Skull Base Surgery (Springer Surgery Atlas Series) 3540742573, 9783540742579

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Springer Surgery Atlas Series Series Editors: J. S. P. Lumley · James R. Howe

Anthony Cheesman Ghassan Alusi H. Ian Sabin  Editors

Skull Base Surgery

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Springer Surgery Atlas Series Series Editors J. S. P. Lumley James R. Howe

More information about this series at http://www.springer.com/series/4484

Anthony Cheesman  •  Ghassan Alusi H. Ian Sabin Editors

Skull Base Surgery

Editors Anthony Cheesman Department of ORL and Skull Base Surgery St Bartholomew's Hospital London UK

Ghassan Alusi Otolaryngology & Head and Neck Surgery Barts and The London NHS Trust London UK

H. Ian Sabin The Wellington Hospital Neurosurgical Unit London UK

ISSN 2626-9015     ISSN 2626-9023 (electronic) Springer Surgery Atlas Series ISBN 978-3-540-74257-9    ISBN 978-3-540-74259-3 (eBook) https://doi.org/10.1007/978-3-540-74259-3 © Springer-Verlag GmbH Germany, part of Springer Nature 2022 This work is subject to copyright. All rights are solely and exclusively licensed 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-Verlag GmbH, DE part of Springer Nature. The registered company address is: Heidelberger Platz 3, 14197 Berlin, Germany

We thank our wives for their enduring support.

Foreword: Skull Base Surgery

Skull Base Surgery by Cheesman, Alusi, and Sabin is a beautifully illustrated comprehensive surgical atlas of surgical procedures used to remove tumors mainly using anterior approaches. The text provides a compendium of detailed, meticulous descriptions of a variety of techniques tailored to the resection of tumors both benign and malignant that take origin in the nasal and paranasal sinus mucosa, nasopharynx, orbit and palate with extension through the anterior and middle bony supports of the brain. The step-by-step descriptions are precise and detailed and provide an easy guide to the resection of lesions that invade this complex area. Each of the 8 chapters provides a different approach and describes the neurosurgical and, in some cases, the maxillofacial aspects of the procedures. Professor Cheesman’s experience of over 500 cases of resections of tumors in this region validates the efficacy of these approaches. My personal experience strongly supports the principles he describes in this excellent surgical Atlas. Professor Cheesman is well known worldwide as an authority on the management of skull base tumors. This book is completely supportive of his marvelous reputation. Paul Donald Professor Emeritus, Department of Otolaryngology/Head and Neck Surgery University of California Davis El Macero, CA, USA

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Preface

Surgical procedures on the anterior skull base were the subject of case reports during the early part of the last century. The neurosurgical giant, Cushing, is perhaps best known for his early adoption of transnasal and trans-sphenoidal approaches to the pituitary gland, but he also published approaches to the anterior skull base and transfacial approaches for pathology in the sinuses, including a ‘spectacle incision’ used to remove a frontal sinus osteoma and frontal lobe abscess in 1909. Walter Dandy also reported a case of an orbital tumour resected through the anterior fossa, with additional resection of the ethmoid sinuses. The first significant series of craniofacial skull base resections, however, was reported by Ketcham in 1963. He was a general surgeon with a broad range of practice, which included pelvic exenteration and breast-conserving surgery for cancer. This period also saw the beginning of ENT-based head and neck surgery led by John Conley in the USA and Donald Harrison in the UK, but even these pioneers thought that intracranial resections carried too much risk. This mirrors the attitude of Harvey Cushing, who abandoned transnasal surgery due to inadequate exposure given the instruments of the day and the risk of CSF leak in the pre-antibiotic era. Peter Clifford and Tony Cheesman subsequently developed Ketcham’s work and reported a large series of successful resections, proving that skull base surgery was both safe and effective, resulting in higher cure rates. Initially, they worked with neurosurgeons, but then developed single-specialty approaches. Their results, however, encouraged surgeons from different specialties including ENT, maxillofacial, plastics, ophthalmology, and neurosurgery to develop expertise in approaches to the skull base. The result was the subspecialty of skull base surgery built on the combined experience of a multidisciplinary team. We have been influenced by many fellow surgeons, and we hope that we have also helped to ‘push the boundaries’. UK Lindsay Symon Alan Crockard Don Harrison Peter Clifford Danny Archer Michael Gleeson Italy Paolo Cappabianca Germany Wolfgang Draf Magid Samii Rudi Farbouef Axel Perneczky

USA Alfred Ketcham Paul Donald Ian Jackson Jatin Shah Derald Brackman Al Rhoton Hae-Dong Jho Australia Paul Fagan Switzerland Ugo Fisch Yoram Raveh

To become a skull base surgeon requires exposure to these different specialties in order to develop the necessary techniques, and we hope that this atlas will be of value to those starting in this fascinating sub-specialty. We have concentrated on the external approaches as these are not routinely seen in this era of endoscopy, yet they remain extremely useful in selected cases. ix

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We would like to thank the many artists who have produced the illustrations according to our complex requirements. We especially thank Merlin Evans and Philip Wilson who have allowed us to work conjointly with them. John Lumley as Series Editor has been a fount of knowledge and encouragement when problems have inevitably occurred. We also thank Springer for putting everything together to make a presentable and useful atlas. London, UK London, UK London, UK 

Anthony Cheesman Ghassan Alusi H. Ian Sabin

Acknowledgments

The volume editors acknowledge the following illustrators’ contribution to the preparation of the book’s iconography: Merlin Evans London, UK [email protected] Figs. 2.1–2.22, 7.2–7.12, 7.14–7.23 Revision of Figs. 7.13b, 7.13c, 7.13d Jenny N. R. Smith Bristol, UK [email protected] Figs. 4.7, 8.8, 8.11, 8.12, 8.13 Philip Wilson Launceston, UK [email protected] Figs. 7.13b, 7.13c, 7.13d (original version)

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Contents

1 General Considerations �����������������������������������������������������������������������������������������������  1 Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin 2 Sub-frontal Approach (Spectacle Incision Approach)����������������������������������������������� 11 Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin 3 Supraorbital Craniotomy��������������������������������������������������������������������������������������������� 23 Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin 4 Orbitozygomatic Approach����������������������������������������������������������������������������������������� 29 Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin 5 Le Fort 1 Approach������������������������������������������������������������������������������������������������������� 35 Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin 6 Midfacial Degloving ����������������������������������������������������������������������������������������������������� 43 Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin 7 Lateral Rhinotomy������������������������������������������������������������������������������������������������������� 59 Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin 8 Bicoronal Flap, Frontal Craniotomy��������������������������������������������������������������������������� 81 Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin

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General Considerations Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin

1.1

 oncepts Underlying Anterior Skull C Base Surgery

Traditionally the dura has been a boundary between neurosurgical and otolaryngological practice; if an otolaryngologist were to breach this boundary there was a potential for significant intracranial infection. The extensive pneumatisation of the anterior and central skull base provides the anatomical basis for access to the anterior and central skull base by way of the paranasal sinuses (Fig. 1.1). The advent of antibiotics and trauma involving the anterior skull base showed that the dura may be breached without major consequence, provided that the dura is always repaired to restore the integrity of the intracranial cavity.

Infections of the paranasal sinuses have always had the potential to cause intracranial infections, but in such cases, the treatment was generally managed independently and depending on the clinical problem, an intracranial abscess would be treated neurosurgically prior to the otolaryngologist eradicating the sinus infection at a subsequent operation. It was the joint management of sinonasal malignancies that breached the dura which resulted in the development of joint skull base procedures to cure or to treat these patients. Initially these procedures tended to use standard neurosurgical approaches such as the frontolateral craniotomy combined with an otolaryngological medial maxillectomy.

A. Cheesman (*) · G. Alusi Department of Otolaryngology and Skull Base Surgery, Barts Health NHS Trust, The Royal London Hospital, London, UK e-mail: [email protected] H. I. Sabin The Wellington Hospital, Neurosurgical Unit, London, UK e-mail: [email protected]

© Springer-Verlag GmbH Germany, part of Springer Nature 2022 A. Cheesman et al. (eds.), Skull Base Surgery, Springer Surgery Atlas Series, https://doi.org/10.1007/978-3-540-74259-3_1

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Frontal sinuses

Ethmoidal cell

Orbital plate of ethmoid bone Maxillary sinuses

Roots of posterior upper molars

Fig. 1.1  Pneumatisation of paranasal sinuses

1.2

 volution of Anterior Skull Base E Surgery

We have been performing craniofacial resections for tumours of the nose and paranasal sinuses over the last 40  years. Beginning with the initial joint rhinological and neurosurgical procedures, we have developed various specialised skull base approaches, including the current endoscopic resections of the skull base. These developments are outcomes of a careful audit of our results and have led to better survival and decreasing morbidity. The most significant features of the audit have been: • The value of preoperative imaging • The accurate histological classification of each tumour prior to deciding the treatment plan • Careful but simple reconstruction of the skull base Our current aim is to use well-defined surgical approaches dependent upon the type and extent of each tumour. For most tumours, a combination of radiotherapy and surgical resection has been consistently shown to produce the best results. There does not seem to be any significant difference between pre- and post-operative irradiation [1]. Over the last four decades, using a variety of techniques, there has been a significant advance in surgery of the anterior skull base. The development of these techniques was driven by the need for more radical resection of tumours of the nose and paranasal sinuses that invaded the skull base. The initial approaches used traditional transfacial techniques to the ethmoid and sphenoid, combined

with a standard neurosurgical anterior craniotomy, to expose the upper extent of the tumour. Although in good hands the results were encouraging, the complexity and duration of this type of surgery rendered it inappropriate for most cases. The next step in the evolution of the procedure was to use more limited craniotomies that gave exposure and access to the roof of the nose and paranasal sinuses [2–4]. Following our experiences with joint neurosurgical procedures we developed a single-team craniofacial approach, which used a small window craniotomy to access the floor of the central anterior fossa. This was termed the Type I craniofacial resection. An extended lateral rhinotomy was used to encompass the inferior and lateral extent of the tumour. The results of our initial series were very encouraging, with dramatic improvements in curative resections accomplished by a surgical procedure that could be completed in a reasonable timescale of a few hours. This enabled us to offer a craniofacial resection to all patients with tumours encroaching the roof of the nose and paranasal sinuses, and this further improved cure rates. For smaller tumours, we found that limited dural resections could be successfully accomplished from the extended lateral rhinotomy approach, which gave a wide exposure of the anterior central skull base. We termed this procedure a Type II craniofacial resection, and it became our standard approach for small tumours. Currently we use an endoscopic approach for such tumours, obviating the need for a lateral rhinotomy approach. A consistent problem area was the anterior roof deep to the glabella. This required resection of the upper nasal

1  General Considerations

pyramid, including the glabella. The improved exposure resulting from this resection often enabled us to preserve the bone flap and use it in the reconstruction. If the tumour involved the glabella bone flap, it was removed, and a satisfactory reconstruction could be performed using a rib graft. The successful use of this technique, along with the dramatically improved exposure, encouraged us to modify the craniofacial resection and to routinely use a glabella bone flap approach for exposure of both the nasal cavities and floor of the anterior fossa, and this obviated the need for the small window craniotomy. We initially termed this procedure a Type III craniofacial resection. Subsequently Raveh [5] developed a similar approach in the context of maxillofacial trauma experience. He termed his approach a sub-frontal approach, and this term has become the common usage [6]. Currently, with modern imaging, tumours of the nose and paranasal sinuses are being detected more readily when they are small. If the imaging suggests tumour formation, an initial biopsy of the tumour is made. This early confirmation of tumour type is vital, as we have found that the histological type is a good indication of the natural history of the many and varied tumours of this region. Knowing its natural history enables us to plan a comprehensive approach using both radiotherapy and surgery. It is mandatory that such procedures be performed in centres with a wide experience of skull base procedures. One of the problems of the widespread use of endoscopic sinus surgery by routine ENT surgeons is that some of these tumours are being resected as part of the standard FESS procedure; the diagnosis of malignancy is made only after histological examination of the material removed from the nose. Sadly, some of these cases are referred directly for radiotherapy without a full surgical workup in an oncology unit. In addition, the resections are often limited and do not encompass the true extent of the tumour. Subsequent recurrence of the tumour 2 years later results in the old surgical problem of tumour extension involving the skull base or orbit, for which skull base surgery was initially developed, and the resultant overall cure rate has deteriorated. A separate volume of Endoscopic Skull Base Surgery is in preparation.

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1.3

Skull Base Approaches

Pathology in the anterior and central skull base can be approached by three different routes (Fig. 1.2). Traditionally the route was via a transcranial approach; however with the evolution of skull base surgery further routes, transfacial and transoral, have been developed. Today with the considerable interest in endoscopic surgery, endoscopic approaches to the skull base have become popular, but their success depends on good results and low complications. Sadly, there are few studies to support the long-term benefits to the patient and complications such as cerebrospinal fluid leaks are still a significant problem. Consequently, the external approaches must remain the gold standard. These various approaches are described in detail in the following chapters.

Trans cranial

Trans facial

Trans oral

Fig. 1.2  Routes to the anterior and central skull base

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 eed for Good Anatomical Knowledge N with Transnasal Approaches The depth of the nose is not always appreciated, but it is 6–7 cm from the anterior nasal spine to the anterior wall of the sphenoid sinus. The nasal cavity itself is very narrow but the procedure of medial maxillectomy enlarges its width giving good exposure of both the lateral nasal wall and the associated paranasal sinuses. In Fig.  1.3a the nasal cavity has been artistically split along the left side of the nasal septum to show the extent of the lateral nasal wall. In Fig. 1.3b a craniofacial resection has been performed and the diagram shows its major features.

a

• On the left side a medial maxillectomy has been performed which removes the whole of the lateral wall of the nose exposing the orbital periosteum and widely opening the left antral cavity. • The sphenoid cavity has been widely opened and its bony roof has been resected along with the roof of the left ethmoid sinuses. The associated dura of the floor of the anterior fossa has also been resected and repaired with a fascia lata graft. • On the right side a radical ethmoidectomy has been performed to expose the orbital periosteum; this results in removal of both the middle and superior turbinates giving an enlarged middle meatal antrostomy into the right antrum. The right inferior turbinate is left in place.

b

Fig. 1.3 (a, b) Three-dimensional representation of the anterior craniofacial resection

1  General Considerations

1.4

5

 eneral Workup for Skull Base G Procedures

Image Guidance Image guidance is usually used for more complex cases and is particularly useful when first starting this surgery. However, for straightforward craniofacial resections particularly with transfacial approaches we prefer to dispense with image guidance as the skull fixation inhibits our movement of the head that is necessary to visualise all the operative areas (Fig. 1.4).

Most skull base procedures require a similar workup prior to surgery.

Imaging All patients need to undergo preoperative imaging using a combination of high-resolution, contrast-enhanced CT scans (both axial and coronal planes) plus three-planar MRI scans enhanced with gadolinium [1, 7].

Fig. 1.4 (a, b) Image guidance

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Fig. 1.4 (continued)

1  General Considerations

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Patient Positioning The patient is positioned supinely upon the operating table; the table is then broken, and the upper half elevated by 40° to facilitate good venous drainage and hypotensive anaesthesia (Fig. 1.5). The head is then extended by 10–20° and placed in a supporting head ring. This position facilitates the movement of the head to allow direct visualisation of the various parts of the operative field.

Fig. 1.5  Patient position

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Anaesthesia Both general and local anaesthesia are combined with this form of nasal surgery. The use of local anaesthesia using Moffett’s technique provides the added advantage of causing vasoconstriction of the nasal mucosa, which dramatically reduces bleeding and hence improves the surgeon’s ability to visualise the anatomy. Moffett’s technique is a traditional procedure for local anaesthesia of the nasal cavity using a 10% cocaine solution (Table 1.1). Its major advantage is the extreme vasoconstriction of the nasal mucosa that it causes, and this greatly facilitates all nasal surgery. In some countries, the use of cocaine is Table 1.1  Moffett’s solution 2 mL 10% 1 mL 1/1000 2 mL 1%

Cocaine solution Adrenaline solution Sodium bicarbonate solution

banned and an alternative solution for nasal vasoconstriction is a combination of lidocaine 5% with phenylephrine 0.5%; but the use of cocaine, if available, is highly recommended. The Moffett’s solution is placed into both nasal cavities with the head extended to ensure that the solution bathes the upper areas of the nasal mucosa. Ideally it should be left in place for at least 15 min prior to the onset of the surgery (Fig. 1.6). Moderate hypotensive anaesthesia is used depending on the patient’s cardiovascular status and the anaesthetist preference. Endotracheal intubation is preferred with the tube being placed in the midline with no distortion of the upper lip. If the surgical resection is planned to include a total maxillectomy, then a transoral tube will interfere with the fitting of the post-operative stent. In such cases, the endotracheal tube should be passed via the uninvolved side of the nose; the surgical team may also consider performing a temporary tracheotomy.

a

b

c

d

Fig. 1.6  Positioning of the head to fill the upper nasal cavities with Moffett’s solution. (a) The head is extended and the blunt nasal tube is inserted into the nose. (b) Shows the nasal tube fully in the nasal cavity.

(c) It is then rotated so its end is drected towards the nasal roof. (d) Moffet’s solution is infiltrated to fill the upper nasal cavity. It should be left in place for 15 minutes

1  General Considerations

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To prevent any post-operative seizures all patients are given phenytoin 50 mg once daily for 6 weeks.

Temporary Tarsorrhaphy A temporary tarsorrhaphy (Fig.  1.7) to both eyes is performed at the beginning of the procedure to protect the cornea from inadvertent damage. The tarsorrhaphy is made by passing a silk suture through the centre of both lid margins, which are recognised by a grey line running along the lid margin. This results in normal apposition of the eyelids and protects the eyes during surgery.

