Chronic subdural hematoma following bypass surgery--report of three cases.

Bypass surgery is a safe procedure with low mortality and morbidity, and few reported surgical complications. Three patients developed postoperative chronic subdural hematoma (CSDH): two with stroke after superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis and one with moyamoya disease after STA-MCA anastomosis combined with encephalomyosynangiosis. The factors inducing CSDH after revascularization in the seven reported and present cases included postoperative subdural effusion associated with brain atrophy, and postoperative anticoagulant therapy such as aspirin. CSDH may occur in patients with pre-existing brain atrophy and postoperative subdural effusion. Anticoagulant therapy should be avoided at the early postoperative stage after bypass surgery.