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.