くも膜下出血で発症した前下小脳動脈内耳道内動脈瘤の2例

Intrameatal Aneurysm of Distal Anterior Inferior Cerebellar Artery Manifesting a Subarachnoid Hemorrhage:A Report of 2 Cases

Ⅰ．はじめに

　前下小脳動脈（anterior inferior cerebellar artery：AICA）に発生する脳動脈瘤は，全頭蓋内動脈瘤の1%未満で，さらにその遠位部（distal）に発生する頻度は0.1〜0.5%と非常に稀である⁶⁾．くも膜下出血（subarachnoid hemorrhage：SAH）で発症することが多く，その際，顔面神経麻痺や聴神経障害を伴うことが多い．今回われわれは，SAHで発症したdistal AICA内耳道内動脈瘤の2例を経験したため，症例を提示するとともに，その特徴と治療について若干の文献的考察を加え報告する．

　Two female patients presented with a subarachnoid hemorrhage because of ruptured intrameatal aneurysms of the distal anterior inferior cerebellar artery, which is extremely rare. Each patient underwent microsurgical direct neck clipping or trapping, as needed, by a retrosigmoid craniectomy with an unroofing of the internal auditory meatus. After the surgery, both patients manifested low hearing ability. In recent years, an endovascular therapy or occipital artery-anterior inferior cerebellar artery bypass with aneurysm trapping are being employed to treat intrameatal aneurysms. We present a review of literature, and referred features and treatment techniques for intrameatal aneurysms.