External carotid artery occlusion after carotid endarterectomy: Risk factors and exoscope use.

OBJECTIVE: Although carotid endarterectomy (CEA) is the standard treatment for carotid stenosis, the incidence, predictors, and clinical significance of external carotid artery (ECA) occlusion after CEA remain poorly characterized. We assessed these factors and whether exoscope introduction influenced the ECA occlusion rate. METHODS: We retrospectively analyzed 75 consecutive CEA cases with a patent preoperative ECA performed between January 2020 and December 2025 (mean age 73.4 years; 60 male). Preoperative ECA diameter was measured on MRA. Intraoperative indocyanine green (ICG) angiography was routinely performed, and postoperative MRA or CTA and diffusion-weighted imaging (DWI) were obtained within one week. An exoscope replaced the microscope in January 2024; periods were compared using Fisher's exact test. RESULTS: ECA occlusion occurred in 3 cases (4.0%), all asymptomatic and without new DWI lesions. The occlusion group had a significantly smaller preoperative ECA diameter (2.57 vs. 3.92 mm, P = 0.027; ROC AUC 0.880, cutoff 2.10 mm) and more frequent poor intraoperative ICG perfusion (67% vs. 1%, P = 0.003). Occlusion occurred in 2 of 46 microscope cases (4.3%) and 1 of 29 exoscope cases (3.4%; P = 1.000). Insufficient distal ECA endarterectomy was the suspected cause in all cases. CONCLUSIONS: ECA occlusion after CEA was uncommon and asymptomatic. A small preoperative ECA diameter and poor intraoperative ICG perfusion were significant predictors. Because ECA patency matters for future EC-IC bypass and comparable rates are reported after stenting, surgeons should preserve ECA flow through adequate distal endarterectomy and intraoperative ICG assessment.