Cerebral palsy
Cerebral palsy is a disorder of movement and posture due to a non-progressive lesion of motor pathways in the developing brain. Although the lesion is non-progressive, the clinical manifestations emerge over time, reflecting the balance between normal and abnormal cerebral maturation. Cerebral palsy is the most common cause of motor impairment in children, affecting about 2 per 1000 live births. In addition to disorders of movement and posture, children with cerebral palsy often have other problems reflecting more widespread brain dysfunction. These include:
• learning difficulties (about 60%)
• epilepsy (40%)
• squints (30%)
• visual impairment from errors of refraction and cortical damage (20%)
• hearing impairment (20%)
• speech and language disorders (due to hearing loss, oro-motor incoordination and learning difficulties)
• behaviour disorders
• feeding problems
• joint contractures, hip subluxation, scoliosis.
Causes
About 80% of cerebral palsy is antenatal in origin due to vascular occlusion, cortical migration disorders or structural maldevelopment of the brain during gestation. Some of these problems are linked to gene deletions. Other antenatal causes are genetic syndromes and congenital infection.
Only about 10% of cases are thought to be due to hypoxic-ischaemic injury at birth and this proportion has remained relatively constant over the last decade.
About 10% are postnatal in origin. Preterm infants are especially vulnerable to brain damage from periventricular leucomalacia (PVL) secondary to ischaemia and/or severe intraventricular haemorrhage. The rise in survival of extremely preterm infants has been accompanied by an increase in survivors with cerebral palsy, although the number of such children is relatively small. Other postnatal causes are meningitis/encephalitis/encephalopathy, head trauma from accidental or non-accidental injury, symptomatic hypoglycaemia, hydrocephalus and hyperbilirubinaemia.
MRI brain scans may assist in identifying the cause of the cerebral palsy. Haematological problems due to thrombophilia or clotting disorders should be excluded in neonatal stroke.
Clinical presentation
Many children who develop cerebral palsy will have been identified as being at risk in the neonatal period. Early features of cerebral palsy are:
• abnormal limb tone and limb and/or trunk posture in infancy with delayed motor milestones (Fig. 4.3); may be accompanied by slowing of head growth
• feeding difficulties, with oromotor incoordination, slow feeding, gagging and vomiting
• abnormal gait once walking is achieved
• asymmetric hand function before 12 months of age.
In cerebral palsy, primitive reflexes, which facilitate the emergence of normal patterns of movement and which need to disappear for motor development to progress, may persist and become obligatory
The diagnosis is made by clinical examination, with particular attention to assessment of the pattern of tone in the limbs and trunk, posture, hand function and gait. There are three main clinical types of cerebral palsy, each reflecting dysfunction of a specific motor pathway, namely spastic (70%), ataxic hypotonic (10%), dyskinetic (10%). There may also be a mixed pattern (10%).
Spastic cerebral palsy
In this type, there is damage to the upper motor neuron (pyramidal or corticospinal tract) pathway. Limb tone is increased (spasticity) with associated brisk deep tendon reflexes and extensor plantar responses. The increased limb tone may suddenly yield under pressure in a 'clasp knife' fashion. Spasticity tends to present early and may even be seen in the neonatal period. Sometimes there is initial hypotonia, particularly of the head and trunk. There are three main types of spastic cerebral palsy:
• Hemiplegia - unilateral involvement of the arm and leg (Fig. 4.4). The arm is usually affected more than the leg, with the face spared. Affected children often present at 4-12 months of age with fisting of the affected hand, a flexed arm, a pronated forearm, asymmetric reaching or hand function. Subsequently a tiptoe walk (toe-heel gait) on the affected side may become evident. Affected limbs may initially be flaccid and hypotonic, but increased tone soon emerges as the predominant sign. The past medical history is usually normal, with an unremarkable birth history with no evidence of hypoxic-ischaemic encephalopathy. However, in some the condition is caused by a neonatal stroke.
• Quadriplegia - all four limbs are affected, often severely. The arms may be affected more than the legs. The trunk is involved with extensor posturing and poor head control and low central tone (Fig. 4.5). This form of cerebral palsy is often associated with seizures, microcephaly and moderate or severe intellectual impairment. There may have been a history of hypoxic-ischaemic encephalopathy after birth.
• Diplegia - all four limbs, but the legs are affected to a much greater degree than the arms, so that hand function may appear to be relatively normal. It is with functional use of the hands that motor difficulties in the arms are most apparent. Walking is abnormal.
Ataxic hypotonic cerebral palsy
Signs are relatively symmetrical. There is early trunk and limb hypotonia, poor balance and delayed motor development. Incoordinate movements, intention tremor and an ataxic gait may be evident later, reflecting dysfunction in the cerebellum or its connections.
Dyskinetic cerebral palsy
Cerebral palsy
A child with a right spastic hemiplegia. His right arm is hyperpronated, flexed, hand fisted.
A child with spastic quadriplegia showing scissoring of the legs from excessive adduction of the hips, pronated forearms and 'fisted' hands.
There is dyskinesia (fluctuating tone) leading to frequent involuntary movements (generally of all four limbs) especially evident with movement or stress. These involuntary movements may be:
• chorea - irregular, sudden and brief non-repetitive movements
• dystonia and athetosis - simultaneous and sustained contraction of agonist and antagonist muscles involving the trunk or proximal limbs (dystonia) or distal parts of the limb (athetosis).
Intellect may be relatively unimpaired. Affected children often present with floppiness, poor trunk control and delayed motor development in infancy, with abnormal movements sometimes not appearing before 1 year of age. The signs are due to damage to the basal ganglia or their associated pathways (extrapyramidal). In the past, hyperbilirubinaemia due to rhesus disease of the newborn was a common cause.
Management
Summary
Cerebral palsy:
• has many causes. Only about 10% follow hypoxic-ischaemic encephalopathy
• usually presents in infancy with abnormal tone and posture, delayed motor milestones and feeding difficulties
• may be spastic, ataxic hypotonic, dyskinetic or mixed pattern.
Parents should be given details of the diagnosis as early as possible, but prognosis is difficult during infancy until the severity and pattern of evolving signs and the child's developmental progress have become clearer over several months or years of life.
