Cerebral palsy

What is cerebral palsy?

NICE defines cerebral palsy (CP) as 'an umbrella term that encompasses a group of permanent movement and posture disorders that limit activity'. They go on to say that the underlying cause is an acquired pathology within the developing brain, during the prenatal, neonatal or early infant period and that the impaired movement associated with CP results from centrally-mediated abnormal muscle tone which leads (most commonly) to spasticity. ¹

Although the disorder causing cerebral palsy is not progressive, the symptoms and restriction of activities (which can range from mild to severe) may be progressive and become worse with time.

The motor disorders of cerebral palsy are often accompanied by other abnormalities, including disturbances of sensation, perception, cognition, communication and behaviour, and also associated with other problems such as epilepsy, bladder and bowel problems, feeding and swallowing difficulties and secondary musculoskeletal problems. ¹

What causes cerebral palsy? (Aetiology)²

Cerebral palsy is caused by damage to the immature brain during the prenatal, neonatal or early infant period.

For 50-75% of children with cerebral palsy, the causative lesion occurs between 24 weeks of postmenstrual age and term. This is the period during which brain development is characterised by a high rate of widespread and complex developmental processes.³

The damage may be vascular, hypoxic-ischaemic, teratogenic, genetic or due to infection, toxins, metabolic problems or trauma. Prenatal, perinatal and postnatal circulatory dysfunction lead to different physical impairments and thus different clinical patterns.⁴

• Congenital malformations as a cause of cerebral palsy:

  • Are more common in children born at term than in those born prematurely.

  • May occur in children with any functional level or motor subtype.

  • Are associated with higher levels of functional impairment than other causes.

• Neonatal encephalopathy can result from various pathological events, such as a hypoxic-ischaemic brain injury or sepsis, and if there has been more than one such event, they may interact to damage the developing brain.

• Neonatal encephalopathy has been reported at the following approximate prevalences in children with cerebral palsy born after 35 weeks:

  • Attributed to a perinatal hypoxic-ischaemic injury: 20%.

  • Not attributed to a perinatal hypoxic-ischaemic injury: 12%.

• For cerebral palsy associated with a perinatal hypoxic-ischaemic injury:

  • The extent of long-term functional impairment is often related to the severity of the initial encephalopathy.

  • The dyskinetic motor subtype is more common than other subtypes.

• For cerebral palsy acquired after the neonatal period, the following causes and approximate prevalences have been reported:

  • Meningitis: 20%.

  • Other infections: 30%.

  • Head injury: 12%.

• Until recently, 1-2% of cerebral palsy (mostly familial) had been linked to causative mutations. Recent genetic studies of sporadic cerebral palsy cases using new-generation exome sequencing show that 14% of cases have likely causative single-gene mutations and up to 31% have clinically relevant copy number variations.⁵

• Although it was long considered that the main causes of cerebral palsy occurred during the perinatal period, it is now considered that perinatal causes account for less than 10% of people with cerebral palsy.

Classification^{4 6}

Classification based on type of movement disorder

• Spastic type - there may be intermittently increased tone and pathological reflexes.

• Athetoid - this is characterised by increased activity (hyperkinesia). This has been described as 'stormy movement'.

• Ataxic type - there may be a loss of orderly muscular co-ordination so that movements are performed with abnormal force, rhythm or accuracy.

• Mixed - there may be a combination of several forms.

How common is cerebral palsy? (Epidemiology)

The prevalence of CP in resource-rich countries is 2-3.5 per 1,000 live births. It has been suggested that the prevalence may be three times higher in resource-poor countries, due to less access to safe antenatal and perinatal care, and poorer nutrition. The prevalence is significantly higher (35%) in those born prior to 26 weeks of gestation and it is also increased in multiple births, with 12.6 cases per 1,000 live births in twins and 44.8 cases per 1,000 live births in triplets.¹

Th UK pooled data set showed that the severity of impairment increased with increasing gestational age at birth in bilateral spastic cerebral palsy but severity did not vary with gestational age in unilateral palsy. This suggests a different aetiology for the two conditions.

