Pathogenesis of aphasia in deep-seated lesions: likely role of cortical diaschisis

In order to study the pathophysiology of language disorders due to deep-seated left-hemisphere lesions not involving the cortex, a population of 43 right-handed stroke patients (29 aphasic) presenting with such lesions was studied clinically and by regional cerebral blood flow measurements (two-dimensional xenon-133 inhalation method). Most of the patients were studied sequentially between the 1st and 3rd months after stroke. Cortical diaschisis did not account for the whole clinical picture: the remote effect on the cortex could explain the occurrence of aphasia and its severity but not the type of aphasia. Furthermore, the clinical improvement observed in most cases was not accompanied by the disappearance of the diaschisis.