There are three main types of cerebral palsy reflecting damage to different areas of the brain.
- Spastic cerebral palsy arises from motor cortex damage. Muscles appear stiff/tight.
- Ataxic cerebral palsy arises from cerebellum damage. Movement appears jerky, and balance and spatial awareness is poor. Muscles may be floppy.
- Dyskinetic cerebral palsy (including athetoid and dystonic cerebral palsy) arises from damage to the basal ganglia and is characterised by involuntary movement.
Mixed cerebral palsy arises from damage to more than one area of the brain.
You may see these types of cerebral palsy additionally described as hemiplegic or diplegic, referring to the area of the body and number of limbs affected.
In the medical community, spastic cerebral palsy is referred to as pyramidal and non-spastic (ataxic/dyskinetic) as extrapyramidal.
Cerebral palsy may also be described as hypertonic or hypotonic:
- Hypertonic cerebral palsy (spastic cerebral palsy) is characterised by stiff and rigid muscles with excessive tone.
- Hypotonic cerebral palsy (ataxic cerebral palsy) is characterised by diminished muscle tone or loose/floppy muscles.
Each type of cerebral palsy will affect a person’s muscle control and movement in different ways, and many people with cerebral palsy will have a combination of types.
Cerebral palsy is also classified by its severity (mild, moderate or severe) and no two cases of cerebral palsy are the same.
Families and health professionals can use the Gross Motor Function Classification System (GMFS) to describe the abilities of children and young people with cerebral palsy. It categorises abilities into five levels that are used to decide on the most appropriate and effective treatment and therapies.
We describe the different types of cerebral palsy and the classification system in more detail below.
What is spastic cerebral palsy?
Spastic cerebral palsy is the most common type of cerebral palsy occurring in more than 70% of all cases. Spasticity, a form of hypertonia, is a state of increased muscle tone or excessive muscle contraction affecting different areas of the body.
It is a neuromuscular (nerve and muscle) mobility impairment, caused by injury to the brain in the pyramidal tract. This type of injury is also referred to as upper motor neuron damage. See also Causes of cerebral palsy.
It’s characterised by an often painful rigidity, tightness or ‘pull’ in the muscle that decreases its range of movement. The muscle(s) may often go into spasm.
Along with limbs, the tongue may be affected, which affects speech, eating, breathing and swallowing.
What is ataxic cerebral palsy?
Ataxic cerebral palsy features in 5-10 per cent of people with cerebral palsy. It is caused by damage to the cerebellum – the region of the brain that coordinates muscle movement.
The condition causes an interruption of muscle control in the arms and legs, resulting in a lack of balance, coordination and depth perception.
The movements of someone with ataxic cerebral palsy may seem jerky or shaky. The person may also experience tremors/shaking in their muscles when carrying out specific actions, such as writing.
The condition can affect limbs, eye movements and the muscles involved in swallowing. People with ataxic cerebral palsy may walk with a wide gait.
Ataxic cerebral palsy can cause hypotonia (reduced muscle tone or floppy/loose muscles) which further impedes movement. Young babies with ataxic cerebral palsy are often noted to be ‘floppy’.
What is dyskinetic cerebral palsy?
Dyskinetic cerebral palsy includes both athetoid cerebral palsy and dystonic cerebral palsy, affecting around 15% of people with the condition. It can also be described as extrapyramidal cerebral palsy.
A person with dyskinetic cerebral palsy will experience variable movements outside of their control and these are made worse by an attempt to move. The condition is caused by damage to the basal ganglia, the area of the brain responsible for regulating voluntary movements.
Different forms of dyskinesia result from damage to different structures within the basal ganglia (athetoid cerebral palsy, dystonic cerebral palsy and choreoathetoid cerebral palsy).
Athetoid cerebral palsy chiefly affects the arms, legs, hands and dystonic cerebral palsy, chiefly affects the trunk but also limbs. These forms can be differentiated further by the type of involuntary movement the person experiences.
What is athetoid and choreoathetoid cerebral palsy?
Athetoid cerebral palsy is a type of dyskinetic cerebral palsy characterised by involuntary slow, continuous writhing movements, usually affecting the hands, feet, arms or legs and sometimes the whole body. Facial muscles, lip and tongue movements can also be affected, and therefore speech, eating and drinking can be difficult. Movements are made worse by attempts to move and increase under emotional or physical stress. They are present even when the body is at rest but disappear when the person is asleep.
