純粋失読を呈した多発性硬化症の1例

A CASE OF MULTIPLE SCLEROSIS WITH PURE ALEXIA

　抄録　純粋失読を呈した多発性硬化症（MS）の症例を報告した。症例は28歳，男性，右利き。一過性の純粋失読，右同名半盲で発症し，その後頭痛，歩行時のふらつき，全身痙攣発作などがみられ，寛解増悪を繰り返した。MSにより，失語症状を呈することは稀であり，純粋失読を呈した報告はない。頭部X線CTおよびMagnetic Resonance Imagingにより病巣の検討をおこない，本例の純粋失読の発症には左後頭葉内側の皮質下白質と大鉗子が同時に障害されたことが関与し，単一の小病巣では出現しにくい失読症状が小病巣が複合することにより出現し得ると推察した。

We report here a case of multiple sclerosis (MS) showing pure alexia. The patient was a 28 year-old, right-handed male student of medicine. He had been healthy prior to college, but when he tried to read the newspaper one morning in Jan-uary of 1983, he suddenly became aware that he could not. He could speak fluently and had no disturbances of auditory comprehension. No signs of abnormality were noted in his writing ability. Thereafter, the patient occasionally experienced difficulty in reading, together with right homony-mous hemianopsia. These symptoms, however, usu-ally vanished following sleep. In April, 1984, the patient experienced headache and ataxia when walking, followed by repeated remission and ex-acerbation of the symptoms. Corticosteroid therapy produced complete disappearnce of the headache and ataxia. In September of 1985, he was hospi-talized at our department due to the clouding of consciousness accompanied by convulsions. Neu-rologically, no abnormalities of the ocular fundus were noted and Babinski's sign was negative, but left hemiplegia was observed. Neuropsychologi-cally, his intelligence was normal and he had no difficulty in writing, but paralexia was noted. There were no disorders of spontaneous speech or auditory comprehension. Examination by CT scan and magnetic resonance imaging revealed a number of lesions in the white substance of the cerebrum, including the left occipital lobe. The abnormal signs seen radiographically vanished when cortical hormones were administered. It has been thought that the symptoms of multiple sclerosis are due mainly to disorders of the white substance, and that MS seldom produces symptoms of aphasia, due to the fact that the lesions in this disease are generally small. There have conse-quently been few reports of aphasic symptoms due to MS, particularly of pure alexia. However, the existence of cases, such as that reported here, suggests that it is necessary to take MS into con-sideration in the differential diagnosis of diseases which show symptoms of aphasia.