Classified by group of muscles involved
Based on the group of muscles involved (typically only used to further describe spastic CP):
1. Tetraplegia or Quadriplegia : Involvement of the four limbs, the trunk and the head. The great majority of these individuals will not be able to stand up or walk.
2. Diplegia: Both lower limbs are affected to a degree although most people with diplegia have limited use of their legs. Some diplegic individuals are able to walk either fully independently (although their CP is noticeable), with Splints or AFO's or with a walking aid such as crutches or a walker. In diplegia, arms are unaffected or there are only slight affects.
3. Hemiplegia: Only the right side or the left side of the body is involved. People with hemiplegia are the most likely to walk, even though people with the above two types can often walk without assistance, if severity allows.
Classified by presentation
1. Ataxia (ICD-10 G80.4): Persons with ataxia have damage to their cerebellum which results in problems with balance, especially while walking. It is the most rare type, occurring in at most 10% of all cases.
2. Athetoid or dyskinetic (ICD-10 G80.3): Persons with this type generally have involuntary body movements. The damage occurs to the extrapyramidal motor system and/or pyramidal tract and to the basal ganglia. It occurs in ~20% of all cases.
3. Spastic (ICD-10 G80.0-G80.1): Persons with this type have damage to the corticospinal tract, motor cortex, or pyramidal tract. It occurs in ~70% of all cases.
These three types may be found together. In 30% of all cases of cerebral palsy, the spastic form is found with the one of the other types. There are a number of other minor types of cerebral palsy, but these are the most common.