Subarachnoid hemorrhage not due to ruptured aneurysm in moyamoya disease

A patient with moyamoya disease presenting with subarachnoid hemorrhage (SAH) is reported. A 38-year-old Japanese woman developed a sudden onset headache and nausea during hospitalization for a cerebral infarct in the right frontal lobe. CT scan showed SAH in the left frontal sulci. Cerebral angiogram showed stenosis of the distal bilateral internal carotid arteries with moyamoya vessels, and significant transdural anastamoses from the left external carotid artery to cortical arteries on the left frontal cortex. The patient was kept normotensive and underwent a right-sided surgical revascularization procedure, remaining well for three years. SAH not due to ruptured aneurysm in moyamoya disease is rare. The cause of the SAH was thought to be disruption of the transdural anastomotic vessels. Recognition of these fragile vessels in moyamoya disease is essential.