Occlusion of Extracranial-Intracranial Bypass Anastomosis-Associated Aneurysms Following Contralateral High-Flow Extracranial-Intracranial Bypass in a Patient with Impaired Cerebrovascular Reserve.

BACKGROUND AND IMPORTANCE: Extracranial-intracranial (EC-IC) bypass anastomosisassociated aneurysms are rare sequelae of cerebral revascularization surgery. Although treatment paradigms are not well defined, clipping, trapping with revision bypass, and donor vessel ligation represent the most common microsurgical approaches. CLINICAL PRESENTATION: A 53-yr-old male presented with cognitive decline, left extremity weakness, and left visual field blurriness. Computed tomographic angiography of head/neck demonstrated bilateral cervical internal carotid artery occlusion and magnetic resonance imaging of brain showed a small right parieto-occipital lobe infarct. The patient's symptoms worsened despite aggressive medical management. Therefore, a right superficial temporal artery to middle cerebral artery (STA-MCA) bypass was performed for flow augmentation. Follow-up digital subtraction angiography (DSA) approximately 1 yr after surgery noted 2 new aneurysms adjacent to the patent STAMCA anastomosis. Perfusion imaging at that time showed persistently reduced blood flow in the left cerebral hemisphere. A left STA-MCA bypass was performed, and intraoperative blood flow measurements showed this to be a high-flow bypass. Follow-up DSA 4 mo later demonstrated involution of the right STA-MCA bypass and occlusion of the anastomosis-associated aneurysms with increased perfusion of the right cerebral hemisphere via collateral blood flow from the patent high-flow left STA-MCA bypass. At 7 mofollowing left STA-MCA bypass, the patient's neurological examination remained stable and perfusion imaging showed improved blood flow in the left cerebral hemisphere. CONCLUSION: We present a unique case in which a high-flow left EC-IC bypass with robust contralateral collateral blood flow was associated with subsequent occlusion of a right EC-IC bypass and 2 anastomosis-associated aneurysms in a patient with bilateral impaired cerebrovascular reserve.