Risk factors²

Risk factors for cerebral palsy include:

Antenatal factors:

• Preterm birth (with risk increasing with decreasing gestational age).

• Congenital malformations.

• Multiple births: twins, triplets, etc.

• Intrauterine infections - eg, toxoplasmosis, rubella, cytomegalovirus, HIV.⁷

• Chorioamnionitis.

• Toxic or teratogenic agents - eg, maternal smoking, alcohol, cocaine or teratogenic drugs such as warfarin.

• Maternal respiratory tract or genitourinary infection needing treatment in hospital.

• Maternal illness - eg, thyroid abnormalities or iodine deficiency.

• Maternal thrombotic disorders including factor V Leiden mutations.

• Placental abruption.

• Fetal brain malformations or genetic/metabolic disorders.

Perinatal factors:

• Low birth weight.

• Chorioamnionitis.

• Neonatal encephalopathy.

• Neonatal sepsis (particularly with a birth weight below 1.5 kg).

• Maternal respiratory tract or genitourinary infection treated in hospital.

• Prematurity.

• Intraventricular haemorrhage.

Postnatal factors:

• Meningitis.

• Intracranial haemorrhage.

• Trauma.

• Infection.

• Hyperbilirubinaemia.

• Hypoxia.

• Seizures.

The main causes of CP are prematurity, multiple gestation and maternal infection such as chorioamnionitis.¹

Cerebral palsy symptoms and presentation⁶

Cerebral palsy is associated with a low Apgar score five minutes after birth.⁸ However, the majority of babies with low scores DO NOT develop cerebral palsy.

It may be suspected when developmental milestones are delayed. 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. The abnormalities may affect one limb (monoplegia), one side of the body (hemiplegia), both lower limbs (paraplegia) or all four limbs (quadriplegia).

The prevalence of the different types of motor disability has remained remarkably constant over the period of 20 years.⁴ Bilateral spastic cerebral palsy is the most prevalent, followed by unilateral or hemiplegic cerebral palsy. Bilateral dystonic cerebral palsy is the least common.

Possible early motor features in the presentation of cerebral palsy include:^{1 2}

• Unusual fidgety movements or other abnormalities of movement, including asymmetry or paucity of movement. Fidgety movements can be present in neurotypical infants up to 5 months of age - if these are absent or unusual (eg, exaggerated speed or jerkiness), this may suggest CP.

• Abnormalities of tone, including hypotonia (floppiness), spasticity (stiffness) or dystonia (fluctuating tone)

• Abnormal motor development, including late head control, rolling and crawling

• Feeding difficulties.

The most common delayed motor milestones in children with cerebral palsy are:^{1 2}

• Not sitting by 8 months (corrected for gestational age).

• Not walking by 18 months (corrected for gestational age).

• Early asymmetry of hand function (hand preference) before 1 year (corrected for gestational age).

Refer all children with delayed motor milestones or who have persistent toe walking to a child development service for further assessment.

Associated conditions, difficulties and symptoms

In a large proportion of individuals with cerebral palsy, the motor impairment is accompanied by other problems, which may include:

Learning disability (IQ below 70) occurs in around 1 in 2 children and young people with cerebral palsy. Severe learning disability (IQ below 50) occurs in around 1 in 4 children and young people with cerebral palsy.

Communication difficulties occur in around 1 in 2 children and young people with cerebral palsy. At least 1 in 10 need augmentative and alternative communication because of cognitive and sensory impairments and communication difficulties (signs, symbols and speech generating devices). Communication difficulties may occur with any functional level or motor subtype but are more common in children and young people with dyskinetic or severe bilateral spastic cerebral palsy.

