Variations in external carotid artery branches and common carotid bifurcation level: a computed tomography angiography study

Abstract Background The common carotid bifurcation level is an important surgical landmark during head and neck surgery, especially endarterectomy, that could be omitted in patients with high bifurcation levels to reduce damage to neighboring structures like the hypoglossal nerve. Additionally, having a thorough understanding of the variations in the external carotid artery branches is crucial for head and neck cancer surgeries and thyroidectomy. However, cadavers were employed in the majority of studies on these variations. In previous research, there were significant disparities in the incidence of these variations according to gender, laterality, and ethnicity. In order to identify these changes in Egyptian patients and to compare them in terms of gender and laterality, we used computed tomographic angiography. Methods The level of the common carotid bifurcation was assessed in a cross-sectional study utilizing computed tomographic angiography, which included 80 patients (160 carotid sides) for comparing the common carotid artery bifurcation level with the relevant vertebrae and anterior neck structures, and they were compared with regard to gender and laterality. Variations in the external carotid artery branches were also evaluated. Results The most frequent location of the common carotid bifurcation level was between C3 and C4 (33.8%). It was 36.9% between the thyroid and the hyoid. 47.5% of patients had a high common carotid bifurcation (higher than the C3/4 level). The highest bifurcation was at C2, while the lowest was at D1. For external carotid artery branches variations, the superior thyroid artery emerged at and below the level of the common carotid bifurcation, respectively, at 19.4% and 23.7%. The facial artery had the largest diameter (2.38 ± 0.44 mm), while the ascending pharyngeal artery had the smallest (1.17 ± 0.11 mm). Seven types of trunks were found; the ascending pharyngeal artery-occipital artery trunk was the most common (25%) and was followed by the lingual artery-facial artery trunk (20%). Conclusions Multiple anatomical variations in the external carotid artery branches and the common carotid bifurcation level were found by computed tomographic angiography. As a result, it can be utilized as a useful imaging technique to evaluate these variations before surgery