Unlike with spastic or ataxic cerebral palsy, people with athetoid cerebral palsy will experience fluctuations in muscle tone, i.e. they have both hypotonia (reduced muscle tone) and hypertonia (increased muscle tone). This can make it difficult to maintain a position like sitting or standing.
Choreoathetoid cerebral palsy is when athetoid cerebral palsy occurs with chorea. Chorea is characterised by involuntary movements that are irregular, unpredictable and brief. It affects various parts of the body and also speech and swallowing.
What is dystonic cerebral palsy?
Dystonic cerebral palsy is a type of dyskenetic cerebral palsy resulting in involuntary muscle contractions, characterised by slow twisting or repetitive movements and awkward, sustained postures. These contractions are triggered by an attempt to move, and may become increasingly frequent and painful when the person is tired or stressed.
Dystonic cerebral palsy chiefly affects trunk muscles (resulting in a fixed, twisted posture), but can also affect a combination of limbs and trunk muscles. This is known as generalised dystonia. Speech and swallowing can be affected.
Focal dystonia is when the condition affects only one part of the body, such as a person’s foot, and is triggered by a specific task or movement.
What is diplegic, hemiplegic and quadriplegic cerebral palsy?
Cerebral palsy can affect different parts of the body. The terms diplegic, hemiplegic and quadriplegic are used to describe the number of limbs affected:
- Diplegic cerebral palsy affects both legs. The arms may be affected to a lesser extent
- Hemiplegic cerebral palsy affects just one side of the body (one arm and one leg)
- Quadriplegic cerebral palsy affects both arms and legs and the muscles of the trunk, face and mouth can also be affected.
What is hypertonic and hypotonic cerebral palsy?
Cerebral palsy may be described as hypertonic or hypotonic:
- Hypertonia results in stiff and rigid muscles with excessive tone (as characterised in spastic cerebral palsy)
- Hypotonia results in diminished muscle tone or loose/floppy muscles (as characterised in ataxic cerebral palsy).
People with athetoid cerebral palsy experience both hypertonia and hypotonia.
What is spastic quadriplegia?
Spastic quadriplegia is is the most disabling type of spastic cerebral palsy affecting both arms and legs and often the trunk, face and mouth. People with spastic quadriplegia cannot walk and may experience seizures. While their limb muscles may be stiff, their neck may be floppy and out of their control. Speech can be profoundly affected.
Professionals may be able to diagnose a child with spastic quadriplegia at birth, but it is often postponed until the child is 18-24 months old. This way they can monitor any developments or regression in the child’s symptoms.
Spastic quadriplegia is caused by brain damage or disruptions in normal brain development preceding birth, including:
- Bleeding in the brain (intracranial haemorrhage)
- Abnormal brain development
- Damage to the white matter (periventricular leukomalacia)
- Damage due to lack of oxygen.
Because of the severity of spastic quadriplegia, a person can experience several other medical complications including bowel and bladder problems and limb deformities. The condition can also affect a person’s cognitive abilities.
What is the Gross Motor Function Classification System?
The Gross Motor Function Classification System (GMFCS) is a universal classification system that helps families and health professionals to:
- Categorise the severity of their child’s cerebral palsy
- Provide a clear description of their child’s current motor function (e.g. head control and their ability to walk, sit, run, jump and use wheeled, hand-held, motorised or manual mobility aids)
- Decide on the most appropriate treatment, surgery, therapies and mobility aids.
The tool focuses on what the child can accomplish, categorising their motor function abilities into five different levels.
Children at level 1 will be able to walk without restrictions and their symptoms may be described as mild. Children at level 5 are restricted in their ability and generally transported in a manual wheelchair. Their symptoms would be described as severe. Children are graded upon what they normally can do at home, school and in the community, rather than their best attempts.
There are five age bands (under 2, 2-4 years, 4-6 years, 6-12 years, and 12-18 years). By age 5, a child will be unlikely to improve their GMFCS level.
Health professionals will routinely grade your child using the GMFCS , but you can also complete a family report questionnaire, classifying your own child’s motor abilities.
The GMFCS can be downloaded for personal use at no cost from the CanChild website (based in Canada).