RS10 - Eagle Syndrome and Carotid Artery Dissection: A Potential Ominous Association?

Objectives: Spontaneous Carotid Artery Dissection (CAD is a rare condition (8.93 per 100,000 person-years) but potentially life-threatening. Eagle Syndrome (ES), defined as elongation of the styloid process (>25mm) or ossification of the stylohyoid ligament, has been considered one of the under recognized aetiological factors for CAD. We aim to evaluate the prevalence of ES in a large cohort of patients with CAD and no cardiovascular risk factors.

Methods: Between 2015 and 2025, we analysed 527 CTA (Computed Tomography Angiogram) scans undertaken in young patients with acute stroke and suspected Carotid artery dissection.
Patients with CAD were identified and styloid process length was measured bilaterally using multiplanar reconstruction (MPR) on Sectra Workstation (IDS7 – Version 26.). Two vascular surgeons performed independent measurements. Inter-observer reliability was assessed using a two-way random-effects intraclass correlation coefficient with absolute agreement (ICC).
The prevalence of ES was compared between patients with and without CAD. The prevalence of ES in the general population was considered as 4% and this was used for all statistical analyses. Statistical analysis included Chi-square testing and Odds Ratio (OR) estimation with 95% confidence intervals (CI).

Results: 170 of 527 (32.2%) CT scans had a radiological diagnosis of CAD. Eagle Syndrome (ES) was diagnosed in 120 (70.6%) of the 170 CAD cases. Inter-observer measurement reliability indicated an excellent agreement (ICC of 0.969 [CI 0.96 - 0.98]) The association between ES and CAD was highly significant (χ² = 270.7, p< 0.001) with an odds ratio of 58.82 (95% CI 31.41–110.18).

Conclusions: In our study, the presence of an elongated styloid process (ES) could represent a significant risk factor for carotid artery dissection. Recognition and early detection of this relatively common anatomical variant may help prevent carotid artery dissection and associated stroke, particularly in younger individuals with no cardiovascular risk factors.
Surgical resection may also be considered in asymptomatic individuals with evidence of compression of the internal carotid artery with the neck rotated. It may, also, be a relative contraindication in patients being considered for carotid artery stenting (CAS).
Incorporation of artificial intelligence techniques to automate this process and recognise these high-risk individuals may be considered in a prospective, multi-centre trial.