospective randomized trial has shown an obliteration rate at 6-year follow-up of 95% in the surgical arm of the study, against 40% in the coiled group. There was no statistically difference in bad prognosis between the two groups. Cross-over rate in the surgery arm was 1%, and 36% of the endovascular arm was assigned to surgery. The same authors, in a previous study of the BRAT conclude that posterior circulation aneurysms fare better with coil embolization than with surgery. As the endovascular devices are rapidly evolving, probably the various methods will be suited to specific cases in the near future. As for unruptured aneurysms, the PHASES score has shed more doubts than an orientation to what treatment is more appropriate to the individual patient. The flow diverters, as of today, are not FDAapproved to treat small nonruptured aneurysms. Major advancement has been achieved in acute ischemic stroke patients. The classic 4 h 30 min interval between the event and venous thrombolysis tends to be increased with the use of endovascular devices. Chemical venous thrombolysis has become common practice in emergency rooms. A more precise approach to stroke patients has been achieved with the ASPECTS (Alberta Stroke Program Early CT scores), in 2001. This score identifies patients who would benefit the most with thrombolysis. Computed programs have proved more reliable than the human eyes to established ischemic areas in the early phases of stroke (Brainomix™; e-aspects, Brainomics, Oxford, UK). Bal et  al. have pointed out that the CT angiography would identify acute stroke earlier than the noncontrast CT scan. Moreover, the Computed Tomography (CT)-perfusion stroke imaging enables the examiner to predict infarct volume, compared to traditional methods. Endovascular expertise has allowed patients to be treated by clot retriever devices, or mechanical thrombolysis (MT) therapy. To date, five multicenter, open-­label, randomized controlled endovascular trials have shown the benefits of clot retriever devices (MR CLEAN, ESCAPE, SWIFT PRIME, EXTEND IA, and REVASCAT). Still a matter of discussion is the therapeutic window for acute stroke, but recent trials tend to assess the benefits of extending the therapeutic window (like the DAWN, and the DEFUSE 3 trials). The DEFUSE 3 trial has used the rationale of the penumbral mismatch on perfusion CT or magnetic resonance imaging and patients status (especially late-presenting strokes undergoing intervention) who may benefit from MT between 6 and 16 h. A major implication of stroke treatment has been shown by Hacke

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that concluded that advanced imaging-based patient selection outweighs time-based decision-­making in acute stroke patients, based on the DAWN trial. The DAWN trial was initiated with 6–24 h after stroke onset, but it was terminated early after an interim analysis of the 200 first patients that demonstrated a 73% relative risk reduction in disability (48.65% vs. 13.6% in the control group). Using the MT treatment, however, it is possible to retrieve clots in large vessels. They are limited to M2 segments of the middle cerebral artery. As for posterior circulation acute ischemic strokes, there is one ongoing trial comparing MT plus medical therapy, and medical therapy alone, for basilar artery occlusion. Results are still pending. We refer the interested reader to a thoughtful review paper on the issues regarding all the changes occurred in the treatment of acute stroke, as well as the ongoing and forthcoming clinical trials. Hopefully, development of endovascular devices and endovascular surgery skills will make it possible to treat distal vessel occlusion. Another set of papers seem to establish the beginning of an objective assessment of neurosurgical skills acquirement. Prof. Marcelo Magaldi, from the Federal University of Minas Gerais School of Medicine, started investigating ex vivo hybrid models like the human placenta, with several similarities with brain vessels, which have been used to validate surgical skills. The human placenta allows for the creation of brain aneurysms, Sylvian fissure dissection, bypass surgery, and endovascular procedures such as coiling, stenting, and road-mapping. Among the underway studies, objective assessments like time, right sequence of action, goal achievement, and difficulties or disaster have been measured. The near future seems bright for patients with neurovascular diseases.

Frontiers in Neurosurgery: Neuroocology Ostrom et  al. have reported the results of the 2008–2012 of Primary Brain and Central Nervous System Tumors Diagnosed in the United States. The two more frequent tumors found are the menigiomas followed by glioblastomas. These tumors increase with age, and in meningioma cases, age may be regarded as a risk factor for developing meningiomas. As the aging population increases, these tumors will probably become an increasing problems to deal with. The 2016 Classification of Central Nervous System Tumors was presented, and some modifications, especially the introduction of molecular biology, allied with histological findings were added. This additional information was particularly seen in gliomas, ependymomas, and medulloblastomas. As for gliomas, especially for glioblastomas, several markers were included in the classification. However, a classification needs to classify and differentiate tumors, as well as to establish prognosis. A huge amount of research has been performed on the understanding of tumorigenesis. DNA abnormalities, for most of the central nervous system, have been identified, and treatment has been personalized to different tumor subgroups of patients. Although DNA changes, or genetic changes were identified, some laboratory findings have showed that they could not explain a number of abnormalities observed. So, an epigenetic explanation should be sought. The epigenetic studies try

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to identify changes of gene function, at multiple loci, that initiates sequences of abnormal cascades of events that lead to tumorigenesis. The current status of neural tumor studies is to profiling the epigenetics of theses tumors. A number of abnormal pathways, including suppression of pro-oncogenic genes, over-expression of oncogenic pathways, tumor growth factor production, pro-angiogenesis proteins have been observed in various tumors. Unfortunately, the number of findings, as observed in the laboratory is so great, that it makes it almost impossible to think of interfering in all those epigenetic events. Actually, the basic understanding of this phenomenon does not provide clinical benefits, in a way that a large number of scattered information is gathered without proper clinical use. Computer programs are being used to identify patterns in the investigation findings, in such a way that a more comprehensive understanding of an abnormal pathway towards tumor formation may become a possible target to therapeutic action. As a matter of fact, it has become clear that brain tumors are not primarily a surgical disease. It is rather a molecular disorder. Surgery, however, plays an important hole in cytoreduction and mass effect. It is especially true for glioblastomas. Little progress has been achieved over the past decades. Life expectancy has improved a few months, and the quality of life has improved, especially with the use of more tolerable oral medication, such as temozolomide. And as for meningiomas, the vast majority is considered “benign.” There is no explanation whatsoever to as why grade I meningiomas recur (they eventually recur several times as grade I); why the same meningioma has massive surrounding edema, while others does not; or why some may choose the cranial base or invade a major dural sinus. These are still pending questions for a group of highly heterogeneous lesions that are labeled as “benign.” The abovementioned situations have obvious surgical implications. The molecular biology of meningiomas is poorly understood, although a number of genetic and epigenetic studies have been published. There is hope as to why these lesions occur; is there some action to prevent the tumor from developing? Who hosts these tumors, and what are the interactions of tumor and host? How can doctors strengthen the patient’s immune system? And if a tumor is detected, how to stop it from developing? How can a cascade of events be interrupted? Could a virus-like agent stop an abnormality from happening, in a very precise targeting fashion? Those are pending questions that will be answered the near future. As a matter of fact, Dr. James Patrick Allison, and Dr. Tsoku Honju received the Medicine/Phisilogy Nobel Proze for studyng the immune system. Big Data processing may allow translational studies to connect basic science findings and clinical findings. It is reasonable to say that neurosurgeons will include research (basic science and research or tranlational studies) as a powerfull tool to improve surgical results. Nanomedicine is in the forefront of medical research, and it consists of the medical application of nanotechnology (the manipulation of matter on the atomic, molecular, and supramolecular sizes). The nanoscopic scale ranges from 1 to 100 nanometers (a nanometer being a billionth of a meter). It ranges from the medical applications of nanomaterials and biological devices, to nanoelectronic biosensors, and even the possible future applications of future molecular nanotechnology such as biological machines. The National Nanotechnology Initiative (NNI) is a United

