Anastomotic aneurysm formation after superficial temporal artery – middle cerebral artery bypass surgery in 5 months

SummaryDirect revascularization is beneficial in patients with moyamoya disease under selective conditions. Here, we report the case of a patient with moyamoya disease who developed a complication following revascularization through cerebrovascular bypass surgery. A 42-year-old man experienced an acute onset of weakness in the right limbs with slurred speech. He was initially treated for a suspected transient ischemic attack. Further workup revealed luminal narrowing in the left M1 segment (from the origin of middle cerebral artery to its bifurcation) and total luminal occlusion of the right M1 segment of the middle cerebral artery. Direct revascularization using a superficial temporal artery to the middle cerebral artery bypass procedure was performed. Postoperative follow-up brain computed tomography in the outpatient clinic revealed aneurysm formation at the anastomotic site of the right superficial temporal artery to the middle cerebral artery. Various theories have been postulated to explain this rare complication. Here, we discuss possible etiologies for the formation and management of aneurysms at anastomotic sites with a review of similar cases in the literature.