親動脈を温存し動脈瘤様拡張部の瘤内塞栓術にて治療した破裂前下小脳動脈解離性動脈瘤の1例

Embolization for Aneurismal Dilatation Associated with Ruptured Dissecting Anterior Inferior Cerebellar Artery Aneurysm with Preservation of the Parent Artery：Case Report

Ⅰ．は じ め に

　前下小脳動脈（anterior inferior cerebellar artery；AICA）に発生する動脈瘤は稀であり，その頻度は全頭蓋内動脈瘤のうちの1％未満とされる⁵⁾．またAICAの末梢部に発生する頻度は0.03～0.5％とさらに低く，その多くはmeatal loopに存在すると報告されている^4,16)．

　今回われわれは，AICAの分岐直後のanterior pontine segment屈曲部に発生した破裂末梢性解離性動脈瘤の1例を経験した．同側の後下小脳動脈（posterior inferior cerebellar artery；PICA）は欠損しAICAの分枝がPICA領域を灌流するAICA-PICAと呼ばれるvessel variationを呈していたため，AICAは温存してblebを伴ったaneurysmal dilatation部のみの瘤内塞栓術を行った．過去にAICAの末梢性動脈瘤に対する血管内治療は7例報告されているが，6例では親動脈の閉塞が余儀なくされ，AICAを温存した瘤内塞栓術が施行し得た報告は加藤らの1例のみである^{2,6,7,11,13,16)}．これらの文献的考察を加えて自験例について報告する．

　We report a rare case of a ruptured dissecting anterior inferior cerebellar artery (AICA) aneurysm treated by endosaccular embolization with a Guglielmi detachable coil (GDC). An 85-year-old female presented with headache. Computed tomographic (CT) scan showed subarachnoid hemorrhage and intraventricular hemorrhage in the fourth ventricule. Cerebral angiography and 3D-CT angiography revealed an aneurysmal dilatation at the anterior pontine segment of the right AICA with a diagnosis of arterial dissection. The right posterior inferior cerebellar artery (PICA) was absent and the right AICA supplied the territory normally nourished by the right PICA. The aneurismal dilatation was occluded by endosacullar embolization with preservation of the AICA.

　The distal AICA aneurysm is rare and only seven cases treated with endovascular embolization have been reported. In these,six cases were treated by parent artery occlusion with coil and the subsequent three cases presented with ischemic complications. Only one case was treated by endosaccular embolization with GDC. To our knowledge,this is the second report of the distal AICA aneurysm treated by endosaccular embolization with GDC. Distal AICA aneurysms are briefly discussed while reviewing the literature.