Styloid process morphology in extracranial internal carotid artery dissection: a CTA case-control study

BACKGROUND: To evaluate the association between styloid process (SP) morphology derived from CTA and extracranial internal carotid artery dissection (ICAD). MATERIALS AND METHODS: This retrospective case-control study included 85 patients with unilateral extracranial ICAD and 85 frequency-matched controls who underwent head and neck CTA. Two neuroradiologists independently measured SP length, the distance from the SP tip to the internal carotid artery (SPT-ICA distance), and SP orientation (medial and anterior inclination angles). Group comparisons were performed between the dissection side in the ICAD group and the corresponding matched side in controls. Multivariable logistic regression was used to identify independent morphologic factors associated with ICAD, and ROC analysis was performed to evaluate the diagnostic performance of each individual parameter and of the combined model. RESULTS: Compared with controls, ICAD showed a longer SP, a shorter SPT-ICA distance, and a smaller anterior inclination angle (all p < 0.001). Multivariable logistic regression identified SP length, SPT-ICA distance, and anterior inclination angle as independent factors associated with ICAD. ROC analysis showed that the combined model achieved the best performance (AUC = 0.836), compared with SP length (AUC = 0.752), SPT-ICA distance (AUC = 0.742), and anterior inclination angle (AUC = 0.717). CONCLUSION: The combined model based on SP length, SPT-ICA distance, and anterior inclination angle showed the best performance, suggesting that these CTA-derived SP morphologic features may help identify an anatomic pattern associated with extracranial ICAD.