Prevalence and Morphology of Ossified Caroticoclinoid Ligament: An Updated Systematic Review with Meta-Analysis

Background: The caroticoclinoid ligament (CCL) is between the anterior and middle clinoid processes. The ligament can be variably ossified, creating the caroticoclinoid bar or foramen (CCF). When this variant occurs, it encircles the clinoidal segment of the internal carotid artery (ICA) and can cause morphological changes. The present evidence-based systematic review with meta-analysis aims to describe the CCL ossification variability (complete, incomplete, and contact), their pooled prevalence, and the pooled mean of the CCF. Methods: The systematic review was performed using four online databases to identify articles that had reported CCF prevalence by its morphology, according to the latest guidelines. The meta-analysis used an R programming software with the "meta" and "metafor" packages. The study protocol was registered in PROSPERO (CRD42024623914). Results: The systematic review retrieved a total of 49 studies that had reported on ossified CCL morphological variants. The pooled prevalence of the CCL ossification (irrespective of its morphology) was estimated at 17.47% (95% CI: 14.01-21.23). The most common morphology was the incomplete type, with a pooled prevalence of 10.08% (95% CI: 7.21-13.35). The complete CCF type was calculated at 6.44% (95% CI: 5.30-7.67). The pooled mean diameter of the CCF was 5.00 mm. The geographical distribution, type of study, side, sample size, and sexes did not influence the estimated pooled prevalence. Conclusions: The current study systematically reviewed the prevalence and morphology of CCL ossification. Various subgroup analyses were performed to investigate the possible factors affecting it. This variant has adequate clinical significance due to its close relationship with the ICA.