Fig. 1.7  Temporary tarsorrhaphy

a

Fig. 1.8 (a, b) Lacrimal stents

b

Lacrimal Stenting Whenever the lacrimal system is disturbed, or its duct divided, it should be stented (Fig.  1.8). The inferior and superior lacrimal canaliculi are dilated and then the two probes of an O’Donoghue stent are passed into the canaliculi and then rotated inferiorly into the lacrimal duct and out through the nose. This gives a loop between the two canaliculi at the medial canthus. The nasal ends of the stent are shortened and tied off with a suture so that the ends lie just within the nasal cavity. After 6  weeks the orbital loop is cut, and the stents are withdrawn via the nose.

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References 1. Lund VJ, Lloyd GA, Howard DJ, Cheesman AD, Phelps PD.  Enhanced magnetic resonance imaging and subtraction techniques in postoperative evaluation of craniofacial resection for sinonasal malignancy. Laryngoscope. 1996;106(5 Pt 1):553–8. 2. Howard DJ, Lund VJ, Wei WI. Craniofacial resection for tumors of the nasal cavity and paranasal sinuses: a 25-year experience. Head Neck. 2006;28(10):867–73. 3. Ketcham AS, Wilkins RH, Van Buren JM, Smith RR. A combined intracranial facial approach to the paranasal sinuses. Am J Surg. 1963 Nov;106:698–703.

A. Cheesman et al. 4. Clifford P. Transcranial approach for cancer of the antroethmoidal area. Clin Otolaryngol Allied Sci. 1977;2(2):115–30. 5. Raveh J, Vuillemin T.  Subcranial-supraorbital and temporal approach for tumor resection. J Craniofac Surg. 1990;1(1):53–9. 6. Cheesman AD, Lund VJ, Howard DJ.  Craniofacial resection for tumors of the nasal cavity and paranasal sinuses. Head Neck Surg. 1986;8(6):429–35. 7. Lund VJ, Howard DJ, Lloyd GA, Cheesman AD.  Magnetic resonance imaging of paranasal sinus tumors for craniofacial resection. Head Neck. 1989;11(3):279–83.

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Sub-frontal Approach (Spectacle Incision Approach) Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin

This chapter considers the detailed application of the glabellar flap approach in the management of extensive sino-nasal tumours that invade the skull base. Although the surgical objective has always been the en bloc resection of the tumour this is an updated version of the original procedure (Type I craniofacial, with window craniotomy). This version, the Type III craniofacial, incorporates the lessons we have learned from a detailed audit of over 500 cases of craniofacial resection [1, 2]. Skull base approaches to the anterior fossa developed from the desire to perform a combined craniofacial resection of malignant tumours of the nose and paranasal sinuses that had spread to involve the floor of the anterior fossa. The original approaches generally combined a standard bifrontal craniotomy with a lateral rhinotomy, and many surgeons still prefer this approach as it allows the use of a pericranial flap to repair the dural defect. The major objection to this more traditional approach concerns the large bone flap that is raised. This size of flap whilst being satisfactory for pathology occupying large volumes of the anterior fossa gives limited exposure of the floor and basal cistern, unless excessive retraction of the frontal lobes is performed. This is thought to be a cause of post-operative frontal syndrome which was more common in past practice. Bone exposure can be enhanced by the additional removal of the glabellar bone and supraorbital bars. Surgeons whose practice is more concerned with nasal malignancies have tended to reduce the size of the frontal bone flap limiting their flaps to the removal of the glabellar

A. Cheesman (*) · G. Alusi Department of Otolaryngology and Skull Base Surgery, Barts Health NHS Trust, The Royal London Hospital, London, UK e-mail: [email protected] H. I. Sabin The Wellington Hospital, Neurosurgical Unit, London, UK e-mail: [email protected]

region of the frontal bone generally combined with the upper half of the nasal bones. This has been called the glabellar flap approach or more commonly the sub-frontal approach. This more limited bone removal gives excellent exposure of both the floor of the anterior fossa and the nasal cavity and allows a simultaneous wide exposure of the central skull base. Although possible, it does not allow the easy use of a pericranial flap. In our practice we have found that a simple repair with fascia lata and split skin grafting is superior.

2.1

Workup of Cases

When the patient presents with an obvious malignancy the first requirement is a detailed radiological assessment using both CT and MRI scans. This enables us to clearly distinguish between tumour spread and sinus mucoceles [3, 4]. The next important step is a detailed histological examination by an experienced specialist ENT pathologist. It is essential to determine which of the many potential tumours of this region is present. Each tumour has a different natural history and knowing this enables us to select the most appropriate management regime [5, 6]. In practice, extensive intranasal debulking provides adequate tissue for histological analysis and the clearing of the nasal passages enhances the return of relatively normal nasal physiology. This benefits the patient and in our experience results in the reduction of radiation sequelae. Most tumours benefit from the combination of radiotherapy and surgery. There appears to be no significant difference as to whether the irradiation is used pre- or post-operatively. Most of our early cases had been treated with prior radiation and we found no problems with the postirradiation surgery [7]. Current UK guidelines [8] recommend post-operative irradiation and if this is used, we would recommend that the radiation is delayed for 3  months to allow complete healing of the skull base repair.

© Springer-Verlag GmbH Germany, part of Springer Nature 2022 A. Cheesman et al. (eds.), Skull Base Surgery, Springer Surgery Atlas Series, https://doi.org/10.1007/978-3-540-74259-3_2

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Patient Position

The patient is placed in a supine position with the head slightly flexed. Pin fixation can be used but this limits the free movement of the head which facilitates the nasal surgery.

2.3

Anaesthesia

All patients have topical anaesthesia with Moffett’s technique (see Chap. 1) primarily to reduce nasal mucosal bleeding, but we understand that it also enables better control of hypotensive anaesthesia. All patients are given phenytoin 50  mg daily for 6  weeks to prevent any post-operative epilepsy.

Trans cranial

Trans facial

Trans oral

2.4

Image Guidance

We do not use image guidance routinely as the anatomy is straightforward; however we would recommend its use when initially performing this type of surgery. Fig. 2.1  Trans-facial approach to the skull base

2.5

Microscope

The use of the operating microscope helps at various points during the procedure as it gives excellent coaxial illumination as well as magnification.

2.6

Frozen Section Facilities

We feel that rapid access to frozen section analysis of the frequent tissue biopsies is important and we usually have a histological team in the theatre suite. It certainly improves both the extent of the resection and long-term survival.

2.7

Surgical Approach

Trans-Nasal Approach to the Skull Base The transcranial approach is covered in Chap. 8. However, a few comments regarding the virtues of the trans-nasal route versus the bi-coronal approach are relevant (Fig. 2.1).

Bi-Coronal Approach This is claimed to give a better cosmetic approach, but if you are bald and wear glasses you may not agree.

It gives an excellent exposure of the anterior fossa and may be preferable if most of the disease is in this area; however it gives a more limited exposure of the nasal cavities and needs to be combined with a direct trans-nasal approach. In this situation the transposed scalp flap must be moved back and forth to give exposure. Raising of the lower end of the glabellar flap requires extensive undermining of the skin in this region. Its main advantage is that it allows the easy raising of a pericranial flap used in repairing the defect of the skull base.

 pectacle Incision and Glabella Bone Flap S (Sub-frontal) The trans-facial approach using the spectacle incision is preferable for tumours of the nose and paranasal sinuses as it gives an excellent exposure of the full extent of the disease. It requires a good surgical technique, especially with the skin incision being made vertical to its surface. Resulting scars are virtually invisible, particularly in the elderly face or if the patient wears spectacles, which completely hide the incision. A pericranial flap can be raised by this incision but requires extensive undermining of the forehead skin. The pericranial flap although an effective repair to the anterior skull base requires care in raising it, with attention to preserve its blood supply, and it must be kept moist throughout the operation. Traditionally we have used free fascia lata

2  Sub-frontal Approach (Spectacle Incision Approach)

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The spectacle skin incision should be accurately delineated, and the important landmarks are (Fig. 2.3): • Nasion • Junction of the nasal bones and cartilage • Medial canthus The lower transverse portion of the incision is placed halfway between the nasion and the junction of the bone and cartilage. This is continued laterally to halfway between the nasal midline and the medial canthus. It then curves superiorly up towards the supraorbital foramen, inferior to the eyebrow (which should not be shaved). To ensure a cosmetic incision the curved portion of the incision must be made vertically through the skin to the underlying bone. The skin flap that has been outlined must then be separated from the underlying bone by sharp dissection unless the raising of a pericranial flap is desired. Normally flap elevation is superficial to the pericranium and continued over the lower forehead to facilitate soft-tissue retraction. Wide elevation of the orbital periosteum from the lamina papyracea of the medial orbital wall and adjacent orbital roof is essential (Fig. 2.4). The use of blunt dissection with short strips of ribbon gauze soaked in topical adrenaline 1:1000 facilitates the elevation. The periosteum is easily separated except in the region of the trochlea, where its synovial sheath is adherent to the bone. Therefore the trochlea should be separated from the bone with sharp dissection to preserve its synovial capsule; if Fig. 2.2  Osteotomy for glabellar flap this is done any diplopia is rare. Freeing of the trochlea gives a grafts to repair the dural defect and the results are compara- wide exposure of the medial and superior walls of the orbit and allows the osteotomies to be easily performed. ble if not better than the pericranial flap. Here the outline of the glabellar bone flap is clearly displayed. Soft-tissue retraction is necessary whilst cutting the osteotomies (Fig. 2.5a, b). Design of Bone Flap Prior to mobilising the bone flap miniplates are attached The red lines outline the extent of the glabellar bone flap to the supero-lateral margin of the bone flap to ensure its cor(Fig. 2.2). Superiorly the amount of frontal bone included in rect post-operative position. All four holes are drilled but the the flap can be varied depending upon the extent of intracra- screws are only inserted into the end holes at this stage; this nial disease. Inferiorly the lower border passes through the facilitates good screw fixation when the plates are finally fitmid-portion of the nasal bones. This is cosmetically espe- ted. The miniplates are usually left on the bone flap. The osteotomies are made with a side cutting burr, either cially important, as detachment of the upper lateral cartilages from the lower border of the nasal bones gives an obvious a conventional fissure burr or the peanut burr taken from the cosmetic defect familiar to rhinoplasty surgeons. Raveh [9] craniotome (the craniotome itself cannot be used because of has described a similar sub-frontal approach but he includes the complex bony anatomy in this region). The burr is used free hand to cut a groove in the bone the whole of the nasal bones into his bone flap. His post-­ operative photographs show the obvious cosmetic defect in which is steadily deepened to the internal bony cortex. Final separation of the internal bony cortex can be achieved with a the nasal pyramid. small sharp osteotome. Effectively there are four separate osteotomy cuts.

Soft Tissue Approach

The eyes must be protected with a temporary tarsorrhaphy suture, preferably centralised through the lid margins (see Chap. 1).

• A transverse superior osteotomy which generally enters a large frontal sinus: If the frontal sinuses are absent or small this osteotomy will enter the anterior fossa. To protect the dura here the osteotomy depth is limited to leav-

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ing a thin layer of the inner cortex over the dura. This thin layer is fractured with a small sharp osteotome. • The inferior osteotomy is deepened through the nasal bones and into the vomer of the septum. When the bone flap is removed the vomer osteotomy must be completed. • The two lateral osteotomies join the two transverse osteotomies, and these are full-thickness cuts into the nasal cavity and frontal sinus. The glabellar bone flap is then elevated out using a curved osteotome to divide the intra-sinus septum and vomer. It is preserved in moist drapes (Fig. 2.6).

Fig. 2.3  Spectacle incision. C—the upper border of the cartilaginous nasal pyramid; G—glabella region; N—the nasion, the suture line between the nasal and frontal bones

a

Fig. 2.5 (a, b) Osteotomies for the glabellar bone flap

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The removal of the bone flap reveals the posterior wall of the frontal sinus (Fig. 2.7). This gives a wide exposure of the dura of the anterior fossa and its elevation is continued widely over the floor of the anterior fossa by careful blunt dissection, except where it is bound down in the olfactory groove (Fig. 2.8). This is removed initially using a roundhead burr to protect the underlying dura. When the dura is exposed it is widely elevated from the inner table of the cranium and the whole of the posterior wall of the frontal sinus is removed with bone nibblers to cranialise the frontal sinus.

Fig. 2.4  Freeing of the orbital periosteum from the bony orbit

b

2  Sub-frontal Approach (Spectacle Incision Approach)

Fig. 2.6  Raising the glabellar bone flap

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Fig. 2.8  Removing the posterior wall of the frontal sinus

Fig. 2.7  Exposed frontal sinus cavity

Here the dura is freed from the groove and olfactory nerves by sharp dissection with a scalpel. Often erosion of the ethmoid roof is apparent at this stage (Fig. 2.9).

Clearance of Nasal Extent of the Disease Having prepared the access to the floor of the anterior fossa and cribriform plate regions, it is now more appropriate to clear the tumour from the nasal cavity before opening the dura. This allows the degree of skull base resection to be defined more accurately in relation to the tumour extent. The clearance of the nasal cavity facilitates the exposure of the skull base. It significantly decreases the time of exposure of

Fig. 2.9  Dura is widely mobilised from the floor but as shown in the left lobe it is tightly adherent to the olfactory groove. On the right side the dura has been cut free leaving a small dural tear

the intracranial space, which reduces any risk of infection or other complications resulting from the opening of the intracranial space. The resection involves a medial maxillectomy (this is discussed in more detail in Chap. 7) (Fig. 2.10).

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On the involved side the orbital periosteum is elevated from the orbital floor and the lacrimal canal is opened anteriorly to determine whether the lacrimal duct is involved medially with tumour. If it is free of disease it is sectioned inferiorly to preserve its valves. The orbital contents are then elevated supra-laterally to widely expose the roof of the antrum and an osteotomy is a

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made into the antral roof and then continued anteriorly to the orbital rim lateral to the lacrimal canal. This is continued inferiorly in the anterior wall of the antrum. It continues medially to enter the nasal cavity at its floor. This is the lateral extent of the medial maxillectomy. The osteotomy is then continued posteriorly along the lower extent of the lateral nasal wall deep to the mucosa. b

c

Fig. 2.10  Medial maxillectomy. (a) Facial osteotomy. (b) Outline of the medial maxillectomy block. (c) Post-medial maxillectomy anatomy

2  Sub-frontal Approach (Spectacle Incision Approach)

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The bony block thus outlined can be freed from the nasal mucosa and its removal gives a view of the deep aspect of the nasal mucosa which helps identify any tumour involvement. Also, the subsequent division of the lateral mucosal wall and depressing it into the antrum enhance the visualisation of the nasal cavity. Attention is then transferred to the ethmoid sinuses, which are systematically opened and checked for tumour involvement under frozen section control. This dissection is carried back through the posterior ethmoid cells into the sphenoid cavity. This encompasses the nasal tumour on the involved side of the nose. We then generally clear the ethmoid cells on the uninvolved side back to the sphenoid sinus. This includes the medial and superior turbinates and opens the uninvolved antrum widely. At this stage, the lateral and inferior extents of the tumour will have been encompassed and it is necessary to free the posterior septum with the block. This is achieved by a curved osteotomy through the posterior septum down to the floor of the nose leaving the tumour-involved part of the septum attached to the anterior wall of the sphenoid sinus. This completely encompasses the nasal extent of the tumour and attention must now be directed to resecting the intracranial portion of tumour along with the roof of both ethmoid sinuses and the roof of the sphenoid sinus.

 esection of the Skull Base and Intracranial R Portion of the Tumour The dura is then opened transversely at an appropriate level to visualise the anterior fossa and also preserve uninvolved dura; the underlying falx is divided to free the dural flap (only rarely is it necessary to clip the anterior sagittal sinus) (Figs. 2.11 and 2.12). Careful separation of two frontal lobes gives excellent exposure of the central floor of the anterior fossa and this can be extended posteriorly over the planum sphenoidale towards the central skull base. This exposure informs us regarding the extent of the intracranial disease and tells us how much dura must be excised to encompass the tumour. Having defined the extent of dural involvement necessary to resect the tumour it is outlined with a dural cut to the floor of the anterior fossa (Fig. 2.13). Osteotomies along this dural cut are now made through the roof of the ethmoid and sphenoid sinuses clear of the involved area and this is depressed into the nasal cavity. To achieve this depression the sphenoid septum must be divided along with its anterior wall; this is best achieved using a curved osteotome directed forward through the posterior osteotomy of the sphenoid roof (Fig. 2.14). It is used to

Fig. 2.11 and 2.12  Raising dural flap and exploring floor of anterior fossa

divide the sphenoid septum and then the anterior walls of the sphenoid sinuses. This osteotomy frees the whole tumour block which can be removed through the combined glabellar bone defect. The mucosa of the nasopharynx is divided to free the block with Mayo scissors. Following the removal of the tumour block the nasal cavities must be carefully inspected for any residual tumour again with frozen section control. The margins of the operative cavity should be cleared of any bony projections, but any normal nasal mucosa should be preserved if possible. The intracranial cavity must be carefully examined to control any venous or arterial bleeding. Any capillary ooze is controlled with Surgicel dressing.

