Aphasia Induced by Infratentorial Ischemic Stroke: Two Case Reports.

Aphasia induced by an infratentorial stroke has rarely been reported, and its mechanism has not been fully identified. We evaluated two individuals who had been admitted to Saiseikai Kumamoto Hospital in Kumamoto, Japan, due to acute ischemic stroke in order to determine whether their aphasia was induced by an infratentorial stroke. The first patient, a 59-year-old man with a history of left parietal embolic stroke with very mild sequelae of anomia, developed Wernicke's aphasia, nonfluent speech, and right limb ataxia as a result of the stroke. The second patient, a 76-year-old woman with a history of chronic renal failure, experienced transcortical sensory aphasia and right one-and-a-half syndrome as a result of the stroke. Both patients' recent ischemic lesions were limited to the right cerebellar hemisphere and the right medial portion of the midbrain. However, SPECT showed low-uptake lesions in both patients' left cerebral hemisphere that did not include the recent ischemic lesions but that had spread to an extent that was difficult to be explained by the old or recent ischemic lesions and that might be responsible for their recent aphasia. We believe that the aphasia experienced by these two patients may have been caused by crossed cerebello-cerebral diaschisis.