[Mixed transcortical aphasia due to multiple deep white matter infarction in the dominant cerebral hemisphere: a case report].

We report a case of mixed transcortical aphasia (MTA) due to multiple cerebral infarction in the dominant hemisphere in an 80-year-old right-handed woman without hemiplegia. Her spontaneous speech was markedly reduced and auditory comprehension, reading and writing were severely disturbed. Although the repetition of sentences (at most 3 words) was relatively preserved, her speech was echolalic. Brain MRI showed bilateral multiple deep white matter infarction and subcortical infarction of the left parietal lobe, including left angular gyrus, but no abnormal signal intensities were detected in either Wernicke's or Broca's area. SPECT indicated a significant decrease in mean cerebral blood flow in both hemispheres, but there was no focal hypoperfusion in either speech area. We thought that the focal hypoperfusion observed in the right cerebellum indicated crossed cerebellar diaschisis. Electroencephalogram showed a diffuse reduction in the incidence of alpha waves in the left cerebral hemisphere. From these findings, we suggest that widespread hypofunction in the dominant hemisphere was important for the occurrence of MTA.