Tachdjian’s Pediatric Orthopaedics [4]

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CHAPTER 35

Disorders of the Brain Chapter Outline Levels of Involvement Cerebral Palsy Rett Syndrome Hereditary Spastic Paraparesis Ataxia Syndromes

Levels of Involvement The neuromuscular system may be affected at various levels, each of which is characterized by changes in motor function peculiar to the site and extent of involvement.1 The differential features of various levels of motor function are illustrated in Table 35-1. Spinomuscular Level. At the spinomuscular level, motor activity is simple; impulses arising in the anterior horn cells of the spinal cord are transmitted through peripheral nerves to myoneural junctions and then to individual muscles. In disorders at the spinomuscular level, the loss of motor power is focal and segmental, with complete paralysis of the muscles or muscle groups that are supplied by a peripheral nerve or by the anterior horn cells in the spinal cord. Muscular paralysis is laccid or hypotonic, and degeneration, atrophy, ibrillations, and fasciculations are typical indings. The deep tendon and supericial relexes are diminished or absent. Pyramidal tract signs, abnormal involuntary movements, and ataxia are absent. Trophic changes may be seen in the skin, nails, and bone. Spinal Level. Pathologic processes at the spinomuscular level may be further classiied into various sublevels. When the disease originates in the anterior horn cells, as in poliomyelitis, the spinal level of the motor system is affected. Other examples of diseases at the spinal level are progressive spinal muscular atrophy of the Werdnig-Hoffmann type, progressive bulbar palsy, syringomyelia, and intramedullary neoplasm. Loss of function of the anterior horn cells or the motor nuclei of the brainstem results in clinical indings of laccid paralysis, atrophy, arelexia, degeneration, and fasciculations. Neural Level. At the neural level of the motor system, the peripheral nerves and nerve roots are affected, as in obstetric brachial plexus palsy and progressive neuromuscular atrophy (Charcot-Marie-Tooth disease). In processes affecting nerves, the sensory ibers are usually involved, with resultant sensory changes such as anesthesia or hyperesthesia. Otherwise, the clinical indings are similar to those of involvement of the spinal level; that is, laccid paralysis, atrophy, degeneration, and arelexia develop as a result of e2

Lori A. Karol

loss of conduction of motor impulses. In the absence of sensory changes, it is dificult to distinguish between diseases of the peripheral nerves, anterior roots, and anterior horn cells. Myoneural Level. If the pathologic process arises at the myoneural junction, as in myasthenia gravis and familial periodic paralysis, it is a disease at the myoneural level. In diseases of primarily muscular origin, the motor system is involved at the muscular level. The muscular dystrophies are familiar examples of disturbance at the muscular level in diseases with spinomuscular involvement. The paralysis is laccid, but relexes persist until the late stages, when marked atrophy has already occurred. Contractility is lost but not excitability; that is, the muscle ibers have degenerated and have been replaced by ibroadipose tissue, but the peripheral nerves and anterior horn cells are normal. Extrapyramidal Level. Disorders of the motor system at the extrapyramidal level are characterized by generalized involvement of the muscles of the limbs and trunk. Muscle tone is hypertonic. Atrophy, fasciculations, and degeneration are absent. Motion of the limbs is hyperkinetic, with loss of associated or automatic movements. The deep tendon and supericial relexes are normal. No pyramidal tract responses or sensory deicits are present. Athetoid cerebral palsy (CP) is a common example of a disease at the extrapyramidal level. Pyramidal (Corticospinal) Level. At the pyramidal or corticospinal level, motor deicit arises from involvement of motor nuclei of the cerebral cortex. The paresis is usually generalized and associated with hypertonicity or spasticity of muscles. Pyramidal tract signs and pathologic relexes are generally present. Usually some atrophy that is not focal is present; it is caused by chronic paralysis and disuse. Fasciculations, trophic disturbances, degeneration, and abnormal movements are absent. The deep tendon relexes are hyperactive, and the supericial relexes are diminished or absent. Spastic CP illustrates the pyramidal level of motor involvement. Cerebellar Level. Lesions at the cerebellar level are characterized by loss of coordination and control, or ataxia. No real loss of motor power occurs. Fasciculations, degeneration, atrophy, and trophic disturbances are absent. The deep tendon relexes may be diminished, but the supericial relexes are normal.

Reference Levels of Involvement 1. Tachdjian MO: Pediatric orthopaedics, ed 2, Philadelphia, 1990, Saunders.

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Table 35-1 Differentiation of Motor Disorders at Various Levels of Neuromuscular Function Type of Disturbance

Spinomuscular Muscular

Neural

Spinal

Extrapyramidal

Pyramidal

Cerebellar

Loss of motor power

Focal-segmental Usually proximal and axial muscle groups Complete

Focal-segmental Usually distal limb musculature Complete

Focal-segmental Usually distal limb musculature Complete

Generalized Entire limb and movements Incomplete

Generalized Entire limb and movements Incomplete

None Ataxia may simulate loss of power

Tone

Flaccid

Flaccid

Flaccid

Rigid

Spastic

Hypotonic (ataxia)

Atrophy

Present

Present

Present

Absent

Minimal (caused by disuse and chronic paresis)

Absent

Fasciculations

May be present

Absent

May be present

Absent

Absent

Absent

Reaction of degeneration

Present

Present

Present

Absent

Absent

Absent

Diminished and preserved until late Diminished

Absent early

Absent early

Normal or variable

Hyperactive

Diminished or pendular

Absent

Absent

Normal or increased

Diminished or absent

Normal

Sensory deicit

Absent

Usually present

Absent

Absent

May be present

Absent

Trophic disturbance

Present

Present

Present

Absent

Usually absent

Absent

Ataxia

Absent

Absent

Absent

Absent

Absent

Present

Abnormal movements

Absent

Absent

Absent

Present

Absent

May be present (intention tremor and ataxia)

Relexes Deep

Supericial

Adapted from DeJong RN: The neurological examination, ed 3, New York, 1967, Harper & Row, p 382; and Farmer TW: Pediatric neurology, New York, 1964, Harper & Row, p 612.