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States federal government program for the science, engineering, and technology research and development for nanoscale projects. Such a promising field of research received the President’s 2018 Budget of $ 1.2 billion (the National Nanotechnology Initiative Supplement to the President’s 2018 Budget, www.nano.gov). The nanoparticles may be delivered to diagnose and to treat cancer, as well as other medical conditions. They may be encapsulated inside synthetic materials like polymers or lipid-like molecules. Target-specific agents like antibodies and other molecules created to bind specific cell proteins may be added to the particle’s surface. This flexibility enables nanoparticles to be versatile and able to execute complex, and yet precise functions inside the patient system. One of the main challenges of nanoparticles as anticancer agents is the potential for toxicity, since it can be delivered to cancer cell as well as to the whole body. In general, nanoparticles less than 10 nm are secreted by the kidney and pose no harm to the patient, while particles larger than 100 nm tend not to move inside the tumor. On the other hand, particles ranging from 10 to 100 nm tend to circulate seeking for tumors, and it enters the vascular tumor bed via the usually larger tumor vessel gaps. The development of inorganic nanoparticles that undergo renal clearance may prevent side effects. Ferber et al. have reported to have delivered paclitaxel to a dendritic polyglycerol sulfate nanocarrier in murine glioblastoma. Other approaches are described with the real potential to clinically benefit patients.

Frontiers of Neurosurgery: Spine Surgery The field of spinal surgery has suffered a tremendous improvement recently. A whole set of studies were performed in order to understand spinal biomechanics. Open spinal surgery instrumentation is being replaced by minimally invasive surgery, with various degrees of surgical orientation (C-arm, neuronavigation, or robotic arms). Advanced navigation tools have allowed inserting pedicle screws safer. Some of the rigid spinal constructs have developed into dynamic constructs, thus maintaining movement and keeping biomechanics. A great advance has been provided by stereolithography, or 3D printing. Complex spinal disorders can be studied before surgery, and planning can be well performed, as well as rehearsed. This is also an important learning tool. 3D printing is also useful in vascular and skull base surgery. The specific literature does not describe trustworthy simulators for spinal surgery, although some virtual reality and augmented reality devices are described. It seems that robotics took an important hole in spite of virtual reality simulators. The development of biocompatible and absorbable materials has also greatly contributed to spine surgery development. As far as instrumentation, and surgery indications, the literature seems to show a “steady status.” Spine surgery is the most commonly surgery performed under the scope of neurosurgery. According to Darwin’s theory, and paleontology data, our ancestors had already (6 to 5 million years) adopted the standing, strict biped position. It seems that the force vectors on the lumbar spine are an evolutionary issue to be solved, since the vast majority of people will develop back pain at some point in time. To be added to this scenario,

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osteoporosis is the most frequent cause of spine compression fracture. It has a major impact in the fast growing old population. In this context, prevention, excluded the inherited causes of back problems, will be key to avoid spine surgery.

Conclusions Looking to the past, one can foresee a bright future for neurosurgery. This is a fast-­growing science that has the brain and the spine as the matter of study. The brain, to some extent, is still a mystery. The technological advancements reported above meet the concept of the fourth industrial revolution. On the era of 5G internet speed (10 to 20 times faster thjan 4G tecchnology, and launched on April 2019 in the USA and North Korea, most of the other components of this revolution find their place in the various fields of neurosurgery. As a matter of fact, Heath have reported that Moore’s Law has been broken. This law determines that the number of information put together into a microprocessor doubles every 18 months and at the same time its price falls 50%. They emphasize the current microprocessors are storing and processing data at a faster rate. For instance, the first sequencing of the human genome took 3–4 years to be ready, at a cost of 300 million dollars. They believe that in 10 years from the publication (2019, original publication on March 2009), a personal human sequencing will cost 1000 dollars and will take a day to be performed (300,000 less). As pointed out by Shwab, some degree of artificial intelligence is found in neurosurgical practice (computer programs seem to have better judgment when analyzing radiologic data and finding out patterns in huge molecular medicine databases); robotics is present, especially in the field of spinal surgery; fast Internet is everywhere; as a matter of fact, the 5G internet technology has been launched on April, 2019, simultaneously in the US, ad in South Korea, and it is 10 to 20 times faster than the 4G; 3D impression is available to various neurosurgical fields; nanotechnology is already a reality and will inexorably develop; and biotechnology may play a hole when prosthesis are concerned in neurosurgery. It seems that a limitless field of research and study is just unfolding before us. Acknowledgement  The author would like to express his gratitute for the input and feedback from Dr. Robert F, Spetzler, from the Barrow Neurological Institute, Phoenix, AZ.

Suggested Readings and References 1. Burkhardt JK, Zinn PO, Bozinov O, et al. Neurosurgical education in Europe and the United States of America. Neurosurg Rev. 2010;33(4):409–17. 2. Schwab K. The fourth industrial revolution. New York: Crown Business, Crown Publishing Group; 2016. 3. D’Andrea G, Trillo G, Picotti V, Raco A. Functional Magnetic Resonance Imaging (fMRI), pre-intraoperative tractography in neurosurgery: the experience of Sant’ Andrea Rome University Hospital. Acta Neurochir Suppl. 2017;124:241–50.

