血管屈曲部に発生したAICA-PICA Aneurysmの1例

A Ruptured Aneurysm of the Anterior and Posterior Inferior Cerebellar Artery : a case report

I．はじめに

　後下小脳動脈瘤（PICA An．）は全脳動脈瘤中の0.5-3％を占め^5,6,11），比較的稀な動脈瘤である．その大部分は椎骨動脈，後下小脳動脈分岐部動脈瘤（VA-PICA An．）であり，その末梢に生じたいわゆる末梢性後下小脳動脈瘤（distal PICA An．）となるとさらに稀で全頭蓋内動脈瘤の0.3-1％と報告されている^{5,6,9,11,12,16）}，今回，われわれが経験した症例はAICAが欠損しその灌流域をPICAが補っており，その末梢に発生した動脈瘤であった．いわゆるAICA-PICA An．であり，瘤の一部は頭蓋外に認められた．今回の自験例をもとにその臨床像，診断，治療法などにつき検討を加えて報告する．

We report a case of an anterior and posterior inferior cerebellar artery (AICA-PICA) aneurysm. The pa-tient was a 62-year-old woman who suffered from sudden onset of severe headache and nuchalgia. Com-puted tomography (CT) scan revealed subarachnoid hemorrhage in the ambient cistern and blood clots inthe 3rd and 4th ventricles. Vertebral angiography demonstrated an aneurysm located at the distal segmentof the left AICA-PICA. Three demensional CT scan was very useful for the decision concerning surgicalstrategy. The patient underwent bilateral occipital craniectomy and the aneurysm was clipped sucessfullyvia the midline suboccipital approach. Her postoperative course was uneventful. Postoperative angiographyshowed successful clipping of the aneurysm. Distal AICA-PICA aneurysm is a very rare disease and onlyone case has been reported in the literature. The clinical features, CT findings, and surgical approach ofdistal AICA-PICA aneurysms are briefly discussed while reviewing the literature.