Aim: The aim of this study was to deliver the most complex study on the prevalence of the FA and its clinical significance.
Introduction: Foramen arcuale (FA) is an osseous prominence formed in place of a sulcus for the vertebral artery on the posterior arch of the atlas. The presence of an FA can make a threat during neurosurgery by giving a false notion of a wider posterior arch when viewed dorsally during C1 lateral mass screw insertion.
Methods: An comprehensive search of the major electronic databases was performed in order to find and identify all studies which reported relevant data on the FA. No date or language restrictions were applied. Data on the prevalence, type (complete and incomplete), side, gender, laterality, and morphometrics of the FA were extracted and pooled into a meta-analysis.
Results: A total of 127 studies (n=55,985 subjects) were included into the quantitative analysis. The overall pooled prevalence of a complete FA was 9.1% (95%CI: 8.2–10.1), while the overall pooled prevalence of an incomplete FA was 13.6% (95%CI: 11.2–16.2). The complete FA was found to be most prevalent in North American (11.3%) and European (11.2%) populations, and least prevalent among Asian (7.5%) populations, especially Chinese (4.4%) and South Koreans (5.8%). In the presence of a complete FA, a contralateral FA (complete or incomplete) was found in 53.1% of cases.
Conclusion: The FA is a commonly present anatomical structure. Awareness of a complete variant of the FA during procedures performed on the atlas vertebra is essential in reducing the risk of iatrogenic injury. Therefore, risk for the presence of an FA should be considered by surgeons prior to procedures on the atlas in each patient according to gender and ethnic group. As such, we highly advise preoperative screening with CT as the gold standard for finding the presence of an FA.