Cerebral Palsy Deinition CP was irst described by William Little in 1862.351 Little correlated the indings seen in young children with CP and associated them with dificult births. The term cerebral palsy originated with Freud.202 Static encephalopathy has been used interchangeably with cerebral palsy. A succinct and accurate deinition of CP is dificult to construct because of wide variability in the manifestations of CP.52,423 In 2008 CP was proposed as “a group of permanent disorders of the development of movement and posture, causing activity limitation, that are attributed to non-progressive disturbances that occurred in the developing fetal or infant brain.”448 In all cases, the following must be true:

• CP is the result of a brain lesion; therefore, the spinal cord and muscles are structurally and biochemically normal. • The brain lesion must be ixed and nonprogressive. Thus, all the progressive neurodegenerative disorders are excluded from the deinition. • The abnormality of the brain results in motor impairment. The insult to the brain may occur prenatally, perinatally, or during childhood. Although older children with brain damage were traditionally excluded from the deinition, this is not clinically relevant from an orthopaedic standpoint. Certainly, any orthopaedist caring for a child who has sustained an anoxic injury after nearly drowning or who is spastic after infectious meningitis would argue that these slightly older children functionally have CP.

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The clinical manifestations of CP depend on which part and how much of the brain are involved. The range of manifestations is huge, with both a young child who is intellectually bright but walks on his toes and a noncommunicative wheelchair-bound child with seizures meeting the aforementioned deinition of CP. The orthopaedic surgeon is consulted by a pediatrician or family for management of the musculoskeletal problems that follow from the underlying brain lesion. It is of utmost importance for the orthopaedist to evaluate the child thoroughly to ascertain why the child has CP. If the child was born full-term, if no perinatal medical problems were noted, and especially if the child began to develop normally and then regressed, prompt neurologic consultation must be sought. The neurologist will differentiate CP from such dangerous entities as brain and spinal cord tumors, metabolic encephalopathies, and progressive neurodegenerative diseases, some of which are treatable.

Epidemiology The incidence of CP is increasing slightly.63 In recent reports the incidence has been estimated to be between 2.4 and 2.7 per 1000 live births.86,419,443,534 The prevalence of CP appears to be increasing secondary to an increase in the number of infants with very low birth weight being born and the increased survival of these tiny neonates, whereas the rate of CP in infants of a given birth weight has remained stable.332,423,428,451,480 This increase in incidence is of concern because the economic impact of CP is considerable, with the cost per case estimated at $503,000 in 1992.109 The risk for CP in a child born full-term is approximately 1 in 2000.534 The incidence of CP has been correlated with both gestational age and birth weight.250 CP was diagnosed in 12.3% of infants born at between 24 and 33 weeks of gestation.604 Approximately 50% of children with CP have low birth weight, and 28% weigh less than 1500 g at birth.135,481 The prevalence of birth weight–speciic CP ranges from 1.1 per 1000 neonatal survivors weighing 2500 g or more to 78.1 per 1000 infants weighing less than 1000 g.480 The incidence of CP is increased with multiple births. In more recent studies of multiple births the incidence of CP is 9 to 12 per 1000 in twins, 31 to 45 per 1000 in triplets, and 111 per 1000 in quadruplets.239,479,690 The predisposition to CP in twin pregnancies is present even when controlling for birth weight and gestational age.678 The risk for CP is high for a surviving twin when the other twin dies in utero.478,479

Etiology Prenatal The brain of the fetus is susceptible to damage from maternal infections and toxins. The TORCHES group of infections (toxoplasmosis, rubella, cytomegalovirus, herpes, and syphilis) is known to cause signiicant damage to the developing brain of the fetus, and such damage leads to very neurologically involved infants with mental retardation, microcephaly, and seizures. Orthopaedic deformities are noted in 82% of these children.351

Fetal exposure to drugs and alcohol through maternal use can also result in injury to the developing brain. Unfortunately, this problem is being seen more frequently in newborn nurseries. Cocaine, heroin, and marijuana can all cross the placental barrier and cause damage to the central nervous system of the fetus. Congenital malformations of the brain that occur during early pregnancy often result in severe CP. It has been stated that approximately 10% of patients with CP have congenital brain malformations that are apparent on neuroimaging.326 Rhesus blood group incompatibility resulting in kernicterus as a cause of CP is decreasing in incidence with improvements in prenatal care. RhoGAM treatment of Rh-negative mothers has led to a decline in kernicterus, which often resulted in the development of such movement disorders as athetoid CP. Maternal health problems, such as renal failure or infections, can lead to problems with brain development in the fetus.487 Prenatal chorioamnionitis and maternal infection have been associated with an increased risk for premature onset of labor and CP in the infant.25,421,449,450 Placental abnormalities have been linked with a higher frequency of CP.137 Fetal biophysical proile scores are prenatal noninvasive tests used to monitor the health of the developing fetus. These scores are often obtained in high-risk pregnancies. Abnormally low fetal biophysical proile scores are thought to result from antenatal hypoxia and have been associated with an increased incidence of CP.372

