Aphasia due to lesions of the kinesthetic speech areas

The study of two groups of right handed aphasics, group A and group B, is presented. Each group was formed by four subjects, both groups showed an aphasic syndrome craracterized by alteration in the efferent sphere of oral and written language, principally in the latter. There was almost no alteration in the sensory interchange sphere, except for a right hypoesthesia and astereognosis in two subjects of each group. The aspect in which both groups differed profoundly was the efferent sphere of written language. Group B patients could not write with the dominant hand because of a right hemiplegia. Nevertheless, they could do it with the left, nondominant hand. Group A patients were unable to write with either hand in spite of the absence of motor deficit or incoordination which could explain this inability. The different possible topographical localizations responsible for the deficit are analyzed. It is concluded that there are three main possibilities that could explain the writing difficulty found in group B patients: a) a lesion located in the white frontal matter of the left hemisphere just underneath the kinesthetic area; b) a lesion in the kinesthetic dominant area itself; c) a lesion in the dominant cerebral hemisphere white matter underlying the primary receptor somesthetic and the primary effector areas, but without directly involving them, and extending also in depth toward the anterior third of the corpus callosum. Any one of these lesions could impair the transmission of information from the dominant kinesthetic hand area to the primary effector motor area of both cerebral hemispheres.