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4. D’Andrea G, Familiari P, Di Lauro A, et al. Safe resection of gliomas of the dominant angular gyrus availing of preoperative FMRI and intraoperative DTI: preliminary series and surgical technique. World Neurosurg. 2016;87:627–39. 5. Nakagawa S, Murai Y, Matano F, et al. Evaluation video angiography of patency after vascular anastomosis using quantitative evaluation of visualization time in indocyanine green. World Neurosurg. 2018;110:e699–709. 6. Roessler K, Krawagna M, Dörfler A, et al. Essentials in intraoperative indocyanine green videoangiography assessment for intracranial aneurysm surgery: conclusions from 295 consecutively clipped aneurysms and review of the literature. Neurosurg Focus. 2014;36(2):E7. 7. Wright JM, Huang CL, Sharma R, et  al. Cardiac standstill and circulatory flow arrest in surgical treatment of intracranial aneurysms: a historical review. Neurosurg Focus. 2014;36(4):E10. 8. Intarakhao P, Thiarawat P, Rezai Jahromi B, et  al. Adenosine-induced cardiac arrest as an alternative to temporary clipping during intracranial aneurysm surgery. J Neurosurg. 2018;129(3):684–90. 9. Coelho G, Chaves TMF, Goes AF, et  al. Multimaterial 3D printing preoperative planning for frontoethmoidal meningoencephalocele surgery. Childs Nerv Syst. 2017; https://doi. org/10.1007/s00381-017-3616-6. 10. Govsa F, Karakas AB, Ozer MA, Eraslan C. Development of life-size patient-specific 3D-printed Dural venous models for preoperative planning. World Neurosurg. 2018;110:e141–9. 11. Choque-Velasquez J, Colasanti R, Collan J, et al. Virtual reality glasses and “Eye-hands blind technique” for microsurgical training in Neurosurgery. World Neurosurg. 2018;112:126–30. pii: S1878–8750(18)30110–4. 12. Gmeiner M, Dirnberger J, Fenz W, et  al. Virtual cerebral aneurysm clipping with real-time haptic force feedback in neurosurgical education. World Neurosurg. 2018;112:e313–23. pii: S1878–8750(18)30082–2. 13. Rhoton AL Jr. Cranial anatomy and surgical approaches. The Congress of Neurological Surgeons ed. Schaumberg; 2003. 14. Tang Y, Sun W, Toga AW, et al. A probabilistic atlas of human brainstem pathways based on connectome imaging data. NeuroImage. 2018;169:227–39. 15. Abdallah CG, Averill LA, Collins KA, et al. Ketamine treatment and global brain connectivity in major depression. Neuropsychopharmacology. 2017;42(6):1210–9. 16. Li T, Wang Q, Zhang J, et al. Brain-wide analysis of functional connectivity in first-episode and chronic stages of schizophrenia. Schizophr Bull. 2017;43(2):436–48. 17. Lu FM, Dai J, Couto TA, et al. Diffusion tensor imaging tractography reveals disrupted white matter structural connectivity network in healthy adults with insomnia symptoms. Front Hum Neurosci. 2017;11:583. 18. Ji GJ, Yu Y, Miao HH, Wang ZJ, Tang YL, Liao W. Decreased network efficiency in benign epilepsy with centrotemporal spikes. Radiology. 2017;283(1):186–94. 19. Whelan CD, Altmann A, Botía JA, et al. Structural brain abnormalities in the common epilepsies assessed in a worldwide ENIGMA study. Brain. 2018;141(2):391–408. 20. T Vu A, Jamison K, Glasser MF, et al. Tradeoffs in pushing the spatial resolution of fMRI for the 7T human connectome project. NeuroImage. 2017;154:23–32. 21. Bari AA, Thum J, Babayan D, Lozano AM.  Current and expected advances in deep brain stimulation for movement disorders. Prog Neurol Surg. 2018;33:222–9. 22. Martinez-Ramirez D, Jimenez-Shahed J, et al. Efficacy and safety of deep brain stimulation in Tourette syndrome: the international Tourette syndrome deep brain stimulation public database and registry. JAMA Neurol. 2018;75(3):353–9. https://doi.org/10.1001/jamaneurol.2017.4317. 23. Lozano CS, Tam J, Lozano AM. The changing landscape of surgery for Parkinson’s disease. Mov Disord. 2018;33(1):36–47. 24. Bari AA, Thum J, Babayan D, Lozano AM.  Current and expected advances in deep brain stimulation for movement disorders. Prog Neurol Surg. 2018;33:222–9. 25. Elias GJB, Namasivayam AA, Lozano AM. Deep brain stimulation for stroke: current uses and future directions. Brain Stimul. 2018;11(1):3–28.

290

M. A. T. Ferreira

26. Beckett LA, Harvey DJ, Gamst A, et  al. The Alzheimer’s disease neuroimaging initiative: annual change in biomarkers and clinical outcomes. Alzheimers Dement. 2010;6(3):257–64. 27. Ponce FA, Asaad WF, Foote KD, et  al. Bilateral deep brain stimulation of the fornix for Alzheimer’s disease: surgical safety in the advance trial. J Neurosurg. 2016;125(1):75–84. 28. Dalton B, Bartholdy S, Campbell IC, Schmidt U. Neurostimulation in clinical and sub-clinical eating disorders: a systematic update of the literature. Curr Neuropharmacol. 2018;16(8):1174– 92. https://doi.org/10.2174/1570159X16666180108111532. 29. Lipsman N, Lam E, Volpini M, et  al. Deep brain stimulation of the subcallosal cingulate for treatment-refractory anorexia nervosa: 1 year follow-up of an open-label trial. Lancet Psychiatry. 2017;4(4):285–94. 30. de Oliveira Souza C, de Lima-Pardini AC, Coelho DB, et al. Peduncolopontine DBS improves balance in progressive supranuclear palsy: instrumental analysis. Clin Neurophysiol. 2016;127(11):3470–1. 31. Thevathasan W, Debu B, Aziz T, et al. Pedunculopontine nucleus deep brain stimulation in Parkinson's disease: a clinical review. Mov Disord. 2018;33(1):10–20. 32. Lizarraga KJ, Gorgulho A, Chen W, De Salles AA. Molecular imaging of movement disorders. World J Radiol. 2016;8(3):226–39. 33. Spetzler RF, Zabramski JM, McDougall CG, et  al. Analysis of saccular aneurysms in the Barrow Ruptured Aneurysm Trial. J Neurosurg. 2018;128(1):120–5. 34. Spetzler RF, McDougall CG, Zabramski JM, et  al. The Barrow Ruptured Aneurysm Trial: 6-year results. J Neurosurg. 2015;123(3):609–17. 35. Bijlenga P, Gondar R, Schilling S, et al. PHASES score for the management of intracranial aneurysm a cross-sectional population-based retrospective study. Stroke. 2017;48:1–8. 36. Greving JP, Wermer MJ, Brown RD Jr, et al. Development of the PHASES score for prediction of risk of rupture of intracranial aneurysms: a pooled analysis of six prospective cohort studies. Lancet Neurol. 2014;13(1):59–66. 37. Pexman JH, Barber PA, Hill MD, et al. Use of the Alberta Stroke Program Early CT Score (ASPECTS) for assessing CT scans in patients with acute stroke. AJNR Am J Neuroradiol. 2001;22(8):1534–42. 38. Bal S, Bhatia R, Menon BK, et al. Time dependence of reliability of noncontrast computed tomography in comparison to computed tomography angiography source image in acute ischemic stroke. Int J Stroke. 2015;10(1):55–60. 39. Fransen PS, Beumer D, Berkhemer OA, et al. MR CLEAN, a multicenter randomized clinical trial of endovascular treatment for acute ischemic stroke in the Netherlands: study protocol for a randomized controlled trial. Trials. 2014;15:343. 40. Goyal M, Dermchuk AM, Menon BK, et al. Randomized assessment of rapid endovascular treatment of ischemic stroke. N Engl J Med. 2015;372:1019–30. 41. Saver JL, Goyal M, Bonafe A, et al. Stent-retriever Thrombectomy after intravenous t-PA, vs. t-PA alone in acute stroke. N Engl J Med. 2015;372:2285–95. 42. Campbell BCV, Mitchell PJ, Kleinig PJ, et al. Endovascular therapy for ischemic stroke with perfusion-imaging selection. N Engl J Med. 2015;372:1009–18. 43. Jovin TG, Bonafe A, Cobo E, et al. Thrombectomy within 8 hours onset of acute stroke. N Engl J Med. 2015;372:2296–306. 44. Nogueira RG, Jadhav DC, Haussen DC, et  al. Thrombectomy 6-24 hours after stroke with mismatch between deficit and infarct. N Engl J Med. 2018;378(1):11–21. 45. Albers GW, Kemp MS, Christensen JP, et al. Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging. N Engl J Med. 2018;378:708–18. https://doi.org/10.1056/ NEJMoa1713973. 46. Hacke W. A new DAWN for imaging-based selection in the treatment of acute stroke. N Engl J Med. 2018;378(1):81–3. 47. van der Hoeven EJ, Schonewille WJ, Vos JA, et al. The basilar artery international cooperation study (BASICS): study protocol for a randomised controlled trial. Trials. 2013;14:200. 48. Bashkar S, Stanwell P, Cordato D, et al. Reperfusion therapy in acute ischemic stroke: dawn of a new era? BMC Neurol. 2018:18–8.

