Cerebral Palsy

This can best be described as a syndrome in which there is a non-progressive impairment of movement and posture relating to a defect or lesion in the brain.

The basic aetiology is damage to the immature brain. Most authorities agree this damage occurs up to the post-natal period, but some classify cerebral palsy as damage occurring before the age of 3 years. The damage may be vascular, hypoxic-ischaemic, teratogenic, genetic or due to infection, toxins, metabolic problems or trauma. In many cases, no cause can be identified.¹

Various systems of classification exist;¹

Classification based on type of movement disorder

• Spastic - the predominant feature is muscle spasticity.
• Athetoid - this refers to the involuntary sinuous movements seen in some patients.
• Ataxic - the main features are balance problems, hand tremor and speech difficulties.
• Mixed - there may be a combination of several forms.

Classification based on affected area²

• Hemiplegic
• Diplegic (upper or lower limbs)
• Quadriplegic

Gross Motor Function Classification System (GMFCS)

This is an attempt to standardise the assessment of motor function in cerebral palsy patients. It has been modified and enhanced since its introduction in 1997, but it is basically a five-level system assessing the patient's daily motor function. The system may be used as a classification tool and an assessment of responsiveness to treatment.^3,4

The latest modification Gross Motor Function Classification System - Expanded and Revised (GMFCS-ER) has been extended to include patients aged 12-18. It emphasises the concepts inherent in the World Health Organisation's International Classification of Functioning, Disability and Health (ICF) and encourages assessment of what patients actually do rather than what they are capable if doing at their best.⁵

Cerebral palsy is a relatively rare condition. Pooled data from five active cerebral palsy registers in the UK suggest a mean annual prevalence rate of 2.0 per 1000 live births for birth years 1986-1996. Where type is recorded, 91 per cent had spastic cerebral palsy. Where data are available, nearly one-third of children had severely impaired lower limb function and nearly a quarter had severely impaired upper limb function.⁶

Risk factors

The incidence is higher in premature infants and twin births.² Other risk factors include maternal age greater than 35, black ethnicity and intrauterine growth restriction.⁷

Cerebral palsy may be suspected when delayed milestones are observed (e.g.reaching for toys at 3-4 months, sitting at 6-7 months and walking at 10-14 months). A definitive diagnosis may be difficult until specific signs of cerebral palsy appear and this may not happen until the child is 12-18 months old. Abnormalities of posture and movement are common throughout the different types of cerebral palsy.

Other presenting features will depend on the type of cerebral palsy i.e:

• Spastic type - there may be intermittent increased tone and pathological reflexes (e.g. Babinski response - upward pointing of the big toe on stroking the sole of the foot from the heel to the base of the toe).
• Athetoid - this is characterised by increased activity (hyperkinesia). This has been described as 'stormy movement'.
• Ataxic type - there may be loss of orderly muscular coordination so that movements are performed with abnormal force, rhythm or accuracy.

The list of differential diagnoses may be wide ranging and can include normal recovery from perinatal hypoxia, transient dystonia, mental retardation and a plethora of metabolic and genetic diseases.⁸

The following list are commonly considered in the differential diagnosis of cerebral palsy:¹

• Acute poliomyelitis
• Becker muscular dystrophy (a group of genetic diseases causing muscle weakness, affects only males)⁹
• Charcot-Marie-Tooth disease
• Kugelberg Welander spinal muscular atrophy - a rare inherited disorder causing progressive degeneration of the anterior horn cells of the spinal cord.¹⁰
• Neonatal brachial plexus palsies
• Stroke motor impairment
• Traumatic brain injury

The type investigations will depend upon the presentation and the list of differential diagnoses that need to be excluded.

A suggested protocol is as follows:^1,8

Laboratory investigations

• Thyroid studies
• Chromosome analysis
• Lactate and pyruvate levels to exclude mitochondrial cytopathies (a group of systemic diseases caused by inherited or acquired damage to the mitochondria.¹¹
• Organic and amino acid levels - to exclude organic acid and amino acid conditions presenting with neurological symptoms.¹²
• Cerebrospinal fluid - protein, lactate and pyruvate levels may be helpful in determining whether there has been any asphyxia in the neonatal period.

Neuroimaging studies

Although there are no definitive diagnostic tests, neuroimaging can help to identify patients who are likely to be at risk.

• Ultrasound can help to identify very preterm babies at risk of cerebral palsy. One study found a strong link between severe cranial abnormalities identified in the neonatal period and the incidence of cerebral palsy 2 years later, although one third of children with cerebral palsy had no detectable ultrasound abnormalities.¹³
• MRI scans are useful for detecting white matter lesions in older children, but traditional methods used in younger children have failed to provide good predictive results.¹⁴ However, newer developments and the use of sequential MRI has proven of value in demonstrating the various injuries (e.g. asphyxia) and anomalies that can lead to cerebral palsy. Fetal MRI has also yielded useful information.¹⁵
• CT may provide information about structural congenital malformations and vascular abnormalities and haemorrhages, especially in babies.¹

Other tests

• Evoked potentials - these are the electric signals produced by the nervous system in response to sensory stimuli. Measuring them can help to detect abnormalities of hearing and vision.¹⁶
• EEG - this can help to detect damage from hypoxia and vascular insult.

