両側性後下小脳動脈末梢部動脈瘤の1例

A Case of Distal Aneurysms of Bilateral Posterior Inferior Cerebellar Arteries

I．はじめに

　後頭蓋窩における動脈瘤の頻度は全頭蓋内動脈瘤の10-15％と少なく，その大半は脳底動脈のupperportion，及び椎骨動脈後下小脳動脈分岐部に発生し，後下小脳動脈末梢部の動脈瘤は稀である．更に両側性のものは極めて稀であり，渉猟し得た限りでは3例の報告があるのみである．われわれは両側後下小脳動脈の末梢部動脈瘤（distal PICA An）の1例を経験したので若干の文献的考察を加えて報告する．

A case of aneurysms of bilateral distal posterior in-ferior cerebellar arteries (PICAs) is reported. A 61-year-old man experienced a sudden onset of headache and nausea and was admitted to a hospital immediately. His neurological examination showed no abnormalities, but headache and nausea continued in spite of conservative treatment. The patient was referred to our hospital two days after the onset and the neurological examination re-vealed slight dysmetria of the right upper extremity. A computed tomography (CT) scan demonstrated a round and heterogeneous high density mass at the cerebellar vermis and some blood coagula at the fourth ventricle and vermis. Angiography showed two aneurysms of the bilateral distal PICAs : The right aneurysm was at the cortical segment and the left one was at the teloveloton-sillar segment. The patient underwent a suboccipital era-niectomy and both aneurysms were clipped successfully. Sleepiness and headache continued postoperatively clue to hydrocephalus. After ventricular drainage he soon recovered without having V-P shunt and was discharged with no neurological deficits.

Aneurysms of bilateral distal PICAs are very rare and only three cases have been reported in the literature. The etiology, clinical symptom, CT finding and prognosis in the literature reviewed were briefly discussed.