CEREBRAL PALSY

Cerebral palsy (CP) is non-progressive neuromotor deficit of cerebral origin due to antenatal, perinatal or early postnatal insult of the developing brain, more precisely defined 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”.

Mental retardation, although present in gt;50-75% cases, is not an essential feature of CP.

Incidence: CP is the commonest cause of motor handicap in Indian children after control of poliomyelitis, with estimated prevalence of ~ 2/1000 live births.

Despite major improvements in perinatal care during recent years, incidence of CP has not declined due to increasing survival of high-risk neonates, e.g. preterm and low birth weight.

Etiology: Brain growth is nearly complete by 2 years of age. CP is a clinical manifestation of developing brain injury during this period, irrespective of the cause, commonest being the adverse perinatal event, e.g. prematurity and birth asphyxia. Important etiological factors for CP include:

• Prenatal causes (20%)

± Congenital brain malformations

± Intrauterine infections

± Intrauterine hypoxia

± Maternal exposure to toxins

• Perinatal causes (70%)

± Prematurity

± Birth asphyxia

± Birth trauma/inj ury

• Postnatal causes (lt;10%)

± Kernicterus

± Neonatal meningitis, septicaemia or stroke

± Prolonged hypoglycemia

Clinical manifestations of CP range from minor motor incapacitation to crippling handicaps, depending on the extent, site and timing of neurological injury. While it is a static neurological defect, signs may evolve over a period of time with maturity of brain and full clinical picture of handicap may not be obvious till late infancy. According to the clinical neurodeficit, CP is classified into five main categories:

a.

b. Extrapyramidal (~20%)

Fig. 18.10: Scissoring in spastic cerebral palsy.

c. Ataxic/cerebellar (lt;5%)

d. Atonic (rare)

e. Mixed (10-15%) a. Spastic CP is the commonest type, representing cortical or pyramidal tract injury and mostly seen in preterms or following birth asphyxia. Depending on the topographic distribution, spastic CP is further classified as quadriplegia, diplegia, hemiplegia or monoplegia.

Spastic diaplegia, i.e. quadriparesis with more prominent involvement of lower limbs than upper limbs, is more common in preterms due to higher incidence of periventricular leukomalacia. Periventricular lesions mainly affects medially located nerve fibers in pyramidal tracts, which supply lower limbs. Important signs of spastic CP include:

• Abnormal tone: Hypotonia is common in neonatal period, which gradually evolves into intermittent dystonia and then the spasticity, presenting with:

± Clasp-knife spasticity in involved limbs,

± Scissoring of legs due to persistent spasm of adductor muscles (Fig. 18.10),

± Commando-crawl due to spastic, extended lower limbs,

± Restricted joint mobility, e.g. reduced popliteal angle and ankle dorsiflexion,

± Intermittent dystonia with arching of back/neck and stiffening of limbs, and

± Decreased spontaneous movements of body, e.g. hand-swing during walking. Difficulty in changing the diaper may be an early indicator of hypertonia in spastic CP.

• Abnormal gait and posture due to abnormal tone or contractures, which may also cause shortening of limbs and present with:

- Postural distortions, which tends to worsen during activity or excitement,

- Hemiplegic gait or Commando-crawl (dragging of feet while crawling), and

- Cortical thumb with hyperextension at meta­carpophalangeal joint and flexion at interdigital joint

• Abnormal reflexes including:

- Persistence of neonatal reflexes, and

- Hyerreflexia, clonus and positive Babinski sign.

• Abnormal function, e.g.

- Feeding difficulties with sialorrhea and recurrent aspiration due to pseudobulbar palsy and gastro­esophageal reflux,

- Dysarthria due to palatopharyngeal incoordination,

- Delayed motor development due to tone and posture abnormalities.

• Associated abnormalities include mental retardation (~50%), seizures (~33%), visual/hearing impairment and subtle sensory defects, e.g. stereognosis.

b. Extrapyramidal CP, also termed as Athetoid or Dyskinetic CP, represents basal ganglia injury, usually following kernicterus. These cases presents with: (a) lead- pipe rigidity, (b) dystonia, (c) choreo-athetoid movements, and (d) dysarthria. Unlike spastic diplegia, upper extremities are generally more affected than lower extremities in extrapyramidal CP.

