精神分裂病様幻聴と特異な健忘・書字障害を呈した左内包膝部梗塞の1例

A CASE OF LEFT INTERNAL CAPSULAR INFARCTION WITH AUDITORY HALLUCINATION AND PECULIAR AMNESIA AND DYSGRAPHIA

　物品の使用障害，感覚失語様の書字障害，体験性幻聴で発症し，軽度の言語性記銘障害を残した左内包膝部梗塞の1例（46歳，男性，右きき）を報告した。CTおよびMRIで左視床前方に隣接し，内包膝部に限局する小病巣がみられ，ポジトロンCTでは左前頭葉，側頭葉，視床および右小脳半球に10〜26％の血流代謝の低下が認あられた。本症例の特異な臨床症状の発現に視床皮質問の連絡路の障害が関与している可能性が示唆された。

A 46-year-old businessman suddenly became to behave curiously on the morning, September 1, 1988. He forgot how to go through an automatic ticket gate, which he used every day. In his com-pany, he also forgot how to open the cash box,and he wrote a meaningless report for his business. From the night on that day, he had experienced auditory hallucination in which whis-pering words of some criticism to his performance for a few days. On the next day, he was admitted to a psychiatric hospital because he was suggested to have schizophrenia. By day 6 after the onset, his curious symptoms completely disappeared. However, slight verbal memory disturbanceand cognitive dysfunction still rema-ined. Because the brain CT on day 6 showed a small localized subcortical infarction in the left hemisphere he was transferred to our clinic on day 20 to elucidate the relation between the abnormal behavior and the infarction. His blood pressure was 116/64 mmHg and pulse was regular 63/min. He was clear and did not have any neurological deficit. He kept his episodic memory regarding the events at the onset and could almost recall them precisely. Results of standard blood tests, electrocardiogram, ultrasound cardiogram, electroencephalogram as well as cerebral angiography were normal. Computed tomography and magnetic resonance imaging sho-wed an infarcted lesion in the genu of the left internal capsule and a part of the head of left caudate nucleus, adjacent to the anterior part of the thalamus. The images of the positron emission computed tomogram on day 22 revealed decrease in cerebral blood flow and cerebral metabolic rate of oxygen in the left frontal and temporal cortex, the left thalamus and the right cerebellar hemisphere, where 10-26% decrease of asymmetry index were observed. Wechsler Adult Intelligence Scale score increased from a total IQ 80 (verbal IQ 83, performance IQ 100) on day 16 to 121 (129, 118) on day 27 after the onset. His speech ability examined by Western Aphasia Battery on day 33 had already normal. The results of Benton visual retension test and paired associates word learning at the same day were also normal. Although these neuropsychological tests were almost within normal limits, he had subjective verbal memory impairment. From the results of positron emission CT study, it is suggeted that the disconnection of neuronal fibers between the left thalamus and cerebral hemisphere, especially frontal and temporal cortex might play an important role in the development of the sym-ptoms of this patient.