Approximately ten percent of children suffering from cerebral palsy have a combination of two or more types. Mixed cerebral palsy and it is the result of an injury to both the extrapyramidal and pyramidal areas of the brain.
The most common form of Mixed CP is a combination of spastic and athetoid movements (accounting for 10% of all mixed cases, but other combinations are also possible. Although by no means common, there are patients who have a combination of ataxic, athetoid and spastic CP.
Since spastic CP causes one or more muscle groups to become tight, patience experience severe movement limitations. As a result, children with this disability have stiff and jerky movements often having trouble changing positions and find it difficult to hold and let go of objects.
Due to the injury they experienced to both the pyramidal and extra pyramidal areas of the brain, patients suffering from mixed CP often exhibit the involuntary movements of athetoid CP as well as the tight muscle tone of spastic CP. The spasticity is often more dominant, while the involuntary athetoid movements increase as the child begins to grow, usually between nine months and three years. It can take years until the symptoms of mixed CP are noticed.
Other combinations (beside the joint affects of spastic and athetoid CP) are prevalent. While any mix of types can occur (including all three types), the rarest combination is athetoid and ataxic.
Mixed CP involving athetoid movements result from damage to either the basal ganglia part of the brain or the cerebellum because these areas are process the signals which facilitate coordinated movements and correct body posture. Injury to either of these areas will often cause a child to exhibit involuntary movements, in the face, arms, and trunk.
This type of involuntary movement is not controlled by the brain. A “twitch” which is a common example of involuntary movement in healthy people is caused by electrical stimulation of the muscle. In individuals suffering from mixed CP, the frequency of the involuntary movement interferes with their ability to perform otherwise “simple” activities like grasping, reaching, eating and speaking, and similar skills.
Uncontrolled sticking their tongue out and grimacing often result in drooling, slurred speech and swallowing problems which will disappear while they are sleeping and increase during periods of emotional stress. Mixed CP children often have low muscle tone and can not maintain posture for either sitting or walking.