Intra-operative hemorrhage due to hyperperfusion during direct revascularization surgery in an adult patient with moyamoya disease: a case report.

Hemorrhagic complication is one of the notable surgical complications of the revascularization surgery for moyamoya disease (MMD). Cerebral hyperperfusion (CHP) has been considered as the underlying cause of this complication. It mostly occurs several days after surgery, but the intra-operative hemorrhage immediately after bypass has not been reported previously. A 21-year-old woman presented right thalamic hemorrhage and was diagnosed as having MMD by cerebral angiography. In light of the location of the hemorrhage at the vascular territory of posterior circulation and the manifestation of transient ischemic attack during the follow-up period, she underwent revascularization surgery to prevent future ischemic attack and rebleeding. Superficial temporal artery (STA) was uneventfully anastomosed to the temporal M4 branch of the middle cerebral artery in an end-to-side manner. A few minutes after the completion of the anastomosis, hemorrhage occurred in the fissure adjacent to the site of anastomosis. Indocyanine green (ICG) video angiography just before hemorrhage showed focal early filling through the STA graft with early venous filling around the site of the anastomosis. The bleeding was controlled by immediate hypotensive therapy (systolic blood pressure 117 to 91 mmHg). The mean blood flows of the STA graft measured by ultrasonic flowmetry before and after hypotensive therapy were 52.8 and 24.2 ml/min, respectively. Single-photon emission computed tomography (SPECT) on the next day after surgery showed focal hyperperfusion in the surgical side. Intra-operative ultrasonic flowmetry, ICG, and postoperative SPECT would explain that CHP was the potential cause of the hemorrhagic complication. This is the first case describing intra-operative hemorrhagic complication during revascularization surgery for MMD. Surgeons need to be aware of this rare complication and its management method.