Dural Repair The dura is then closed meticulously using fascia lata from the thigh (Fig. 2.15). The fascia patch is cut about 1–2 cm

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Fig. 2.15  The anterior nasal structures have been artistically cut away to show the dural repair and post-resection view of the nasal cavity

Fig. 2.13  Osteotomy in the floor of anterior fossa. A antrum; IT inferior turbinate; NC nasal cavity

Fig. 2.16  The exposed dura and graft are then covered with a thin split skin graft held in place with Tisseel glue on its edges. It also covers the exposed orbital fat if a resection of the orbital periosteum was performed

underlying fascia with a continuous suture to produce a watertight closure of the dura. We normally use a silk suture and a 12 mm atraumatic needle to achieve a good closure in the confined operative space (Fig. 2.15). The exposed dura and fascia graft are then covered with a thin split skin graft. This takes both to the fascia graft and dura remarkably well and results in a remarkably low incidence of CSF leakage (Fig. 2.16). Fig. 2.14  Curved osteotome dividing the anterior wall of sphenoid. The dotted red line indicates the previous division through the posterior septum and vomer

larger than the defect and is placed deep to the dura with a split on either side of the falx. The dura should overlie the patch with a good overlap. The dura is then sutured to the

Resection of Involved Orbital Periosteum At this stage of the resection the orbital periosteum must be checked to see whether it is involved by the tumour and if there is any doubt such as when the lamina papyracea has been eroded, frozen section biopsies of the orbital ­periosteum

2  Sub-frontal Approach (Spectacle Incision Approach)

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Fig. 2.17  Resection of involved orbital periosteum

must be made. If the orbital periosteum is involved with disease it must be excised widely and the underlying orbital fat again checked with frozen sections. Only if the orbital fat is positive for tumour should the orbit be exenterated (Fig. 2.17). Repair of the excised orbital periosteum is best performed with a split skin graft applied during the repair phase of operation. The use of split skin enables any recurrence in the orbit to be readily identified and its natural retraction during healing fortuitously corrects any enophthalmos.

Lacrimal Stenting It is important to preserve lacrimal drainage and O’Donoghue splints are placed through both upper and lower canaliculi into the nasal cavity (see Chap. 1). The splints are removed after 6 weeks.

Packing of the Craniofacial Cavity The skin grafts are covered with antibiotic-soaked Sterispon sponge and then the cavity is packed with a Whitehead’s varnish pack (Figs. 2.18 and 2.19). We feel much of our success and extremely low complication rate is due to the use of the Whitehead’s varnish pack. This is a traditional dressing, initially used following glossectomy and frequently used in infected cavities. The Whitehead’s varnish contains iodoform in varnish with ether as a solvent [10]. As the ether evaporates the pack assumes a rigid structure supporting the repair of the anterior skull base. The

Fig. 2.18 and 2.19   The split skin grafts are covered with a Sterispon dressing and the cavity is packed with a Whitehead’s varnish pack

iodoform has remarkable antiseptic properties and even if left in place for 4 weeks the pack can be removed with no sign of infection either in the pack or in the cavity. Routinely we remove the pack under general anaesthesia after 2 weeks and carefully inspect the repair. The Sterispon is sucked away and invariably the split skin graft will have taken completely. With time the combined repair of fascia and skin thickens to a fibrous sheet approximately 1  cm thick. The main complication of this procedure is crusting of the craniofacial cavity. This is not related to the split skin graft which rarely becomes crusted, but rather to the loss of the ciliated nasal mucosa which has been excised. The nasal cavity becomes re-epithelialised with a cuboid epithelium which becomes crusted from lack of cilia. Many techniques have been devised to reduce crusting but in our experience none

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have been successful. Our patients control their crusting with twice-daily douching with an alkaline nasal douche.

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niques and we have subsequently been involved with further curative attempts, the cosmetic results had been poor and the incidence of recurrence high.

Bone Repair The defect in the floor of the anterior cranial fossa generally does not require bone repair as the fascia/split skin repair thickens considerably with time and gives a robust support to the anterior fossa. In one case where the patient had a history of hydrocephalus we were concerned about a post-operative increase in intracranial pressure and accordingly used some split rib grafts which took well, but we do not feel this is necessary routinely. Similarly in those cases where the glabellar bone flap has been involved with the disease and needed resection, we have used split rib grafts to repair the nasion and frontal bone with excellent results because the preservation of the lower half of the nasal bones gives excellent support to the bone repair.

Bone Flap Repair At the completion of the operation and following packing of the nasal cavity the glabellar bone flap is replaced and fixed with miniplates. We also use bone pâté to fill in the gaps of all the osteotomies (Fig. 2.20). Repair of the lamina papyracea is unnecessary as the orbit resumes its normal position with no need to replace the lamina papyracea or the medial canthal ligament. Indeed, in many of those cases where surgeons have used such tech-

Fig. 2.20  The bone flap is replaced with the previously inserted mini-­ plates and all osteotomy gaps are packed with bone pate

Skin Closure The incision must be closed very carefully in two layers (Fig. 2.21). 3-0 Vicryl is used for the subcutaneous layer and the skin is closed with a subcuticular nylon suture. The wound is then dressed with Steristrip sutures placed along the length of the wound to facilitate even wound closure. Skin sutures are removed after 5 days.

Alternative Methods of Dural Repair • Pericranial flap (Fig. 2.22): It is possible to raise a long pericranial flap via the spectacle incision which can be rotated into the cavity to repair the dura. The pericranial flap is most readily used with the bi-coronal approach when it enters the operative cavity deep to the glabellar bone flap. • Raveh and Vuillemin [9] in their approach use several layers of fascia lata and rely on mucosal migration to restore epithelialisation. • Free flap repair using a microvascular anastomosis. The use of underlay fascia lata repair covered with a split skin graft has been remarkably successful in over 500 cases

Fig. 2.21  Skin closure

2  Sub-frontal Approach (Spectacle Incision Approach)

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a

b

c

d

Fig. 2.22  Raising of pericranial flap via spectacle incision. (a) The skin flap is raised superficial to the pericranium. (b) Extensive undermining of the skin is necessary before the pericranial flap can be

reflected inferiorly. (c) The mobilised pericranial flap. (d) The pericranial flap is shown extended to its full length and its donor area seen over the frontal bones

of craniofacial resection. The split skin graft readily takes to both dura and fascia. Our incidence of post-operative CSF rhinorrhoea is much lower than the reported series of repair with both pericranial and free microvascular flaps. Careful long-term follow-up is indicated and is routinely performed endoscopically with any suspicious areas being biopsied. MRI scans are performed routinely at 3 months to check the full status of the patient. Details of our results after 25 years are published [2].

3. Lund VJ, Howard DJ, Lloyd GA, Cheesman AD. Magnetic resonance imaging of paranasal sinus tumors for craniofacial resection. Head Neck. 1989;11(3):279–83. 4. Lund VJ, Lloyd GA, Howard DJ, Cheesman AD, Phelps PD. Enhanced magnetic resonance imaging and subtraction techniques in postoperative evaluation of craniofacial resection for sinonasal malignancy. Laryngoscope. 1996;106(5 Pt 1):553–8. 5. Harrison D, Lund VJ.  Tumours of the upper jaw. New  York: Churchill Livingstone; 1993. 6. Michaels L. Ear, nose, and throat histopathology. Springer-Verlag; 1987. 7. Lund VJ, Howard D, Wei W, Spittle M.  Olfactory neuroblastoma: past, present, and future? Laryngoscope. 2003;113(3):502–7. 8. Lund VJ, Clarke PM, Swift AC, McGarry GW, Kerawala C, Carnell D.  Nose and paranasal sinus tumours: United Kingdom National Multidisciplinary Guidelines. J Laryngol Otol. 2016;130(S2):S111–8. 9. Raveh J, Vuillemin T.  Subcranial-supraorbital and temporal approach for tumor resection. J Craniofac Surg. 1990;1(1):53–9. 10. Lim M, Lew-Gor S, Sandhu G, Howard D, Lund VJ. Whitehead’s varnish nasal pack. J Laryngol Otol. 2007;121(6):592–4.

References 1. Cheesman AD, Lund VJ, Howard DJ.  Craniofacial resection for tumors of the nasal cavity and paranasal sinuses. Head Neck Surg. 1986;8(6):429–35. 2. Howard DJ, Lund VJ, Wei WI. Craniofacial resection for tumors of the nasal cavity and paranasal sinuses: a 25-year experience. Head Neck. 2006;28(10):867–73.

3

Supraorbital Craniotomy Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin

The use of smaller, less invasive approaches has appeal. Supraorbital craniotomies that required small eyebrow incisions were popularized in the 1990s, and endoscopes were used in combination with microscopes to allow a variety of pathologies to be tackled during the procedure, including aneurysms, anterior fossa meningiomas, and parasellar tumours. Supraorbital craniotomy is a useful approach to have available, but it is not performed as frequently as in the past due to new and evolving treatments such as interventional radiology and radiosurgery.

3.1

elevator and the anterior temporalis muscle is freed and reflected posteriorly to expose enough bone to allow a small entry point to be drilled. The scalp is easily retracted with sutures. Avoid using a self-retaining retractor, which may obstruct the view later in the operation. The loose skin over the eye socket will tend to retract more easily than the forehead scalp, and a self-­ retaining retractor exposes more of the orbit than the frontal bone (Figs. 3.1–3.3).

Skin Incision

Patient positioning is very important. The head may be held in pins or rest on a Mayfield horseshoe. Head-up tilt of approximately 30 degrees reduces the intracranial venous pressure. When coupled with extension of the neck, the angle allows the brain to fall away from the skull base owing to gravity. The incision is made in the eyebrow. The eyebrow should not be shaved, which ensures that the incision will be in the hair-bearing skin and thus less visible post-operatively. The incision runs from the supraorbital foramen medially to the lateral extent of the eyebrow and beyond, if necessary, to the frontozygomatic suture. To avoid injury to the frontal branch of the facial nerve, the incision is taken through the frontal pericranium and temporalis fascia adjacent to the lateral wall of the orbit. The scalp is mobilized with a periosteal

Fig. 3.1  Marked skin incision

A. Cheesman (*) · G. Alusi Department of Otolaryngology and Skull Base Surgery, Barts Health NHS Trust, The Royal London Hospital, London, UK e-mail: [email protected] H. I. Sabin The Wellington Hospital, Neurosurgical Unit, London, UK e-mail: [email protected] © Springer-Verlag GmbH Germany, part of Springer Nature 2022 A. Cheesman et al. (eds.), Skull Base Surgery, Springer Surgery Atlas Series, https://doi.org/10.1007/978-3-540-74259-3_3

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3.2

Placement of the Initial Entry Point

A small burr hole is drilled deep to the retracted temporalis for better post-operative cosmesis. If the orbital rim is to be removed with the bone flap, this should open both the orbit and the anterior fossa. The dura is freed from the margins to allow the footplate of the craniotome to be introduced. If the orbital rim is to form part of the flap, the periorbita is reflected carefully from the orbital roof (Fig. 3.4).

Fig. 3.2  Skin incision: use of needle-point diathermy

Fig. 3.4  Use of the craniotome to cut the bone flap. Note the use of sutures to retract the scalp

Fig. 3.3  Exposure of orbital rim and temporalis muscle reflection to expose temporal bone to allow an entry point burr hole to be cut for the craniotome

3  Supraorbital Craniotomy

3.3

Bone Flap Completed

The bone flap is then cut and the craniotome taken as low as possible on the anterior fossa floor to reduce the need for subsequent brain retraction (Figs.  3.5 and 3.6). If a lower angle of approach is needed, the superior orbital rim can be removed as a separate piece after reflection of the dura from the orbital roof intracranially to allow the craniotomy to be completed with a drill or saw. It is not unusual for the frontal air sinus to be opened as the flap is cut. The defect is too small to allow marsupialization of the sinus, as traditionally recommended. Instead, the margins of the sinus mucosa are mobilized and pushed into

Fig. 3.5  Bone flap dimensions

Fig. 3.6  Removal of bone flap

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the sinus before the bone defect is plugged, either with pericranium harvested at the time of the exposure or with a small piece of temporalis muscle. The small flap is prevented from drying out by wrapping in an aqueous betadine-soaked swab.

3.4

The Dura

If not already performed, the dura is mobilized from the orbital roof and the bony projections from the orbit are drilled flat to aid exposure. It is helpful to bevel the inner table of the skull at the inferior margin of the flap for the same reason (Figs. 3.7 and 3.8).

Fig. 3.7  Dural exposure

Fig. 3.8  Drilling of inferior flap and orbital roof bony prominences to reduce the need for brain retraction

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Dural Opening

Once sufficient bone has been removed, the dura is opened in a ‘U’ and flapped inferiorly. The brain bulges into the exposure and it is necessary to aspirate cerebrospinal fluid (CSF) progressively until the intracranial pressure reduces sufficiently to let the surgery proceed without the need for brain retraction (Figs. 3.9 and 3.10).

3.6

Intracranial Exposure

The natural corridor over the orbital roof is followed to expose the ipsilateral carotid artery, optic nerve, and optic chiasm. Opening the basal cisterns allows more CSF to be removed and further reduces intracranial pressure. Once the brain has ‘relaxed’ it is possible to place and fix an endoscope in position to aid the surgery (Fig. 3.11).

Fig. 3.9  Dural opening Fig. 3.11  Placement of endoscope. If required the endoscope can be fixed in a position, as shown

Fig. 3.10  Reflection of dura inferiorly

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3.7

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Closure

The dura is approximated with an absorbable suture (5-0 or 6-0 Vicryl), as this has a small needle and is easy to introduce into a limited exposure. The bone flap is secured with low-­ profile titanium miniplates, and if the frontal sinus has been opened the flap is pushed against the repair to secure the muscle or fascia used to plug the defect. The scalp wound is then closed in two layers, with the skin suture being subcuticular and absorbable (Figs. 3.12 and 3.13). a

Fig. 3.13  Closure: subcuticular absorbable suture

Suggested Reading

b

Fig. 3.12 (a, b) Miniplates to fix bone flap

Reisch R, Perneczky A. Ten-year experience with the supraorbital subfrontal approach through an eyebrow skin incision. Neurosurgery. 2005;57(4 Suppl):242–55. discussion 242–55 Tai AX, Sack KD, Herur-Raman A, Jean WC. The benefits of limited orbitotomy on the supraorbital approach: an anatomic and morphometric study in virtual reality. Oper Neurosurg (Hagerstown). 2020;18(5):542–50. Warren WL, Grant GA. Transciliary orbitofrontozygomatic approach to lesions of the anterior cranial fossa. Neurosurgery. 2009;64(5 Suppl 2):324–9. discussion 329–30

4

Orbitozygomatic Approach Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin

The orbitozygomatic approach has often been described as the workhorse of skull base surgery. It evolved from a standard frontotemporal flap, to give greater exposure of the skull base while reducing the need for brain retraction during surgery. It has been used for many intracranial pathologies, but consideration should be given to the additional time it requires and the potential for complications from the additional bone cuts and the subsequent reconstruction. Some of the original indications (basilar aneurysms, cavernous sinus tumours) are no longer primarily treated surgically, and the possible alternative of the standard pterional approach should always be considered.

4.1

Head Position (Fig. 4.1)

The head is held in pins and rotated. The head-up tilt reduces venous pressure and lateral flexion of the neck allows the frontal lobe to fall away from the anterior fossa under gravity.

4.2

Skin Incision

The incision does not extend below the hairline onto the forehead. The lower end can be extended into the skin of the tragus and dissected superficial to the tragal cartilage to allow access to the root of the zygoma. There is no need to

Fig. 4.1  Head position. The degree of rotation depends on the pathology being approached and may require more rotation to the opposite side

shave the hair, although a thin shave along the line of the incision is common. Haemostatic Raney clips can be used to reduce bleeding from the scalp, but if needle diathermy is used for the incision, the vessels are usually cauterised, and scalp clips can be avoided. After incision of the galea, the scalp flap is reflected to expose the temporalis fascia. This is incised and reflected with the flap to reduce the risk of injury to the frontalis branch of the facial nerve.

A. Cheesman (*) · G. Alusi Department of Otolaryngology and Skull Base Surgery, Barts Health NHS Trust, The Royal London Hospital, London, UK e-mail: [email protected] H. I. Sabin The Wellington Hospital, Neurosurgical Unit, London, UK e-mail: [email protected] © Springer-Verlag GmbH Germany, part of Springer Nature 2022 A. Cheesman et al. (eds.), Skull Base Surgery, Springer Surgery Atlas Series, https://doi.org/10.1007/978-3-540-74259-3_4

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Completed Scalp Flap

The scalp flap must be taken low enough to expose the superior and lateral orbit (Fig. 4.2). It may be possible to reflect the supraorbital nerve, but if enclosed in a foramen it will need to be freed with a drill or osteotome. The periorbital fascia will need to be dissected free of the orbit to allow the orbitotomy cuts. The zygoma can be dealt with by removing it in one piece with the bone flap or as a separate free component. We prefer that it remains attached to the masseter, and it is reflected with the scalp flap and lateral orbit to maintain blood supply to the bone and to reduce the risk of damage to the temporalis muscle nerve supply.

Fig. 4.2  Scalp flap

4.4

Pterional Bone Flap (Fig. 4.3)

The temporalis muscle is freed from the lateral orbital margin and the underlying temporal bone. Diathermy is not used for this, as current spread may damage the motor nerves supplying the muscle. It is reflected inferiorly and over the zygomatic arch, which will be down fractured later. A standard pterional bone flap is cut, starting with a high-speed drill and small burr to the pterion, allowing the lateral sphenoid wing to be partly removed and exposing both the middle and anterior fossae dura. A craniotome cuts the bone flap, removing more bone anteriorly or posteriorly depending on the exposure required.

