Incidence and Risk Factors of the Retropharyngeal Carotid Artery on Cervical Magnetic Resonance Imaging

Study Design. Retrospective cohort. Objective. Define incidence of anomalous carotid vasculature and associated risk factors as pertains to the anterior approach. Summary of Background Data. The carotid artery system, including the common, internal, and external branches, is lateral to the foramen transversarium. If unrecognized, aberrancies in carotid vessel anatomy can lead to devastating complications. Methods. A total of 1000 cervical magnetic resonance imagings were screened to localize the carotid artery respective to medial/lateral location of the vessel at each segment from C2-C3 to C6-C7 bilaterally. Vessel location was classified in 3 zones: lateral to the vertebral foramen (type I) (normal); between the lateral foramen and uncoverterbral joint (type II); and medial to the uncovertebral joint (type III). Type III locations were compared with age-matched controls for assessment of cervical alignment via the Ishihara index, C2-C7 angle, and degree of spondylosis. Results. A total of 123 patients demonstrated carotid artery anomalies (type II and III) (12.3%). Twenty-six patients had type III aberrancy (2.6%). Patients with anomalies were significantly older and more likely to be female (60 vs. 51 yr of age, 74% vs. 57% female, respectively, P < 0.05). The type III group average age was 66.1 years and 88% were female. Aberrancies were more likely right-sided and at C3-C4 or cranial. C2-C7 angle showed significantly greater kyphosis in patients with anomalies compared with controls (6.2 vs. 14.4, P = 0.03). The number of severely spondolytic segments was significantly greater in patients with Type III locations than controls (2.0 vs. 1.1 P < 0.05). Conclusion. Carotid arterial anomalies occurred in 12.3% of cases; severe aberrancy was present in 2.6% of patients. In elderly females with kyphotic alignment, a high index of suspicion must be raised for aberrancy. Preoperative assessment of the vasculature in the anterior neck may avoid catastrophic complications.