Hearing impairment is very common but intellect is relatively preserved. Incidence of extrapyramidal CP has declined in recent years due to aggressive management of neonatal hyperbilirubinemia.

c. Ataxic CP denotes cerebellar malformations or involvement, presenting with—(a) hypotonia, (b) hypo- reflexia (Note: only CP with hyporeflexia), and (c) ataxia with intention tremors, by 2-3 years of age. Mental retardation is uncommon.

d. Atonic CP is extremely rare, presenting with unusual combination of hypotonia with brisk reflexes. Severe mental retardation is common.

Diagnosis: Early diagnosis of CP is essential to achieve maximum functional potential and it is usually possible to suspect it by 3 months of age. Early indicators of CP (Table 18.27) should be specially looked for during follow-up of high-risk newborns at 6 weeks, 3 months, 6 months and 1 year. Investigations primarily aim to detect comorbidities, which may further contribute to child's handicaps.

All cases need—(a) EEG to detect underlying seizure disorders, (b) hearing assessment by BERA test, and (c) assessment of vision.

Neuroimaging (CT/MRI), though not essential for diagnosis, may reveal cerebral atrophy, infarcts, leukomalacia and dilated ventricles, etc.

TABLE 18.27: Early indicators of cerebral palsy

Newborns

• High-risk perinatal history

• Unexplained feeding difficulties

• Asymmetric limb movements or Moro's response

• Spontaneous startle response

• Episodes of inconsolable cry

• Difficulty in changing diapers (hypertonia)

Early infancy

• Delayed early milestones, e.g. neck holding

• Abnormal persistence of neonatal reflexes

• Stereotype movements, e.g. chewing, lip smacking

• Paucity of fidgety limb movements gt;6-12 weeks

• Abnormal posture, tone, reflexes (see text)

• Persistence of cortical thumb gt;8 weeks

• Slower growth in head size

with family history also require chromosomal studies or plasma/urine chromatography for inborn errors of metabolism.

Management of CP needs a holistic team-approach, with an aim to achieve the maximum functional status and independent life despite physical handicaps. Important components of care include:

a. Physiotherapy is the cornerstone of therapy in CP, which should be started as early as possible to prevent contractures and maximize functional achievement. Various specialized techniques, e.g. Vojta's method are commonly used to relax contralateral group of muscles in these cases.

CIMT (Constraint induced movement therapy) is commonly used to improve functions of the affected hand based on the principle that restricting the use of good hand forces use of affected hand and improves its function by neuroplasticity of the brain.

b. Orthotic support with splints and braces are usually necessary for mobility, though splinting should not prevent physiotherapy. Orthopedic correction of postural deformities/contractures may be necessary before orthotic support in some cases.

c. Muscle relaxants, e.g. PO Clonazepam (0.01-0.1 mg/ kg/day), Baclofen (0.2-2.0 mg/kg/d q12hr) or Dantrolene (0.5-2 mg/kg/d q12hr) can be used to treat spasticity in selected cases. Intrathecal baclofen via an implanted pump has been used successfully in cases with severe spasticity.

Selective dorsal rhizotomy, i.e. cutting of 25-60% of dorsal roots at L₂-S₁ level to decrease muscle tone in corresponding extremity at 2-7 years has been reported as beneficial in diplegia, though risk of complete paralysis precludes it routine use.

d. Treatment of co-existing defects in hearing, speech and vision is the priority in CP to maximize functional potential. Anticonvulsant therapy may be required but prophylactic anticonvulsants are not indicated.

Choreo-athetoid movements may be controlled with PO Tetrabenazine (6.25 mg BD, maximum 50 mg/day) and/or Clonazepam (0.01-0.1 mg/kg/day). Severe dystonia may be treated with PO Trihexyphenidyl (0.25 mg/day q12h) and/or Levodopa (1-5 mg/kg/day).

e. Occupational therapy in early life aims to maximize independence in day-to-day activities, e.g. feeding, dressing, etc., while suitable vocational skills, e.g. typing, may be offered to older children for financial independence.

f. Psychological support and motivation to the patient, parents and family is vital for successful adaptation of these children within their functional limits. Community awareness is equally important to accept and support these cases.

g. Institutional care is the last resort, reserved for seriously handicapped children.

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