巨大内頸動脈瘤による圧迫性視神経症の1例

A case of optic nerve compression neuropathy caused by giant internal carotid aneurysms

　76歳の男性に左眼視力障害が突発した。左眼矯正視力は0.6であったが，その4か月後に0.02に低下した。眼底に異常所見はなかった。脳血管造影などで両側の内頸動脈瘤が発見され，動脈瘤による圧迫性視神経症と診断された。左は内頸動脈サイフォン部から中大脳動脈に及ぶ巨大血管瘤であった。動脈瘤は両側性なので手術は行わなかった。以後右眼にも視野狭窄が生じ，初診から2年後の現在，矯正視力は左眼指数弁，右眼0.4である。原因不明の視力障害が内頸動脈瘤に続発しうることを示す症例である。

A 76-year-old male noted sudden visual loss in his left eye. His corrected visual acuity was 0.9 right and 0.6 left. The left visual acuity decreased to 0.02 4 months later. There were no funduscopic abnormalities. Neurological examinations including cerebral angiography showed bilateral internal carotid aneurysms, leading to the diagnosis of optic nerve compression neuropathy. The left aneurysm was a giant one extending from the carotid siphon to the middle cerebral artery. No surgery was performed due to the bilaterality of the aneurysms. Visual field defect developed in the right eye later. Two years after his initial visit, his corrected visual acuity is 0.4 right and counting fingers left. This case illustrates that idiopathic visual loss may occur secondary to internal carotid aneurysms.