出血を繰り返し術前診断が困難であった後下小脳動脈末梢部に発生した多発性脳動脈瘤の1例

Multiple Aneurysms of the Distal Posterior Inferior Cerebellar Artery with Recurrent Hemorrhage Undetectable on Preoperative Neuroradiological Findings : Case Report

　Ⅰ．はじめに

後下小脳動脈（posterior inferior cerebellar artery : PICA）が椎骨動脈から分岐した後の末梢部に発生する脳動脈瘤（distal PICA AN）は全脳動脈瘤の1％以下とされ比較的稀なものと考えられるが^11,13,14,21)，さらに同一のPICA末梢部に多発する脳動脈瘤は非常に珍しいとされている．

　今回，1年半の経過で出血を繰り返し，動脈瘤などの血管病変の術前診断で手術に臨んだが，術中所見からPICA末梢部に発生した多発性脳動脈瘤と診断し得た1例を経験したので文献的考察を加えて報告する．

　We report a rare case of multiple aneurysms of the distal posterior inferior cerebellar artery (PICA) associated with recurrent hemorrhage undetectable on preoperative neuroradiological findings.

　A 68-year-old woman was admitted to our hospital in April,2003 because of a sudden onset of headache,back neck pain and nausea. CT scan at the time of admission showed a hematoma in the 4th ＆ 3rd ventricles,and a mild subarachnoid hemorrhage (SAH) in the basal,right ambient ＆ quadrigeminal cisterns.

　She had had a similar history of previous intraventricular hemorrhage and SAH in October,2001. Three-dimensional CT angiograms and left vertebral angiograms performed at that time revealed an irregular vascular lesion at the tonsillomedullary segment (TMS) of the left PICA. However,the final diagnosis was unclear.

　Left vertebral angiograms at the time of the 2003 admission revealed an irregular vascular lesion in the same region more clearly and the size of aneurysmal dilatations had increased considerably. So,preoperative diagnosis of an irregular vascular lesion at the TMS of the left PICA (distal PICA aneurysm was not ruled out) was based on the above neuroradiological findings. The patient was surgically treated through the suboccipital approach. The TMS of the left PICA had made a difficulty loop formation was observed. Five distinct aneurysma were found on the TMS of the left PICA. To prevent bleeding,the ruptured aneurysm ＆ three unruptured aneurysms were clipped and the residual unruptured one was wrapped with Bemsheets. Postoperative left vertebral angiograms demonstrated neither clipped aneurysms nor occlusive findings at the TMS of the PICA. The patency of the PICA was preserved. The postoperative course was uneventful and the patient was discharged without new neurological deficits. There has been no rebleeding during the one year since surgery.

　The 23 reported cases of multiple aneurysms of the distal PICA including our case were reviewed and their neuroradiological and clinical features are discussed.