Non-aneurysmal perimesencephalic subarachnoid hemorrhage caused by a cavernous angioma

Background: Cavernous angiomas are responsible for intracranial hemorrhages, but bleeding is infrequently confined to the subarachnoid space. Methods: We describe an elderly, yet healthy man who sought medical attention for subarachnoid hemorrhage. Results: Vascular imaging failed to reveal a cerebral aneurysm, however magnetic resonance imaging done late in the course showed a cavernous angioma, on the surface of the left upper cerebellar peduncle, that had bled. Conclusions: The so-called "angiography- negative" subarachnoid hemorrhage could have its source in small cavernous angiomas lying on the surface of basal skull brain structures.