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.