Cerebral hyperperfusion syndrome associated with non-convulsive status epilepticus following superficial temporal artery-middle cerebral artery anastomosis

A 77-year-old man developed cerebral hyperperfusion syndrome with temporal deterioration of consciousness and worsening of left hemiparesis on the 6th postoperative day following superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis for right M₁ occlusion. Electroencephalography (EEG) revealed frequent ictal discharges in the right hemisphere, although convulsive seizures were not apparent. Administration of anticonvulsants was performed based on the diagnosis of non-convulsive status epilepticus (NCSE). Complete recovery from hyperperfusion syndrome was achieved with rapid improvement of EEG findings. The present case demonstrates the pathophysiological mechanism of hyperperfusion syndrome associated with NCSE after STA-MCA anastomosis.