4  Orbitozygomatic Approach

a

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b

Fig. 4.3 (a, b) Pterional bone flap

4.5

Orbitozygomatic Osteotomy (Fig. 4.4)

With the lateral orbit exposed, the periorbita is mobilized and the contents of the orbit are gently reflected to expose the bone, allowing osteotomies to be cut with less risk of damage to the orbital content. The osteotomies can be performed with a drill, oscillating saw, or osteotome and extended as shown. Before any cuts are made, titanium plates are bent to shape and placed over the proposed osteotomies in the orbit and maxilla. Their position is marked by drilling the holes for the self-tapping screws needed to secure the plates at the time of the bony reconstruction. The zygomatic arch runs from the temporal bone to the maxilla and forms the superior aspect of the mandibular fossa. When making the posterior osteotomy, it is important not to enter the fossa. Use of a dissector placed deep to the zygoma and posteriorly as far as possible will guide the osteotomy and remove this risk. The cut is made at an angle to prevent the bone displacing medially. Plating is not necessary to retain this component of the flap (screws risk penetrating the mandibular joint).

Fig. 4.4  Zygomatic osteotomy

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The zygoma and lateral orbital margin are freed by the osteotomies, but any small areas of bony attachment can be easily fractured using flap elevators. Once free, the zygoma and orbital rim are displaced inferiorly with the temporalis muscle and retracted with hooks or sutures.

4.6

Dural Exposure (Figs. 4.5 and 4.6)

The exposed dura is reflected from the remaining sphenoid wing to allow bony resection with the high-speed drill. Bone removal exposes the dura of the anterior and middle fossae. If resecting a medial sphenoid meningioma, the tumour and bone are removed progressively, aiming for macroscopic resection wherever possible. If more exposure is

Fig. 4.5  Orbitozygomatic: completed dural exposure

required the superior orbital fissure can be exposed by drilling. If approaching pathology in the middle fossa, the dura is reflected from the floor, exposing the middle meningeal artery, which is divided and coagulated. Further dural retraction exposes the foramen ovale and the exiting mandibular nerve.

4.7

Dural Reflection (Fig. 4.6)

After the required bony removal has been completed, the dura is opened in a ‘U’ and flapped inferiorly. This exposes the inferior frontal lobe, the sylvian fissure, and the temporal pole.

Fig. 4.6  Extent of bone removal

4  Orbitozygomatic Approach

4.8

 ural Closure 9 Replacement of D Orbitozygomatic Bony Flap (Fig. 4.7)

Resection of pathology which involves the dura will leave a defect. This can be patched with dural substitutes including pericranium, temporalis fascia, or collagen mesh. Wherever possible, the dura is closed with sutures. There is no requirement to reinforce the closure with sealants, but if the petrous bone has been drilled and air cells have been opened, these should be closed with fascia, fat, or muscle. The orbit and zygoma are replaced and held in position with the titanium plates and screws fitted before the osteotomies were completed.

4.9

Replacement of Pterional Bone Flap

The bone flap is replaced. Modern absorbable fixation devices avoid additional metal artefact on post-operative imaging. If much bone has been removed from the sphenoid

Fig. 4.7  Dural reflection shows dura being reflected inferiorly

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wing, the temporalis muscle will prolapse into the defect and leave an obvious hollow in the temple. This is sometimes remarked on by the patient as undue prominence of the maxilla and zygoma.

4.10 Repair of Temporalis Muscle Sutures are not directly placed into the muscle, as this causes pain. Instead, the temporalis fascia is repaired with absorbable sutures before the scalp flap is closed.

4.11 Skin Closure (Fig. 4.8) A subgaleal suction drain is used to reduce post-operative swelling, and is taken out after 48 h. The scalp is closed in the standard fashion with absorbable sutures to galea and continuous nylon to skin. Staples are avoided, as these are sometimes used as a reason not to undertake early post-­ operative MRI scans.

Fig. 4.8  Skin closure—not with metal staples: either interrupted nylon as shown or continuous nylon blanket stitch

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Suggested Reading Bilbao CJ, Stofko DL, Dehdashti AR.  Cranio-orbitozygomatic approach: technique and modifications: operative techniques in otolaryngology. Head Neck Surg. 2013;24(4):229–34. Cohen-Gadol A. In reply: the orbitozygomatic craniotomy and its judicious use. Oper Neurosurg (Hagerstown). 2020;19(4):E462. Cohen-Gadol A.  Orbitozygomatic craniotomy. Neurosurg Atlas. https://www.neurosurgicalatlas.com/volumes/cranial-­base-­surgery/ skull-­base-­exposures/orbitozygomatic-­craniotomy

A. Cheesman et al. Hakuba A, Liu S, Nishimura S.  The orbitozygomatic infratemporal approach: a new surgical technique. Surg Neurol. 1986;26:271–6. Pieper DR, Al-Mefty O.  Cranio-orbito-zygomatic approach. Operat Tech Neurosurg. 1999;2(1):2–9. Seçkin H, Avci E, Uluç K, Niemann D, Başkaya MK. The work horse of skull base surgery: orbitozygomatic approach. Technique, modifications, and applications. Neurosurg Focus. 2008;25(6):E4. Zabramski JM, Kiriş T, Sankhla SK, Cabiol J, Spetzler RF.  Orbitozygomatic craniotomy. Technical note. J Neurosurg. 1998;89:336–41.

5

Le Fort 1 Approach Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin

5.1

Approach Diagram (Fig. 5.1)

The first description of mobilising the maxilla with osteotomies dates back to 1859, when Von Langenbeck discussed utilisation of a maxillary osteotomy to remove nasal polyps. In 1876, Cheever discussed using a unilateral maxillary osteotomy to clear the nasal polyps. When Le Fort described a level 1 fracture of the maxilla in 1901, he effectively clarified the potential for this approach. Le Fort 1 maxillary osteotomy is mainly used nowadays for orthodontic surgical treatment. Countless other surgeons have contributed to the development of this technique in the following decades.

Fig. 5.1  Approach diagram

5.2

A. Cheesman (*) · G. Alusi Department of Otolaryngology and Skull Base Surgery, Barts Health NHS Trust, The Royal London Hospital, London, UK e-mail: [email protected]

Patient Position

The patient is anaesthetised using a controlled hypotensive general anaesthetic. Traditionally, nasotracheal intubation is used to maximise the space required to mobilise the maxilla. The nasotracheal tube is secured to prevent excessive movement during the surgery, which is critical to prevent soft-­ tissue and bony distortion. Endotracheal anaesthesia is preferred for improved access to the post-nasal space. The nasal cavity is prepared with a Moffett’s solution. Hypotensive anaesthesia should be used to reduce bleeding. Aqueous betadine is used to prepare the oral cavity and skin.

H. I. Sabin The Wellington Hospital, Neurosurgical Unit, London, UK e-mail: [email protected] © Springer-Verlag GmbH Germany, part of Springer Nature 2022 A. Cheesman et al. (eds.), Skull Base Surgery, Springer Surgery Atlas Series, https://doi.org/10.1007/978-3-540-74259-3_5

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Sublabial Incision Marking (Fig. 5.2)

Retractors are used to elevate the upper lip and the incision is marked 0.5–1 cm from the junction of the gum (muco-buccal fold). This is to enable easier suturing and closure of the incision at the end of the procedure, as the gum flap will often shrink. The lateral extents of the incision extend to the first molar, though they can be extended further if required. This will allow exposure of the lateral maxillary buttress.

5.4

Sublabial Incision to Bone (Fig. 5.3)

The incision is made from the first molar to the midline of the fornix. The incision is then extended to the region of the contralateral first molar. The incision is made down to the maxillary bone. Using a periosteal elevator, tissue elevation is commenced in the subperiosteal plane from the pterygomaxillary junction to the nasal spine and then to the contralateral pterygomaxillary junction. The periosteum is reflected up to expose the infra-orbital nerves bilaterally, which must be preserved. The lateral walls of the maxilla are exposed back to the pterygoid plates. The nasal mucosa is elevated to expose the inferior section of the pyriform aperture. Adequate soft-tissue exposure is essential to perform a Le Fort 1 osteotomy. Nasal mucosa is incised and the cartilaginous septum is dislocated from the nasal spine. The cartilaginous septum is dislocated from the bony septum, which can be removed to improve access.

Fig. 5.2  Sublabial incision marking

Fig. 5.3  Sublabial incision to bone

5  Le Fort 1 Approach

5.5

Placement of Metal Plates (Fig. 5.4)

The plates must be placed prior to performing the osteotomy to ensure accurate placement at the end of the procedure. These are then removed to perform the osteotomies.

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5.6

 nterior Maxillary Osteotomy A (Fig. 5.5)

A reciprocating saw or a side-cutting burr is used. The osteotomy is placed 35–40 mm from the occlusal plane. Care is taken to place the osteotomy above the roots of the teeth. The maxillary sinus will be entered.

Fig. 5.4  Placement of metal plates Fig. 5.5  Anterior maxillary osteotomy

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5.7

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Posterior Osteotomy (Fig. 5.6)

A second osteotomy is performed through the pterygoid plates posteriorly at the pterygomaxillary junction, which is often fused, using curved osteotome.

5.8

Mobilisation and Retraction (Fig. 5.7)

The maxillary artery is preserved. A malleable retractor is used to protect the artery prior to performing the posterior osteotomy. The maxillary plate is then displaced inferiorly. Care must be taken to protect the descending palatine vessels. Further mobilisation may be achieved by thinning the posterior wall of the maxillary sinus.

Fig. 5.6  Posterior osteotomy. Inset shows the curved end of the osteotome separating the maxilla from pterygoid plates

Fig. 5.7  Mobilisation and retraction

5  Le Fort 1 Approach

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Lateral View of Mobilisation (Fig. 5.8)

5.9

Archer Retractor (Fig. 5.9)

This view shows the positioning of the curved osteotome on the pterygomaxillary junction.

This retractor was first produced by Mr. Danny Archer, a maxillofacial surgeon working at the Royal Marsden Hospital. He proposed and popularised this approach to facilitate access to the central and anterior skull base. In particular, this approach allows a good access to the post-nasal space for the management of nasopharyngeal lesions.

Fig. 5.8  Lateral view of mobilisation shows position of placement of the curved osteotome

Fig. 5.9  Archer retractor

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Archer Retractor In Situ (Fig. 5.10)

5.10 Placement of Metal Plates (Fig. 5.11)

The retractor is placed after the osteotomies have been performed. It has five retractors that are positioned as shown below.

The titanium plates are positioned back using the predrilled holes. Screws are then used to secure the plates in position. In following these steps, bite misalignment is prevented.

Fig. 5.10  Archer retractor in situ

Fig. 5.11  Placement of metal plates

5  Le Fort 1 Approach

5.11 Mucosal Closure (Fig. 5.12) An absorbable suture is used to close the mucosal incisions.

Fig. 5.12  Mucosal closure

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6

Midfacial Degloving Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin

6.1

Introduction

The development of the midfacial degloving procedure [2] allows for a limited medial maxillectomy to be perMidfacial degloving allows a modified medial maxillectomy formed. The superior anatomical elements of the medial to be performed without any facial incisions. It is the stan- maxillectomy cannot be resected due to the limited superior dard soft-tissue approach for skull base pathology and non-­ exposure given by midfacial degloving. However, it gives malignant nasal pathology. Most malignant nasal tumours adequate exposure of the central skull base from the spheare approached by a lateral rhinotomy approach as discussed noid cavity to the foramen rotundum. The midfacial degloving procedure is a soft-tissue in Chap. 7; this allows a traditional en bloc approach to the approach that uses a combined sublabial and rhinoplasty eradication of the tumour. Medial maxillectomy is a surgical approach originally approach to enable the elevation and superior retraction of designed for the resection of tumours involving the lateral the skin and soft tissues of the middle third of the face. wall of nose and paranasal sinuses (Fig.  6.1). It normally Although there is some oedematous swelling of the face entails resection of the whole of the lateral wall of the nose post-operatively, this rapidly settles and there is no change including the turbinates and the whole of the ethmoid com- in the cosmetic appearance of the face following the proceplex, along with the lamina papyracea of the medial orbital dure [3]. The resulting bony exposure allows a medial maxillecwall. tomy to be performed up to and including the middle turbi• It can be extended superiorly as part of a craniofacial nate; additional exposure can be obtained by temporary resection. osteotomies through the remaining inferior orbital rim on • It can be extended posteriorly via the sphenoid sinus and either side of the lacrimal apparatus. clivus to the central skull base medial to the carotid artery. Raising the soft-tissue flap requires the help of a surgeon • It can be extended posterolaterally via the pterygopalatine familiar with rhinoplasty techniques, and the bony part of the fossa to the skull base lateral to the carotid artery. medial maxillectomy and skull base resection benefits from the use of an operating microscope. This gives coaxial illuThese latter approaches, giving access to pathology of the mination and magnification. skull base, interested the neurosurgeons of the skull base Although these approaches were developed prior to the team [1]. However, the standard soft-tissue approach of a lat- era of image guidance, its use in such cases is frequently eral rhinotomy was a strong disincentive for many patients considered to be essential if the skull base is to be who did not wish for a facial incision (Fig. 6.2). explored.

A. Cheesman (*) · G. Alusi Department of Otolaryngology and Skull Base Surgery, Barts Health NHS Trust, The Royal London Hospital, London, UK e-mail: [email protected] H. I. Sabin The Wellington Hospital, Neurosurgical Unit, London, UK e-mail: [email protected] © Springer-Verlag GmbH Germany, part of Springer Nature 2022 A. Cheesman et al. (eds.), Skull Base Surgery, Springer Surgery Atlas Series, https://doi.org/10.1007/978-3-540-74259-3_6

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6.2

Trans cranial

Trans facial

Trans oral

The patient is positioned supinely upon the operating table; the table is then broken, and the upper half elevated by 40° to facilitate good venous drainage and hypotensive anaesthesia. The head is then extended by 10–20° and placed in a supporting head ring. This position facilitates the movement of the head to allow direct visualisation of the various parts of the operative field. In those cases where image guidance is considered important for the performance of the operation, such as the exploration of the skull base, the head would have been fixed in a three-point Mayfield clamp; alternatively, a navigational head frame can be applied over the forehead, with either screw fixation or a headband. In rhinological practice, free movement of the head is preferred to rigid head fixation, hence the use of the forehead frame.

6.3 Fig. 6.1  Trans-maxillary approach

a

Patient Position

Anaesthesia

This is discussed in detail in Chap. 1.

b

Fig. 6.2 (a, b) Meningioma resected by medial maxillectomy and midfacial degloving (reprinted from Allibone et al. [1]; with permission from Taylor & Francis)

6  Midfacial Degloving

Control of bleeding in this type of surgery is essential and best achieved by vasoconstriction of the nasal mucosa, preferably using Moffett’s technique with a 10% cocaine solution. The Moffett’s solution is placed into both nasal cavities with the head extended for at least 15 min prior to the onset of the surgery. In view of the extensive soft-tissue elevation of the facial tissues, additional infiltration with lignocaine and adrenaline 1:200,000 is used both to the nose and sublabial region, extending superiorly over the anterior face of the maxilla. Moderate hypotensive anaesthesia is used depending on the patient’s cardiovascular status and the anaesthetist’s preference. Endotracheal intubation is preferred, with the tube being placed in the midline with no distortion of the upper lip. Prior to the commencement of the resection, a temporary protective tarsorrhaphy of the eyes is important to prevent inadvertent trauma. See Chap. 1.

6.4

Rhinoplasty Approach

Specific local anaesthesia and vasoconstriction for the rhinoplasty approach (Fig. 6.3). Using a fine needle, lignocaine and 1:200,000 adrenaline are infiltrated into the columella and over the lateral cartilages into the subcutaneous tissues of the nasal bridge. At the same time, the sublabial mucosa and maxillary areas are also infiltrated. Transfixion incision. The first step is to separate the columella and its medial crus from the anterior septal cartilage with a transfixion incision. a

45

A twin-hook retractor is used to draw the columella forward and using a 15 blade, a transfixion incision is made from the top of the columella down to its base through both sides of the anterior nasal skin (Fig. 6.4). Inter-cartilaginous incision (Fig.  6.5). An extended inter-cartilaginous incision is made between the upper and lower lateral cartilages. At its anterior end, it is continued forward to join the upper end of the transfixion incision. Posterolaterally the incision is continued further laterally and inferiorly to the floor of the nose (this is an extension of the normal inter-cartilaginous incision). This frees the lower lateral or alar cartilages along with the columella from the rest of the cartilaginous bridge. Completion of circumferential (elliptical) incision (Fig. 6.5b). The lower end of the inter-cartilaginous incision is curved forward to join the lower end of the transfixion incision. The result of this circumferential incision is an ellipse rather than a circular incision, and this helps prevent any post-operative stenosis. Elevation of soft tissue over the upper lateral cartilages and the nasal bones (Fig.  6.6). The tissue plane between the skin and upper lateral cartilages and nasal bones is developed using a small pair of blunt iris scissors. One needs to use a combination of blunt and sharp dissection to elevate the soft tissues over the whole of the upper lateral cartilages and nasal bones; the elevation is carried laterally onto the face of the maxilla (this is further laterally than one would do for a simple rhinoplasty). The objective is to free the skin over the nasal pyramid completely to join with the skin elevation over the front of the maxilla. b

Fig. 6.3 (a, b) Prior injection of lignocaine and 1:200,000 adrenaline, into nasal pyramid and subcutaneously over both maxillae

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a

b

Fig. 6.4 (a, b) Transfixion incision to separate columella from septum

a

b

Lateral nasal cartilage Major alar cartilage

A C B

Fig. 6.5 (a, b) Extended inter-cartilaginous incision to separate the alar cartilages from upper nasal pyramid. Panel b shows extension necessary to complete separation of alar cartilages

6  Midfacial Degloving

47

men. Care should be taken to preserve the infra-orbital nerve and retractors should never be used in this region (Fig. 6.10). The elevation of the facial skin is generally readily achieved, but on some occasions, further dissection over the nasal bones is necessary to facilitate a tension-free elevation of the facial skin.

