Age-associated medialization of the cervical internal carotid artery: CT morphometric findings and an exploratory combined mucosa–midline grading framework

Purpose Cervical internal carotid artery (ICA) medialization may narrow anatomical safety margins during transoral and pharyngeal procedures. We quantified age-associated ICA morphometric changes on computed tomography (CT), assessed age-based discrimination for study-defined critical medialization, and developed an exploratory combined mucosa–midline grading framework. Methods This retrospective study included 471 patients. ICA curved length and distances to the neck midline, internal jugular vein, and pharyngeal mucosa were measured. Critical medialization was defined as a mucosa-to-ICA distance ≤ 3 mm or an ICA-to-midline distance ≤ 5 mm. Age-related associations, receiver operating characteristic analysis, and the five-grade framework were evaluated. Results The cohort included 247 males and 224 females (mean age, 50.0 ± 23.6 years; range, 3–94 years). Age correlated positively with ICA curved length (r = 0.672) and ICA-to-internal jugular vein distance (r = 0.846), and negatively with ICA-to-midline (r = − 0.795) and mucosa-to-ICA distances (r = − 0.814; all p < 0.001). Critical medialization was present in 66 patients (14.0%). Within this cohort, age showed excellent discrimination (AUC = 0.930), with an exploratory Youden-derived threshold of ≥ 70 years (sensitivity, 89.4%; specificity, 85.9%; negative predictive value, 98.0%). Grade III–IV anatomy increased from 1.2% in patients aged < 40 years to 74.6% in those aged ≥ 80 years. Conclusion Older age was strongly associated with ICA elongation, medialization, and reduced pharyngeal mucosal safety margins. The exploratory grading framework may support standardized anatomical description on CT but is not a validated predictor of procedural risk. Independent prospective validation is required before clinical implementation.