• Intrauterine infections - e.g. rubella, HIV, cytomegalovirus, toxoplasmosis.
• Congenital malformations - this is often due to intrauterine events such as vascular insult and particularly affects the cerebellum, periventricular regions and corpus callosum.¹⁸ A recent study found that cerebral malformations were much more frequent among children with cerebral palsy that among all livebirths in the population. The study also found an increase in non-cerebral malformations close to the brain (e.g. eye, facial clefts) in such children.¹⁹
• Toxic or teratogenic agents - including alcohol, cocaine and cigarette smoke (probably relates to low birth weight).
• Maternal abdominal trauma - very rare unless there is extensive injury causing co-existent fetal brain trauma.
• Maternal illness - e.g. intrauterine infections, thyroid abnormalities and any condition leading to low birth weight.¹⁸
• Intracranial haemorrhage
• Trauma
• Infection
• Hyperbilirubinaemia
• Hypoxia
• Maternal iodine deficiency
• Seizures

There is no formal staging method as such but the GMFCS is a useful method of assessing severity. It can be applied to younger age groups, but is most suitable for children aged 6-12.

The treatment of cerebral palsy needs to be multidisciplinary and goal-directed. There is a danger that various abnormalities (e.g. movement disorder) are treated in a jigsaw fashion without any overall view of the benefits to the patient and the family. The GMFCS is a useful guide as to the effectiveness of any particular treatment.

Many disciplines will need to be involved and treatment will often involve input from:¹

• Physiotherapists
• Occupational Therapists
• Speech Therapists
• Recreational Therapists

Medical treatment¹

• Baclofen - this is helpful in relieving muscle spasm. It is usually given orally but can be administered in the form of an intrathecal cannula and pump in cases of diffuse spasticity. This sometimes obviates the need for surgical intervention.
• Dantrolene - this may work better than baclofen when muscle spasm is severe.
• Diazepam - another option for severe muscle spasm.

Surgical treatment¹

A variety of surgical procedures may be helpful in certain situations, including:

• Repair of scoliosis and hip dislocation.
• Tendon lengthening or transfer to decrease the imbalance from muscle spasticity.
• Osteotomy to realign a limb.
• Selective posterior rhizotomy - this involves operating on nerve roots emanating from the spinal cord and is useful in selected patients with muscle spasticity. It is used less often now that the baclofen infusion pump is available.

Other treatments^1,2

• Mobility aids - these may include orthotic devices, wheelchairs and powered mobility walkers.²⁰
• Botulinus toxin - this can afford the relief of spasticity for 3-6 months.
• Phenol injections - sometimes used in larger muscles, where botulinus would be ineffective.
• Physical methods of spasticity relief include heat, cold and vibration.
• There is some evidence that cranial osteopathy and myofascial release can improve mobility in patients with moderate to severe cerebral palsy.²¹
• Splinting can help to improve the range of movement of a joint; this can be particularly effective for ankle joints.

Other issues

• The psychological and physical health of carers should not be forgotten.
• With improved care, the life expectancy of cerebral palsy patients is lengthening. The social and educational integration of young adults into the community is a matter of increasing importance.

• Contractions - the development of these can be minimised by effective treatment of spasticity.
• Gastrointestinal symptoms - this includes reflux and oropharyngeal muscle disorders affecting swallowing and clearance of saliva. Failure to thrive and osteoporosis can result from nutritional deficiencies.
• Pulmonary complications include aspiration pneumonia and bronchopulmonary dysplasia.
• Dental problems can occur.
• Mental retardation (in 30-50% of patients) is often associated with severe spastic quadriplegia.
• Hearing loss - this is particularly seen where the secondary cause is hyperbilirubinaemia or exposure to ototoxic drugs.

Many patients with a mild form have a normal life expectancy. A two year old with mild palsy has a 99% chance of living to the age of 20, compared with a patient who has severe disease, where the figure can be as low as 40%.²²

A poor prognosis is associated with severe quadriplegia, epilepsy, mental retardation and medical complications such as reflux and pulmonary disease.¹⁷

Studies suggest that if a child can sit up unaided at the age of 2 they will eventually be able to walk. If they are unable to sit by the age of 4, they will be unable to walk.¹⁷

Much has been done to reduce the incidence of cerebral palsy, including the recognition and treatment of maternal iodine deficiency, the prevention of kernicterus associated with rhesus isoimmunisation and modern obstetric techniques to reduce birth trauma.² Proactive treatment to minimise the effects of perinatal brain injury, including magnesium sulfate in the preterm newborn and hypothermia in the term newborn, is currently being investigated. Many cases of cerebral palsy are still unexplained, however and further work needs to be done on the aetiology of perinatal brain injury.²³