Perinatal Anoxia as a result of perinatal complications may lead to the development of CP. A tight nuchal cord430 or placental abruption605 can lead to anoxia and thus result in CP. Fetal hypoxia may be detected by fetal heart rate monitoring, but changes consistent with hypoxia, such as late deceleration of the heart rate with uterine contractions, are common and not speciic.429 The frequency of CP associated with birth asphyxia is estimated to be 1 in 3700 full-term live births.692 Fetal distress during delivery has been documented in some children with CP.204 The mode of delivery—vaginal or cesarean—has not been found to inluence the incidence of CP.565 Premature delivery, either from premature onset of labor or from premature rupture of membranes, is commonly associated with CP.144 Sepsis in the neonatal period can predispose to the development of CP in a low–birth weight infant.679 Bronchopulmonary dysplasia and prolonged ventilation in preterm infants may result in hypoxia, which predisposes the infant to CP.20,234,420 Extracorporeal membrane oxygenation (ECMO) has been used to sustain babies with severe cardiorespiratory failure. CP has been diagnosed in up to 20% of surviving children who were treated with ECMO.233 Cardiac surgery for the treatment of severe congenital heart disease has been linked with an increased incidence of CP. Heart surgery before the age of 1 month resulted in CP in 25% of infants.400 Clearly, these children are quite ill, with an increased risk for hypoxia, sepsis, and prolonged ventilation.

CHAPTER 35 Disorders of the Brain

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Postnatal Infections such as meningitis in early childhood can lead to CP. Any episode of hypoxia, such as cardiopulmonary arrest, near-drowning, and suffocation, can also produce brain damage leading to CP.7 Trauma, such as motor vehicle accidents producing head injury, severe falls, and child abuse, may result in CP as well.

Classiication Physiologic The irst classiication is physiologic and describes the type of movement disorder present. The most common movement abnormality is spasticity. Spasticity results from damage to the pyramidal system, particularly the motor cortex in the brain. Disinhibition of pathologic relex arcs leads to increased tone in the extremities. The tone is dependent on velocity, which means that if a muscle is stretched rapidly, tone increases more than if the same muscle group were stretched gradually and gently. Hypotonia is, as its name implies, abnormally decreased tone. Infants with CP are often described as loppy or hypotonic. Hypotonia is usually a phase and most frequently leads to spasticity as the infant matures. Dystonia is described as increased tone, which is not dependent on velocity. Whereas tone in spasticity is described as “clasped knife,” tone in dystonic CP is described as “lead pipe,” which means that tone does not decrease with gentle prolonged stretching. Athetosis is characterized by abnormal writhing movements that the patient cannot control. The movements become more exaggerated as the patient tries to complete a purposeful motion. Athetosis results from damage to the basal ganglia. Speech is often garbled and dificult to understand, yet affected patients may be intelligent. Athetosis has frequently been the result of neonatal kernicterus.201 Cerebellar lesions lead to ataxic CP. The disturbed balance of these children results in a wide-based and clumsy gait. Pure ataxic CP is rare. Patients with CP frequently have a mixed form of movement disorder. It is important to correctly classify the movement disorder of a patient with CP because the results of surgical treatment are unpredictable for all but purely spastic patients.

Geographic The second classiication system is geographic and describes what part of the body is affected by CP. Hemiplegia is present when only one side of the body is involved, with the upper extremity usually more involved than the lower extremity (Fig. 35-1). Patients with spastic hemiplegia can be further divided by their degree of gait impairment. Winters and colleagues subdivided patients with spastic hemiplegia into four groups: (1) loss of swing-phase ankle dorsilexion (i.e., footdrop) but stance-phase dorsilexion present; (2) loss of stance- and swing-phase ankle dorsilexion (equinus) and possible knee hyperextension in stance phase; (3) ankle involvement plus increased stance-phase knee lexion with limited range of knee motion; and (4) ankle, knee, and hip involvement with increased stancephase hip lexion and limited range of hip motion.682

FIGURE 35-1 A 7-year, 6-month-old girl with left hemiparesis. Note the posturing of the left upper extremity in lexion and the relative atrophy of the calf.

Diplegia implies involvement of both sides of the body, with both lower extremities being involved (though not always symmetrically) and lesser involvement of the upper extremities (Fig. 35-2). A word of caution is needed. If the patient has abnormal tone in both lower extremities but the upper extremities are completely normal, the examiner should beware. Patients with diplegia will have some abnormality in the upper extremities, such as decreased ine motor control, spasticity, or increased relexes. If the upper extremities are normal, it is imperative to evaluate the spinal cord. Spinal cord pathology, including tumor, may masquerade as CP. Involvement of both lower extremities and one upper extremity is termed triplegia. Quadriplegia, or total body involvement, is present when all four extremities are severely involved, with poor trunk control as well (Fig. 35-3). Clinicians often disagree over the difference between severe diplegia and quadriplegia.423 Familial spastic paraparesis, a genetic neurologic disease, may resemble CP in that both lower extremities are spastic yet the upper extremities are normal. Various forms of the disease exist, and a history of other affected family members is helpful.

