Cerebral palsy (CP) describes a group of disorders of the development of movement and posture, which limit activity. They are caused by damage that occurred in the developing foetal or infant brain. The movement disorder is often accompanied by disturbances of sensation, cognition, communication, perception, and/or behaviour, and/or by epilepsy (see Accompanying Impairments).
The damage to the brain persists during the lifetime, but does not progress. However because the damage has occurred to an immature brain which is still developing, the disorder of movement and posture can change over time in the way it affects a child and adult.
There are several types of movement disorder. The most common involves the child having:
- Spastic hypertonus (stiffness of muscles), which can vary in severity between children, making movement in the affected body parts slow and difficult. It is caused by damage to the motor cortex of the brain, the part that controls movement.
- Athetosis results in uncontrolled involuntary movements which produce fluctuations in muscle tone – muscles can sometimes be too stiff or too floppy and this can change suddenly. Movement is disorganised and this makes it difficult for children with athetosis to stay still in one position like sitting or controlling limb movements precisely, such as using their hands to hold objects. It arises from damage to the basal ganglia (a group of nuclei within the brain).
- Ataxia usually involves damage to the cerebellum which results in difficulties with balance and planning of movement. They often have difficulty with the fine control of movement and may have a tremor which increases on activity. Their muscle tone is usually low (slightly floppy).
- Hypotonia results in a child having reduced muscle tone (floppiness) throughout their body, making any movements against gravity difficult, and sustaining upright postures such as sitting and standing difficult.
Cerebral palsy varies in the parts of the body it affects:
- Quadriplegia affects the whole body with the arms usually being as affected or more affected than the legs.
- Diplegia affects the whole body with the legs being more involved than the arms.
- Hemiplegia predominantly or only affects one side of the body.