Emotional and behavioural difficulties (eg, low self-esteem) are reported in up to 1 in 4 children and young people with cerebral palsy. Children and young people with cerebral palsy have an increased prevalence of mental health and psychological problems, including depression, anxiety and conduct disorders. There is also an increased prevalence of challenging behaviours (may be triggered by pain, discomfort or sleep disturbances), problems with peer relationships, neurodevelopmental disorders, including autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD).

Difficulties with learning and movement may be exacerbated by difficulties with registering or processing sensory information, which can affect function and participation. Sensory difficulties may include primary sensory disorders (such as processing of visual or auditory information - eg, difficulties with depth perception may affect the ability to walk on stairs) and disorders of sensory processing and perception, such as planning movements or being able to concentrate and pay attention.

Around 1 in 2 children and young people with cerebral palsy will have some form of visual impairment. Hearing impairment occurs in around 1 in 10 children and young people with cerebral palsy.

Pain is common in people with cerebral palsy, especially those with more severe motor impairment. Common condition-specific causes of pain, discomfort and distress include:

• Musculoskeletal problems (eg, scoliosis, hip subluxation and dislocation).

• Increased muscle tone (including dystonia and spasticity).

• Muscle fatigue and immobility.

• Constipation.

• Vomiting.

• Gastro-oesophageal reflux disease.

Vomiting, regurgitation and gastro-oesophageal reflux are common in children and young people with cerebral palsy. Around 3 in 5 children and young people with cerebral palsy have chronic constipation.

Epilepsy occurs in around 1 in 3 children with cerebral palsy. It may occur in children and young people with any functional level or motor subtype, but prevalence increases with increasing severity of motor impairment. It is reported in around 1 in 2 children with dyskinetic cerebral palsy.

Other associated problems include:

• Eating, drinking and swallowing difficulties and poor nutrition: failure to thrive and malnourishment.

• Bladder problems: incontinence and infections are common.

• Sleep disturbances: for example, fragmented sleep, which can occur in up to 50% of children.

• Drooling associated with poor saliva control.

• Orthopaedic problems: eg, progressive joint contractures, shortened muscles, hip or foot deformities and scoliosis.

• Increased risk of low bone mineral density and therefore fractures due to osteomalacia or osteoporosis.

In some cases, features such as feeding difficulties may emerge before motor symptoms, or be more obvious in the early years than motor symptoms.

Differential diagnosis

The list of differential diagnoses may be wide-ranging. Because the diagnosis is mainly clinical, it is important to observe the child on several occasions. Some authorities suggest deferring the diagnosis until the patient is 1-2 years old to exclude short-term conditions such as transient hypotonia.⁶ The following are examples of conditions that may be considered in the differential diagnosis of cerebral palsy:⁹

• Acute poliomyelitis.

• Becker's muscular dystrophy.

• 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.

• Neonatal brachial plexus palsies.

• Stroke motor impairment.

• Brain tumour.

• Myelodysplasia.

• Spinal muscular atrophy.

• Spinal stenosis or a tethered spinal cord.

Red flag indicators for neurological disorders other than cerebral palsy include:²

• Absence of known risk factors for cerebral palsy.

• Family history of a progressive neurological disorder.

• Loss of already attained cognitive or developmental abilities.

• Development of unexpected focal neurological signs.

• MRI findings suggestive of a progressive neurological disorder.

• MRI findings not in keeping with clinical signs of cerebral palsy. Consider repeating the MRI scan if there is a change in the expected clinical and developmental profile or if any red flags for a progressive neurological disorder appear.

Investigations⁹

The diagnosis of cerebral palsy is based on clinical examination and parental observation. However, investigations occasionally required to exclude other diagnoses might include:

• Thyroid studies.

• Chromosomal analysis.

• Pyruvate and lactate levels to exclude mitochondrial cytopathies (a group of systemic diseases caused by inherited or acquired damage to the mitochondria).¹⁰

• Organic and amino acid levels to exclude inborn errors of metabolism presenting with neurological symptoms.¹¹

• Cerebrospinal fluid - protein, lactate and pyruvate levels may be helpful in determining whether there has been any asphyxia in the neonatal period.

