Cerebral palsy is a broad term which encompasses many different disorders of movement and posture.  To describe particular types of movement disorders covered by the term, pediatricians, neurologists, and therapists use several classification systems and many labels.  To understand different types of cerebral palsy more clearly, you must first understand what professionals mean by muscle tone .

All children with cerebral palsy have damage to the area of the brain that controls muscle tone.  As a result, they may have increased muscle tone, reduced muscle tone, or a combination of the two (fluctuating tone).  Which parts of their bodies are affected by the abnormal muscle tone depends upon where the brain damage occurs.

There are three main types of cerebral palsy: Spastic Cerebral Palsy (stiff and difficult movement), Athetoid Cerebral Palsy (involuntary and uncontrolled movement), and Ataxic Cerebral Palsy (disturbed sense of balance and depth perception). Some people may have a combination of any of these types of cerebral palsy.

Spastic Cerebral Palsy

Spastic cerebral palsy is the most common type of cerebral palsy, accounting for nearly 80 percent of all cerebral palsy cases.  Children with this type of cerebral palsy have one or more tight muscle groups which limit movement.  Children with spastic cerebral palsy have stiff and jerky movements.  They often have a hard time moving from one position to another.  They may also have a hard time holding and letting go of objects.

Athetoid Cerebral Palsy

About 10 percent of children with cerebral palsy have athetoid cerebral palsy.  Athetoid cerebral palsy is caused by damage to the cerebellum or basal ganglia.  These areas of the brain are responsible for processing the signals that enable smooth, coordinated movements as well as maintaining body posture.  Damage to these areas may cause a child to develop involuntary, purposeless movements , especially in the face, arms, and trunk.  These involuntary movements often interfere with speaking, feeding, reaching, grasping, and other skills requiring coordinated movements.  For example, involuntary grimacing and tongue thrusting may lead to swallowing problems, drooling and slurred speech.  The movements often increase during periods of emotional stress and disappear during sleep.  In addition, children with athetoid cerebral palsy often have low muscle tone and have problems maintaining posture for sitting and walking.

Ataxic Cerebral Palsy

Low muscle tone and poor coordination of movements is described as ataxic cerebral palsy.  Children with ataxic cerebral palsy look very unsteady and shaky.  This rare form of cerebral palsy affects the sense of balance and depth perception.  Affected persons often have poor coordination and walk unsteadily with a wide based gait , placing their feet unusually far apart.  They have a lot of shakiness, like a tremor you might have seen in a very old person, especially when they are trying to handle or hold a small object such as a pen.  Because of the shaky movements and problems coordinating their muscles, children with ataxic cerebral palsy may take longer than other children to complete certain tasks such and writing a sentence.  This form affects about 5-10 percent of the children diagnosed with cerebral palsy.

Mixed Cerebral Palsy

About 10 percent of children with cerebral palsy have what is known a mixed-type cerebral palsy.  These children have both the tight muscle tone of spastic cerebral palsy and the involuntary movements of athetoid cerebral palsy .  This is because they have injuries to both the pyramidal and extrapyramidal areas of the brain.  Usually the spasticity is more obvious at first, with involuntary movements increasing when the child is between nine months and three years old.  The most common mixed form includes spasticity and athetoid movements, but other combinations are also possible.