What is cerebral palsy?

What is cerebral palsy?

Whilst cerebral palsy can be described in various ways, in 2006/7 it has been defined as:

“A group of permanent disorders of the development of movement and posture, causing activity limitations that are attributed to non-progressive disturbances that occurred in the developing fetal or infant brain. The motor disorders of cerebral palsy are often accompanied by disturbances of sensation, perception, cognition, communication and behaviour, by epilepsy and by secondary musculoskeletal problems.” (1)

Obviously this is a clinical definition meaning that cerebral palsy is a condition in which there may be abnormal brain development or injury to the brain as it develops. This can occur before, during, after birth or during early childhood.

Children with cerebral palsy have difficulties in controlling muscles and movements as they grow and develop. The nature and extent of these difficulties may change as children grow but cerebral palsy itself is not progressive: the injury or impairment in the brain does not change. However, the effects of the brain injury on the body may change over time for better or worse. Physiotherapy and other therapies can often help people with cerebral palsy reach their full potential and become more independent therefore children with cerebral palsy will often be referred to a therapist or see a multi-disciplinary team through referral to the local Child Development Centre.

Depending on the precise area of the brain that is affected, there may be associated difficulties which become obvious during development; for example, in vision, hearing, learning and behaviour.

It is not unusual for a diagnosis not to be given until the child’s motor development is nearly complete as doctors observe the child through the development stages of sitting, crawling and walking. There is currently no test before birth that will identify cerebral palsy.

Cerebral palsy is often referred to as an “umbrella term” (Focusing on Cerebral Palsy – 2) as it applies to a collection of conditions where there is primarily a disorder of voluntary movement and/or co-ordination. No two people will be affected by their cerebral palsy in the same way and it is important to ensure the focus of treatments and therapies are tailored to individual needs.

Prevalence of cerebral palsy

In the UK, cerebral palsy affects about one in every 400 children (2 – 2.5 per 1,000 live births – (3). Cerebral palsy can affect people from all social backgrounds and ethnic groups.

Causes and risk factors of cerebral palsy

It can be very difficult for doctors to give an exact reason as to why part of a baby’s brain has been injured or failed to develop. In some instances, there may be no obvious single reason why a child has cerebral palsy. It is generally accepted that causes of cerebral palsy can be multiple and complex (4). These can include:

  • Infection in the early part of pregnancy
  • Oxygen deprivation to the brain
  • Abnormal brain development
  • Restricted intrauterine growth
  • Neonatal stroke
  • Blood such as rare abnormalities of platelets
  • A genetic link (though this is quite rare)

Risk factors

A risk factor is not a cause; it is a condition or characteristic which, if present, can increase the chance of something occurring, in this case, cerebral palsy. Even though a risk factor may be present it does not mean that cerebral palsy will occur; nor does the absence of a risk factor mean it will not occur. Focusing on Cerebral Palsy (5) in 1994 mentioned the following risk factors.

  • Difficult or premature birth
  • Twins or multiple birth
  • Mother’s age being below 20 or over 40
  • Father under 20 years
  • First child or child born fifth or more
  • Baby of low birth weight (less than 2.5 pounds)
  • Premature birth (less than 37 weeks)

More than one risk factor can be present at the same time (for example, low birth weight and being a twin) and such a combination can further increase the probability of cerebral palsy occurring.

Types of cerebral palsy

In general we talk about three main types of cerebral palsy – spastic, dyskinetic (often known as athetoid or dystonic) and ataxic cerebral palsy. These describe effects on the body and muscle tone that are dependent upon, which part of the brain has been affected. Many people with cerebral palsy will have a mixture of these types.

Spastic cerebral palsy

This is present in 75% – 88% of people with cerebral palsy (6), spasticity refers to the muscle tone being unyielding and tight (hypertonia) with a decreased range of movement. It can affect different and many areas of the body so a person with spastic cerebral palsy could, in addition to impaired mobility, have difficulties with speech or continence.

If the person is only affected on one side of their body the term used to describe this is hemiplegia or unilateral cerebral palsy. If two limbs are affected (usually legs more than arms), the term is diplegia and if all four limbs are affected the term used is quadriplegia.

Dyskinetic cerebral palsy

Sometimes referred to as dystonic, athetoid or choreoathetoid. Present in about 15% of people with cerebral palsy (7). People with dyskinetic cerebral palsy experience uncontrolled, involuntary, sustained or intermittent muscle contractions as the tone of the muscle can change from floppy and loose (hypotonia) to tight with slow, rhythmic twisting movements. The whole body can be affected resulting in difficulties maintaining an upright position. Speech can be hard to understand as there may be difficulty controlling the tongue, breathing and vocal chords.

Ataxic cerebral palsy

This is present in about 4% of people with cerebral palsy (8). Ataxia is defined as an “inability to activate the correct pattern of muscles during movement” (9). People with ataxic cerebral palsy find it very difficult to balance. They may also have poor spatial awareness, which means it is difficult for them to judge their body position relative to things around them. Ataxia affects the whole body. Most people with ataxic cerebral palsy can walk but they will probably be unsteady with shaky movements. Speech and language can also be affected.

Mixed presentation

It can be difficult to say what type of cerebral palsy a person has as it is common to have a combination of two or more types. As mentioned, it is important to bear in mind that no two people with cerebral palsy are affected in the same way. Some have cerebral palsy so mildly that it’s barely noticeable. Others may be profoundly affected and require help with many or all aspects of daily life.

Associated difficulties

All people with cerebral palsy are individuals; some may have associated difficulties while others may not. These can include:

  • Secondary musculoskeletal problems and motor control. Often contractures of muscles of the spine or hip dislocation. Here it is important to look at postural management such as asymmetry (balance, proportion and co-ordination) of the body. A referral to a physiotherapist may be helpful.
  • Learning or cognitive impairment. These difficulties can be mild, moderate or severe and generalised or specific. The reported incidence varies because different studies define the impairment in different ways. However it is estimated that the incidence of intellectual impairment is around 45% with 25% classified as severe (meaning an IQ score of less than 50) (10). As with the rest of the population there is a huge range of intelligence and many children perform well at school or further education.
  • Constipation, muscle spasms or problems with sleeping and sleep patterns. The doctor or health visitor should be able to offer advice about this. If you or your child is experiencing difficulties in sleeping, you may find our sleep information helpful.
  • Sensory impairment such as difficulties with hearing and visual acuity. Hearing impairment is only present in 8% of cases (11). An audiologist may be able to offer more specialized advice. If you are concerned ask your doctor for further information and/or referral to a specialist.
  • With speech, language or feeding difficulties, it may be useful to have contact with a Speech and Language Therapist. Again speak to your doctor or Paediatrician if it involves a child.
  • Epilepsy can occur in up to a third of children with cerebral palsy (12). Seizure types can vary. Consult your doctor as medication can help to manage this.
  • Spatial awareness and perception. This is about a person’s ability to interpret what they have seen as opposed to problems with vision/eyesight.
  • Sometimes behavioural or psychological behaviours (inattention, anxiety, over activity) may develop in one in four children with cerebral palsy (13).



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