De Novo Aneurysm Formation at the Anastomosis Site Incidentally Detected 2 Years after Single-Barrel STA-MCA Bypass Surgery: Case Report and Review of the Literature

This case report describes the de novo aneurysm formation at the anastomosis site 2 years after single-barrel superficial temporal artery to middle cerebral artery bypass surgery. Correct bypass patency and morphology of the anastomosis site was documented intraoperatively and immediately postoperatively by indocyanine green videoangiography and digital subtraction angiography (DSA). Aneurysmatic dilatation at the anastomosis site was observed 2 years postoperatively upon computed tomography angiographic follow-up examination. After repeat DSA, the patient underwent microsurgical reexploration and clip ligation of the aneurysmatic portion of the donor artery. The possible underlying mechanisms are discussed and the current literature is reviewed.