[Asymptomatic intracerebral hemorrhage under strict blood pressure control due to postoperative cerebral hyperperfusion in a patient with moyamoya disease].

We report a case of moyamoya disease manifesting as asymptomatic intracerebral hemorrhage due to postoperative cerebral hyperperfusion, despite the prophylactic intensive blood pressure control. This 35-year-old man initially suffered from right upper quadrantanopsia and was found to have cerebral infarction in the left occipital lobe due to moyamoya disease. He also manifested preoperatively a small intracerebral hemorrhage at the left caudate nucleus. The left cerebral hemisphere showed apparent hemodynamic compromise, thus he underwent left superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis with indirect pial synangiosis. He was subjected to prophylactic strict blood pressure control postoperatively to avoid hyperperfusion syndrome. The N-isopropyl-p-I-Iodoamphetamine SPECT (I-IMP-SPECT) 1 day after surgery showed intense increase in cerebral blood flow (CBF) at the site of the anastomosis, and further blood pressure lowering was attempted. He did not suffer from neurologic deterioration during the postoperative period, while computed tomography (CT) 7 days after surgery revealed asymptomatic intracerebral hematoma (ICH) at the subcortex under the site of the anastomosis. Cerebral hyperperfusion is a potential complication of revascularization surgery for moyamoya disease. Accurate diagnosis and proper management of hyperperfusion are essential to avoid deleterious neurologic event due to hyperperfusion.