Cerebral Palsy (static encephalopathy)
Generic descriptive term for a broad heterogeneous group of clinical syndromes that is characterised by a chronic, static, non-progressive disorder of motor control due to an injury to the nervous system resulting in abnormalities of posture, muscle tone and motor control. Occurs in 1 to 5/1000 births – higher incidence in premature low birthweight infants.
Lesion causing cerebral palsy is non-progressive (not an active disease process), but resultant deformities can be progressive.
Exact aetiology is not clear but risk factors well established
Many conditions can injure the developing brain:
• prenatal – infections (eg rubella); maternal alcohol and drug abuse; congenital deformity; genetic disorders; exposure to toxins or radiation; cerebral infarcts
• perinatal – prematurity; birth trauma; delivery complications
• postnatal – infections (eg meningitis); traumatic injury to CNS; anoxia (eg near drowning); acute metabolic disorders; blood group incompatibility
Factors associated with increased risk of cerebral palsy include
• respiratory distress syndrome
• decreased gestational age
• foetal malformations
• birth weight <2100g • maternal intellectual impairment • delayed first cry • neonatal seizures Clinical features: 50% diagnosed in first 6 months. Early diagnosis of mild cases is difficult; early clues include suspicion from perinatal history, psychomotor delay, asymmetry and retention of primitive reflexes, hypotonia, hyperreflexia, clonus Types: Cerebral palsy can be classified in a number of ways depending on tonus variations, distribution of tonus changes, severity, functional ability and type: Swedish Classification: 1. Spastic: • hemiplegic (upper limb and lower limb on same side; contractures more severe distally; feet in equinus and/or varus; scoliosis is common; walking delayed); diplegic (both lower limbs more involved than upper limbs; most common type; ); monoplegic (single limb involved); triplegic; quadriplegic (all four limbs equally involved) • can be symmetric or asymmetric • most common type of motor dysfunction • due to injury in pyramidal system • usually present with hypertonia, rigidity, tendon reflexes exaggerated’ persistence of primitive reflexes 2. Dyskinetic: • dystonic (bizarre positions and movements of limb); choreoathetotic (irregular writhing movements; variable muscle tone); hypotonic (lack or reduced muscle tone) • impaired voluntary muscle control (slow writhing movements of flexion/extension and pronation/supination of feet and hands) • assumed to be due to lesion in basal ganglia 3. Ataxic • complete or partial lack of muscle coordination and decrease in proprioception balance problems • due to injury in cerebellum • rarer form 4. Mixed • combination of types variety of movement disorders Associated disabilities: • intellectual impairments and learning disabilities are common; 65% have some degree of mental retardation (often correlates with motor handicap, but with a lot of individual variability) • increased frequency of seizures • up to a third have visual problems • up to 10% have hearing defects • 50% have speech and language problems The foot in cerebral palsy: Undiagnosed mild cases may present to Podiatrist due to involvement of foot (most often a severe pes planus/pronated foot) Pattern of foot deformity depends on type and extent of involvement. Most common is a spastic equinus caused by an unbalanced action of the extensor and flexor muscles with prolonged activity of the calf muscles Torsional problems of the limbs are common. Hallux valgus common- due to muscle imbalance Management: Multidisciplinary Social and psychological services Occupational therapy - Adaptive equipment (eg devices for standing); mobility aids (eg wheelchairs) Night splints Botulinum toxin Cast correction Equinus – if mild stretching and orthoses; if severe- surgery Orthoses – used to facilitate function, inhibit reflex activity, prevention/correction of deformity