LAUSR

BACKGROUND Hyperperfusion syndrome associated with aneurysm surgery is rare. The occurrence of the syndrome after trapping with high-flow bypass has not been described previously. Herein, we present a case of the syndrome that occurred after trapping with high-flow bypass of an unruptured giant paraclinoid internal carotid artery (ICA) aneurysm. CASE DESCRIPTION The patient was a 68-year-old woman with progressive loss of vision in her left eye. After a diagnosis of left giant ICA aneurysm, she underwent successful trapping with high-flow bypass. No new neurologic deficits were observed after surgery. Computed tomography on the same day and magnetic resonance imaging on the next day revealed no hemorrhage or infarction. The patient had a headache and transit motor aphasia on postoperative day (POD) 8. Arterial spin-labeling magnetic resonance perfusion imaging on the same day and single photon emission CT on POD 10 demonstrated hyperperfusion in the left cerebral cortex. The symptoms gradually improved over a week, and she had no new neurologic deficits when discharged from hospital. CONCLUSIONS This report suggests that hyperperfusion syndrome after trapping with high-flow bypass, although rare, should be considered in patients with giant aneurysm if they present with headache and neurologic deficits after a delay.