Cerebral palsy refers to a group of disorders that affect a person's ability to move and to maintain balance and posture. It is due to a non-progressive brain abnormality, which means that it does not get worse over time, though the exact symptoms can change over a person's lifetime.
People with cerebral palsy have damage to the part of the brain that controls muscle tone. Muscle tone is the amount of resistance to movement in a muscle. It is what lets you keep your body in a certain posture or position.
For example, it lets you sit up straight and keep your head up. Changes in muscle tone let you move. For example, to bring your hand to your face, the tone in your biceps muscle at the front of your arm must increase while the tone in the triceps muscle at the back of your arm must decrease. The tone in different muscle groups must be balanced for you to move smoothly.
There are four main types of cerebral palsy - spastic, athetoid, ataxic, and mixed.
Spastic: People with spastic cerebral palsy have increased muscle tone. Their muscles are stiff. Their movements can be awkward. Seventy to eighty percent of people with cerebral palsy have spasticity. Spastic cerebral palsy is usually described further by what parts of the body are affected. In spastic diplegia, the main effect is found in both legs. In spastic hemiplegia, one side of the person's body is affected. Spastic quadriplegia affects a person's whole body (face, trunk, legs, and arms).
Athetoid or dyskinetic: People with athetoid cerebral palsy have slow, writhing movements that they cannot control. The movements usually affect a person's hands, arms, feet, and legs. Sometimes the face and tongue are affected and the person has a hard time talking. Muscle tone can change from day to day and can vary even during a single day. Ten to twenty percent of people with cerebral palsy have the athetoid form of the condition.
Ataxic: People with ataxic cerebral palsy have problems with balance and depth perception. They might be unsteady when they walk. They might have a hard time with quick movements or movements that need a lot of control, like writing. They might have a hard time controlling their hands or arms when they reach for something. People with ataxic cerebral palsy can have increased or decreased muscle tone. Five to ten percent of people with cerebral palsy have ataxia.
Mixed: Some people have more than one type of cerebral palsy. The most common pattern is spasticity plus athetoid movements.
The symptoms of cerebral palsy vary from person to person. Symptoms can also change over time. A person with severe cerebral palsy might not be able to walk and might need lifelong care. A person with mild cerebral palsy, on the other hand, might walk a little awkwardly, but might not need any special help.
People with cerebral palsy can have other disabilities as well. Examples of these conditions include seizure disorders, vision impairment, hearing loss, and intellectual disability.