20  The Frontiers of Neurosurgery

291

49. Oliveira Magaldi M, Nicolato A, Godinho JV, et al. Human placenta aneurysm model for training neurosurgeons in vascular neurosurgery. Neurosurgery. 2014;10(Suppl 4):592–600. 50. De Oliveira MMR, Ferrarez CE, Ramos TM, et  al. Learning brain aneurysm microsurgical skills in a human placenta model: predictive validity. J Neurosurg. 2017;128(3):846–52. 51. Ostrom QT, Guttleman H, Fulop J, et al. CBTRUS statistical report: primary brain and central nervous system tumors diagnosed in the United States in 2008–2012. Neuro-Oncology. 2015;17:iv1–iv62. 52. Louis DN, Perry A, Reifenberger G, von Deimling A, Figarella-Branger D, Cavenee WK, Ohgaki H, Wiestler OD, Kleihues P, Ellison DW.  The 2016 World Health Organization classification of tumors of the central nervous system: a summary. Acta Neuropathol. 2016;131:803–20. 53. Font-Burgada J, Reina O, Rossell D, Azorín F. chroGPS, a global chromatin positioning system for the functional analysis and visualization of the epigenome. Nucleic Acids Res. 2014;42(4):2126–3. 54. Chikawa K, Morishita S. A linear time algorithm for detecting long genomic regions enriched with a specific combination of epigenetic states. BMC Genomics. 2015;16(Suppl 2):S8. 55. Hortobágyi T, Bencze J, Varkoly G, et  al. Meningioma recurrence. Open Med (Wars). 2016;11(1):168–73. 56. De la Garza-Ramos R, Flores-Rodríue JV, Martínez-Gutierrez JC, Ruiz-Valls A, Caroso-­ Rio E.  Current standing and frontiers of gene therapy for meningiomas. Neurosurg Focus. 2013;35(6):E4. 57. Bi WL, Abedalthagafi M, Horowitz P, et al. Genomic landscape of intracranial meningiomas. J Neurosurg. 2016;125:525–35. 58. Galani V, Lampri E, Varouktsi A, et al. Genetic and epigenetic alterations in meningiomas. Clin Neurol Neurosurg. 2017;158:119–25. 59. Tang M, Wei H, Han L, et al. Whole-genome sequencing identifies new genetic alterations in meningiomas. Oncotarget. 2017;8(10):17070–80. 60. Olar A, Wani KM, Wilson CD, et  al. Global epigenetic profiling identifies methylation subgroups associated with recurrence-free survival in meningioma. Acta Neuropathol. 2017;133(3):431–44. 61. NNI Supplement to the President’s 2018 Budget. NSTC/COT/NSET. Nov 30, 2017. 62. Peng C, Gao X, Xu J, et al. Targeting orthotopic gliomas with renal-clearable luminescent gold nanoparticles. Nano Res. 2017;10(4):1366–76. 63. Ferber S, Tiram G, Sousa-Herves A, et al. Co-targeting the tumor endothelium and P-selectin-­ expressing glioblastoma cells leads to a remarkable therapeutic outcome. Elife. 2017;6:pii: e25281. 64. Zhang B, Wang H, Jin K, Jiang T, Shen S, Luo Z. BQ123 selectively improved tumor perfusion and enhanced nanomedicine delivery for glioblastomas treatment. Pharmacol Res. 2017;132:211–9. pii: S1043–6618(17)31332–4. 65. Panek WK, Khan OF, Yu D, Lesniak MS. Multiplexed nanomedicine for brain tumors: nanosized Hercules to tame our Lernaean Hydra inside? Nanomedicine (Lond). 2017; https://doi. org/10.2217/nnm-2017-0260. 66. Játiva P, Ceña V.  Use of nanoparticles for glioblastoma treatment: a new approach. Nanomedicine (Lond). 2017;12(20):2533–54. 67. Zhang B, Jiang T, Tuo Y, et al. Captopril improves tumor nanomedicine delivery by increasing tumor blood perfusion and enlarging endothelial gaps in tumor blood vessels. Cancer Lett. 2017;410:12–9.