Functional Current emphasis is on classifying patients with CP by functional level (Fig. 35-4). The Gross Motor and Functional Classiication System (GMFCS) is most commonly used to describe the patient’s level of function before and after an intervention.535 The GMFCS scale has ive levels. GMFCS 1 describes a patient who ambulates without aids on all surfaces and keeps up with peers. In GMFCS 2, the patient is fully ambulatory, may use lower extremity orthoses, and does not keep up fully with peers. At GMFCS 3, the patient uses ambulatory aids such as a walker or crutches and may use a wheelchair for longer distances. GMFCS 4 describes nonambulatory patients who are able to propel

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SECTION VI Neuromuscular Disorders

A FIGURE 35-3 Fifteen-year-old girl with spastic quadriplegia.

Evaluation History

B FIGURE 35-2 A and B, Five-year-old girl with spastic diplegia. She walks with the aid of a walker and bilateral ankle–foot orthoses.

their own wheelchair, whereas GMFCS 5 indicates an inability to transfer, propel a wheelchair, or support the trunk. A comprehensive review of nine CP registries throughout the world revealed the following proportion of GMFCS levels: level 1, 34.2%; level 2, 25.6%; level 3, 11.5%; level 4, 13.7%, and level 5, 15.6% .505 Because levels 1 and 2 are considered lesser involvement, most patients are mildly involved, although more severely involved children are more apparent in a pediatric orthopaedic practice.

The irst step in the evaluation of a child with CP is to obtain a complete history, especially the birth history. Birth weight, gestational age, complications, and whether the child required ventilator assistance or hospitalization in the neonatal intensive care unit are important data. If the birth history is normal, neurologic consultation should be considered. Evaluation of motor milestones will reveal delayed development. Head control should be present at 3 to 6 months, sitting by 6 to 9 months, crawling by 9 months, standing and cruising by 10 to 12 months, and walking between 12 and 18 months. Adjustments for prematurity should be made; a premature child may not walk by 15 months of age. Preferential use of one hand or leg and early handedness, particularly left-handedness in small infants, are often clues that spastic hemiparesis may be present. Likewise, dragging one leg when crawling or scooting may also be an indication of hemiparesis. Ascertaining whether the child has other problems, such as strabismus, dificulty swallowing, frequent choking, delayed speech development, poor eyesight, and seizures, is important. Some 20% to 40% of children with CP have seizures, most common in hemiplegic and quadriplegic patients.13,247,333,443 These observations may all be clues leading to the diagnosis of CP.

Physical Examination Muscle Tone Physical examination of a child with CP should include muscle tone in the extremities. With the patient relaxed (even sitting on the lap of a parent), the extremities are brought through a full range of motion. Spasticity feels like

CHAPTER 35 Disorders of the Brain

Level 1

Level 3

e7

Level 2

Level 4

Level 5

FIGURE 35-4 Gross Motor and Functional Classiication System. Level 1: Children walk without limitations and can run and jump, but speed and coordination are reduced. Level 2: Walk without aids indoors and with assistive mobility devices such as crutches, walkers, and/ or orthotics. Level 3: Walk indoors and outdoors with assistive mobility devices such as crutches, walkers, and/or orthotics. Level 4: Rely on a wheelchair for most mobility. Children may have a very limited ability to take steps but are not functionally ambulatory. Level 5: No independent mobility and unable to maintain an upright trunk without support.

tightness in the muscles, which become tighter the quicker the limbs are passively moved. Greater range of motion can be gained by slowly and gently stretching the joints in question. The Tardieu test is a measure of spasticity. For example, if the examiner is assessing hamstring spasticity, the angle at which a “grab” of resistance occurs when quickly extending the knee with the hip in lexion is compared with the amount of extension possible when the knee is stretched slowly.639 Fine motor activities should be assessed. Passing the child a toy or a pen often reveals spastic hemiplegia in one extremity. Having the child clap the hands or wiggle the ingers may reveal dificulties in ine motor control.

Relexes Deep tendon relexes are increased in patients with CP. Repetitive tapping of the deep tendons or quick passive dorsilexion of the ankle may produce clonus, which establishes the presence of an upper motoneuron neurologic abnormality. In hemiparesis, relexes will be asymmetric. Infantile relexes disappear in normal children by 3 to 6 months of age as the motor cortex matures; however, they are retained in children with CP.66 Bleck’s textbook on CP

outlines these relexes in clear detail.72 The startle relex, or the Moro relex, which should disappear by 4 months of age, is elicited by letting the infant’s head drop back into extension with the infant supine but slightly elevated. This causes the legs and arms to extend abruptly. A sudden loud noise can likewise cause an older child to extend and lurch from a wheelchair. The parachute relex is tested by holding the child in the air and then lowering him quickly headirst toward the examining table. Children older than 5 months will reach out with both arms to protect themselves. Children with CP cannot do so, and those with hemiplegia will reach out with only one arm. The tonic neck relex is elicited by turning the supine infant’s head to one side. The ipsilateral arm and leg will extend while the contralateral arm and leg lex. This relex should disappear in infancy; persistence should raise suspicion for CP.

Balance, Sitting, and Gait Balance, sitting, and gait are assessed by noting whether the child can sit unsupported without use of hands or get into a sitting position without assistance or whether balance is easily disturbed in the sitting position or as the child walks.

