Syndrome of Semantic Aphasia Caused by Bilateral Thalamic Lesions

A case is reported of a 60' year- old right-handed man in whom syndrome of semantic aphasia developed 5 months after the onset of a left thalamic hemorrhage preceded by a right thalamic hemorrhage which has occured about 21 months before. He was admitted to Kuwana Hospital because of vomiting and left hemiparesis on April 23, 1983. CT scanning disclosed a hematoma measuring about 11 ml which occupied the postero-lateral portion of the right thalamus rupturing into the trigon of the lateral ventricle. Left spatial agnosia, construetional disturbance and left homonymous hemianopia were found. He showed improvement and was discharged about 1 month after the admission. On July 18, 1985, he was admitted again because of the occurrence of a hematoma measuring about 4 ml which involved the postero-lateral portion of the left thalamus extending medially and upwards. Examinations revealed transcortical sensory aphasia as well as left spatial agnosia and constructional disturbance which had been found during the first admission. About 5 months after the admission, the transcortical sensory aphasia disappeared and a syndrome of semantic aphasia developed associated with simultaneus agnosia. Four months later, the syndrome of semantic aphasia improved greatly and the other syndrome showed some improvement. Our case with semantic aphasia had all the components of typical semantic aphasia described by Ohashi et al and was similar to cases with semantic aphasia caused by cortical lesion reported by Hier. This semantic aphasia lasted for a relatively long period was considered to be due to the bilateral thalamic lesions.