Fig. 6.6  Elevation of skin from underlying upper lateral cartilages and nasal bones

6.5

 levation of the Facial Skin over E the Anterior Aspect of the Maxilla

Fig. 6.7  Sublabial infiltration with lignocaine and 1:200,000 adrenaline. The incision line is shown in the lax mucosa of the upper lip approximately 1.5 cm above the alveolar margin

 osition and Injection for Sublabial Incision P (Figs. 6.7, 6.8, and 6.9) Ideally the mucous membrane in the sublabial area should have been infiltrated with 1:200,000 adrenaline at the time that the nasal pyramid was injected. An incision is made through the free mucosa, approximately 1.5  cm above the alveolar margin; in this area the mucosa is not adherent to the alveolus. This ensures that there is a free mucosal edge, which is important when this incision is closed at the end of the operation. The incision extends laterally on both sides to approximately the second premolar (first premolar for Le Fort 1 approach), but the lateral extent can obviously be changed depending on the amount of elevation of the facial skin that is required. The facial skin is then elevated by a combination of blunt gauze dissection and occasionally sharp dissection. The elevation is continued over the anterior face of the maxilla and superiorly towards the infra-orbital fora-

Fig. 6.8  The incision line is marked in blue

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6.6

 inking the Labial and Nasal Incisions L and Flap Elevation

The elliptical incision through the nasal mucosa is now linked with the sublabial incision (Fig.  6.11). This is best achieved by inserting a pair of McIndoe scissors, with the curve forward, anterior to the transfixion incision to p­ erforate the sublabial mucosa, and then the elliptical nasal incision is joined completely with the sublabial incision. This frees the columella and lower lateral cartilages to be elevated with the facial skin flap. At this stage, there is a wide exposure of the anterior facial skeleton, consisting of the nasal bones, upper lateral cartilages, and anterior face of both maxillae. Both infra-­ orbital nerves should be clearly identified (see Fig.  6.10). The potential exposure is seen in Fig. 6.12.

Fig. 6.9  Elevation of facial skin

Fig. 6.11  McIndoe scissors are inserted trans-nasally on either side of the base of the columella and cut through to the mucosal flap

Fig. 6.10  The facial skin flap has been elevated and shows the infra-­ orbital nerve. Care must be made to avoid retraction in this area. The facial skin must be elevated on both sides to give mobility to the flap, but generally the operative retraction is only on the side where the approach is being made

6  Midfacial Degloving

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 levation of Nasal Mucosa from Lateral Wall E (Figs. 6.13 and 6.14) Normally with medial maxillectomy we resect the whole of the mucosa of the lateral nasal wall, but where we are using the procedure for the exposure of the skull base with midfacial degloving we leave a circumferential strip of nasal mucosa (10–15 mm) just anterior to the anterior end of the inferior turbinate. Just anterior to the insertion of the inferior turbinate, a vertical incision should be made to parallel to the inter-cartilaginous incision. The purpose of this incision is to leave a vertical strip of mucosa between the elliptical incision and the resected mucosa of the medial maxillectomy. This is important in preventing any nasal stenosis. The rest of the nasal mucosa must be dissected free from its underlying bone. This is easily achieved along the floor and up to the origin of the inferior turbinate. The turbinate can be freed from its attachment to the lateral wall at this stage with Mayo scissors or alternatively later when the bony wall is removed. Further dissection with the Freer elevator is made superiorly into the middle meatus and ethmoid cells, freeing the lateral mucosal contents of the ethmoids from the nasal surface of the lamina papyracea. This superior elevation is sometimes difficult due to limited elevation of the facial soft tissues. This completes the exposure of enough of the maxillary bone for us to perform the medial maxillectomy. Fig. 6.12  Potential exposure of the anterior facial skeleton. The elevation is only utilised on the side of the operative approach

6.7

 edial Maxillectomy to Expose M the Antrum and Skull Base

The wide elevation of the skin over both maxillae is necessary to give the maximum mobility of the skin flap. The medial maxillectomy is performed only on the involved side and the exposed bone is more than enough to enable the bony osteotomies to be safely executed. The first step is to complete the soft-tissue approach by elevating the nasal mucosa off the lower part of the lateral wall of the nose. We only need to extend this superiorly to the middle meatus which is just below the level of the orbital floor and this forms the upper limit of our exposure.

Fig. 6.13  The nasal mucosa and turbinates are separated from the lateral bony wall

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Fig. 6.14  Following dissection of nasal mucosa, a further parallel incision is made to leave a strip of mucosa 1 cm wide just posterior to the inter-cartilaginous incision

6.8

 ony Steps of the Medial B Maxillectomy

The medial maxillectomy as described in Chap. 7 is generally an en bloc clearance for cancer. Its use with midfacial degloving is a systematic removal of bone to expose the central skull base. Accordingly, we proceed with the bone resection in separate steps:

tates the identification of the lacrimal duct) (Fig. 6.15). The bulge of the root of the incisor tooth must also be recognised and avoided by the bone resection. A large window in the anterior wall of the maxilla is outlined using a fissure burr; this should avoid the infra-orbital foramen, and as the cut extends medially it usually becomes obvious where the lacrimal canal lies adjacent to the lateral wall of the nose and therefore the osteotomy should be directed inferiorly from this point, preserving the lacrimal canal. At this stage, the anterior wall of the maxilla is removed, giving wide access into the antrum. The dotted line indicates the desired osteotomy, avoiding infra-orbital foramen (IOF), lacrimal duct (LD), and incisor root (I). Alternative methods of constructing the antral window. An alternative, and perhaps safer, way to remove the anterior wall of the antrum is with a rose head cutting burr or making a window with an osteotome (Figs. 6.16 and 6.17). A curved osteotome can also be used to remove the bone and open a window into the maxillary sinus which can then be enlarged with a rongeur. Extending the bony exposure (Fig. 6.18). With the initial antral window completed the important anatomy can be identified and the bone removal extended as necessary to give an adequate exposure. The remaining overhanging walls following the window osteotomy can be enlarged by removing its margins back with bone nibblers or a rose head burr.

1. Removal of the anterior wall of the antrum 2. Removal of bone around the lacrimal canal to free the lacrimal sac and duct 3. Removal of the lateral wall of the nose up to the level of the medial canthus, clearing the inferior and middle turbinates and the lower ethmoid cells 4. Finally removal of the posterior wall of the antrum and the anterior wall of the sphenoid, depending on the required exposure

Removal of the Anterior Wall of the Maxilla The first step is to identify the probable region of the bony lacrimal canal, which passes down from the orbit into the inferior meatus of the nose (image guidance, if used, facili-

Fig. 6.15  Removing antral window

6  Midfacial Degloving

51

Fig. 6.16  The use of a rose head burr to make the osteotomy

Fig. 6.18  Enlargement of antral window with a rongeur

I dentification and Opening of the Lacrimal Canal

Fig. 6.17  The initial cut with the osteotome to enter the antrum. The initial hole is enlarged with a rongeur

Extending the window medially is best achieved with a rose head burr as this is the safest way of identifying the canal (Fig. 6.19). As the canal is opened anteriorly the remnants of the frontal process of the maxilla and adjacent nasal bone are removed to unite the antral window with the nasal cavity. The remaining walls of the canal are drilled away using either a rose head burr or bone nibblers to free the sac and its duct. When the lacrimal duct is clearly identified, the antral window is opened further superiorly up to just short of the orbital rim; again the bone around the infra-orbital foramen is preserved (Fig. 6.20). We can now see the lacrimal duct passing postero-­ inferiorly into the inferior meatus, and the lacrimal duct is divided inferiorly, including a cuff of mucosa from the inferior meatus, where it enters the meatus. At this point the duct is wide open and any stenosis is unlikely.

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Removal of the Lateral Bony Wall

Fig. 6.19  Exposure of lacrimal duct

Figure 6.21 shows the wide exposure obtained by removal of the anterior wall of the maxilla and the bony canal of the lacrimal duct. The next step is to resect the lateral wall of the nose up to and including the middle turbinate. Using a fissure burr, the bony lateral wall of the nose is divided from the nasal floor (which is higher than the floor of the antrum) back to the posterior wall of the antrum. Using a rose head burr, a vertical osteotomy is made between the posterior wall of the antrum and the lateral wall of the nose. The lateral wall of the nose can now be fractured medially, as the bone lateral to the ethmoid cells is very thin. The lateral wall of the nose is then excised using scissors to cut mucosa adjacent to the osteotomies. The block removed will include the lateral wall along with both the inferior and middle turbinates, and sometimes additional removal of the ethmoids cells is necessary using Tilley Henkel cup forceps. The lacrimal duct is then reflected superiorly with a suture, so it is outside the subsequent operative field. We now have a wide exposure of the nasopharynx via the combined antral and nasal cavities (see Fig. 6.25).

Fig. 6.20  The bone surrounding the lacrimal duct has been drilled away and the freed duct is reflected out of the operative field by a superior suture Fig. 6.21  Following the freeing of the lacrimal duct the remainder of the bony lateral wall is removed

6  Midfacial Degloving

6.9

Management Juvenile Angiofibroma

The midfacial degloving procedure is excellent for children with juvenile angiofibromata, as it does not appear to interfere with the growth of the facial skeleton, as sometimes happened with the lateral rhinotomy approach (Figs. 6.22, 6.23, and 6.24) [4]. We think intra-arterial embolisation of the tumour some 7 days before the operation reduces bleeding, and with a systematic approach there is a minimal chance of leaving a small area of residual tumour. Our understanding of the natural history is that these tumours are vascular anomalies that start in vascular mesenchymal tissue found in the region of the pterygoid canal. Many CT scans show enlargement of pterygoid canal with the tumour expanding through sphenopalatine foramen and expanding into the postnasal space [5, 6]. They also erode through the back wall of the antrum, giving a large antral component. Of greater concern are those tumours which expand via the pterygopalatine fossa into the infra-temporal fossa and lateral skull base. (Some surgeons

53

have recommended a trans-petrous infra-temporal fossa approach, but we feel that they are best managed by an anterior approach.) Figure 6.24 shows the angiofibroma filling the postnasal space and extending into the antrum. The tumour needs to be mobilised medially to gain access to the posterolateral walls of the antrum. If these walls had not been eroded, they need to be drilled away to gain access to the lateral pterygopalatine fossa. We are looking for the maxillary artery as it enters the fossa, but it is not always clearly visible due to excess fat in the region. Blunt dissection of the fat with adrenaline-­ soaked gauze generally results in the artery making itself obvious, and it can then be clipped with a Ligaclip to reduce any bleeding left after the embolisation. Carotid angiography often shows multiple small vessels passing between the angiofibroma and the carotid wall. This gives concern to many surgeons that the carotid is supplying the angiofibroma. Our view is that these vessels are arising from the adventitia of the carotid wall and can therefore be easily separated from the tumour by blunt dissection with ribbon gauze (Fig. 6.22).

Fig. 6.22  CT scan (left) and carotid angiogram (right) show an extensive angiofibroma. The apparent vascularisation from the carotid artery arises for the blood vessels of the adventitia of the artery and can be separated by gentle dissection

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Fig. 6.23  Medial maxillectomy approach

A. Cheesman et al.

on the sphenopalatine vessels or inferiorly on the nasopharyngeal mucosa and its rich blood supply. This is discussed fully in Chap. 7 where the lateral rhinotomy approach enables better display of the procedure. Ideally it is pedicled on the sphenopalatine vessels as they pass medially over the front of the sphenoid to reach the posterior septum. However, if the exploration of the skull base requires the pterygopalatine fossa to be opened, then we cannot rely on the sphenopalatine vascular pedicle. In this case, the septal mucosal flap is based widely on the mucosa of the posterior pharyngeal wall. In some cases where considerable resections are necessary in the region of the sphenoid, a septal mucosal flap can be raised from the contralateral side of the septum based upon the sphenoid vessels of the other maxilla. To easily identify the mucosal surface of the flap it is useful to paint its anterior mucosal surface with gentian violet. We tend to raise a large flap with horizontal incisions along both the superior and inferior borders of the septum, freeing it with a vertical incision anteriorly. The large size makes it easier to place with little tension on its pedicle. The flap is raised from the septal cartilage and stored on the floor of the nose or into the nasopharynx, protected by a large moist neurosurgical patty.

Fig. 6.24  The antral component of the angiofibroma has been dissected medially to expose the posterior wall of the antrum, which is removed to gain access to the supplying maxillary artery

6.10 R  econstruction of the Skull Base: Nasal Septal Flap With the completion of the medial maxillectomy back to the nasopharynx it is important to plan the reconstruction of the central skull base if the dura has been exposed or if there is a CSF leak (Figs. 6.25 and 6.26). A nasal septal mucosal flap will need to be raised. This needs to be based either laterally

Fig. 6.25  The completed medial maxillectomy gives wide exposure of the nasopharynx. The next step is to raise a nasal septal mucosa flap. E remnant of ethmoid cells; NP nasopharynx; SP soft palate; A antrum

6  Midfacial Degloving

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Image guidance is mandatory for this stage of the procedure. 1. If the pathology is lateral to the carotid artery, we need to open the pterygopalatine fossa. 2. If the pathology is more central and medial to the carotid artery, we need to extend the exploration via the sphenoid sinus.

Fig. 6.26  The nasal septal flap has been raised and stored in the nasopharynx. The sphenoid cavity has been widely exposed by resection of the posterior septum, rostrum, and anterior walls of the sphenoid. E remnant of ethmoid cells; NP nasopharynx; SP soft palate; A antrum; V remnant of vomer; C carotid bulge; ON bulge over optic nerve

 xtension of the Bone Removal of the Medial E Maxillectomy to Expose the Central Skull Base  natomy of the Pterygopalatine Fossae A Figures 6.27, 6.28, and 6.29 show the essential anatomy of the fossa indicating the potential access of the skull base. Depending on the site of the pathology and as to whether it is medial or lateral to the carotid artery, further bone removal is necessary to explore the skull base.

 xploration of the Lateral Skull Base via E Pterygopalatine Fossa Using the operating microscope and diamond burrs, the posterior wall of the antrum is drilled away to expose pterygopalatine fossa with its sphenopalatine artery anterior to the maxillary nerve as it leaves the foramen rotundum. The fossa is also full of fat, and this inhibits the identification of the artery and nerve. The artery itself is frequently composed of several loops, and it is important to identify its lateral origin. The fat can be dispersed by firm pressure with a gauze bud and the artery easily identified. It is clipped laterally with a Ligaclip and then divided. With the artery retracted, the foramen rotundum should be clearly visible with the maxillary nerve. Just medial to the foramen rotundum there is a vertical ridge, and medial to this is another small foramen, the pterygoid canal, and the nerve issuing from it is the Vidian nerve. (The pterygoid canal and its containing Vidian nerve pass back to the carotid canal, where the Vidian nerve joins a sympathetic plexus surrounding the carotid artery. Prior to the days of image guidance, we followed the nerve back to locate the carotid canal and artery.) Using image guidance and a diamond burr, the skull base between the foramen rotundum and carotid artery can be widely open.

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Superior Rostrum of Lesser wing orbital fissure sphenoid of sphenoid

Orbital plate of great wing of sphenoid Maxillary nerve Position of pterygopalatine fossa

Sphenopalatine 'bundle' Maxillary artery

Lateral pterygoid plate

Medial pterygoid plate

Pyramidal process of palatine

Fig. 6.27  Neurovascular anatomy of pterygopalatine fossa

Optic foramina

Optic foramina

Medial 'buttress'

Maxillary antrum

Orbital process of palatine

Foramen rotundum Pterygoid canal

Fig. 6.28  Posterior anatomy of pterygopalatine fossa giving access to the central skull base

Pterygoid process of palatine Pterygoid canal

Pterygopalatine fossa

Greater wing of sphenoid

Foramen ovale Foramen spinosum

Fig. 6.29  The relations of the pterygopalatine fossa to the antrum and middle fossa

6  Midfacial Degloving

 xploration of the Pituitary Fossa and Its E Surrounding Structures To explore the skull base around the pituitary fossa and lateral walls of the sphenoid sinus, it is necessary to remove the rostrum of the sphenoid along with the adjacent vomer posterior third of the septum (see Fig. 6.26). Prior to this bone removal, it is essential that the prepared septal mucosal flap is protected from inadvertent damage resulting from gauze dressings being caught in a cutting burr. Consequently, the moist gauze protecting the flap should be covered with either a silastic sheet or the foil from an opened suture pack. The initial opening of the sphenoid cavity is best done with a rose head burr, but the whole of the front wall of both sinuses, rostrum, and inter-sinus septum can be achieved more quickly using bone nibblers. Overhanging bone edges should be drilled away to give a smooth entry to the sphenoid cavity. Often the carotid and optic canals can be clearly identified by ridges in the lateral wall of the sphenoid, but ideally, image guidance should be used to direct any drilling of the skull base at this point. (A Doppler probe can also be used to define course of the carotid artery.) Due to the obliquity of the approach, if the exploration is primarily lateral to the sphenoid sinus, then the skull base approach is best made via the contralateral antrum. If the exploration requires removal of the clivus inferior to the sphenoid sinus, a direct coaxial approach can be hindered by the prominence of the inferior medial orbital rim. If this occurs, the ring can be fractured away temporarily with osteotomies on either side of the lacrimal apparatus.

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6.11 R  econstruction of Skull Base and Closure If the dura has been breached at any point it should be repaired with a fascia lata graft placed between the dura and the overlying bone. In most cases, a wide septal mucosal flap will widely cover the operative defect. The use of endoscopes extends the reach of this approach and facilitates reconstruction of skull base defects. If there is a particularly deep cavity into which the septal flap will not lie in contact, then consideration should be given to filling the cavity with a dermal fat graft, with the dermis outwards so as to be in contact with the deep surface of the septal flap. A dermal fat graft is made by excising an ellipse of skin with its underlying fat. The epidermis is then shaved off with a sharp scalpel blade, leaving the underlying dermis to vascularise the flap. The low metabolism of fat makes these grafts highly successful (Fig. 6.30).

