低形成前大脳動脈水平部（A1）に発生した破裂脳動脈瘤の1例

A Ruptured Aneurysm in the Hypoplastic Proximal Anterior Cerebral Artery (A1 portion); Case report

I．はじめに

　前大脳動脈領域の脳動脈瘤の好発部位は，前交通動脈と前大脳動脈遠位部である．比較的稀ではあるが，前大脳動脈水平部（A₁）にも脳動脈瘤が発生することが報告されている．しかし，今回われわれが経験したような低形成なA₁部に発生し，しかも明らかな穿通枝や皮質枝の分岐とは無関係に存在したsaccular typeの破裂脳動脈瘤の報告は見られないので，若干の文献的考察を加え報告する．

Abstract

A case of ruptured aneurysm in the hypoplastic prox-imal anterior cerebral artery (A₁ portion) is reported. This 25-years old man complained of the sudden onset of severe headache and vomiting on January 11, 1989. He was referred to Our hospital on the same day, and CT scan revealed subarachnoid hemorrhage. Cerebral angiography on the next day revealed an aneurysm in the hypoplastic A₁ portion of the right anterior cerebral artery, and no branch was present at the site of the aneurysmal neck. He was operated on using the right pterional approach. The A₁ portion was trapped and the aneurysm was removed successfully. The histology of the aneurysm was that of the usual type of the saccular aneurysm. The post-operative course was un-eventful. He was discharged with no neurological de-ficit two months after the operation.

As far as we know, there has been no report on a ruptured aneurysm in the hypoplastic A, portion. We also reviewed the 55 aneurysms in the A, portion that have been reported in the literature.