Spontaneous Subdural Hematoma and Intracystic Hemorrhage in an Arachnoid Cyst.

We report the case of 22-year-old man with nontraumatic intracystic hemorrhage into a middle cranial fossa arachnoid cyst associated with a contiguous subacute subdural hematoma. Arachnoid cysts are benign intra-arachnoidal fluid collections frequently detected incidentally during neuroimaging. Rare complications of arachnoid cysts such as intracystic hemorrhage or subdural hematomas and subdural hygromas typically occur after head trauma. Our review of the literature identified fewer than 30 cases of arachnoid cysts with complicating intracystic hemorrhage and ipsilateral subdural hematomas.