脳底動脈窓形成を伴った破裂脳動脈瘤の2例

Fenestrated Basilar Artery with Ruptured Cerebral Aneurysms: Case report

I．はじめに

　脳底動脈窓形成の頻度は剖検上0.5-5.3％また，脳血管撮影上0.6％とされており，極めて稀な血管奇形といえる^8,11）．一方，脳底動脈に窓形成があり同部に動脈瘤が見られた症例は渉猟しえた限りでは，現在までに文献上36例の報告があり，このうち直達手術が行われたのは10例にすぎない^1,3-9,14）．

　今回著者らは，脳底動脈窓形成部の破裂脳動脈瘤に対し直達手術を行った1例と，多発性動脈瘤例に認められた脳底動脈窓形成の1例とを経験したので文献的考察を加えて報告する．

Two cases of aneurysms with basilar artery fenestra-tion are presented. A 45 year-old lady had a saccular aneurysm associated with a fenestrated basilar artery. The fenestration was located in the proximal third of the basilar artery. The aneurysm arose from the prox-imal end of the fenestration, projecting antero-inferiorly. Via a left retromastoid craniectomy, the aneurysm was successfully obliterated through the space between the eighth cranial nerve and the lower cranial nerve complexes. Postoperative deficit in the lower cranial nerves was minimal and transient.

The other patient, a 63 year-old lady, had multiple aneurysms arising from the anterior circulation associ-ated with a basilar artery fenestration. These aneu-rysms were clipped uneventfully. Surgical approach to an aneurysm arising from the basilar artery fenestration is discussed with other related literature. Full study of posterior circulation with multiple projection is manda-tory to detect basilar artery fenestration, and the pos-sible presence of saccular aneurysm at the site of the anomaly.