くも膜下出血で発症した蝶形骨縁髄膜腫—その出血機序についての考察

A Case of Sphenoid Ridge Meningioma Presenting as Subarachnoid Hemorrhage

　くも膜下出血で発症した蝶形骨縁髄膜腫を報告し，その出血源，出血機序を中心に考察する。患者は56歳男性で排便時に生じた激しい頭痛を主訴に来院した。入院時，項部硬直やKernig徴候などの髄膜刺激症状を認め，腰椎穿刺にて血性髄液を得た。CTでは頭蓋内出血は明らかではなかったが，左蝶形骨縁内側部に造影CTで均一に増強される腫瘍性病変を認めた。脳血管撮影では，腫瘍による脳血管の圧排所見以外に異常は認められなかった。同腫瘍に対して開頭腫瘍摘出術を施行し，術中に腫瘍と脳表静脈との強い癒着を確認した。癒着部位には凝血塊が付着しており，また癒着した静脈周辺の脳表を中心としてくも膜下出血が認められた。病理組織診断はmeningotheliomatous meningiomaで，腫瘍内出血は認められなかった。以上より本症例の出血原因として腫瘍と癒着した静脈の破綻が強く疑われた。

The authors present a case of sphenoid ridge meningioma pressenting as subarachnoid hemor-rhage.

A 56-year-old man came to our hospital with a complaint of severe headache developed during evacuation of the bowels. Computed tomogram on admission revealed a mass lesion of high density, which was homogenousely enhanced with contrast media, in the medial part of the left sphenoid ridge, but no evidence of the intracranial hemorrhage. Nevertheless, the cerebrospinal fluid obtained by lumbar puncture was bloody, indicating the occur-rence of subarachnoid hemorrhage. Cerebral angio-grams showed no abnormality except for the down-ward displacement of the supraclinoidal segment of the left internal carotid artery. During the opera-tion, the adhesion between the tumor and the cor-tical vein was observed and the subarachnoid hem-orrhage was recognized exclusively around the vein. These findings indicates that the present hemor-rhage may be dirived from the vein. In the previous reports of meningioma associated with intracranial hemorrhage, the origin of hemorrhage and the path-ophysiological mechanism for hemorrhage have been speculated from both operative and his-tological findings. In consideration of these specula-tions, we discussed the possible mechanism for the braeakdown of the cortical vein in the present case.