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SECTION VI Neuromuscular Disorders

Clinical assessment of gait requires that the child’s joints be readily seen, so the child should be barefoot and in shorts or a short gown. The evaluation should be conducted with the examiner seated on a stool at the level of the child. Enough room should be available for the child to walk naturally. Heel-to-toe walking, hopping on either foot, and running are observed. A patient with mild hemiplegia may walk nearly normally but exhibit abnormal movement patterns while running; the affected upper extremity will draw upward and not have a normal arm swing. Gait should be observed from the front of the child and then from the side, and the hips, knees, and ankles should be systematically assessed from each perspective. A crouched gait consisting of increased lexion at the hip and knee, toe-walking with genu recurvatum, or a footdrop in the swing phase of gait may all be indicative of CP. Disturbance in clearance of the swing-phase limb may be caused by footdrop or an inability to lex the knee.

Gait Analysis Gait analysis has become popular in the assessment of movement disorders in children with CP, but the usefulness of such studies is controversial. Accurate documentation of dynamic range of motion may help in planning surgical treatment and assessing the results of orthopaedic operations, but it does not replace a good clinical examination. When gait analysis graphs are scrutinized together with information from the clinical examination and slow-motion videotape, better understanding of a patient’s gait can be gained.151 A detailed discussion of gait analysis can be found in Chapter 5. The Functional Mobility Scale is a questionnaire that assesses the child’s ambulatory ability at 5 m (within the home), 50 m (short distances), and 500 m (community ambulation) and should be considered in conjunction with gait analysis in surgical decision making.229,230

Histopathologic and Imaging Findings

Cadence. Cadence parameters include walking speed, step length, number of steps per minute, and the proportion of time spent in stance and swing phases. Patients with CP usually have disturbances in cadence parameters. In good walkers with spastic diplegia, walking velocity is maintained despite decreased step length by increasing cadence (quick, short steps). Good walkers with CP increase their speed by increasing cadence, but spasticity interferes with increasing step length.4 In those with more severe diplegia and quadriplegia, walking speed is diminished, with decreased cadence and step length. The proportion of time spent in stance phase, particularly double-limb stance, increases because the child has greater dificulty with balance and advancing the limb. Children with hemiplegia show asymmetry in step length and in single- and doublesupport time.437

Two indings frequently described on histopathologic examination or imaging studies of the brain in children with CP are periventricular leukomalacia and intraventricular and periventricular hemorrhage. Periventricular leukomalacia is deined as patchy areas of necrosis in the periventricular white matter adjacent to the lateral ventricles. It results from an ischemic insult to the arterial watershed area close to the ventricular walls. Pyramidal tract ibers mapping to the lower extremities pass through this area and are therefore more susceptible to injury than ibers responsible for the upper extremities and face. The bigger the lesion, the more ibers that are injured and the greater the proportion of the body that is affected by CP.65 The areas of the brain immediately adjacent to the ventricles are also most susceptible to hemorrhage. Hemorrhage may be seen on ultrasound, MRI, or CT. Mild hemorrhages involve the germinal matrix adjacent to the ventricles, whereas more severe hemorrhages extend into the ventricles themselves and into the parenchyma of the brain. Hypoxia is known to predispose to periventricular and intraventricular hemorrhage.65 Approximately one half of preterm infants with CP are found to have abnormalities on neuroimaging, such as echolucency in the periventricular white matter or ventricular enlargement on cranial ultrasound. In children with CP born at or near term, about two thirds have abnormalities on neuroimaging, including focal infarction, malformations, and periventricular leukomalacia.448

Kinematics. Certain kinematic patterns are seen in patients with CP.158,208,280,629,682,683 In the hip, scissoring, which is caused by tightness in the adductor musculature and, in part, by weakness of the hip abductors, leads to a narrow base of gait and dificulty advancing the swing-phase limb past the stance-phase limb (Fig. 35-5). In the sagittal plane, increased hip lexion and anterior pelvic tilt may be part of crouch gait as a result of increased tone in the iliopsoas (Fig. 35-6). Increased femoral anteversion may be documented by gait analysis as increased internal rotation of the hips. Asymmetric pelvic rotation may be present, and gait analysis is particularly helpful when the examiner is trying to ascertain whether the abnormal rotation is originating from the pelvis, hips, or tibiae (Fig. 35-7).158 At the knee, sagittal-plane motion is usually abnormal. In patients with tight hamstrings, the knee remains lexed at initial contact and is unable to extend normally during stance phase. In swing phase, spasticity of the rectus femoris may inhibit the patient’s ability to lex the knee and clear the loor (Fig. 35-8). Genu recurvatum during stance phase may be present in response to a tight Achilles tendon, which causes dificulty advancing the tibia forward over the foot. Ankle kinematics often shows disturbances in plantar lexion, dorsilexion, and push-off. Plantar lexion on weight acceptance is generally abnormal in patients with equinus contractures. Dorsilexion during midstance is diminished in the presence of a tight Achilles tendon, and push-off is

Other Assessments Rarely are imaging studies ordered by orthopaedic surgeons when establishing the diagnosis of CP. If questions persist regarding a correct diagnosis, referral to a pediatric neurologist is indicated. At the neurologist’s discretion, imaging studies such as cranial ultrasonography, brain magnetic resonance imaging (MRI), and computed tomography (CT) may be pursued.322 Similarly, laboratory studies may be necessary to look for evidence of metabolic diseases associated with delays in development and CP-like symptoms, such as congenital hypothyroidism or dopa-responsive dystonia. A detailed discussion of these metabolic conditions is beyond the scope of this chapter, however.

