The impact of the styloid process angulation on the carotid arteries.

Purpose: To evaluate the impact of the temporal bone styloid process (SP) angulation on the carotid arteries (CA), both internal and external carotid arteries (ICA and ECA). The SP topographical variability and the clinical significance will be further discussed.

Materials: One hundred computed tomography angiographies (CTAs) (200 sides of 50 male and 50 female patients) were retrospectively studied. The sample's mean age was 62.72 ± 14.77 (range: 20-89 years). The SP length and angle were measured on CTA sagittal and coronal sections, and the relationship with the ICA and ECA was measured in axial sections. The SP elongation was considered when the SP length > 33mm in accordance with prior studies in the same population.

Results: Patients with elongated SPs had an average SP sagittal angle of 59.97 ± 7.75 degrees, while those without elongation had an average sagittal angle of 67.12 ± 9.43 degrees (p<0.001). The correlation between SP length and sagittal angle was statistically significant (R=-0.433, p<0.001), as well as between SP length and coronal angle (R=-0.361, p<0.001). Patients with elongated SPs had an average SP coronal angle of 69.20 ± 5.35 degrees, while those without elongation had an average angle of 76.89 ± 4.02 degrees (p=0.002). After excluding patients with elongated SP, the remaining patients (n=57) had an average SP sagittal angle of 67.77 ± 9.51 degrees, and a mean SP coronal angle was 75.83 ± 5.19 degrees. The SP sagittal and coronal angles influenced none of the measured ICA and ECA parameters after excluding patients with elongated SPs.

Conclusion: The current imaging study has enhanced our understanding of the SP's topographical variability in relation to the CA. Our findings indicate that the length of the SP influences this relationship, whereas the angle (coronal and sagittal) of the SP does not-particularly when excluding patients with elongated SPs. Therefore, clinicians must recognize the variability in the position of the ICA and ECA within the neck.