Morphometric and Morphological Variations of the External Aperture of the Carotid Canal: A CT Study

Objectives: The aim of this study was to determine the morphometric and morphological variations of the external apertura of the carotid canal (EACC), which is of critical importance in skull base surgery, and to evaluate their relationship with age and gender. Methods: In this retrospective computed tomography (CT) study, 700 EACCs from 350 adults (175 males, 175 females) aged 18–80 years were analyzed. The measured morphometric parameters included the length, width, and area of the EACC, as well as its distances to the midline, the supramastoid crest (SC), and the mandible. In addition, shape variations of the EACC were recorded. Results: The vast majority of EACC measurements were found to be significantly higher in men than in women (p < 0.05). The predominant shape was determined to be oval (62.29%); the round shape, however, was more common in women (p = 0.011). The average width (6.11 ± 0.89 mm) was significantly greater than the length (4.53 ± 0.75 mm), and values on the left side were higher than those on the right. It was observed that the distance to the mandible increased with age (p < 0.05). Conclusion: The morphometric data obtained contribute to predicting the position of the internal carotid artery (ICA) in lateral skull base surgery and reducing the risk of vascular injury; meanwhile, gender-based dimensional differences provide reference values that enable patient-specific preoperative planning.