Index

A AAN guidelines, 266–271 Absent corneal reflex, 270 Acquired hydrocephalus, 151 Acute ischemic stroke (AIS) CAS, 135 CEA, 132, 134, 135 computed tomography, 130 decompressive craniectomy, 136–138 extra-intracranial bypass, 136 IV thrombolytics, 131 mechanical clot retrieval, 131–133 penumbra, 130 symptoms, 129 Adamantinomatous tumor, 257 Adult SCAT 5, 63 Advanced Trauma Life Support (ATLS) Protocol, 81 Airway, 68 protection, 57 American Spinal Injury Association (ASIA), 83 American Spinal Injury Association Impairment Scale (AIS), 84, 96 Ancillary testing, 271–273, 276 Aneurysmal subarachnoid hemorrhage (aSAH), see Intracranial aneurysms Anterior cord syndrome, 85 Anterior insular lobe (AIL), 15 Anterior plagiocephaly, 181 Antifibrinolytic therapy, 117 Antiseizure prophylaxis, 72 AOSpine Thoracolumbar Injury Classification System (AOSpine TL), 99, 100 Aphasia, 237 Apnea, 270 testing, 271, 276 Apparent diffusion coefficient (ADC) values, 32, 243 Aqueduct stenosis, 34 Arterial spin labeling (ASL), 34

Arteriovenous malformations (AVMs), 139, 140 ASIA Impairment Scale (AIS), 83 Asomatognosia, 12 Ataxia, 41 Atypical terathoid rhabdoid tumor, 245–247 Axial chronic back pain, 216, 217 Axonotmesis, 202 B Barbiturates, 58, 71 Barrow Ruptured Aneurysm Trial (BRAT), 119 Benzodiazepines, 44, 267 Blast injury, 62 Brain frontal lobe executive function, 8 lateral surface, 5, 6 left hemisphere, lateral view of, 8 medial surface, 6, 7 motor lobe, 8 insula lobes/Island of Reil, 14–16 lateral sulcus, 5 limbic lobe, 4, 16 occipital lobes, 12–14 parietal lobe angular gyrus, 12 asomatognosia, 12 functions of, 12 postcentral gyrus, 12 pre-cuneus, 12, 13 primary sensory cortex, 11 superior and inferior parietal lobules, 11 supramarginal gyrus, 12 temporal lobe basal surface, 9 Klüver-Bucy syndrome, 10 lateral surface, 9 medial surface, 9, 10 posterior and superior, 10

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Index

294 Brain death ancillary testing, 271–273 apnea testing, 271 blood flow, assessment of, 273, 274 causes of, 265, 266 clinical determination, 268–271 definition of, 263 drug intoxication, 267, 268 EEG, 273 historical perspective, 264 hypothermia, 266, 267 international perspective, 264, 265 magnetic resonance angiography, 275 radionuclide imaging of brain perfusion, 274 special consideration, children, 275, 276 transcranial Doppler ultrasonography, 274 Brain oxygenation monitoring and threshold for treatment, 71 Brainstem tumors, 249, 250 Brainsuite, 280 Brain Trauma Foundation (BTF), 67–72 Brain tumors in adults antiepileptic drugs, 238 aphasia, 237 classification, 231 clinical management, 238 cognitive dysfunction, 236 diagnostic neuroimaging, 237, 238 epidemiology, 231–234 headache, 235, 236 ICP, 236 lumbar puncture, 237 muscle weakness, 237 seizures, 236 sensory loss, 237 signs and symptoms, 235 surgical management, 238, 239 WHO classification, 234, 235 in children atypical terathoid rhabdoid tumor, 245–247 brainstem tumors, 249, 250 clinical presentation, 241, 242 craniopharyngioma (see Craniopharyngioma) ependymomas (see Ependymomas) epidemiology, 241, 242 germ cell tumors (see Germ cell tumors) high-grade gliomas, 250 low grade gliomas, 247–249 medulloblastomas, 242–245 PNETs, 242

Broca’s area, 8 Brodman’s brain areas, 1, 2, 39 Brown-Sequárd syndrome, 38, 85, 86 Burst fractures, 101 classification, 100, 101 imaging, 101 treatment, 102 C Calcar avis, 14 Cardiopulmonary resuscitation (CPR), 68, 69, 81 Carotid artery stenting (CAS), 135 Carotid endarterectomy (CEA), 132–135 Carpal tunnel syndrome (CTS), 205 Cauda equina syndrome, 85 Caudal cell mass, 163 Caudal regression syndrome (CRS), 164, 170, 171 Cavernous malformations, 143, 144 Central Brain Tumor Registry of the United States (CBTRUS), 231 Central cord syndrome, 84, 86 Central nervous system (CNS), 1, 3, 4 arachnoid membrane, 4 cerebral cortex, 4 cranial nerves, 3 dura-mater, 3 neurocranium, 3 nucleus, 3 pia mater, 4 posterior cranial fossa, 4 viscerocranium, 3 Cerebellar hematomas, 138 Cerebello-pontine fissure, 19 Cerebral blood flow (CBF), 53, 75, 76 Cerebral hemispheres, 4 Cerebral perfusion pressure (CPP), 53, 55, 57, 71 Cerebrospinal fluid (CSF), HCP, 147–149 CSF-cisternography, 35 CSF drainage, 58 Cerebrovascular resistance (CVR), 53 Cervical axial pain, 223 Cervical myelopathy clinical course, 226 surgical treatment, 228 Cervical radiculopathy, 223 characteristics, 223, 224 physical examination, 224 provocative tests, 224 surgical treatment, 228 symptoms and signs, 223 Cervical spine injuries, 68

Index Cervical spondylosis (CS), 222 Chance fractures, 102 classification, 102 imging, 103 treatment, 103 Chiari I malformation, 168 Chiari II malformation, 168 Child SCAT 5, 63 Choriocarcinoma, 257 Closed neural tube defects (NTD) without subcutaneous mass CDS, 169 CRS, 170, 171 filum terminale, 169, 170 LDM, 169 SCM, 169, 170 with subcutaneous mass lipomas, 171, 172 meningocele, 171 terminal myelocystocele, 171 treatment, 172, 173 Cognition, 40 Coma, 40, 44, 62, 265, 269 Common carotid artery (CCA), 133 Communicating hydrocephalus, 150 Complete neurological deficit, 83 Compression and burst fractures, 89 Computed tomography (CT), 87, 90 CECT, 26 chance fractures, 103 Hounsfield units, 25, 26 metopic craniosynostosis, 27 multiplanar image reconstructions and creation of 3D images, 27 NECT, 26 in trauma patients, 26 traumatic brain injury, 65–68 windowing, 26 Computed tomography angiography (CTA), 74, 274, 275 Congenital connective tissue disorders, 141 Congenital dermal sinus (CDS), 169 Congenital hydrocephalus, 151–153 Congenital kyphosis, 168 Consciousness, 40, 47 Contrast-enhanced computed tomography (CECT), 26 Contusions/intracerebral hemorrhage, 67 Conus medullaris syndrome, 85 Coronal synostosis, 181, 183, 184 Cortical blindness, 39 Corticosteroid therapy, 249 Cranial nerves, 45 abducens nerve, 46 facial nerves, 46

