Cerebral palsy is divided into three major classifications to describe different movement impairments. The classifications are also significant to different areas of the brain.
The broad classification includes:
Spastic type
This is the most common type of cerebral palsy. It occurs in 70 to 80% of all cases. This type also accompanies nearly a third of other types of cerebral palsy as well.
The features of this type of cerebral palsy include increased muscle tome. The damage is said to be in the corticospinal tract or the motor cortex. This part affects the areas that receive gamma amino butyric acid or GABA that is an inhibitory neurotransmitter.
Spastic cerebral palsy is further divided into types according to the areas of the body that it affects. For example:
- In Spastic hemiplegia one side of the body is affected. It occurs when injury to muscle-nerves controlled by the brain's left side will cause a right body deficit, and vice versa. These patients have a fair amount of capability to move around.
- In Spastic diplegia the lower limbs are affected with little to no upper-body spasticity. The most common form of the spastic forms is spastic diplegia. Most people with spastic diplegia are fully ambulatory and have a scissors gait. This means their legs cross over while they attempt to walk. They may also have other problems like hip problems, dislocations, crossed eyes or strabismus. The intelligence of a person with spastic diplegia is unaffected by the condition.
- In Spastic tetraplegia all four limbs affected equally. These patients are least likely to be able to walk. This is because their muscles are too tight and they may also develop an uncontrollable shaking that affects the limbs on one side of the body that impairs normal movement.
- Other forms include monplegia (one limb affected), paraplegia (two limbs affected), triplegia (three limbs affected) etc.
Ataxic type
This type of cerebral palsy occurs due to damage to the cerebellum or lower part of the brain at the back of the head. This area normally deals with movement, gait and coordination.
This is one the less common types of cerebral palsy forming around 10% of all cases. There may be additional tremors or shaking. These children have problems with other motor skills like writing, typing, using their fingers for fine movements as well as have balance problems while walking. They may also have trouble with visual and/or auditory processing.
Athetoid/dyskinetic type of cerebral palsy
Here the muscle tone is mixed. At times it may be too lax or hypotonic and at times it may be too tight or hypertonic. Hypotonia will usually occur before 1 year old. The muscle tone increases with age and progress to Hypertonia.
The damage occurs to the extrapyramidal motor system and/or pyramidal tract and to the basal ganglia. It occurs in 10% to 20% percent of all cases. Athetoid cerebral palsy may be seen in newborns who have had severe jaundice and kernicterus.
These patients have trouble holding themselves in an upright, steady position for sitting or walking, and often show involuntary motions. For these patients it is difficult to bring their hands or limbs together for any form of concentrated work. This could be something simple such as picking up a glass to drink water.
Mixed type
There may be a combination of several forms. The most common type of mixed cerebral palsy is spastic-dyskinetic cerebral palsy.
Other classification methods
Classification may also be based on the timing of the brain injury. This could be prenatal (most common) or those occurring before birth, natal or those during birth and postnatal or those occurring after birth.
Alternatively classification may be based on actual cause:
- Congenital cerebral palsy – this could be due to developmental, malformations or due to syndromes
- Acquired cerebral palsy due to injuries, infections, lack of oxygen or hypoxia, ischemic or those caused by TORCH and other infections.