CHAPTER 35 Disorders of the Brain

Hip abduction/adduction

Pelvic rotation 45

Abduction

0 –10

Internal

10

30 15 0

External

20

Degrees

Adduction

30

Degrees

e9

–20

–15 –30 –45

Hip rotation

–30 50

Stance phase

75

45

100

Swing phase

FIGURE 35-5 In normal gait (black dotted curve), the hip adducts slightly in stance phase as the contralateral hemipelvis drops, and it abducts slightly in swing phase. In patients with scissoring as a result of cerebral palsy (red curve), adduction of the hip is increased. Vertical lines designate divisions between the stance and swing phases for each leg.

Degrees

Percentage of gait cycle

Internal

25

30 15 0

External

0

–15 –30 –45

Foot progression

Internal

60

Anterior

Degrees

20

0

Shank–based foot rotation

–10

Degrees

40 20

30

0

External

60

Internal

60

Hip flexion

Flexion

–30

–60

80

Degrees

30

0

10

Post.

Degrees

30

External

Pelvic tilt 40

–30

–60

Stance phase Ext.

0 –20

Stance phase

Swing phase

FIGURE 35-6 Normal kinematics for pelvic tilt and hip sagittalplane motion is represented by the black dotted curve. Patients with cerebral palsy (red curve is the right side, blue dotted curve is the left side) may crouch at the hip joint, which is represented on gait analysis as increased anterior pelvic tilt and lack of hip extension at terminal stance phase. Vertical lines designate divisions between the stance and swing phases for each leg.

Swing phase

FIGURE 35-7 Transverse-plane kinematics is useful in determining the cause of intoeing or outtoeing in cerebral palsy. In this hemiplegic patient, the involved hemipelvis is characteristically externally rotated (red curves), excessive femoral anteversion is present, and the foot is internally rotated relative to the knee because of equinovarus deformity of the foot. This results in a foot progression angle of 40 degrees internally. The uninvolved side is represented by the blue dotted curves, and normal transverse-plane kinematics is represented by the black dotted curves. Vertical lines designate divisions between the stance and swing phases for each leg.

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SECTION VI Neuromuscular Disorders

Knee flexion

132

90

mV

Flexion

150

Degrees

Rectus femoris

Vastus medialis

mV 66

Med. hamstrings

Ext.

mV 154

Tibialis anterior

mV

–15 0

25

50

Stance phase

75

100

Swing phase

85.1

Percentage of gait cycle

Gastrocnemius

mV

FIGURE 35-8 Crouch at the knee in a diplegic patient (red curve is the right knee, blue dotted curve is the left knee) is documented as increased knee lexion throughout stance phase. As the leg enters swing phase, the knee slowly lexes and reaches maximal lexion later than in the normal gait (black dotted curve) because of rectus femoris spasticity, which interferes with clearing of the foot as it swings forward. Vertical lines designate divisions between the stance and swing phases for each leg.

252 mV 244

Vastus medialis

mV 73.4

Ankle flexion

Rectus femoris

Med. hamstrings

mV

Dorsal

45

158

Tibialis anterior

Degrees

mV 172

Gastrocnemius

Plantar

mV

0

10

20

30

40

50

60

70

80

90

100

Percentage of gait cycle –60 0

25

Stance phase

50

75

100

Swing phase

Percentage of gait cycle FIGURE 35-9 Sagittal-plane kinematics of a patient with cerebral palsy who has bilateral equinus (red curve is the right side, blue dotted curve is the left side). The ankle remains in plantar lexion during stance phase rather than progressively dorsilexing, as in the normal second rocker (black dotted curve). Vertical lines designate divisions between the stance and swing phases for each leg.

reduced if the ankle is already plantar-lexed from the equinus. Swing-phase dorsilexion may be absent as a result of weakness or inactivity of the tibialis anterior and lead to footdrop (Fig. 35-9). Gait analysis is particularly useful in assessing the cause of toe-walking. It is tempting to attribute all toe-walking to tight Achilles tendons; however, some children walk on their toes in response to crouch above the ankle and have neutral ankle dorsilexion but increased lexion at the knee and hip. Lengthening of the Achilles tendon in these children would result in a calcaneus gait, with persistent crouch

FIGURE 35-10 Typical electromyographic pattern during gait in a child with cerebral palsy. The horizontal bars represent the situation in which a muscle is normally “on.” Stance phase is represented from 0 to 60 and swing phase from 60 to 100. Contraction of all muscles is inappropriate during gait.

at the hip and knee but excessive dorsilexion at the ankle leading to ineficient push-off. Electromyography. Spasticity leads to electrical overactivity on electromyography (EMG) during gait, and it seems that the more spastic the child, the greater the EMG signal and the less phasic the muscles in their contraction (Fig. 35-10). Dynamic EMG data collected during gait analysis can be correlated with kinematic and kinetic graphs to gain a fuller understanding of the biomechanics of the child’s gait.470 For example, normally at initial contact, the ankle plantar-lexes while the anterior tibialis ires on the EMG. Kinetic plots show absorption of power as weight acceptance occurs. In stance phase a child with CP may exhibit early heel rise, seen as plantar lexion on kinematic plots, which correlates with gastrocsoleus overactivity on EMG. We ind data from EMG most useful when evaluating a child with a stiff

CHAPTER 35 Disorders of the Brain

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FIGURE 35-11 A normal hip generates power at terminal stance phase as the iliopsoas pulls the leg off the ground (black dotted curve). In patients with cerebral palsy (red curve is the right side, blue dotted curve is the left side), hip kinetics can be disturbed. This patient generates little power at terminal stance phase and is therefore less eficient. Vertical lines designate divisions between the stance and swing phases for each leg.