Lacrimal Stenting Prior to nasal packing O’Donoghue lacrimal stents are inserted to prevent any stenosis. This is discussed in Chap. 1.

Nasal Packing The septal mucosal flap is covered with antibiotic-soaked Sterispon, and then the whole cavity is packed with a Whitehead’s varnish pack (see Chap. 2).

Suturing The columella transfixion incision is closed on both sides with fine Vicryl sutures. The sublabial incision is closed loosely in one layer with Vicryl sutures. This is best done with a continuous suture to ensure airtight closure. Patients will then be able to eat and drink without leaking into the nasal/maxillary cavity.

6.12 Immediate Post-operative Care Fig. 6.30  Preparation of dermal fat graft. An ellipse of skin and underlying fat is excised from the thigh. The epidermis is then removed as a flap leaving the underlying dermis attached to the fat and readily obtains a blood supply from the overlying septal mucosal flap

If the surgery has been in close relation to the optic nerve, then vision of the patient should be checked following recovery from anaesthesia.

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The nasal pack is removed under general anaesthesia after 2 weeks. Nasal toilet using saline sprays and nasal douches is necessary for about 4 weeks, though often much longer if radiotherapy is used post-operatively. Lacrimal stents are removed in the clinic after 6 weeks.

References 1. Allibone JB, Casey AT, Powell M, Cheeseman AD.  The midface degloving approach for intracranial tumours. Br J Neurosurg. 2001;15(2):109–15. 2. Casson PR, Bonnano PC, Converse JM.  The midfacial degloving procedure. Plast Reconstr Surg. 1974;53:102–3. 3. Maniglia AJ, Phillips DA. Midfacial degloving for the management of nasal, sinus, and skull-base neoplasms. Otolaryngol Clin N Am. 1995;28(6):1127–43. 4. Diver J, Badia L, Turner N, Lund V, Howard D, Cheesman A. Juvenile nasopharyngeal angiofibroma: a discussion of the midfa-

A. Cheesman et al. cial degloving approach and review of therapeutic options. Acoustic Neuroma and Skull Base Surgery. 1995:629–34: Proceedings of the 2nd International Conference on Acoustic Neuroma Surgery and 2nd European Skull Base Society Congress, Paris, France, April 22–26 1995. 5. Lloyd G, Howard D, Phelps P, Cheesman A.  Juvenile angiofi broma: the lessons of 20 years of modern imaging. J Laryngol Otol. 1999;113:127–34. 6. Howard DJ, Lloyd G, Lund V. Recurrence and its avoidance in juvenile angiofibroma. Laryngoscope. 2001;111(9):1509–11.

Suggested Reading Howard DJ, Lund VJ. The midfacial degloving approach to sinonasal disease. J Laryngol Otol. 1992;106(12):1059–62. Kotecha B, Diver J, Hellier W, Cheesman A.  Trans-nasal approach for cerebrospinal rhinorrhea. Acoustic Neuroma and Skull Base Surgery, pp 641–4: Proceedings of the 2nd International Conference on Acoustic Neuroma Surgery and 2nd European Skull Base Society Congress, Paris, France, April 22–26 1995.

7

Lateral Rhinotomy Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin

In this chapter we look at the trans-maxillary approaches to the central skull base. Traditionally these approaches were used for malignant disease of the paranasal sinuses. The central skull base is a difficult area to access by traditional neurosurgical approaches and the maxilla has always been a boundary to a more anterior approach. The inter-­ specialty surgical collaboration in dealing with the anterior skull base has enlightened neurosurgeons to the potential of trans-maxillary approaches for access to the central skull base. Malignancies of the upper jaw are particularly unpleasant for those suffering from such conditions. These tumours have a long natural history and cause considerable functional and cosmetic defect. Consequently, there has been a long history of surgical procedures to try and manage these conditions, dating back to the early 1800s. Unfortunately, until more recent times, the results of such surgery were poor, often due to intracranial spread and orbital involvement. Furthermore, the procedures themselves often aggravated the mutilation and did little to improve the patient’s quality of life [1].

Over the last 50 years with improvements in surgical technique, aided by better anaesthesia and availability of antibiotics, we have seen more satisfactory outcomes. The advent of craniofacial surgery to deal with the problems of intracranial spread and orbital involvement has further improved survival rates for these tumours. Today, they are generally managed by medial maxillectomy and in a few cases, with more extensive pathology, total maxillectomy and occasionally orbital exenteration are still necessary. Medial maxillectomy entails the resection of the whole of the lateral wall of the nose including the turbinates and the ethmoid complex. This gives a wide exposure of the central skull base to be potentially approached via the sphenoid sinus or through the posterior wall of the antrum into the pterygopalatine space and thence into the medial middle fossa. Such access has enabled the more effective management of such tumours as chordomas, chondrosarcomas, angiofibromas, and meningiomas (Fig. 7.1).

A. Cheesman (*) · G. Alusi Department of Otolaryngology and Skull Base Surgery, Barts Health NHS Trust, The Royal London Hospital, London, UK e-mail: [email protected] H. I. Sabin The Wellington Hospital, Neurosurgical Unit, London, UK e-mail: [email protected] © Springer-Verlag GmbH Germany, part of Springer Nature 2022 A. Cheesman et al. (eds.), Skull Base Surgery, Springer Surgery Atlas Series, https://doi.org/10.1007/978-3-540-74259-3_7

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Foramina of Sphenoid Bone

Three other notable approaches to the central skull base have been described: • Maxillotomy by Alan Crockard, 1991 [2] • Maxillary swing by William Wei, 2011 [3], for the tumours of the nasopharynx • Le Fort 1 osteotomy approach popularised by Danny Archer, discussed in Chap. 5

When dealing with malignancies the aim is to perform an en bloc resection, which includes as its resection margin the next normal anatomical boundary that is free of tumour. This invariably entails an approach through normal anatomy. For non-malignant pathology, particularly of the skull base, a more usual practice is to perform a piecemeal dissection through the centre of the tumour which allows an easier resection as it gives a progressive debulking of the tumour. In both surgical approaches the resection margins should be histologically confirmed by frozen section.

Optic nerve in optic canal Superior orbital fissure

Maxillary nerve in Foramen rotundum Vidian nerve in pterygoid canal Fig. 7.1  Potential exposure of central skull base with trans-maxillary approaches

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7.2

Soft-Tissue Approaches

Many different soft-tissue approaches have been described over the last two centuries. Many of these incisions gave poor cosmetic results and there has been an increased use of the midfacial degloving approach to expose the anterior aspect of the maxilla (discussed in Chap. 6). Similarly, endoscopic procedures are frequently used for non-malignant pathology. The decision on when to use a facial incision depends upon both the histology of the tumour and its extent. The midfacial degloving procedure is preferred to a Weber

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Ferguson incision as it allows a more rapid rehabilitation of both speech and swallowing. Unfortunately, it cannot be used with malignant disease involving the superior ethmoid sinuses or the orbital contents. The various incisions are described with the details of each procedure.

7.3

Bony Approaches (Fig. 7.2)

There are two main resections, the conservative medial maxillectomy and radical maxillectomy.

b

Fig. 7.2 (a) Medial maxillectomy osteotomies. (b) Maxillectomy osteotomies

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Maxillectomy

Maxillectomy (sometimes called hemi-maxillectomy) is the surgical resection of the maxilla, including the adjacent ethmoid sinuses, part of the hard palate, floor of the orbit with a lateral osteotomy through the zygomatic process, and a posterior osteotomy detaching the maxilla from the pterygoid plates. For more extensive malignancies, the procedure can be extended superiorly to include the skull base, the whole of the lateral wall of the nose, and the orbit. Laterally the tumour can be followed into the infra-temporal fossa. Many surgeons would consider the posterior wall of the pterygopalatine fossa as the limit of resection. However, depending on the pathology a resection of the posterior wall around the foramen rotundum is easily accomplished and allows the resection to be continued into the middle fossa. After a maxillectomy, the maxilla was traditionally replaced with a maxillary obturator built on top of an upper dental plate to fill the maxillectomy cavity. The advantage of this procedure is that the tumour bed is left wide open for post-operative inspection. Local recurrences in the cavity can often be managed with further local resections using the laser, or with topical chemotherapy using 5-FU cream. The construction of maxillary implants bearing teeth and allowing good mastication requires the skill of an experienced maxillofacial technician. To facilitate their work and help retention of the prosthesis, there are a variety of surgical steps, which will be covered in the description of the operative procedure. There is a current enthusiasm for reconstruction of the maxilla, but this is done at the risk of leaving recurrent disease concealed behind the reconstruction. Often such recurrences do not become obvious until they have reached an inoperable stage. Various flaps have been used, but the most popular reconstruction is a free microvascular flap. It is possible to use bone grafts and Branemark implants. Other sur-

geons have used metallic implants, usually titanium mesh, but with radiotherapy either pre- or post-operatively there is a high incidence of extrusion. We would question the need for immediate reconstruction, particularly in the elderly patient. Our recommendation is to leave the maxilla unreconstructed, but with an obturator until we are sure that we have achieved a cancer cure. We are happy to consider reconstruction when local clearance has been confirmed and the patient is keen for a reconstruction and understands its significance.

7.5

 edial Maxillectomy Procedure M (Fig. 7.3)

Medial maxillectomy entails the resection of the whole of the lateral wall of the nose including the turbinates (which automatically enlarges the view of the nasal cavity), the whole of the ethmoid complex, and the lamina papyracea of the medial orbital wall. • The resection can be extended superiorly as part of the craniofacial resection. • The resection can be extended posteriorly via the sphenoid sinus and clivus to the central skull base medial to the carotid artery. • The resection can also be extended posterolaterally via the pterygopalatine fossa and lateral to the carotid artery. Medial maxillectomy is the key manoeuvre that: • Allows the resection of smaller tumours involving the lateral nasal wall. • Allows wide access to the central and lateral skull base by removing the bony block of the maxilla. The use of medial maxillectomy as the bony approach in midfacial degloving is discussed in Chap. 6.

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Fig. 7.3 (a) Extent of medial maxillectomy. (b) Exposure post-medial maxillectomy

7.6

Patient Workup

This is covered in more detail in Chap. 1.

7.7

Patient Position and Anaesthesia

The patient is positioned supinely upon the operating table; the table is then broken, and the upper half elevated by 40°, which facilitates good venous drainage and hypotensive anaesthesia. The head is then extended by 10–20° and placed in a supporting head ring. This position facilitates the movement of the head to allow direct visualisation of the various parts of the operative field. In those cases where image guidance is considered important for the performance of the operation, the head can be fixed in a three-point Mayfield clamp; alternatively, a navigational head frame can be applied over the forehead either with screw fixation or with a headband. In rhinological practice, free movement of the head is preferred to rigid head fixation, hence the use of the forehead frame. It is essential to control bleeding in this type of surgery. The best way to achieve this is by vasoconstriction of the nasal mucosa, preferably using Moffett’s technique with a 10% cocaine solution. The Moffett’s solution is placed into both nasal cavities with the head extended for at least 15 min prior to the start of the surgery. Moderate hypotensive anaesthesia is used, depending on the patient’s cardiovascular status and the anaesthetist’s preference. Endotracheal intubation is preferred, with the tube being placed in the midline with no distortion of the upper lip. If

the surgical resection is planned to include a total maxillectomy, then a trans-oral tube will interfere with the fitting of the post-operative obturator. In such cases, the endotracheal tube should be passed via the uninvolved side of the nose, or consideration be given to performing a temporary tracheostomy. Prior to the commencement of the resection, a temporary tarsorrhaphy of the eye is important; this is best performed passing the needle through the lid margins into the tarsal plate.

7.8

 echnique for Medial Maxillectomy T Approach

Indications for Use Small tumours in this region are generally managed with an endoscopic resection. If, however, there is lateral extension, then an open approach by lateral rhinotomy is preferred. This allows the tumour to be approached via normal tissue planes and results in a better oncological resection.

Incision Design The usual incision for the exposure of the medial maxilla is the lateral rhinotomy incision and many variations have been described since the 1800s. The most popular variation has been Moure’s lateral rhinotomy, originally described in

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1902. The basic incision is made in the nasal maxillary junction from the level of the medial canthus down to the lateral border of the nasal alar. This limited incision generally has an excellent cosmetic result and adequate undermining of the skin, along with good retraction, gives good access to the medial maxilla (Fig. 7.4). Continuing the incision inferiorly around the alar of the nose generally gives limited further exposure and is cosmetically more obvious due to the sunken alar following healing. Depending upon the extent of exposure of the facial skeleton that is required, the incision may be continued superiorly in a variety of directions. • For access to the complete fronto-ethmoid complex, the incision is continued superiorly halfway between the medial canthus and the apex of the nasal bridge, continuing with a curvilinear extension towards the supraorbital foramen. • For exposure of the nasion and forehead, the incision is curved anteriorly over the nasal bridge and continued superiorly in one of the forehead frown lines (Type I craniofacial incision in Chap. 2).

Fig. 7.4  Moure’s lateral rhinotomy incisions and extensions

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 xposure of Anterior and Superior Walls E of the Maxilla The incision is placed in a skin crease, if possible. The incision is then carried down to the bone along its whole length. Then the soft tissues of the face and nose are elevated by blunt dissection with gauze; the lateral extent of the elevation is the infra-orbital foramen. (Blunt dissection using adrenaline-soaked ribbon gauze is beneficial; giving better control of the elevator and the adrenaline helps reduce and absorb any blood). At the upper end of the incision, level with the medial canthus, sharp dissection with a Freer’s elevator is necessary to separate the orbital periosteum and lacrimal sac from its attachment to the lamina papyracea around the lacrimal groove. Further dissection around the lacrimal sac is necessary to isolate it from its bony canal. The floor of the orbit is exposed by wide elevation of the orbital periosteum which includes the origin of the inferior oblique tendon. As the exposure includes the whole of the lamina papyracea, the trochlea must be separated with sharp dissection from the underlying bone. Sharp scalpel dissection is essential to prevent damage to the synovial capsule around the tendon (Fig. 7.5). At this stage, there is a wide exposure of the medial and inferior walls of the orbit and the anterior wall of the maxilla down to the piriform aperture.

Fig. 7.5  Undermining of flaps to show anterior wall of maxilla and to start freeing orbital contents

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orbital periosteum, and giving excellent exposure of the medial and inferior walls of the orbit (Fig. 7.8).

7.10 Medial Maxillectomy Osteotomies

Fig. 7.6  Development of a submucosal plane by separating the upper lateral cartilage from the bone of the pyriform aperture

 eparation of Nasal Soft Tissues from Medial S Aspect of Maxilla Sharp dissection is used to separate the junction between the upper lateral cartilage and the frontal process of the maxilla, then continuing deeply to elevate the nasal mucosa off the nasal surface of the frontal process (Fig. 7.6). The nasal mucosa is then further separated back along the lateral bony wall of the nose. The attachment of the inferior turbinate is divided with scissors to free the turbinate with the nasal mucosa flap. At this stage, the dissection is facilitated by using some adrenaline-soaked ribbon gauze; this elevates the mucosa and helps reduce bleeding. The elevation of the mucosa also acts as a retractor and increases visibility. The nasal mucosa is dissected widely along the lateral wall and down to the level of the floor.

7.9

Mobilisation of Orbital Floor

To facilitate mobilisation of the orbital contents it is necessary to divide the lacrimal duct low down in its canal, preferably below its valves (Fig.  7.7). This is facilitated by removing the anterior wall of the lacrimal canal with bone nibblers. If you are dealing with a malignancy in this area, careful inspection of the medial aspect of the lacrimal canal is necessary to ensure that tumour invasion has not occurred. Once the lacrimal duct has been divided, it is reflected superiorly, allowing medial and inferior mobilisation of the

These are best cut using a side-cutting fissure burr. We can now perform the osteotomies of the medial maxillectomy, and although ideally we would like to remove it as an oncological block, it is easier to proceed with a systematic staged removal. Oncological principles are maintained by performing frozen section studies on any suspicious tissue, during this dissection. The soft-tissue elevation gives enough bone exposure to perform the osteotomies of the medial maxillectomy. A superior osteotomy is made through the upper part of the ethmoid bones and is carried forward through the frontal process of the maxilla and nasal bones and then continued inferiorly to the pyriform aperture. In some cases, the nasal bone can be preserved and out fractured with the nasal skin to give additional access (Fig. 7.9). The next osteotomy starts posteriorly on the floor of the orbit at the lower border of the lamina papyracea and continues forward to just medial to the infra-orbital foramen; it then continues down through the anterior wall of the maxilla, swinging medially to join the piriform aperture at its lowest point. The mucosa of the lateral wall of the nose has already been widely elevated from the bony lateral wall. This allows a final osteotomy to be made along the floor of the nasal cavity through the lower part of the lateral nasal wall, extending back to the posterior wall of the antrum. Once these osteotomies have been completed, the medial maxillectomy block is fractured medially by inserting an elevator through the anterior wall of the maxilla and using firm pressure posteriorly to fracture the lateral wall at its posterior limit. As the soft tissues have been elevated away from this bony block it can be removed giving wide access to the nasal cavity and antrum. With removal of this part of the medial maxillectomy block, the lateral aspect of the soft tissues of the nasal cavity is clearly visible and can be inspected to see whether there has been any tumour invasion. If this is suspected, then frozen section studies should be made of the orbital periosteum adjacent to the eroded area. This mucosal flap is then mobilised by a cut along the floor of the nasal cavity and then reflected laterally into the antral cavity to give an excellent view of the nasal cavity (Fig. 7.10). This panoramic exposure of the nasal cavity enables us to define the tumour and its extent. A margin of normal mucosa is left surrounding the tumour, and frozen section studies are made to ensure that the resection margins are adequate. The rest of the mucosal flap is excised for subsequent histological examination (Fig. 7.11).

