Prevalence of the Posterior Ponticulus and Arcuate Foramen in a Kenyan Population: A Cross-Sectional Radiological Study

Background: Complete posterior ponticuli and the resultant arcuate foramen may compress the third part of the vertebral artery and the sub occipital nerve as they cross the neural arch of the atlas. This may manifest with neurological deficits and also complicate surgical access to lesions in the craniovertebral junction. The prevalence of the ponticulus has been shown to have sexual dimorphism and population differences. The aim of this study was to determine its prevalence and distribution across the sexes in the study population. Methodology: This was a cross-sectional Survey of 116 patients (equal numbers of males and females) done between August and October 2021 at the Radiology Department of Kenyatta National Hospital after ethical approval. Far lateral sagittal Computed tomography scans of the Craniovertebral junction and 3D reconstructions were analyzed in PACS software. The presence and completeness of the posterior ponticulus and arcuate foramen was determined. Chi square test was used to analyze gender differences in their distribution. Results: The prevalence of complete posterior ponticuli was at 15.5%, with unilateral ponticuli more common than bilateral ones (twelve versus six). There were no significant gender differences in terms of distribution. Conclusion: Variations of the posterior arch of the atlas are relatively high in the studied population, necessitating a low threshold for imaging before surgery, and high index of suspicion in neurological deficits involving the posterior circulation of the brain