もやもや病に合併した微小動脈瘤に対して経頭蓋的運動誘発電位モニタリングを併用したコイル塞栓術が有効であった1例

A case of a small aneurysm associated with moyamoya disease successfully treated with coil embolization under transcranial motor evoked potential monitoring

もやもや病は，内頸動脈終末部に慢性進行性の狭窄を生じ，側副血行路として異常な血管網を形成する疾患であり，側副血行路の破綻や動脈瘤の破裂により脳出血をきたすことが知られている^1）。今回我々は，脳出血を契機に診断されたもやもや病症例において，前脈絡叢動脈遠位部に形成された微小動脈瘤に対し，経頭蓋的運動誘発電位（transcranial motor evoked potential：TC-MEP）モニタリングを併用したコイル塞栓術が有効であった1例を経験したため，ここに報告する。

We report a case of a middle-aged woman presenting with left putaminal hemorrhage and right hemiparesis, subsequently diagnosed with moyamoya disease. Cerebral angiography revealed a small aneurysm in the distal anterior choroidal artery. Coil embolization was performed under transcranial motor evoked potential（TC-MEP）monitoring. Intraoperative MEP amplitude decreased by over 50％ during the third coil placement but recovered after coil removal. The patient experienced no new neurological deficits postoperatively, and no recurrence was observed at six-month follow-up. This case highlights the value of TC-MEP monitoring not only in moyamoya-related aneurysms but also as a potentially useful adjunct in coil embolization of small, deep-seated cerebral aneurysms