Relationship of stylohyoid chain and cervical internal carotid artery detected by 3D angiography.

OBJECTIVE: The calcification of the stylohyoid chain (SHC), elongated styloid process (SP), larger SP' angle and its shortened distance of cervical internal carotid artery (CICA) are risk factors for bony compression and the stylocarotid syndrome. METHODS: 3D-CTAs of 125 patients were analyzed in terms of the SP length, its angulations, type of the SHC and relationships of its proximity to the CICA. RESULTS: Elongated SP was observed frequently both in females (47%) and males (55%). The mean distance of the CICA to the SP was calculated as 8.2 ± 3.3 mm. This short distance between the CICA and the SP was observed more frequently in males (28.1%) and females (10.7%). The anterior and medial angulations of the SP were calculated as 71.2 ± 4.3°, and 57.3 ± 9.3°, respectively. In the present study, the SHC was determined as normal SP (54.2%), absence of the SP (1%), duplication of the SP (1%), elongated SP (26%), complete ossification of the SHC (1%), segmentation of the SHC (9%), fracture of ossification of the SHC (1.6%) and pseudo articulations of the SHC (5.6%). CONCLUSION: 3D-CTA was the most appropriate radiological investigation analyzing and measuring SHC (elongated, larger angle, shorter distances with CICA) and identifying types (duplicated, segmented, complete and fractured) resulting from pressures on the CICA. Our study also revealed the pressure on the artery not only arose from the tip of the SP but could also result from types stretching over the artery wall. In those specimens, there is a higher probability of formation of the stylocarotid syndrome due to the long-term pressure on the sympathetic chain around the CICA.