Moyamoya disease presenting with subarachnoid hemorrhage localized over the frontal cortex: case report

BACKGROUND: In moyamoya disease, intracranial bleeding is known to occur because of the rupture of saccular aneurysms in the circle of Willis or because of the rupture of dilated, fragile moyamoya vessels. The former causes subarachnoid hemorrhage (SAH), and the latter causes intracerebral or intraventricular hemorrhage. CASE DESCRIPTION: In this report, we describe the case of a 34-year-old woman with moyamoya disease who suddenly developed headache and jacksonian seizure. Plain computed tomographic scans on admission revealed SAH localized over the left frontal cortex. The patient was diagnosed with moyamoya disease on cerebral angiography. However, no aneurysm was found on cerebral angiography. Positron emission tomography showed the reduction of CBF and its reactivity to acetazolamide and the elevation of CBV in the left hemisphere. She underwent STA to MCA anastomosis and indirect synangiosis. Intraoperative observations revealed that the pial arterioles were markedly dilated on the brain surface. The CBF in the left hemisphere significantly improved after surgery. The patient has experienced no further episode of cerebral ischemia or intracranial bleeding. CONCLUSIONS: Subarachnoid hemorrhage of unknown cause is quite rare in moyamoya disease. Based on the findings in the present case, the dilated collateral arteries on the brain surface may rupture and cause SAH over the cerebral cortex, which is the third cause of intracranial bleeding in patients with persistent cerebral ischemia due to moyamoya disease.