Cerebral Hyperperfusion Syndrome following the Excision of a Mycotic Aneurysm with Superficial Temporal Artery-to-Middle Cerebral Artery Bypass: Case Report

The authors report a rare case of cerebral hyperperfusion syndrome (HPS) following the excision of a mycotic aneurysm with superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass. A 74-year-old woman with infective endocarditis presented with progressive cerebral infarction and subarachnoid hemorrhage due to a mycotic aneurysm, which was excised with a STA-MCA bypass. Postoperatively, the patient developed HPS that was considered to be exacerbated by a previous ischemic event. Therefore, cerebral hemodynamics should be evaluated before bypass surgery to prevent subsequent hyperperfusion.