椎骨動脈窓形成部に発生した破裂脳動脈瘤の1手術例

An Operated Case of a Ruptured Aneurysm Arising from Fenestration of the Vertebral Artery

Ⅰ．はじめに

　頭蓋内動脈の窓形成（fenestration）部に動脈瘤が発生することはよく知られており，過去の報告によるとfenestration部における発生率は全脳動脈瘤のうち約3％である¹¹⁾．一方，頭蓋内動脈の窓形成率は約0.7％と報告されており¹¹⁾，前交通動脈，中大脳動脈をはじめとした前方循環系に多く，椎骨動脈（vertebral artery：VA）のfenestrationが血管撮影上発見される頻度は近年の報告によると全fenestrationのうち約1％である¹⁴⁾．

　今回私達はfenestration部に発生した破裂脳動脈瘤の1手術例を経験したので，若干の文献的考察を加えて報告する．

　Aneurysm arising from duplication of the vertebral artery (VA) is rare. We report a surgical case of an aneurysm of VA fenestration and provide a literature review. A 42-year-old man suffered from sudden onset of severe headache. CT image revealed subarachnoid hemorrhage predominantly in the posterior fossa. Digital subtraction angiography showed a fenestration of the right VA and the aneurysm arising from the proximal limb of the fenestration. Neck clipping of the aneurysm was performed because embolization was difficult due to the wide neck. The patient was discharged without deficits. Seven cases of an aneurysm of the VA fenestration have been reported. Five cases underwent coil embolization,and 2 underwent craniotomy,trapping,and resection. This is the first case of neck clipping of an aneurysm of the VA fenestration.