Pure vasogenic edema caused by cerebral hyperperfusion after superficial temporal artery to middle cerebral artery anastomosis--case report.

A 63-year-old patient presented with cerebral hyperperfusion manifesting as transient aphasia and general tonic convulsions 3 and 4 days after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis. Diffusion-weighted magnetic resonance (MR) imaging revealed a focal low-intensity area at the site of anastomosis in the left temporal lobe, with high apparent diffusion coefficient, together with focal intense increase in cerebral blood flow in the same region. This lesion was considered to be pure vasogenic edema caused by cerebral hyperperfusion. Additional treatment with intravenous drip infusion of free radical scavenger and reduction in blood pressure with nicardipine improved the patient's symptoms and brain edema. The brain edema gradually decreased on MR imaging and completely disappeared at 3 months after bypass surgery. Cerebral hyperperfusion is often encountered after recanalization of occlusive arteries, removal of arteriovenous malformations, and carotid endarterectomy, but may also occur after STA-MCA anastomosis.