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We can now turn our attention to the residual area of nasal mucosa on the roof containing the tumour (Fig. 7.12). As the tumour is adherent to the bony roof of the nose, it is essential to remove the underlying bone and dura. A wide local mucosal clearance is performed, and the underlying bone and dura are also resected with a circumferential osteotomy well clear of the tumour area; the bone flap is removed with the underlying dura to expose the intracranial cavity around the site of the tumour. Frozen sections are taken to make sure that the resection margins are adequate (Fig. 7.13a and b). Repair of the skull base is made using a free, composite cartilage/mucosal flap. This is harvested from the septum

(Fig. 7.13c). A small area of fascia lata is harvested from the leg. The defect in the anterior fossa is repaired by placing the fascia graft between the bone and underlying dura, holding it in place with a few sutures. An impression of the bony defect is made with the foil of a suture pack; this is used to accurately shape the cartilage portion of the composite graft. The graft is then clicked into place, giving a watertight closure of the anterior fossa. The graft is held in place with Tisseel glue and covered with antibiotic-soaked Sterispon. The nasal cavity is then packed with a Whitehead’s varnish pack (Fig. 7.13d). All the incisions are closed carefully in two layers with fine nylon to the skin (Fig. 7.14).

Fig. 7.7  Ostectomy to open the lacrimal canal

Fig. 7.8  Division of lacrimal duct below its valve

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Fig. 7.9  Osteotomies cut with fissure burr following lateral retraction of mobilised orbital contents

Fig. 7.10  Exposed deep aspect of the mucosa of lateral wall of the nasal cavity

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Fig. 7.11  The mucosal lateral wall has been reflected into the antral cavity giving a panoramic view of the nasal cavity. It inferior turbinate; MT middle turbinate; NP nasopharynx; S septum; ST superior turbinate. Tumour is seen in ethmoid cells

Fig. 7.12  Residual tumour involving skull base at the roof of ethmoids. A antral cavity; NP nasopharynx; SP soft palate. Course of sphenopalatine artery indicated

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d

Fig. 7.13 (a) Full-thickness excision of skull base. (b) Shows dural defect created. (c) Composite graft of septal cartilage and mucosa clicked into bone defect. (d) Completed repair prior to packing with Whitehead’s varnish pack

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Fig. 7.14  Skin closure following medial maxillectomy

7.11 Alternative Method of Reconstruction The Septal Mucosal Flap The septal mucosal flap has made a dramatic improvement in the reduction of cerebrospinal fluid (CSF) leakage following skull base surgery. It was originally described by Hirsch, 1952 [4], who used it for repair following hypophysectomy and was popularised by Montgomery, 1966 [5], for the repair

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of CSF leaks. We have used it for many years both for CSF leakage and for the repair of the skull base following resections of the dura [6]. Its importance was missed in skull base practice until recently but is now the routine method of repair. Although the flap is often used by itself, we prefer to supplement the repair of the dura with a fascia lata graft and if possible to repair small bone defects with septal cartilage grafts cut accurately to the size of the bony defect. The flap is best raised after the medial maxillectomy and prior to any extended resections of the central skull base; this ensures that the flap and its pedicle are not inadvertently damaged by instruments (particularly drills) being passed through the nasal cavity. When it is freed from the septum, we normally store it wrapped in moist gauze and it is reflected out of the operative field into the nasopharynx. The flap is outlined on the septum (Fig.  7.15a) and the upper incision is curved around the upper part of the anterior wall of the sphenoid to reach the lateral nasal wall. We tend to use a large part of the septal mucosa because even if a large size is unnecessary it reduces any tension on the pedicle. Ideally it is pedicled on the sphenopalatine vessels as they pass medially over the front of the sphenoid to reach the posterior septum. However, if the exploration of the skull base requires the pterygopalatine fossa to be opened, then we cannot rely on the sphenopalatine vascular pedicle. In this case, the septal mucosal flap is based widely on the mucosa of the posterior pharyngeal wall (Fig. 7.15b). In some cases where considerable resections are necessary in the region of the sphenoid, a septal mucosal flap can be raised from the contralateral side of the septum based upon the sphenoid vessels of the other maxilla. We have also used septal flaps from both sides of the septum to cover particularly large resections. The flap is raised deep to the perichondrium, a technique familiar to nasal surgeons (Fig. 7.15c). As it is sometimes difficult to identify the mucosal surface of the flap when it comes to be inserted a useful trick is to paint the anterior nasal mucosa with gentian violet prior to raising the flap (Fig. 7.15d).

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Fig. 7.15 (a) Septal mucosal flap outlined on septum. Based on sphenopalatine artery or posterior pharyngeal mucosa. (b) Flap raised and stored in nasopharynx. (c) Raising of flap allows potential exploration of sphenoid sinus. (d) Septal mucosal flap used to repair ethmoid roof

Maxillectomy and Orbital Exenteration Fortunately, the need for maxillectomy and orbital exenteration has dramatically declined over the last four decades. Prior to the availability of CT and MRI scanning the radiological assessment of maxillary malignancies generally suggested that maxillectomy was required in virtually all cases. With modern scanning technique most of these cases are now shown to be antro-ethmoidal tumours which can be resected by medial maxillectomy. Similarly, alveolar carcinomas extending up into the antrum can now be resected by a simple palatal resection. The need for orbital exenteration has also declined with improvements in technique and a better understanding of the

natural history of these malignancies. In the 1970s and 1980s a breach of the bony walls of the orbit was considered a clear indication for orbital exenteration because of the better cure rates that were obtained when the orbit was cleared [7]. Our work on conservative orbital periosteum resections under strict frozen section control has resulted in most eyes being preserved, with acceptable rehabilitation of ocular mobility, particularly when it is the medial orbital periosteum that is resected [8]. Orbital exenteration is only necessary when the orbital periosteum has been breached by the tumour and involves the underlying orbital fat. Fortunately, the orbital periosteum forms a good barrier to tumour spread. Even when the tumour involves the orbital periosteum, it is often possible to

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excise the involved periosteum and, if frozen section study of the underlying orbital fat is free of disease, then the orbit can be preserved. A defect in the medial aspect of the orbit is best repaired using a split skin graft, as discussed in Chap. 2. Defects in the floor of the orbit are more complicated because it is involved in the vertical support of the eye. These defects need to be accurately measured and repaired with a fascia lata graft. In such cases we also use a fascia lata sling to give the orbital contents further support. Other surgeons have used synthetic implants such as titanium mesh but, in our experience, these are frequently extruded, particularly when radiotherapy has been used either pre- or post-operatively.

Operative Technique As maxillectomy is now an operation that is rarely seen it is important to document the technical details of the approach for those rare cases where it is necessary. There are three essential steps: • Soft-tissue exposure of the maxilla • Osteotomies to free the maxilla • Immediate rehabilitation to enable post-operative breathing and eating

Soft-Tissue Approach We need to make incisions in the facial skin, the oral cavity, and the nasal cavity.

Facial Incision (Fig. 7.16a) The classic Weber Ferguson incision used in maxillectomy is an extension of the lateral rhinotomy incision that we used in medial maxillectomy. It continues inferiorly around the nasal alar and continues medially to the centre of the upper lip, which is completely divided with a vertical midline incision.

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(Paramedian and stepped incisions have also been described to divide the upper lip, but they invariably cause a cosmetic defect because of muscular scarring.) The upper end of the lateral rhinotomy incision is curved widely as it passes laterally towards the medial canthus. (This wide circle enhances the vascularity of the flap, particularly important following preoperative radiation.) The incision continues along the lower lid within 2 mm of the hair follicles (leaving a wider strip of skin on the lid generally results in the skin becoming oedematous). The incision ends at the lateral canthus but can be extended laterally if further exposure is necessary. These incisions outline a full-thickness facial flap, which needs to be elevated from the anterior surface of the maxilla. This incision along the lower lid is deepened posterior to the tarsal plates and the orbicularis oculi muscle (if clear of tumour they are preserved with both functional and cosmetic benefits) to reach the bony rim of the orbit and is then continued over the face of the maxilla dividing the inferior orbital nerve where it leaves its foramen. The general elevation of the skin flap is continued medially and inferiorly over the face of the maxilla to widely elevate the facial skin flap. This is best achieved with a combination of sharp and blunt dissection using adrenaline-­ soaked ribbon gauze.

Oral Incisions (Fig. 7.16b) When the facial skin has been elevated from the maxilla, we turn our attention to the oral incision; the first oral incision runs from the midline just superior to the dental margin and continues posteriorly around to the back of the maxillary tuberosity. This completes the mobilisation of the facial skin flap which is raised laterally as far as the zygomatic body. The second oral incision runs posteriorly along the centre of the hard palate as far as the soft palate and then turns laterally to join the initial incision behind the maxillary tuberosity.

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a

b

Fig. 7.16 (a) Classic Weber Ferguson incision. (b) Oral incision for maxillectomy

Nasal Incision An incision is made along the centre of the involved nasal cavity as far back as the soft palate. It mirrors the incision along the oral surface of the hard palate. These two incisions are joined anteriorly over the alveolus and to prevent loosening of the remaining teeth a tooth is removed at the site of the incision so the subsequent osteotomy can be made through the socket (Fig. 7.17).

Fig. 7.17  Raising facial skin flap and maxillectomy osteotomy

7  Lateral Rhinotomy

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7.12 Maxillectomy Osteotomies (Fig. 7.18) The classic maxillectomy removes the whole maxilla including the floor of the nasal cavity; however, depending on the extent of the disease there are considerable advantages in leaving a portion of the hard palate as this gives good medial retention to the post-operative obturator. Similarly, with a posteriorly placed tumour it is possible to retain the whole premaxilla which again aids post-operative rehabilitation. The first osteotomy is through the full length of the hard palate and upper alveolus and is made with a fissure burr. To prevent damage to any remaining teeth we remove the tooth at the site of the osteotomy which is then made through the socket. The second osteotomy is through the nasal bones and the frontal process of the maxilla; it continues back through the lamina papyracea to the inferior orbital fissure. The next

a

osteotomy continues forward from the inferior orbital fissure through the body of the zygoma. The maxilla is now solely attached at the pterygoid plates, and these are best divided using a curved osteotome in the oral cavity directed superiorly behind the maxillary tuberosity (Fig. 7.19). As the maxilla becomes free it can be elevated anteriorly with the osteotome and any residual soft tissues including the maxillary nerve are divided with Mayo scissors. There is frequently some bleeding from one or more of the branches of the maxillary artery; it is initially controlled by packing and then any persistent bleeding is readily controlled with Ligaclips. To complete the resection, all suspect areas are checked by frozen section, and if any are involved, further local resection is necessary. Any residual ethmoid cells should be resected to leave a clean maxillectomy cavity (Fig. 7.20).

b

Fig. 7.18 (a) Maxillary osteotomy anterior view. (b) Oblique view of pterygoid osteotomy

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7.13 P  ossible Resection of the Inferior Orbital Periosteum Following removal of the maxilla a careful inspection of the orbital periosteum is made particularly if the overlying bone has been eroded. If there is any doubt regarding tumour involvement frozen sections are taken from the area. If these are positive, we then remove the surrounding area of the orbital periosteum and take further frozen sections from the underlying orbital fat. If the orbital fat is free of tumour we elect to preserve the orbit. We discussed the removal of the medial orbital periosteum in Chap. 2 but removal of the inferior orbital periosteum is more complicated. The inferior orbital periosteum includes the origin of the inferior oblique muscle and is important for maintaining the vertical support of the orbital contents. Accordingly, we accurately repair the defect in the orbital periosteum with a fascia lata patch sewn deep to the surrounding orbital periosteum and use a further strip of fascia lata to provide a sling to further support the orbit. Problems with the inferior oblique muscle are surprisingly unusual. Fig. 7.19  Separation of pterygoid plates from maxilla

Fig. 7.20  Post-maxillectomy view

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7  Lateral Rhinotomy

7.14 Repair We line the maxillectomy cavity with a split skin graft to the exposed non-mucosal areas securing it with sutures. The cavity is then lined with a thin Whitehead’s varnish pack. The facial incisions are closed in two layers except at the upper lip where an additional muscle layer should be repaired. We tend to use subcuticular nylon sutures for skin closure.

7.15 Immediate Post-operative Rehabilitation As stated previously our approach to rehabilitation is to delay surgical reconstruction until we are happy that there is no recurrent tumour in the maxillectomy cavity. To aid the retention of the immediate post-operative obturator we use a variety of surgical procedures:

contour. The maxillofacial surgeon moulds the gutta-percha into all the supporting areas to aid retention. If it is not possible to obtain good retention of the prosthesis a wire is passed around the zygomatic arch and attached to the wire loop on the side of the prosthesis. After 2  weeks the prosthesis is changed under general anaesthesia, any circum-zygomatic wires are removed, and often a custom-made light obturator can be fitted. Over the next few weeks, the maxillofacial technicians teach the patient how to remove and reinsert the prosthesis and generally how to care for it and the cavity. When the prosthesis is stable within the cavity it is possible to fit replacement teeth into the permanent prosthesis aligned with the lower teeth (Fig. 7.21).

• For medial retention we try to leave a small rim of hard palate. • Posteriorly we suture the lateral aspect of the cut soft palate to the buccal mucosa to give a posterior platform for the stent to fit over. We also line the maxillectomy cavity with a split skin graft sewn into place. During the healing phase this skin graft tends to contract around the obturator giving further retention.

7.16 Maxillofacial Technical Help Prior to the surgery the patient will have been assessed by maxillofacial department and an upper plate constructed to fit any residual teeth on the uninvolved side and on the involved side rather than teeth a metal loop is placed on the lateral border (for support if necessary) and a large loop on its upper surface around which gutta-percha can be moulded. As soon as we have repaired the facial skin flap, the maxillofacial surgeon inserts the upper plate and assesses how much additional hot-moulded gutta-percha is required to fill maxillectomy cavity and maintain a normal facial

Fig. 7.21  Final post-maxillectomy obturator with teeth attached

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7.17 Orbital Exenteration  dditional Steps Needed for Orbital A Exenteration

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middle fossa. For non-malignant pathology we would expose this area by extended medial maxillectomy using midfacial degloving approach (Fig. 7.23). The orbital contents are generally sent as a separate specimen from the maxilla.

If an orbital exenteration is deemed necessary due to tumour involvement deep to the orbital periosteum it is performed prior to the removal of the maxilla. An additional incision is made along upper lid so that the eyelashes are excised and ultimately two lids, including the tarsal plates, are sutured together to form a smooth skin-­ lined cavity (Fig. 7.22). Instead of developing a tissue plane deep to the orbicularis oculi muscle an incision is made in depths of the upper and lower conjunctival sulci. This incision is deepened to locate the bony orbital rim around its complete circumference. The orbital periosteum is then elevated from the underlying orbital walls by both blunt and sharp dissection. As the periosteum is elevated posteriorly it is packed away from the orbital wall by ribbon gauze soaked in topical adrenaline. This helps control bleeding but most importantly pushes the globe forward putting tension on the origins of the muscle cone and the optic artery and nerve which lie in the centre of the cone. When the superior orbital fissure is located its nerves and vessels are divided and sealed with bipolar diathermy. With the optic contents mobilised back to the apex of the orbit the posterior orbital pedicle is divided using the curved blades of a pair of Mayo scissors. The immediate bleeding from the ophthalmic artery is controlled with packing and generally ceases after a couple of minutes. The remaining muscle cone is then inspected and if artery is clearly seen it is clipped off with a Ligaclip. With the subsequent maxillectomy this gives a direct view of the posterior pterygopalatine wall and also a potential extension into the anterior Fig. 7.22  Additional incision for orbital exenteration

7  Lateral Rhinotomy

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Fig. 7.23 Postorbital exenteration view

 dditional Removal of the Orbital Wall A Following Maxillectomy Reconstruction of the orbit with an ocular implant is rarely successful because of the lack of any posterior tissue in the orbital cavity needed to support the prosthesis and maintain its anterior position. There is also loss of the lid elevator. We have found that a more successful rehabilitation following exenteration is achieved using a sculpted orbital prosthesis composed of the complete orbital soft tissues, lids, eyelashes, and a matching eye prosthesis. This is fitted into the skin-lined depression created by suturing the remaining eyelids together. The prosthesis is held in place either with skin adhesive and attached spectacles or by using Branemark implants to secure it.

There is an associated problem with this technique that results from the prosthesis not being adequately posteriorly placed due to the prominence of the remaining lateral bony wall of the orbit. The lack of depth to the medial canthus renders the prosthesis unacceptable. To overcome this problem, we have worked with our maxillofacial technicians, who artistically construct these prostheses, and resect an extra area of the lateral orbital wall, thus enabling the prosthesis to be set more posteriorly in the face giving a normal appearance. This technique is illustrated in a case of the lacrimal gland carcinoma that required exenteration with adjacent involved orbital walls (Fig. 7.24).

