So What IS Cerebral Palsy, Anyway? Part I: Types

So what is Cerebral Palsy, anyway?

Short Answer: It's a condition caused by damage to the brain in utero or during birth, or by an organic inability of the brain to develop and/or grow properly. It is not a pediatric stroke, though the symptoms are similar.

Are there different types of Cerebral Palsy?

Short Answer: Yes. CP is generally accepted as having 4 major types: Spastic, Ataxic, Dyskenetic, and Mixed. Below is a brief description of each type.

Spastic Cerebral Palsy is the most common type of CP. Approximately 80% of people with Cerebral Palsy have a spastic type. Types of spastic CP are categorized by which parts of the body are most affected, and 3 general types have been defined: Spastic quadriplegia (all four limbs affected); Spastic diplegia (two limbs on opposite sides of the body affected, most commonly the legs); and Spastic hemiplegia (affecting one side of the body.) Occasionally you'll see a 4^th type of spastic CP mentioned in medical literature -- Spastic tertraplegia, denoting marked  involvement of both legs and one arm or hand -- but it doesn't seem to be widely accepted as part of the categorization process, and is generally lumped in with diplegia. (Remember, we're categorizing by what is most affected; Cerebral Palsy of any type is a whole body condition.)

Spastic CP is characterized by a noticeable and chronic increase in muscle tone. People with types of Spastic CP often exhibit stiff, labored movements, limb rigidity, and joint problems. They also have trouble with balance and both fine and gross motor skills -- symptoms that are present across the CP spectrum, no matter the type. Problems with sight, hearing, and/or speech are common among all types as well.

The next type of Cerebral Palsy is called Ataxic CP (or Ataxia.) The most marked symptoms of Ataxia are those found in any other type of Cerebral Palsy: problems with walking, balancing, and coordination. Those with Ataxic CP may exhibit an unsteady gait and have an especially difficult time with quick movements or with tasks that require a great deal of fine motor control, such as writing.

Next comes Dyskenetic CP. At one time called "Athetoid" this category has been renamed and expanded to include any type of Cerebral Palsy of which the primary symptom is uncontrollable muscle movement. (Athetoid now falls under this umbrella, as do Choreoathetoid and Dystonia.) Those with a type of Dyskenetic CP exhibit uncontrollable movements of the arms, hands, legs, facial muscles, and tongue. They may have a difficult time swallowing, drinking from a straw, and talking. Muscle movements produced by Dyskenetic CP may be fast and jerky or slow and writhing, and muscle tone can vary from too tight to too loose from day to day, or even within the same day.

Mixed CP occurs when a person exhibits symptoms of more than one type of Cerebral Palsy. The most common type of Mixed CP is Spastic-Dyskinetic. I myself was re-categorized as having a Mixed type of CP when I developed dyskinesia in high school: trouble controlling my arms (they like to bend on their own), and an occasional, sustained, repetitive tic of the neck and face, and I am now classified as Spastic-Diplegic-Dyskinetic. (Mixed.)

Note: Cerebral Palsy is notoriously difficult to classify. Due to the nature of brain abnormalities, symptoms such as dyskinesia, intention tremor, and dysphagia (trouble swallowing) can appear suddenly throughout a person's lifetime. Categorization is mainly for purposes of statistical analysis and broad treatment goals.

What parts of the brain does Cerebral Palsy affect?

Short Answer: All types of CP primarily involve the cerebellum, the area of the brain responsible for balance, coordination, and voluntary movement. Also affected is the cerebrum, which is the main "body" of the brain that houses the areas responsible for all other brain functions. (See diagram below.) Depending on the type of CP, different parts of the cerebrum may or may not be affected. (Some people have trouble with the part of the brain responsible for speech, others with the part of the brain responsible for sight, etc. CP is multi-symptomatic, meaning an individual can have trouble with many of these things simultaneously.)

Diagram of the human brain showing the cerebellum
(against the brain stem)
and the cerebrum, labelled with some of the things
for which different areas are responsible.

This post is one in a series dealing with the technical aspects of Cerebral Palsy. Tune in next week for more information on the side effects of Cerebral Palsy, and its treatment.