Computed Tomography Angiography-Based Morphometry of the Stylohyoid Complex as a Guide for Craniofacial and Skull Base Surgery.

BACKGROUND: This study aimed to establish new morphometric reference values for the styloid process of the temporal bone, with particular emphasis on age- and sex-related differences and standardized 3-dimensional spatial orientation.

METHODS: A retrospective analysis of CT angiographies of the supra-aortic vessels from 339 patients (678 styloid processes) was performed. Patient age and sex were documented. Measurements included styloid process length and diameter, angular orientation in 2 orthogonal planes, distance to the lesser horn of the hyoid bone, and ossification of the stylohyoid ligament. Statistical evaluation was conducted.

RESULTS: CT angiographies of 176 male (51.9%) and 163 female (48.1%) patients were analyzed. The mean styloid length was 26.1±10.4 mm (left) and 26.5±11.9 mm (right). Length increased with age in both sexes and was consistently greater in males. The mean anterior-posterior angle was 70.4°±5.63° (left) and 70.3°±5.9° (right); increasing length correlated with a decreasing AP angle, indicating medial displacement of the tip. The mean lateral angle was 64.2°±6.45° (left) and 64.2°±6.32° (right); increasing length correlated with increasing lateral angle, corresponding to dorsal displacement. The mean diameter measured 3.81±1.09 mm (left) and 3.87±1.16 mm (right), with age-related enlargement.

CONCLUSIONS: This study provides new morphometric reference values for the styloid process, demonstrating age-related elongation and thickening accompanied by dorsomedial deviation of the tip toward the adjacent neurovascular structures.In summary, CTA‑based morphometry of the stylohyoid complex provides a shared quantitative framework linking anatomical variation to clinical presentation in Eagle syndrome. Incorporating these standardized reference values into routine imaging reports may facilitate more consistent recognition of clinically relevant stylohyoid pathology and support targeted treatment decisions.

Copyright © 2026 by Mutaz B. Habal, MD.

PMID: 42479567