295 glossopharyngeal and vagus nerves, 47 hypoglossal nerve, 47 oculomotornerve, 45 olfactory nerve, 45 optic nerves, 45 spinal-accessory nerve, 47 trigeminal nerve, 45 vestibulocochlear nerves, 46 Craniopharyngioma clinical presentation, 258 diagnosis, 258–260 incidence, 257 pathology, 257, 258 prognosis, 261 treatment, 260 Craniosynostosis classification, 179, 180 coronal synostosis, 181, 183, 184 definition, 179 diagnosis, 177, 179, 180 lambdoid synostosis, 184 metopic synostosis, 184 positional plagiocephaly cause of, 185 differential diagnosis, 185 ipsilateral bulging, 186, 187 physical examination, 186 prevalence, 185, 186 risk factors, 185 therapeutic measures, 186 sagittal synostosis, 181, 182 skull sutures, 178, 179 Craniovertebral junction (CVJ), 88 CT, see Computed tomography (CT) D Dawson fingers, 30 Decompressive craniectomy, 136–138 with duraplasty, 58 Deep brain stimulation (DBS), 282 Deep hematomas, 138 Deep vein thrombosis (DVT) prophylaxis, 70 Degenerative cervical spine disease antidepressants and anticonvulsants, 227 cervical axial pain, 223 cervical myelopathy clinical course, 226 surgical treatment, 228 cervical radiculopathy, 223 characteristics, 223, 224 physical examination, 224 provocative tests, 224 surgical treatment, 228 symptoms and signs, 223

Index

296 Degenerative cervical spine disease (cont.) clinical presentation, 222 definition, 221 diagnosis, 226, 227 epidemiology, 222 etiology, 222 gabapentin and pregabalin, 227 non-surgical regimen, 227 Delayed cerebral ischemia (DCI), 119–121 Dementia, 38, 40 Dexmedetomidine, 267 Diffuse axonal injury (DAI), 66 Diffuse brain injury/ICP control, 73 Diffuse fibrillar astrocytoma, 250 Diffusion tensor imaging (DTI), 2, 33, 74, 282 Diffusion-weighted imaging (DWI), 32, 74 Digital subtraction angiography (DSA), 135 Distractive injuries, 90 Dominant hemisphere, 39 Drug intoxication, 267, 268 Dual antiplatelet therapy (DAPT), 142 Durkan’s test, 204 Dynamic susceptibility contrast (DSC), 34 E Electroencephalography (EEG), 75, 273 Electromyoneurography (ENMG), 204, 205 Eloquent brain areas, 3, 39, 40 Embryonic carcinoma, 257 Empty skull sign, 274 Endocrine dysfunction, 258 Endodermal sinus tumor, 256 Endoscopic endonasal surgery, 260 Entrapment syndromes, 205 Ependymomas, 243 clinical presentation, 252, 253 diagnosis, 253, 254 incidence, 251 pathology, 251 prognosis, 255 treatment, 254, 255 Epidural hematoma, 66, 67 Epilepsy, 8 Epithelial scar, 166 External carotid artery (ECA), 133–134 Extrapyramidal system, 41 F Fat suppression, 30 Fentanyl, 267 Fiber tractography (FT), 33 FIESTA/CISS sequence, 34, 35

Filum terminale (FT) disorders, 161, 163, 169, 170 Four vessel cerebral angiography, 273 Fractionated radiotherapy (FR), 254 Frontal lobe, 39 executive function, 8 lateral surface, 5, 6 left hemisphere, lateral view of, 8 medial surface, 6, 7 motor lobe, 8 Functional MRI (fMRI), 281 Functional neurosurgery, 282, 283 Fusiform aneurysms, 113 Fusiform gyrus, 9 G Gadolinium (Gd)-based contrast agents (GBCAs), 31, 32 Gait, 41 Germ cell tumors choriocarcinoma, 257 embryonic carcinoma, 257 germinomas, 254–256 non-germinomas, 256 teratomas, 256 yolk sac, 256 Germinomas, 254–256 Gerstmann’s syndrome, 39 Glasgow Coma Scale (GCS), 40, 47, 54, 62–65, 67, 68, 70, 72, 73 Glial neoplasms, 246 high-grade, 250 low grade, 247–249 Glioblastoma, 33 Glossopharyngeal and vagus nerves, 47 Guillain-Barré syndrome, 266 H Hemisphere, 7 Hemissection cord syndrome, 85 Hemorrhagic stroke AVMs, 139, 140 cavernous malformations, 143, 144 intracranial aneurysm clipping/reconstruction, 140–143 intraparenchymal hematoma, 138, 139 symptoms, 138 Herniation syndromes, 54, 55 Hounsfield units (HU), 25, 26 Human Connectome Project (HCP), 281 Hunt and Hess grading system, 115 Hydrocephalus (HCP), 120, 168 acquired hydrocephalus, 151

Index classification communicating hydrocephalus, 150 congenital hydrocephalus, 151–153 noncommunicating hydrocephalus, 150, 151 types, 149 clinical presentation, 152 CSF, 147–149 definition, 147 epidemiology, 148 radiological findings, 153, 154 brain CT Scan, 154, 155 brain MRI, 154 ultrasound, 153 third ventriculostomy, 157, 158 VPS, 155, 156 Hyperosmolar therapy, 69 Hyperventilation, 72 Hypoglossal nerve, 47 Hypotension, 68, 91 Hypothemia, 266, 267 Hypoxemia, 91 I Idiopathic hydrocephalus, 158 Idiopathic normal pressure hydrocephalus (iNPH), 148 Incomplete neurological deficits (AIS B, C and D), 84 Increased intracranial pressure (ICP), 236 Infection prophylaxis, 69 Insula lobes, 14–16 Internal carotid artery (ICA), 133 International Subarachnoid Aneurysm Trial (ISAT), 119 Intracranial aneurysms clinical outcomes, 121 diagnosis CT imaging, 115, 116 digital subtraction angiography, 115, 117 sentinel headache, 115 epidemiology, 112–114 initial medical management, 117 pathophysiology, 112–114 ruptured treatment, 119 BRAT, 119 endovascular treatment, 118 intervention, 119 ISAT, 119 open surgical clipping, 118 signs and symptoms, 114, 115 vasospasm/DCI, 119–121 Intracranial blood/hemorrhage, 70

297 stages and characteristics, 29 Intracranial hypertension (ICH), 180, 258 Intracranial lesions, 66 Intracranial pressure (ICP), 70 control, 73 definition, 51 direct monitoring, 55, 56 HS, 69 hyperventilation, 72 mannitol, 69 monitor technology, 70 monitoring, 70 neuroimaging, 55 neurosonology, 57 pathophysiology, 51–54 CBF, 53 cranial compartment, 51 CVR autoregulation, 53 intracranial expansive process, 52 intracranial pressure-volume curve, 52 physical examination and clinical features, 54, 55 treatment barbiturates, 58 CSF drainage, 58 decompressive craniectomy with duraplasty, 58 general management, 57, 58 osmotherapy, 58 paralytic agents, 58 Intraoperative neurophysiological monitoring (IONM), 173 Intraparenchymal hematoma, 138, 139 Ischemic stroke (IS), 48 acute management CAS, 135 CEA, 132–135 computed tomography, 130 decompressive craniectomy, 136–138 extra-intracranial bypass, 136 IV thrombolytics, 131 mechanical clot retrieval, 131–133 penumbra, 130 symptoms, 129 Island of Reil, see Insula lobes K Keppra, 267 Klüver-Bucy syndrome, 10 L Lambdoid synostosis, 184 Left fronto-insular low-grade astrocytoma, 33

