Intracystic Hemorrhage of the Middle Fossa Arachnoid Cyst and Subdural Hematoma Caused by Ruptured Middle Cerebral Artery Aneurysm

Summary: We report a case of a cerebral aneurysm arising from the bifurcation of the left middle cerebral artery that ruptured into a left middle cranial fossa arachnoid cyst, associated with acute subdural hematoma. We discuss the relationships of aneurysm, arachnoid cyst, and subdural hematoma. The most common cross-sectional imaging find-ing expected with aneurysm rupture is ordinarily subarachnoid hemorrhage. The intracranial cerebral arteries mostly are contained in the subarachnoid space; nevertheless, there are cases described in the imaging literature of ruptured aneurysm resulting in intracerebral parenchymal hematoma or subdural hematoma (1–3). We report a case of a cerebral aneurysm arising from the bifurcation of the lef