Microsurgical Exclusion of a Giant Thrombosed ICA Bifurcation Aneurysm with STA–MCA Bypass: A Surgical Video Technical Note

Introduction: Giant intracranial aneurysms involving the internal carotid artery bifurcation are associated with progressive mass effect, a high rate of intraluminal thrombosis, and an unfavorable natural history; management remains challenging, often requiring open microsurgical strategies combining cerebral revascularization with aneurysm exclusion.1,2 So, the objective of this study was to describe, through an illustrative surgical video, the microsurgical management of a giant, partially thrombosed left internal carotid artery bifurcation aneurysm using flow-preserving STA–MCA bypass combined with intrasaccular thrombectomy, endarterectomy, and aneurysm exclusion. Case Report: A 53-year-old smoker presented with an eight-month history of progressive right hemiparesis. CT angiography demonstrated a giant, partially calcified and thrombosed left supraclinoid internal carotid artery aneurysm involving the carotid bifurcation, and digital subtraction angiography showed only minimal contrast filling due to extensive thrombosis. A left pterional approach was performed with harvesting of the superficial temporal artery, Sylvian fissure dissection, and repair of an intraoperative arterial bleeding point by microsurgical arteriorrhaphy under temporary proximal carotid control. An end-to-side STA–MCA bypass was constructed onto an M4 cortical branch using 10-0 nylon microsutures, with patency confirmed by indocyanine green videoangiography.3 Ultrasonic aspiration was used for intrasaccular thrombectomy, followed by division of the M1 segment and aneurysm neck; arterial bleeding and atherosclerotic plaque within the arterial wall required microsurgical endarterectomy and reconstruction with interrupted 10-0 nylon sutures.4 Results: Intraoperative Doppler ultrasonography and angiography confirmed adequate flow across the reconstructed carotid artery, preserved anterior cerebral artery circulation, and bypass patency supplying the middle cerebral artery territory, with complete aneurysm exclusion.5 Postoperative imaging confirmed durable exclusion and bypass patency. Conclusion: Combining extracranial-to-intracranial bypass, intrasaccular thrombectomy, microsurgical endarterectomy, and multimodal intraoperative flow assessment allowed definitive exclusion of a giant thrombosed carotid bifurcation aneurysm while preserving cerebral perfusion, reinforcing the relevance of microsurgical revascularization for complex aneurysms unsuitable for standard endovascular treatment.6