前交通動脈動脈瘤を合併した一側内頸動脈欠損症の1例

Unilateral Agenesis of the Internal Carotid Artery in a Patient with Ruptured Aneurysm of the Anterior Communicating Artery; A case report

I．はじめに

　内頸動脈欠損症はこれまでに80例以上が報告されている．内頸動脈欠損症の約1／3の21例に脳動脈瘤が合併したことが知られており^{1,16,27,36,44）}，脳動脈瘤の成因を考える上でも極めて興味深い．われわれは破裂前交通動脈動脈瘤で発症し，神経放射線学的検査で完全な一側内頸動脈欠損を証明し得た症例を経験したので報告する．

This 27-year-old female suffered from subarachnoid hemorrhage. Angiography revealed a ruptured aneurysm of the anterior communicating artery. Uni-lateral absence of the right internal carotid artery was also demonstrated angiographically. Both the right anterior and middle cerebral arteries were perfused from the left carotid artery via the anterior communi-cating artery. Absence of the right carotid canal was proved on bone CT. Neuroradiological difficulties in differential diagnosis between agenesis and aplasia of the internal carotid artery were discussed. Subsequent-ly, a diagnosis of adult type unilateral agenesis of the internal carotid artery with collateral circulation was made. The mechanism of association of cerebral aneurysm in patients with agenesis of the internal caro-tid artery was also discussed. From our experience, abnormal vascular anatomy should be carefully studied prior to direct surgery for a ruptured aneurysm in pa-tients with unilateral agenesis of the internal carotid artery.