Neuroimaging studies

There has been controversy over the use of neuroimaging in the prediction of cerebral palsy in neonates. However, studies have determined that:¹²

• Sequential ultrasound imaging can detect major intracranial lesions in patients who subsequently develop non-ambulatory cerebral palsy.

• MRI:²

  • Can be used to investigate the cause of suspected or known cerebral palsy if this is not clear from the history and results of cranial ultrasound examinations.

  • MRI will not accurately establish the timing of a hypoxic-ischaemic brain injury in a child with cerebral palsy. Subtle neuro-anatomical changes that could explain the aetiology of cerebral palsy may not be apparent until 2 years of age.²

• CT scanning may provide information about structural congenital malformations and vascular abnormalities and haemorrhages, especially in babies.¹³

• Positron emission tomography (PET) scanning is a further enhancement which exposes the patient to less radiation compared with CT scanning.¹⁴

Other tests³

• Evoked potentials - these are the electrical signals produced by the nervous system in response to sensory stimuli. Measuring them can help to detect abnormalities of hearing and vision.

• Electroencephalogram (EEG) - this can help to detect damage from hypoxia and vascular insult.

Cerebral palsy treatment and management^{2 4}

Every person with cerebral palsy is an individual and has specific symptoms, difficulties and management needs. Therefore, the management of cerebral palsy needs to be based on individual multidisciplinary assessment and needs to be reviewed and modified with any change of needs. There is a danger that various abnormalities (eg, movement disorder) may be treated in a disjointed fashion without any overall view of the benefits to the person with cerebral palsy and their family.

Many disciplines will need to be involved in assessment and management, including physiotherapists, occupational therapists, speech therapists and recreational therapists. The relative involvement of each discipline will depend on individual management needs.

There are many possible aspects of management, depending on the particular symptoms and difficulties for each individual person. Mobility aids may include orthotic devices, wheelchairs and powered mobility walkers.¹⁵ Splinting can help to improve the range of movement of a joint; this can be particularly effective for ankle joints.

All presenting difficulties should be assessed in the context of the individual person. For example, sleep disturbance, seizures and pain are all common in people with cerebral palsy and it is essential to consider whether pain or seizures may be the cause of any sleep disturbance.

The mental health of people with cerebral palsy should always be considered and any mental health issues recognised and treated at an early stage. The psychological and physical health of carers should also 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. The challenges for young people with cerebral palsy continue into adulthood. It is very important to ensure that their individual developmental, social and health needs, particularly those relating to learning and communication, are addressed when planning and delivering the future care needs at the time of transition to adulthood. In young people with cerebral palsy there may be more than one transition period in health and social care settings - eg, college, resident educational and adult home settings.

Adults with CP may need regular multidisciplinary reassessment to ensure that their changing needs are met, particular during key milestones such as pregnancy and parenting, or when their support structure changes - eg, if their own parent dies and so a source of support is lost.

Medical treatment¹⁶

• Consider oral diazepam or baclofen in children and young people if spasticity is contributing to discomfort or pain, muscle spasms (for example, night-time muscle spasms) or functional disability.

• Diazepam is particularly useful if a rapid effect is desirable (eg, in a pain crisis). Baclofen is particularly useful if a sustained long-term effect is desired (eg, to relieve continuous discomfort or to improve motor function). If oral diazepam is initially used because of its rapid onset of action, consider changing to oral baclofen if long-term treatment is indicated.

• In children and young people with spasticity in whom dystonia is considered to contribute significantly to problems with posture, function and pain, consider a trial of oral drug treatment - eg, trihexyphenidyl, levodopa or baclofen.

• Botulinum toxin type A can be considered if focal spasticity is impeding fine motor function, compromising care and hygiene, causing pain, disturbing sleep, impeding tolerance of other treatments (such as orthoses) or causing cosmetic concerns to the child or young person.