FIGURE 35-12 As the gastrocsoleus contracts at heel rise, the ankle generates a burst of power (black dotted curve). In patients with either equinus or calcaneus gait secondary to cerebral palsy, power generation is decreased. (Red curve is the right side, blue dotted curve is the left side). Vertical lines designate divisions between the stance and swing phases for each leg.

knee in swing phase for rectus femoris transfer and when assessing a child with an equinovarus foot for tendon transfer (either anterior tibialis or posterior tibialis split transfer).472

not always be in the patient’s best interest. Gait analysis can be an adjunct to clinical examination, but the data should be scrutinized and the videotape reviewed to judge whether the data are representative of the gait seen in the clinic or described by the parents in the home. Very active gait analysis laboratories claim that their studies can change the surgical plan in patients with CP in up to 52% to 70% of instances.160,206 In many cases, gait analysis reduces the number of individual procedures needed in a single-event multilevel surgery (SEMLS) approach.354 The decision-making process with the use of gait analysis data is only as good as the astuteness and familiarity of the orthopaedic surgeon reading the graphs. The Gilette Gait Index (GGI) is a numerical calculation that represents how different the kinematic data are from age-matched normal values. Improvement in the GGI following SEMLS has been documented in various studies.644

Kinetics. Kinetics is the force exerted across joints during gait. Each joint has well-described kinetic patterns, and the reader is referred to work by Gage for descriptions.207 Two particular forces are clinically interesting: hip pull-off power and ankle push-off power. Hip pull-off power, the force exerted by the iliopsoas and other hip lexors to lift the stance-phase limb off the ground and into swing phase, is often diminished in patients with CP and leads to decreased energy eficiency (Fig. 35-11). Ankle push-off power, the force exerted by the gastrocsoleus at terminal stance to push the stance-phase limb off the ground, is diminished in patients with equinus or calcaneus gait (Fig. 35-12). Oxygen Consumption. The goal of orthopaedic intervention is to improve the quality and eficiency of walking. By comparing oxygen cost and consumption with normal values through collection of preoperative and postoperative data, the eficiency of the child’s gait can be measured objectively.84,184,662 Heart rate is an indirect measure of oxygen consumption and can easily be measured in the clinic.431,531,532 Children with CP have been found to have six times higher heart rates when walking than able-bodied peers do, with the highest heart rates seen in children with crouch gait.497 Flaws in Gait Analysis. Critics of gait analysis in patients with CP have pointed out that patients itted with markers and electrodes and placed in front of video cameras do not walk as they do at home or school.670 Considerable variability in how patients walk from clinic visit to clinic visit has been noted. Basing treatment plans on kinematic and kinetic data from a few strides across a gait laboratory may

Summary. Gait analysis in our center is used to 1. Clearly document the three-dimensional movement of the lower extremity during gait preoperatively 2. Document changes in gait over time as the patient grows because gait may deteriorate in children with CP292 3. Allow preoperative and postoperative comparisons of results after tendon or bone surgery and to gather research data 4. Analyze the rotational proile of the patient before surgery to help the surgeon select the correct site and amount of rotational change 5. Conirm a surgical plan when needed Gait analysis does not tell surgeons whether they should operate, but it may help them ine-tune the operative plan when questions exist. Additionally, gait analysis provides an objective assessment of changes seen after SEMLS, including alterations in joint position, dynamic range of motion, and time and distance parameters.6

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SECTION VI Neuromuscular Disorders

Muscle Strength It has long been known that muscles in children with CP are typically spastic and that motor control of the muscles (i.e., the child’s ability to volitionally contract and relax the muscle) is impaired. Reports have documented that muscle weakness is also a problem in children with CP. Documented muscle weakness is worse for children as the CP GMFCS level worsens.648

Prognosis for Ambulation Many authors have proposed criteria for predicting the ultimate ability of a child with CP to walk. Inability to sit by 2 years of age,404 persistence of two or more infantile relexes beyond 12 to 15 months,68 and lack of head control by 20 months imply a poor prognosis for ambulation.148 Beals stated that the severity of involvement of the lower extremities is the most important factor affecting a child’s eventual ability to walk.53 The presence or absence of mental retardation does not inluence the ability to walk. The geographic type of CP that a child has inluences whether the child will walk. All children with spastic hemiplegia develop the ability to ambulate. Eighty-six percent to 91% of children with spastic diplegia become ambulatory and 0% to 72% of patients with spastic quadriplegia learn to walk. The discrepant igures are due to variation in differentiation between spastic diplegia and quadriplegia among studies.548 The age at which children with CP begin to walk varies with the severity of their neurologic disease. Patients with spastic hemiplegia generally walk between the ages of 18 and 21 months. Children with spastic diplegia who walk usually do so by 4 years of age. Many agree that the ability to walk plateaus by 7 years of age, thus implying that if a child is nonambulatory at 7 years, the child will probably never become ambulatory.53,68,133

