Canalis Basilaris Medianus as an Anatomical Variation in the Basilar Part of the Occipital Bone: A Descriptive Cone Beam Computed Tomographic Study

Abstract

Canalis basilaris medianus (CBM) is a unique anatomical variation located in the basal occipital region of the skull, rarely encountered in head and neck radiographic imaging. The aim of the present study was to evaluate the prevalence and types of CBM using Cone Beam Computed Tomography (CBCT) scans. CBCT (Full FOV) images of 200 patients aged between 10 to 70 years were selected for the current retrospective study following the inclusion and exclusion criteria. The image sections from the scan data were scrutinized for the presence of CBM, in addition to its classification based on the type of morphology. The presence and types of CBM were recorded based on the age and gender. The chi-square test was used to analyze the presence and types of CBM with regard to gender and age group. The overall prevalence of CBM was estimated as 9.5%. CBM was present in 13% of males and 3% of females (p = 0.021). Considering the types of CBM, the superior recess type was predominantly observed followed by the inferior recess, superior and inferior type. However, there was no significant gender-based differences noted among the types of CBM (p > 0.05). Also, there was no statistically significant difference noted in the prevalence of CBM in different age groups (p > 0.05). It is necessary for maxillofacial radiologists to have a solid understanding of both normal and variant skull-base anatomy to facilitate recognition of variants such as CBM in order to recognize the associated anomalies. To our knowledge, this was the first study done which assesses the gender-based differences among the various types of CBM.