Apraxia and aphasia: the functional-anatomical basis for their dissociation.

We studied the functional and anatomical relationship between aphasia and apraxia in 177 patients with CT evidence of left hemisphere stroke. In six severe aphasics, praxis was spared; these cases were analyzed in detail. One patient had a small temporal lesion with severe Wernicke's aphasia. Large frontoparietal lesions were found in the others. The sparing of praxis suggested bilateral representation of visuokinesthetic motor patterns, and functionally active right parietofrontal connections. Some of these patients had uncommon patterns of skull asymmetries that may have been related to bilateral distribution of function.