紡錘状椎骨動脈瘤および前下小脳動脈による片側顔面痙攣の1例

Hemifacial Spasm Caused by Vertebral Artery Fusiform Aneurysm and the Anterior Inferior Cerebellar Artery

Ⅰ．はじめに

　片側顔面痙攣は，不随意に顔面の表情筋が痙攣する疾患で，顔面神経のroot exit zone（REZ）への血管圧迫が最も多い原因であるが，稀ながら小脳橋角部腫瘍，脳動静脈奇形，脳動脈瘤による圧迫が原因の例が0.3〜5.1%にあると報告されている^{4,8,11,13,15,17)}．

　今回，紡錘状椎骨動脈瘤およびそのdome上を走行した前下小脳動脈（anterior inferior cerebellar artery：AICA）によりREZが圧迫された片側顔面痙攣に対して，動脈瘤クリッピングとともに，TachoSil^®（武田薬品工業，東京，日本）を用いた微小血管減圧術を行い，良好な結果が得られた1例を報告する．

　We report a case of hemifacial spasm in which the root exit zone（REZ）of the facial nerve was compressed by both the vertebral artery（VA）aneurysm and the anterior interior cerebellar artery（AICA). A 60-year-old female had suffered left hemifacial spasm for 2 years. Three-dimensional rotational angiography with selective arterial infusion of contrast medium（3DRA-IA）revealed that a distal part of the left AICA looping at the cisternal region was contacting the dome of the left VA aneurysm, although other imaging modalities did not show the exact course of the ipsilateral AICA. Constructive interference steady state magnetic resonance imaging revealed that both the left VA aneurysm and the left AICA had compressed the REZ of the left facial nerve. She underwent aneurysm clipping and decompression of the REZ by transposition of both the clipped aneurysm and the AICA using TachoSil^®. Her hemifacial spasm disappeared immediately after surgery without complication. Some fine arteries might compress the REZ in patients with hemifacial spasm associated with VA aneurysms. 3DRA-IA was more effective for accurate evaluation than other imaging modalities. Transposition of vascular structures using TachoSil^® is safe and effective for microvascular decompression surgery in such complicated cases.