Inter-optic Course of ACAに合併した破裂前交通動脈瘤—症例報告と文献的考察

Ruptured Anterior Communicating Artery Aneurysm Associated with Inter-optic Course of Anterior Cerebral Artery:Report of a case and review of the literature

I．はじめに

　頭蓋内内頸動脈近位部から直接前大脳動脈が分岐する血管奇形の報告は，1959年にRobinsonが剖検例の報告をして以来，24例の報告を見るのみである．また名称も，1）inter-optic course of anterior cerebral artery（ACA）^13），2）infra-optic course of ACA^2,12），3）ano—malous origin of internal carotid artery（ICA）^3,5,14），4）carotid-ACA anastomosis^1,7-9,15）などと呼ばれており，その起源についても定説はない．今回われわれは同血管奇形に前交通動脈瘤を合併し，くも膜下出血で発症した1例を経験したので若干の文献的考察を加え報告する．

We report a ruptured anterior communicating artery (ACoA) aneurysm in a patient whose anterior cerebral artery (ACA) arose from the left C3 portion and ascended between the optic nerves. A 50 year-old woman was admitted to our department with com-plaints of headache and vomiting. CT scan showed thick subarachnoid hemorrhage. Left carotid angiogra-phy revealed a saccular aneurysm of the anterior com-municating artery and an abnormal vessel which arose from the left C3 portion and terminated in the territory of the ACoA. Surgery was performed about eight hours after subarachnoid hemorrhage. The abnormal vessel was identified as it ascended between the optic nerves. There are only 25 reported cases of this abnor-mality including our own case. The right carotid artery was the most frequent origin of the abnormal artery (18 cases). 13 aneurysms were associated in 11 cases, in which seven were located in the anterior communi-cating artery. It was the most frequent site of the aneurysm. There were various explanations for this anomalous ACA. Because of the angiographical and operative findings, we prefer to use “inter-optic course of ACA” as the medical terminology better suited to describe this condition.