• Botulinum toxin type A treatment can also be considered if rapid-onset spasticity is causing postural or functional difficulties, or if focal dystonia is causing serious problems, such as postural or functional difficulties or pain.

• Treatment with continuous pump-administered intrathecal baclofen can be considered for spasticity if, despite the use of non-invasive treatments, spasticity or dystonia are causing difficulties with pain or muscle spasms, posture or function, or self-care (or ease of care by parents or carers).

• Phenol and ethyl alcohol are used for severe spasticity when botulinum toxin is not readily available. Phenol and ethyl alcohol are non-selective proteolytic agents and can produce selective denervation when injected into motor nerves or muscles. The duration of denervation with ethyl alcohol injection is about 3−6 months. The duration of denervation of phenol is about 4-8 months.¹⁷

Surgical treatment¹⁶

Timely surgery can prevent deterioration and improve function. An assessment should be performed by an orthopaedic surgeon if there is concern that the hip may be displaced or if there is concern about spinal deformity.

Orthopaedic assessment should also be considered:

• If limb function is limited (eg, in walking or getting dressed) by unfavourable posture or pain as a result of muscle shortening, contractures or bony deformities.

• Where contractures of the shoulder, elbow, wrist or hand are causing difficulty with skin hygiene.

• Where the cosmetic appearance of the upper limb causes significant concern.

Consider selective dorsal rhizotomy to improve walking ability. This procedure involves operating on nerve roots emanating from the spinal cord and is useful in selected patients with muscle spasticity.¹⁸

The role of the GP

Much of what has been discussed so far will be started by secondary care, who may also run the multidisciplinary team. The key responsibilities in primary care are to do with coordinating care, identifying associated problems early and managing them, or referring when necessary, and providing support to the parents or other carers. Ensuring that screening is carried out when appropriate is also a key role of the GP (eg, arranging for a cervical smear to be done if possible, taking into account the patient's disability) and as patients get older there may be a need for advanced care planning.

GPs may also prescribe on a shared-care basis. This should only be done by mutual consent, where the GP, the specialist and the patient feel that shared care is safe. Shared care that requires monitoring should be adequately resourced.¹⁹

Complications

• Contractions.

• Gastrointestinal symptoms and their sequelae - eg, reflux, oropharyngeal muscle disorders, failure to thrive and osteoporosis.

• Pulmonary complications - eg, aspiration pneumonia and bronchopulmonary dysplasia.

• Dental problems.

• Moderate/severe learning difficulties (in 30-50% of patients associated with severe spastic quadriplegia).

• Hearing loss (particularly seen where the secondary cause is hyperbilirubinaemia or exposure to ototoxic drugs).

Prognosis²

• The more severe the child's physical, functional or cognitive impairment, the greater the possibility of difficulties with walking.

• If a child can sit at 2 years of age it is likely, but not certain, that they will be able to walk unaided by the age of 6 years.

• If a child cannot sit but can roll at 2 years of age, there is a possibility that they may be able to walk unaided by the age of 6 years.

• If a child cannot sit or roll at 2 years of age, they are unlikely to be able to walk unaided.

• Around 1 in 2 children with cerebral palsy have some difficulty with elements of communication

• Around 1 in 3 children have specific difficulties with speech and language.

• The more severe the child's physical, functional or cognitive impairment, the greater the likelihood of difficulties with speech and language.

• Uncontrolled epilepsy may be associated with difficulties in all forms of communication, including speech.

• A child with bilateral spastic, dyskinetic or ataxic cerebral palsy is more likely to have difficulties with speech and language compared with a child with unilateral spastic cerebral palsy.

• The more severe the child's physical, functional or cognitive impairment, the greater the likelihood of reduced life expectancy.

• There is an association between reduced life expectancy and the need for enteral tube feeding; however, this reflects the severity of swallowing difficulties and is not because of the intervention.

Cerebral palsy prevention⁶

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.

• Treatments to prolong pregnancy in preterm labour.

• Improved neonatal intensive care.