Index

298 LICOX CMP system, 71 Ligamentous injuries, 88, 91 Limbic lobe, 16 Limited dorsal myeloschisis (LDM), 169 Lipomas, 171, 172 Lobar hematomas, 138 Locked-in-syndrome, 266 Long term sequelae of brain injury, 76 Low back pain, 213 acute brace prescription, 196 intensity and frequency, 195 non-pharmacological treatment, 195 pharmacological treatment, 195 chronic non-pharmacological treatment, 197 pharmacological treatment, 196 psychosocial comorbidities, 196 clinical outcomes, 197 definition, 191 diagnosis laboratory assessment, 194, 195 physical examination, 193, 194 radiologic assessment, 194 epidemiology, 193 primary/non-specific pain, 191 red flags, 192 signs and symptoms, 192 specific/secondary pain, 191, 192 Lumbar degenerative disease (LDD) annulus fibrosus, 212 clinical characteristics, 214 CT scan, 216 definition, 211 electromyography, 216 epidemiology, 212, 213 etiology, 212 LDH, 213, 218 low back pain, 213 MRI, 216 neurogenic claudication, 213 plain radiographs, 215 spinal deformity, 214 treatment, 216–218 Lumbar disc herniation, 213, 217, 218 Lumbar radiculopathy, 218 Lumbar stenosis, 217, 218 M Magerl (AO), 98 Magnetic resonance-guided focused ultrasound (MRgFUS), 283 Magnetic resonance imaging (MRI), 3, 34, 35, 275

chance fractures, 103 DTI, 33 DWI, 32 fat suppression, 30 FLAIR, 29, 30 radio-frequency coil (antenna, 27 SWI, 32 T1, 28 T2, 28, 29, 31, 32 TBI, 74 tissue composition, 27 T1 postcontrast(gadolinium), 31 Malignant infarction, 21 Mannitol, 58, 69 Mechanical clot retrieval, 131–133 Mechanical thrombolysis (MT) therapy, 284 Medical Research Council (MRC) Scale for muscle Strength, 42 Medulloblastomas, 242–245 Meningiomas, 286 Meningocele, 171 Metopic craniosynostosis, 27 Metopic synostosis, 184 Microguidewire, 131, 135 Microneurosurgery, 280 Midazolam, 267 Middle cerebral artery (MCA), 131 Mini Mental Status Examination (MMSE), 40 Modified Fisher grading scale, 115, 116 Monroe foramina, 157 Morphine, 267 Movement disorders, 41 Moya Moya disease, 136 MR perfusion, 33, 34 Multiple sclerosis, 30 Muscle tonus, 42 Muscle weakness, 237 Muscular examination, 41–43 Mycotic/infectious aneurysms, 113 Myelocele, 168 Myelomeningocele (MMC), 167, 168, 172 N Nanomedicine, 286 Nanoparticles, 287 NECT, see Non Enhanced Computed Tomography (NECT) Neural tube closure defects (NTD), 163 Neurapraxia, 202 Neuroanatomy, 281, 282 Brodmann areas, 1, 2 central nervous system, 3, 4 eloquent areas, 3 encephalon/telencephalon

Index basal nuclei, 17, 18 brain (see Brain) brainstem, 19–21 cerebellum, 18–20 diencephalon, 16 vascularization, 21, 22 Neurocysticercosis, 34 Neurofibromatosis type 1 (NF1), 248 Neurogenic bladder dysfunction, 164 Neurogenic claudication (NC), 213 Neurogenic shock, 83 Neurohypophysis, 28 Neuroimaging computed tomography, 25–27 FIESTA/CISS sequence, 34, 35 ICP, 55 MR angiography, 35 MRI DTI, 33 DWI, 32 fat suppression, 30 FLAIR, 29, 30 radio-frequency coil (antenna, 27 SWI, 32 T1, 28 T2, 28, 29, 31, 32 tissue composition, 27 T1 postcontrast(gadolinium), 31 MR perfusion, 33, 34 MR spectroscopy, 34 Neurological deficits, 38 acute onset, 38 chronic onset, 38 fluctuating neurological symptoms, 38 subacute onset, 38 Neurological examination, 37–39 balance, 41 coma, 44 consciousness and cognition, 40 cranial nerves, 45 abducens nerve, 46 facial nerves, 46 glossopharyngeal and the Vagus nerves, 47 hypoglossal nerve, 47 oculomotornerve, 45 olfactory nerve, 45 optic nerves, 45 spinal-accessory nerve, 47 trigeminal nerve, 45 vestibulocochlear nerves, 46 eloquent brain areas, 39, 40 gait, 41 muscular examination, 41–43 pupil examination, 43, 44

299 sensory evaluation, 43 Neuro-ocology, 285–287 Neuro-orthopaedic syndrome, 164 Neurosonology, 57 Neurosurgery, 38, 39, 279 brainsuite, 280 functional neurosurgery, 282, 283 neuroanatomy, 281, 282 neuro-ocology, 285–287 neurosurgeon’s profile, 279, 280 neurovascular surgery, 283–285 spine surgery, 287, 288 tridimensional models, 280 Neurotmesis, 202 Neurovascular surgery, 283–285 Nissl method of cell staining, 1 Non-aneurysmal spontaneous, 121, 122 Non-communicating hydrocephalus, 150, 151 Non-eloquent areas, 40 Non enhanced computed tomography (NECT), 26 Normal pressure hydrocephalus (NPH), 153 diagnosis, 159 etiology, 158 neurological symptoms, 158 prevalence, 158 treatment, 159 Normocapnia, 57 Normotension, 57 Normothermia, 57 Normovolemia, 57 Nutrition, 72 O Occipital lobes, 12–14 Oculocephalic testing, 269 Oculomotor nerve, 45, 64 Oculovestibular reflex testing., 269 Open neural tube defects, MMC, 167, 168, 172 Osmotherapy, 58 Ossification of the posterior longitudinal ligament (OPLL), 222 Osteoporotic vertebral compression fracture classification, 105 imaging, 105 treatment, 105, 106 P Papillary type, 258 Papilledema, 54 Paraclinoid meningioma, 31

