Moyamoya disease causes acute subdural hematomas and sudden death: a case report.

A 59-year-old woman suffered from sudden onset of severe headache and vomiting for five days, with normal consciousness. A computerized tomography (CT) scan showed acute subdural hematomas in the right frontal and left frontotemporoparietal regions. As there was no history of head injury, the patient underwent bilateral carotid angiography. The left carotid angiogram showed total occlusion of the left middle cerebral and anterior cerebral arteries with a moyamoya pattern of collateral circulation. Five days later, the patient suddenly lost consciousness associated with right hemiparesis. An emergency CT scan disclosed diffuse acute brain tissue edema in the left cerebral hemisphere with uncal/transtentorial herniation, caused by acute infarction in the territory of the left middle cerebral artery. The patient died 10 hours later. The acute infarction was considered to have been caused by subdural hematomas compressing the transdural anastomoses, thus eliminating all blood supply to the region of the left middle cerebral artery.