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a

c

Fig. 7.24 (a) Postorbital exenteration for lacrimal gland carcinoma with extended removal of lateral orbital wall. (b) Healed orbital socket posteriorly placed following removal of lateral orbital wall. (c) Anterior

b

d

view of prosthesis. (d) Shows lateral view with eye in normal position. The drawings are overlay copies of a clinical case

7  Lateral Rhinotomy

References 1. Frazell EL, Lewis JS.  Cancer of the nasal cavity and accessory sinuses. a report of the management of 416 patients. Cancer. 1963;16:1293–301. 2. James D, Crockard HA.  Surgical access to the base of skull and upper cervical spine by extended maxillotomy. Neurosurgery. 1991;29:411–6. 3. Wei WI, Chan JY, Ng RW, Ho WK.  Surgical salvage of per sistent or recurrent nasopharyngeal carcinoma with maxillary swing approach  - critical appraisal after 2 decades. Head Neck. 2011;33(7):969–75. 4. Hirsch O. Successful closure of cerebrospinal rhinorrhea by endonasal surgery. Arch Otolaryng. 1952;56:1–12. 5. Montgomery WW.  Surgery for cerebrospinal fluid rhinorrhea and otorrhea. Arch Otolaryn. 1966;84:538–50. 6. Diver J, Kotecha B, Cheesman A.  Trans-nasal closure of Cerebrospinal leaks. Acoustic Neuroma and Skull Base Surgery: Proceedings of the 2nd International Conference on Acoustic Neuroma Surgery and 2nd European Skull Base Society Congress, Paris, France. April 22–26, 1995.

79 7. Ketcham AS, Chretien PB, Van Buren JM, Hoye RC, Beazley RM, Herdt JR. The ethmoid sinuses: a re-evaluation of surgical resection. Am J Surg. 1973;126(4):469–76. 8. Howard DJ, Lund VJ, Wei WI. Craniofacial resection for tumors of the nasal cavity and paranasal sinuses: a 25-year experience. Head Neck. 2006;28(10):867–73.

Suggested Reading Cheesman AD.  Orbital preservation following craniofacial surgery. Proceedings of XV world congress of otolaryngology head and neck surgery. Istanbul, Turkey. 1993. Crockard HA, Cheesman A, Steel T, Revesz T, Holton JL, Plowman N, et al. A multidisciplinary team approach to skull base chondrosarcomas. J Neurosurg. 2001;95(2):184–9. Crockard HA, Cheesman A, Steel T, Plowman N, Singh A, Crossman J, Revesz T, et al. A multidisciplinary team approach to skull base chordomas. J Neurosurg. 2001;95(2):175–83.

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Bicoronal Flap, Frontal Craniotomy Anthony Cheesman, Ghassan Alusi, and H. Ian Sabin

Access to the entire anterior skull base, both orbital roofs, orbital margins, superior nasal bones, and zygomatic arches can only be gained with an extensive scalp flap, and for the best cosmetic result the incision should be placed behind the hairline (Fig. 8.1). The approach can be used for extensive subfrontal tumours, craniofacial resections for tumours involving the nose extending intracranially, and craniofacial remodelling surgery. Complications related to the approach can be avoided by paying attention to the anatomy and to the dissection technique.

Fig. 8.1  Approach diagram

8.1

A. Cheesman (*) · G. Alusi Department of Otolaryngology and Skull Base Surgery, Barts Health NHS Trust, The Royal London Hospital, London, UK e-mail: [email protected] H. I. Sabin The Wellington Hospital, Neurosurgical Unit, London, UK e-mail: [email protected]

Patient Position (Fig. 8.2)

The ideal positioning of the patient is shown. Note the head­up tilt, extension of the neck, and use of a pin headrest. Head-up tilt reduces the intracranial venous pressure; 30 degrees is sufficient. With the operating table at its lowest position, this also allows the surgeon to sit during the operation. It is important to extend the neck, as this will allow the brain to fall away from the skull base without using fixed retraction. Pin fixation can be used to facilitate image guidance as seen in the diagram below, but the use of a horseshoe

© Springer-Verlag GmbH Germany, part of Springer Nature 2022 A. Cheesman et al. (eds.), Skull Base Surgery, Springer Surgery Atlas Series, https://doi.org/10.1007/978-3-540-74259-3_8

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Fig. 8.2  Patient position. The bed is flexed to 40 degrees in the middle with the head extended 10–20 degrees

headrest allows easier repositioning during surgery. It is often easier to have the head flexed for the scalp incision and extended for the intracranial surgery.

8.2

Shaving (Fig. 8.3)

Head shaving is no longer universally practiced and is dependent on the preference of the surgeon. A parting with the hair held away from the wound with gel is commonly used, although a thin shave along the line of the incision allows an adhesive dressing to be applied to the wound. The choice of drape is dependent on scalp preparation. Self-adhesive drapes containing an ‘incise’ panel and a pouch to contain fluid spillage are neat and simple, but will not stick to gelled hair. Some surgeons choose to wash the whole head with antiseptic and cover only the face with drapes. If the eyes are to be left uncovered to facilitate access to the orbits, care must be taken to avoid corneal exposure, and sometimes temporary tarsorrhaphies are used to maintain eyelid closure, after instillation of gel to prevent corneal drying. Alcoholic skin preparation washes are avoided if the eyes are uncovered, again to reduce the risk of corneal injury.

Fig. 8.3  Shaving and clamp

8.3

Incision (Fig. 8.4a, b)

For the best cosmetic results, the incision should run directly over the vertex, posterior to the coronal suture. This allows a larger area of pericranium to be harvested for anterior fossa repair than the incision sometimes seen running just behind the hairline. It is also more cosmetic if the patient subsequently loses their hair, as it is less visible ‘face on’. The lower ends of the incision may have to run into the tragus (dotted line) if a very low approach is needed (see orbitozygomatic approach); the tragal incision avoids injury to the temporal branch of the facial nerve. A scalpel is used to start the incision. It is then completed with needle-point diathermy, allowing coagulation of the scalp vessels. The galea is divided with the diathermy, but over the temporalis muscle care is taken to protect the underlying fascia and muscle.

8  Bicoronal Flap, Frontal Craniotomy

a

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b

Fig. 8.4  Incision design

8.4

 pplication of Haemostatic Clips A (Fig. 8.5)

Raney clips are not used by all surgeons as they may lead to hair loss along the line of the incision due to pressure on the hair follicles. Haemostasis is best achieved with diathermy during the skin incision, and this usually reduces the need for Raney clips unless they are used to hold the drapes in position.

Fig. 8.5  Haemostatic clips applied to the skin edges

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Raising the Scalp Flap (Fig. 8.6)

8.6

 aising the Pericranial Flap (Figs. 8.7 R and 8.8)

The scalp is mobilised on the subgaleal plane. It is important to avoid damage to the underlying pericranium to maintain the integrity of the tissue for the closure of the anterior fossa, and often this is best achieved by sharp dissection with a scalpel, rather than using the fingers and a wet swab. The scalp should only be reflected from the temporalis fascia to the point of exposure of the temporalis fat pad. At this point the fascia should be incised and reflected with the pericranial flap to avoid damage to the frontalis branch of the facial nerve and thus loss of eyebrow elevation. (If this occurs it usually recovers but may take many months to do so.)

The pericranium is incised directly under the scalp incision and along the superior temporal lines bilaterally to the point of the incision of the temporalis fascia, from which point the fascia is elevated in one layer with the pericranium. The extent of the pericranial flap is shown in Fig. 8.7. It should be long enough to reach the jugum sphenoidale without tension and be wide enough to cover the orbital roofs, providing a vascularised seal to the nose if ethmoid air cells are opened or resected.

Fig. 8.6  Raising the scalp flap. The pericranial flap has not been lifted off the skull yet

Fig. 8.7  Raising pericranial flap

Fig. 8.8  Elevated pericranial flap

8  Bicoronal Flap, Frontal Craniotomy

8.7

Anatomical Landmarks (Fig. 8.9)

As the pericranial flap is dissected towards the superior orbital margin, the supraorbital and supratrochlear nerves should be identified to allow them to be protected.

Fig. 8.9  Anatomical landmarks

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8.8

 xposure of the Superior Orbital E Margin (Fig. 8.10)

If the supraorbital nerve is lying in a shallow fossa, it is easy to mobilise it before freeing the orbital fascia from the bony orbit. This is only necessary if the pathology being treated involves the nose and/or orbits. If the nerve is in a foramen, the high-speed drill can be used to cut around the bone and the nerve can be reflected in its bony canal. The scalp flap can then be taken low enough to identify the nasoethmoid, nasofrontal, and frontozygomatic regions.

Fig. 8.10  Extent of elevated flap with the protected supraorbital nerve, reflected anteriorly and shown from a more anterior perspective than in Fig. 8.7

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Glabellar Flap (Fig. 8.11)

If only a small anterior fossa opening is required, a glabellar flap can give access to an intracranial extension of tumour, to the roof of the nose, and to the medial margins of both orbits. The size of the glabellar bone flap can be varied depending on the exposure required. Inferiorly it is placed through the middle of the nasal bones, without disturbance of the lower nasal bones. This is cosmetically important because detachment of the upper lateral cartilages from the lower border of the nasal bones gives a ‘pinched-in’ appearance of the cartilaginous nasal bridge. Superiorly it is advantageous to place the horizontal cut through the anterior wall of the frontal sinus if it is large. Subsequently the posterior wall of the sinus is removed separately to give the dural exposure. With a small sinus, the cut is placed through the frontal bone above the sinus. Laterally the superior cut passes inferiorly medial to the supraorbital notch to join the lateral cut which is placed in the lacrimal fossa. The whole of both ethmoid complexes and the medial wall of the orbit are subsequently excised as part of the en bloc resection.

8.10 A  pplication of Titanium Mini-Plates (Fig. 8.12) There is now a wide range of low-profile, cranial fixation plates to aid in skull reconstruction during wound closure. These should be loosely fitted before making the final craniotomy cuts to give the best realignment and the best cosmetic result. The screws now are normally self-tapping, and many are also self-drilling.

Fig. 8.12  Drill placement

Fig. 8.11  Glabellar flap

8  Bicoronal Flap, Frontal Craniotomy

8.11 Drill Placement (Fig. 8.13) A large burr should not be used for any anteriorly placed flaps, as this leaves a large and cosmetically unacceptable bony defect, instead high-speed drill with a side-cutting burr should be used. Transnasal illumination can be used to determine the limits of the frontal air sinus, though image guidance is increasingly being used. The high-speed drill with a small side-cutting burr allows a narrow ‘trench’ to be cut around the anterior wall of the frontal air sinus. This will mean that the flap is less visible after surgery, as the scalp is less likely to be drawn into the bony defect as the scar matures.

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8.12 E  xposure and Removal of Posterior Wall of Frontal Sinus (Fig. 8.14) When the anterior wall of the sinus is removed, the posterior wall is stripped of mucosa, including the lateral extensions which may be present. This prepares the bone for the high-­ speed drill. A large cutting burr is ideal to uncover the dura. Diamond burrs reduce the risk of dural injury, but are much slower, while cutting burrs, operated with care, can be used with great precision. The bone is progressively ‘eggshelled’ and then removed with upcut rongeurs. Unless there is a surgical plan to open into the nose, the fronto-ethmoidal recess is plugged with muscle before opening the dura.

Fig. 8.13  Application of metal plates

a

Fig. 8.14 (a, b) Exposure of posterior wall of frontal sinus. Following removal of the anterior wall of the frontal sinus, the posterior wall is displayed and this is then removed by further drilling. This is best done

b

using a roundhead burr to protect the underlying dura. Posterior wall of frontal sinus still intact

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8.13 D  ural Incision and Tumour Exposure (See Figs. 2.11 and 2.12) Once the dura is exposed, it is opened with a sharp hook and knife, tenting it away from the brain to reduce the risk of cortical/vascular injury. In the midline, the inferior sagittal sinus is narrow close to the anterior fossa floor and should not pose much of a problem to divide and ligate. If it is larger than normal, it should be ligated with sutures placed superior and inferior to the planned incision. The dura is reflected inferiorly to expose the frontal lobes, and can be rolled up to reduce shrinkage from drying out during surgery.

8.14 Tumour Removal (See Fig. 2.13) If the intracranial component is extradural or extra-­arachnoid, it will not be adherent to the cortical surface and the brain should fall away under gravity as the cerebrospinal fluid (CSF) is aspirated to reduce intracranial pressure. This is aided by extension of the head on the neck. Sometimes tumours invade the brain and need to be dissected free with bipolar diathermy and microscissors.

8.15 Dural Repair (See Figs. 2.15 and 2.16) If there has not been a breach of the basal dura, no formal anterior fossa repair is needed. When such repair is needed, however, the pericranial flap is placed over the basal defect. If large, the defect may need to be covered with an abdominal or thigh fat graft to support the pericranium and reduce the risk of CSF leak. The anterior dural opening is closed with Vicryl sutures and the suture line can be reinforced with collagen mesh and fibrin glue, although this is not usually necessary.

8.16 R  eplacement of Bone Flap (See Fig. 2.20) The bone flap is replaced using the mini-plates previously loosely fitted. Low-profile screw heads are preferable, as these are unlikely to show or erode through the skin of the forehead as the scar matures.

8.17 Unilateral Frontal Flap (Fig. 8.15) Most anterior fossa pathology, including midline tumours, can be approached through a unilateral flap, avoiding the risk

Fig. 8.15  Removal of the posterior wall of the frontal sinus. Underlying dura being exposed

of sagittal sinus injury. If there is very extensive disease, a bifrontal flap may give better access. Burr holes can be placed just lateral to the sagittal sinus as shown, or, alternatively, a single entry point can be cut laterally, which prevents bony defects from becoming visible in the middle of the forehead as the scar matures. If a lateral entry point is used for the craniotome, care must be taken to avoid injuring the sagittal sinus as the flap is cut.

8.18 Bifrontal Flap (Fig. 8.16) Traditionally, burr holes are cut on either side of the sagittal sinus and the cuts between these are made last to reduce the time to exposure of the bleeding site in the event of an injury to the sinus. An alternative approach is to cut a small ‘trench’ across the sinus with a high-speed cutting burr to expose the dura on either side of the sinus before thinning the bone over the sinus—both inferiorly and superiorly at the limits of the proposed flap. The craniotome is then used to cut the bone flaps on either side of the sinus before removing the bone over the sinus for the reasons stated above. The bone flap should be as small as possible to reduce the temptation to retract the frontal lobes.

8  Bicoronal Flap, Frontal Craniotomy

Fig. 8.16  Bifrontal bone flap. The circular entry points are shown either side of the sinus. The bone cuts start from these burr holes

8.19 Craniotome (Fig. 8.17) In a standard approach, a parasagittal burr hole is cut and the craniotome is used to complete the flap working away from the sagittal sinus. Alternatively, the entry burr hole could be made away from the midline, as this is likely to become visible on the forehead when the scar matures. Instead, the temporalis muscle is retracted from the lateral orbit and the frontal lobe dura exposed with a burr. The craniotome is then used to cut the flap, extending as close to the midline and the sagittal sinus as possible.

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Fig. 8.17  Side-cutting burr to cut the bone flap

8.20 Elevation of Bone Flap (Fig. 8.18) Once the flap has been cut, it is carefully stripped from the underlying dura. Usually this is not problematic, but if the patient is elderly or there is a parasagittal or superficial meningioma under the flap, there can be marked adherence to the bone, and sometimes meningiomas will invade the bone flap, requiring the tumour to be cut through to free the flap. In these cases, if the tumour can be drilled away leaving normal bone, the flap can be replaced later. Alternatively, a pre-fashioned cranioplasty can be used to reconstruct the defect either at the of time of surgery or at a later date.

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Fig. 8.18  Elevation of bony flap

8.21 R  etraction of Frontal Lobes and Exposure of Orbital Roofs and Cribriform Plate (Fig. 8.19)

Fig. 8.19  Retraction of frontal lobes. Approach to remove the cribriform plate and the nasal part of the tumour. Note that the bone is the floor of the anterior cranial fossae with the brain falling away under gravity

The dural opening is either unilateral or bilateral depending on the bone flap. It is important not to ligate the sagittal sinus behind the anterior one-third, as there is a grave risk of venous infarction otherwise. Ideally the division of the falx needed to expose bilateral pathology should be made as low on the anterior fossa as possible. The frontal lobes should then fall away from the anterior skull base as CSF is aspirated. If there is a large subfrontal meningioma, the blood supply is divided using bipolar diathermy to separate the tumour from the skull base before removal using the ultrasonic dissector where needed. The anterior fossa is then reconstructed similarly to the reconstruction after a glabellar flap.

8.22 Skin Closure (Fig. 8.20) The scalp is closed in two layers using 2-0 Vicryl to the galea and 3-0 nylon to skin. Metal staples are commonly used but are more painful to remove than nylon, and radiographers are sometimes reluctant to perform early post-operative MRI scans with staples in situ. A subgaleal suction drain reduces post-operative swelling and haematoma, and if used is left for 48 h.

Fig. 8.20  Skin closure

8  Bicoronal Flap, Frontal Craniotomy

8.23 C  ranioplasty: Planned Replacement of Involved Skull with a Preformed Cranioplasty (Figs. 8.21, 8.22, 8.23, 8.24, and 8.25)

Fig. 8.21  Three-dimensional view of tumour bony defect

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Fig. 8.22  Three-dimensional inferior view of defect

Fig. 8.24  Design of prosthesis—anterior view

Fig. 8.23  Planned bony resection

Fig. 8.25  Design of prosthesis—posterior view (inferior view)

Suggested Reading

operative neurosurgical techniques: indications methods and results. 6th ed. Philadelphia: Elsevier; 2012. p. 417–27. Safaee MM, McDermott MW, et  al. Tailored extended bifrontal craniotomy for anterior skull base tumors: anatomic description of a modified surgical technique and case series. Oper Neurosurg. 2018;14:386–94.

Bilsky MH, Bentz B, Vitaz T, Shah J, Kraus D. Craniofacial resection for cranial base malignancies involving the infratemporal fossa. Neurosurgery. 2005;57(4 Suppl):339–47. discussion 339–47. Kirsch M, Krex D, Schackert G. Chapter 34: Surgical management of midline anterior skull base meningiomas. In: Schmidek and sweet: