小腦天幕遊離縁の腦膜腫の1例

A case of Meningioma of the Free Margin of Cerebellar Tentorium

I．緒言

　腦膜腫が小腦天幕の遊離縁から發生したものの報告例はまれである。本例は小腦虫部腫瘍の症状を有しヨード油腦室造影法により，Sylvi氏導水管附近の腫瘍と診斷し，後頭下開頭術を行つたが，腫瘍剔出にいたらなかつた。そのご腦壓亢進症状が持續するため，第3腦室瘻を作つたが，ついに死亡したものである。剖檢により腫瘍は小腦天幕と大腦鎌状膜の結合都にちかく，前者の遊離縁から發生し，下前方には四丘體を，下後方には小腦虫部を壓排していることが發見された。

　かくこの腫瘍の發生部位が珍らしいので，こゝにその臨床經過と剖檢所見とを記載し，いささか考察をくわえてみたいとおもう。

Very few cases have been reported about the meningioma originating from the free margin of the cerebellar tentorium. This case had the vermis syndrome and was diagnosed as a tumor around the sylvian aqueduct through iodoil-ventriculography.

Suboccipital craniectomy failed to remove the tumor. The third ventriculostomy was then performed to relieve the persisting intr-acranial pressure, but the patient died six days after the operation.

At autopsy it was discovered that the tumor was located infratentorially and was surround ed by quadrdrigeminal body, cerebellar vermis and pineal body. The tumor, 2.3×3×4cm in size, depressed and deformed considerablly the region of the quadrigeminal body.

The tumor attached with the width of 1.5cm. to the free margin of the cerebellar tentorium on the right, 1 cm apart from its junction with the great vein of Galen.