[Subacute subdural hematoma associated with moyamoya phenomenon--a case report].

A case of subacute subdural hematoma associated with moyamoya phenomenon is reported. On May 8, 1986, a 61-year-old female was referred to Mito National Hospital for evaluation of a left-sided hemiparesis and headache 8 days after minor head injury. Seventeen years ago she experienced the sudden onset of a left-sided hemiparesis which improved by rehabilitation. CT scans showed a thin high density area on the right cerebral convexity and a small low density area in the right semiovale center. On May 12, she was admitted because of aggravation of her symptoms. A repeat CT scan showed an enlarged right temporoparietal subdural hematoma with significant mass effect. Cerebral angiograms revealed the occlusion of right internal carotid artery. There were so-called moyamoya vessels bilaterally and transdural anastomosis on the right side. Avascular area confirmed subdural hematoma. The hematoma was evacuated via two burr holes with preservation of the middle meningeal and superficial temporal arteries. By the time of discharge two months postoperatively, she was walking well without assistance. We reviewed four cases of acute or subacute subdural hematoma associated with moyamoya phenomenon and emphasized the possibility of occurrence of acute or subacute subdural hematoma due to rupture of vault moyamoya vessels.