Medialization of Common Carotid Artery is Associated with Cervical Kyphosis

Introduction: Reportedly, the medialization of the common carotid artery (MCCA) to be a vascular anomaly with a potential risk of intraoperative carotid artery injury. Nevertheless, among spine surgeons, the presence of MCCA has not been well recognized. Methods: We retrospectively reviewed consecutive patients who underwent cervical radiographs and magnetic resonance imaging (MRI) examinations in a single spine center. Using MRI, the MCCA grade was classified into grades 1 to 3 in order of severity. Radiographic measurement included C2-C7 angles as cervical lordosis, cervical sagittal vertical axis (C-SVA), T1 slope (T1S), and T1S-cervical lordosis mismatch. We compared each patient's background and radiographic parameters between patients with each of the three MCCA grades. The continuous variables were compared using the Jonckheere-Terpstra trend test and the proportions were compared using the Cochran-Armitage trend test to investigate the trend of variables in three grades. Results: The present study included data from 133 eligible patients (65 males and 68 females) with a mean age of 63.7 (±14.2) years. The details of MCCA grading were as follows: grade 1, n=101; grade 2, n=27; and grade 3, n=5. With an increasing MCCA grade, age (61.9±14.0, 68.2±13.8, and 76.4±9.4 years for grades 1, 2, and 3, respectively, p=0.005) and proportion of female (p<0.001) had an increasing trend, whereas cervical lordosis had a decreasing trend (11.7±13.5°, 7.0±14.5°, and −10.0±19.2° for grades 1, 2, and 3, respectively, p=0.011). Conclusions: Several patient backgrounds including the female gender, older age, and kyphotic alignment were determined as MCCA risk factors. Careful preoperative neck vasculature assessment would avoid a catastrophic complication during anterior cervical surgery.