[A case of sphenoid ridge meningioma presenting as subarachnoid hemorrhage].

The authors present a case of sphenoid ridge meningioma presenting as subarachnoid hemorrhage. 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 homogeneously 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 occurrence of subarachnoid hemorrhage. Cerebral angiograms showed no abnormality except for the downward displacement of the suprachnoidal segment of the left internal carotid artery. During the operation, the adhesion between the tumor and the cortical vein was observed and the subarachnoid hemorrhage was recognized exclusively around the vein. These findings indicates that the present hemorrhage may be derived from the vein. In the previous reports of meningioma associated with intracranial hemorrhage, the origin of hemorrhage and the pathophysiological mechanism for hemorrhage have been speculated from both operative and histological findings. In consideration of these speculations, we discussed the possible mechanism for the breakdown of the cortical vein in the present case.