300 Parietal lobe angular gyrus, 12 asomatognosia, 12 functions of, 12 postcentral gyrus, 12 pre-cuneus, 12, 13 primary sensory cortex, 11 superior and inferior parietal lobules, 11 supramarginal gyrus, 12 Parkinson’s disease, 20, 38 Patrick’s sign, 194 Penetrating injury, 68 Pentobarbital, 58 Peripheral nerve surgery clinical outcome, 208 definition, 201 ENMG, 204, 205 entrapment syndromes, 205 epidemiology, 202, 203 etiology, 201, 202 physical examination, 203, 204 traumatic injury, 206–208 Phalen maneuver, 204 Pharyngeal/gag reflex, 270 PHASES score, 284 Phenobarbital, 267 Phenytoin, 58, 267 Pilocytic astrocytoma, 243, 248, 249 Pneumocephalus, 65 Polycystic kidney disease (PKD), 141 Posterior insular lobe (PIL), 15 Posterior ligamentous complex (PLC), 101, 102 integrity, 98, 99 Posterior longitudinal ligament (PLL), 97 Post-traumatic seizures, 72 Primitive neuroectodermal tumors (PNETs), 29, 242 Prophylactic hypothermia, 69 Propofol, 71, 267 Pulmonary embolism (PE), 70 Pupil examination, 43, 44 Pyramidal motor systems, 42 Q Quality of life, 201 R Radionuclide imaging of brain perfusion, 274 Riluzole, 82 Rocuronium, 267

Index S Saccular intracranial aneurysms, 140 Sacral dimples, 165 Sacral fractures, 89 Saddle anesthesia, 48 Sagittal synostosis, 181, 182 Scaphocephaly, 181 Seddon’s classification, 202, 203 Sensory dysphasia, 10 Sensory evaluation, 43 Single photon emission computed tomography (SPECT), 75 Smoking, 197 Spasticity, 42 Spetzler-Martin (SM) classification, 140 Spinal-accessory nerve, 47 Spinal cord injury without radiographic abnormality (SCIWORA), 86 Spinal deformity, 214 Spinal dysraphism classification, 167 closed NTD treatment, 172, 173 without subcutaneous mass, 169–171 with subcutaneous mass, 171, 172 MRI, 166 open NTD, 167, 168, 172 outcome and prevention, 173, 174 ultrasound, 166 urological evaluation, 167 Spinal shock, 85 Spine surgery, 287, 288 Spine trauma Advanced Trauma Life Support Protocol, 81 classification and definitive treatment craniovertebral junction, 88 sacral fractures, 88, 89 subaxial cervical spine, 88, 89 thoracic and lumbar fractures, 88, 89 upper cervical spine, 88 diagnosis atropine, 83 neurogenic shock, 83 neurological assessment, 83–86 radiologic assessment, 87 epidemiology, 82, 83 injury morphology and mechanism, classification compression and burst fractures, 89 distractive injuries, 90 penetration injuries into spine, 90 translation/rotational, 90

Index primary injury, 82 rationale, 82 secondary injury, 82 in special age group, 90, 91 Split cord malformation (SCM), 169, 170 Spondylosis, 211 Spurling test, 224 Steroids, 72 Stroke, 111 Subacute infarcts, 30 Subarachnoid hemorrhage (SAH) intracranial aneurysms (see Intracranial aneurysms) morbidity and mortality, 111 non-aneurysmal spontaneous, 121, 122 pia mater and arachnoid mater, 111, 112 Subaxial cervical spine, 88, 89 Subcutaneous lipoma, 165 Subdural hematomas (SDH), 67 Sunderland’s classification, 203 Susceptibility weighted imaging (SWI), 32 Suxamethonium, 267 T Temporal lobe basal surface, 9 Klüver-Bucy syndrome, 10 lateral surface, 9 medial surface, 9, 10 posterior and superior, 10 Teratomas, 256 Terminal myelocystocele, 171 Terminologia Anatomica, 4 Tethered cord syndrome (TCS) clinical presentation, 164–166 definition, 161 gastrulation, 162 primary neurulation, 163 secondary neurulation, 163, 164 spinal cord, conus and filum terminale, 161, 162 spinal dysraphism (see Spinal dysraphism) Third ventriculostomy, 157, 158 Thoracic and lumbar fractures, 89 Thoracolumbar fracture-dislocations classification, 103, 104 imaging, 104 treatment, 104, 105 Thoracolumbar Injury Classification System (TLICS), 98, 99 Thoracolumbar spine, 95, 96

301 Thoracolumbar spine trauma burst fractures (see Burst fractures) chance fractures classification, 102 imaging, 103 treatment, 103 classification systems anterior column, 97 AOSpine Thoracolumbar Injury Classification System, 99, 100 appearance and mechanism of injury, 97 isolated mechanical instability, 97 Magerl (AO), 98 neurologic deterioration, 97 posterior column, 97 TLICS, 98, 99 osteoporotic vertebral compression fracture classification, 105 imaging, 105 treatment, 105, 106 thoracolumbar fracture-dislocations classification, 103, 104 imaging, 104 treatment, 104, 105 Thunderclap headaches, 114 Time of flight (TOF) angiography, 35 Tinel’s signal, 204 TLICS, see Thoracolumbar Injury Classification System (TLICS) Tourrete syndrome, 282 Transcranial Doppler ultrasonography (TCD), 57, 76, 274 Transient paralysis, 85 Traumatic brain injury (TBI) bedside physical exam general examination, 64 neurological examination, 64 CBF, 75, 76 clinical electrophysiology, 63, 75 CTA, 74 imaging and diagnostic procedures contusions/intracerebral hemorrhage, 67 CT scanning, 65, 66 epidural hematoma, 67 intracranial lesions, 66 penetrating injury, 68 SDH, 67 long term sequelae of brain injury, 76 mechanism, 62 medical therapy airway, 68 anesthesia, analgesics and sedatives, 71 antiseizure prophylaxis, 72

Index

302 brain oxygenation monitoring and threshold for treatment, 71 cardiopulmonary, 68, 69 DVT prophylaxis, 70 hyperosmolar therapy, 69 hyperventilation, 72 infection prophylaxis, 69 intracranial pressure monitor technology, 70 intracranial pressure monitoring, 70 nutrition, 72 prophylactic hypothermia, 69 steroids, 72 treatment thresholds and optimal cerebral perfusion pressure, 70, 71 MRI, 74 severity, 62, 63 special considerations in examination motor function, 65 pupils, 64 surgical therapy for diffuse brain injury/ICP control, 73 indications, 73 penetrating head injury, 73, 74 treatment, 68 Tumorigenesis, 285

U Uniform Determination of Death Act (UDDA), 263, 264, 268, 272 Unruptured intracranial aneurysms (UIAs), 112, 141 Upper cervical spine, 88 V Vasospasm, 119–121 Vecuronium, 267 Vein of Labbè, 14 Ventricular peritoneal shunt (VPS), 155, 156 Vertebroplasty, 105, 106 Vestibulocochlear nerves, 46 Volume rendering (VR) techniques, 27 W Weber’s test, 46 Wernicke’s area, 8, 39 White matter fiber dissection techniques, 2 Windowing, 26 Wingless group (WNT), 242