Cone-Beam Computed Tomographic Evaluation of Variant Foramina of the Clivus: A Retrospective Study From a Tertiary Dental Institution in South India

Introduction: Anatomical variants involving the clivus, including Canalis Basilaris Medianus (CBM), Craniopharyngeal Canal (CPC), and Fossa Navicularis Magna (FNM), are uncommon developmental osseous defects that are usually identified incidentally during radiographic examination. Although generally asymptomatic, these variants may mimic pathological lesions or fractures and may possess important clinical and surgical implications. Large field-of-view cone-beam computed tomography (CBCT) scans provide an opportunity for incidental identification of such variants during routine dental imaging. The present study aimed to evaluate the prevalence and demographic distribution of anatomical variant foramina involving the clivus in archived CBCT scans obtained from a tertiary dental institution in South India. Materials and methods: This retrospective observational study was conducted using 50 archived large field-of-view CBCT scans retrieved from the Department of Oral Medicine and Radiology, Meenakshi Ammal Dental College and Hospital, Chennai. CBCT scans were evaluated in axial, coronal, and sagittal sections for the presence of CBM, CPC, and FNM. Demographic distribution and prevalence of variants were assessed using descriptive statistics, and associations between variables were evaluated using the Chi-square test and Fisher’s exact test. Results: Clival anatomical variants were identified in 20 (40.0%) subjects. CBM was the most frequently observed variant (12, 24.0%), followed by CPC (5, 10.0%) and FNM (5, 10.0%). CBM demonstrated a relatively uniform age distribution, whereas CPC showed a statistically significant association with age group (p = 0.033). FNM was identified only among male subjects in the present sample, although this association did not reach statistical significance. Co-occurrence of two variants was identified in two (10.0%) positive cases. Conclusion: Clival anatomical variants may be encountered as incidental findings on large field-of-view CBCT scans and can be identified during routine radiographic evaluation. Adequate knowledge regarding their radiographic appearance is essential to avoid misdiagnosis and facilitate accurate CBCT interpretation, appropriate referral, and effective preoperative planning. Given the relatively small sample size and single-center design, further studies are required to better characterize the prevalence and clinical significance of these variants.