長期に及ぶ変形視をきたした多発性脳梗塞の1例

A Case of Long-term Metamorphopsia Caused by Multiple Cerebral Infarction

はじめに

　広義の変形視（metamorphopsia）とは，視覚対象の形態の歪みだけではなく，大きさ，距離，方向，色，立体感のいずれか，または複数における変容と定義される^1，2）。歪んでみえる対象として多いものは，顔面，特に目や手のような身体部分であり，実際より対象者が老けてみえることや，顔半分が溶けてみえたり，小さくみえるなどと多様な報告例がある^3－5）。その多くは，てんかん由来であったり，また脳波異常がなくても，発作性や一過性の経過を示す報告が大半である。

　本症例は，約3年に及ぶ変形視を責任病巣と同側視野に認め，従来の変形視をきたしうる解剖学的な機序からでは説明が困難なために，文献的考察を踏まえ検討したので報告する。

Abstract

　This report presents the case of a 79-year-old right-handed woman. One day on waking, she realized that the faces of her family members appeared distorted. She consulted an ophthalmologist at a nearby clinic in the vicinity and was diagnosed with left homonymous hemianopsia. Since a cerebrovascular disease was suspected, she was referred to clinic A. Brain MRI revealed a cerebral infarction in the right temporo-occipital area. Neurologically there was no other significant sign besides left homonymous hemianopsia and the visual disorder. Metamorphosia was the major visual disorder detected; in the patient's word "left half of the faces of people walking on the street in the opposite direction appeared distorted; they looked like monsters." With conservative medical treatment, the condition remitted; nevertheless, the right visual field metamorphopsia persisted for over 3 years.

　This unique case suggests that metamorphopsia occurs due to lesions in not only the contralateral parietooccipital lobe, as usually reported, but also in other resions, including the ipsilateral hemisphere.