Treatment Once the diagnosis of CP has been made, the physician must select a course of treatment. Treatment choices are now more numerous than ever and include observation, physical therapy, botulinum toxin, intrathecal administration of baclofen, neurosurgery, and orthopaedic surgery.406 With the increasing popularity of nonorthopaedic management of spasticity, some centers have noted an overall decrease in orthopaedic surgical procedures in this patient group.251 Treatment, whether surgical or nonsurgical, must be goal oriented. The goals of treatment of children with CP that have been linked to productive lives as adults are communication, education, mobility, and ambulation. Note that walking ranks below mobility. Although ambulation remains a desirable goal, it should not be pursued so fervently that attention to overall development of the child is ignored. Bleck68 quoted Rang as advising orthopaedists to remember that “the child with cerebral palsy becomes the adult with cerebral palsy.” Childhood is the optimal time for intervention to maximize the function of a patient with CP. It is the orthopaedists’ duty to ensure that the musculoskeletal treatment of the child prevents future problems with

pain and deformity as an adult.71 Patients with CP do not usually have severely shortened life spans. In a study of all children with CP born between 1966 and 1984, the 20-year survival rate was 89%. If the patients were ambulatory, had manual dexterity, and were not mentally retarded, the 20-year survival rate was higher than 99%.281 Survival is clearly linked with the patient’s GMFCS level. In a study from the Swedish database, all GMFCS level 1 and 2 children survived to 19 years of age, whereas only 60% of GMFCS 5 children were still alive. Patients with gastrostomy tubes were most likely to succumb to early death, which is indicative of their medical fragility rather than the presence of the gastrostomy itself.672 The overall 30-year survival rate is estimated to be 87%; it is lower in those with spastic quadriplegia, seizure disorders, and profound mental retardation.132

Nonsurgical Treatment Physical Therapy Frequently, the irst treatment rendered to a child with CP is physical therapy. Yet no controlled studies have conirmed that regular physical therapy improves the outcome of a child with CP.656 One of the irst well-designed studies investigating the effect of physical therapy was performed by Wright and Nicholson in 1973. They found no difference in motor skills or relexes after 12 months in children who had neurodevelopmental training or physical therapy and those who did not.686 Other studies followed and again showed no discernible improvement after different forms of therapy.264,377,457,484 In defense of physical therapy, these studies are dificult to carry out because they involve different age groups and children with varying severity of neurologic impairment and usually encompass just a brief period of therapy. However, as Bleck72 pointed out, “The burden of proof is on the proponents of the treatment. Critics need not prove ineffectiveness but can insist on positive data.” The eficacy of physical therapy can be proved or disproved only with a properly designed, collaborative, multicenter, randomized, controlled trial. Such a trial has yet to be undertaken.649 Physical therapy, ranging from the medical model, with the aims of attaining ambulation, range of motion, or transfers, to neurodevelopmental training, sensory integration, and even craniosacral therapy, has been proposed. Electrical stimulation of the muscles has also been used in these patients.101,257 Families like physical therapy and attribute gains in their young child’s ability to interaction with the therapist. However, some of these gains are simply the result of neurologic maturation of the child. Our approach to physical therapy is to establish therapy for monitoring the developmental milestones of very young children, around the age of 2 or 3 years. Therapy is continued if gains are being made in attaining ambulation. Schoolbased programs are used in elementary school and often include adaptive physical education. Postoperative intensive physical therapy is essential to reestablish range of motion and strength after surgical intervention. Strength training of weak muscles has been successful in improving motor function.140,143 We also draw on the expertise of physical therapists in assessing orthotic needs and wheelchair seating when appropriate. No evidence supports the continued use

CHAPTER 35 Disorders of the Brain

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FIGURE 35-13 A to C, Different views of common ankle-foot orthoses (AFOs) used in patients with cerebral palsy. The orthosis on the left is a ground reaction AFO that extends across the anterior aspect of the tibia to prevent lexion of the knee in stance. The center orthosis is a conventional solid ankle AFO. The orthosis on the right is a hinged AFO that allows dorsilexion of the ankle but prevents equinus.

of physical therapy for range of motion, particularly in a nonambulatory child. Physical therapists play an important consultative role in making treatment decisions for patients whom they treat on a regular basis and whom we examine on a relatively infrequent basis. It is common for parents of children with CP to resist discontinuing physical therapy. We believe that goals must be set for therapy and, if progress toward these goals is not being made, either the goals need to be reassessed or therapy should be stopped because it is not useful. Setting measurable functional goals has led to greater success after physical therapy.85 In an older child, transitioning from physical therapy to therapeutic recreation is desirable and generally met with enthusiasm by the patient.501 Adaptive sports or swimming allows the child to participate with peers and affords greater enjoyment than exercises in the therapy gym do. Time in school should be spent on education at this age and not on physical therapy.

Casting Inhibitive casting has waxed and waned in popularity as a mode of treatment of spasticity in children with CP. It is based on the presence of areas on the feet that are target centers for increased tone at the ankle and, some believe, throughout the lower extremities in certain patients. Usually, short-leg casts are applied with extended toe plates, careful molding of the heel, and metatarsal head control. This has been used by physical therapists and by some physicians. The time spent in casts varies but is generally a minimum of 6 weeks and is followed by the use of orthoses. In our experience, casting has a limited role in patients with CP. We have used casting in rare cases of very young children (