Prospective Ramdomized Trial of Extracranial-intracranial (EC-IC) Bypass Surgery for Adults with Moyamoya Disease with Hemorrhagic Onset

INTERVENTION: EC‐IC bypass on both sides (each side with some interval between). As the operative maneuver, the direct bypass procedures such as STA‐MCA anastomosis are essential. A surgeon can add an indirect bypass procedure with direct bypass. Indirect bypass alone or high flow bypass graft such as venous graft or radial artery graft is not allowed. Conservative therapy CONDITION: Moyamoya disease PRIMARY OUTCOME: (1) recurrent bleeding (2) completed stroke causing significant morbidity in daily life activities (3) significant morbidity or mortality from other causes (4) the additional performance of EC‐IC bypass by the decision of the participating neurologist such as in cases with progressive stroke, or crescendo TIA SECONDARY OUTCOME: The following events which occurs 3 months after enrollment: (1) recurrent bleeding on the same side of the previous bleeding (2) hemorrhage‐related death or severe disability INCLUSION CRITERIA: 1. Clinical requirements. (1) Age: between 16 and 65 at the time of the initial bleeding episode. (2) Independent in their daily lives :modified Rankin disability scale 0‐2 or 3 (supplement trial). (3) Intracerebral hemorrhage, intraventricular hemorrhage, or subarachnoid hemorrhage within the preceding 12 months (4) At least one month should have passed after the last stroke episode, either ischemic or hemorrhagic. (5) At least one month should have passed after the completion of acute phase treatment for the hemorrhages and for the related secondary pathophysiology (e.g. hydrocephalus) . 2. Radiological requirements (1) CT/MRI (a) Lack of large infarction which widely spreads over the territory of a main arterial trunk. (b) Lack of contrast enhancement in the infracted area (2) Angiography (a) Angiographic findings should satisfy the diagnostic criteria of the spontaneous occlusion of the Circle of Willis (Moyamoya disease) published by the Ministry of Health, L