[Hyperperfusion after Revascularization for Quasi-moyamoya Disease Associated with Graves' Disease:A Case Report].

: We report a case of cerebral hyperperfusion syndrome accompanied by postoperative intracerebral hemorrhage following blood flow reconstruction for quasi-moyamoya disease associated with Graves' disease that had caused cerebral infarctions. A 44-year-old woman presented with repeated sensory impairment of the fingers on the left hand and weakness of the right lower limb and multiple cerebral infarctions developed in the bilateral frontal lobes. Magnetic resonance angiography and cerebral angiography suggested quasi-moyamoya disease. On hospitalization, untreated Graves' disease was identified and treated first. Revascularization was performed in the region of the right middle cerebral artery, where reduced cerebral blood flow and depressed vascular reactivity persisted half a year after treatment of Graves' disease, but postoperative cerebral hemorrhage appeared after 5 days due to hyperperfusion syndrome around the anastomotic site. Lethal hyperperfusion syndrome following revascularization of quasi-moyamoya disease associated with Graves' disease appears very rare and has not been reported previously.