前下小脳動脈遠位部動脈瘤—3症例の報告と文献的考察

Distal Anterior Inferior Cerebellar Artery Aneurysms : Report of Three Cases and Literature Review

I．はじめに

　前下小脳動脈遠位部に位置する動脈瘤は比較的稀な疾患であり，文献上55例が報告されているに過ぎない^1-7,9-47）．その多くはmeatal loopの内耳動脈分岐部近傍に発生し，meatal loop以外に生じるものはさらに稀である．解剖学的に第7，8脳神経と密接するため，くも膜下出血以外に脳神経麻痺にて発症する場合がある．また外科治療の際にもこれらの解剖学的特徴を考慮しなければならない．最近われわれが経験した3例の前下小脳動脈遠位部動脈瘤を報告するとともに，これまでの報告例をレビューし，その臨床像と血管内治療を含めた治療法につき考察する．

Aneurysm at the distal portion of the anterior inferior cerebellar artery (AICA) is uncommon and only55 cases have been documented in the literature. Here we report an additional three cases with review ofthe literature.

All three patients presented with subarachnoid hemorrhage. The ruptured aneurysms were located at themeatal loop of the AICA in all three patients and one patient had another unruptured aneurysm at thelateral branch distal to the meatal loop. Two patients underwent surgical trapping of the aneurysms, andthe other patient was treated with endovascular coiling because of poor clinical condition. Increase of hear-ing disturbance was found in two patients who underwent surgery or endovascular coiling, respectively. Clinical features and treatment of these rare lesions are discussed with reference to the 7 th and 8 thnerve impairments as preoperative symptoms arid postoperative complications.