[Page 288]The term apraxia designates higher order disorders of movement. It has been applied to a multitude of disturbances, but there is a core of clinical manifestations that have been and continue to be recognized as apraxia. The movement disorders associated with apraxia tend to occur in the following three domains of human motor actions: (1) imitation of gestures, (2) performance of communicative gestures on command, and (3) skillful use of tools and objects. They are caused predominantly by lesions in the left hemisphere of the brain, often by lesions of the parietal lobe. Because the left hemisphere is dominant for language, apraxia is very frequently associated with deficiencies of language diagnosed as aphasia.

Apraxia differs from other motor symptoms of unilateral hemisphere lesions by the ...