Anatomical variations of clivus: a descriptive anatomical study

Area of Science:

• Anatomy
• Radiology
• Skull Base Anatomy

Background:

• The clivus, part of the sphenoid bone, exhibits anatomical variations like fossa navicularis magna (FNM), canalis basilaris medianus (CBM), and craniopharyngeal canal (CPC).
• These variations are linked to potential health issues such as meningitis and skull base tumors.
• Accurate diagnosis and treatment planning necessitate a thorough understanding of these anatomical variations and their prevalence.

Purpose of the Study:

• To determine the prevalence and types of fossa navicularis magna (FNM), canalis basilaris medianus (CBM), and craniopharyngeal canal (CPC) using cone-beam computed tomography (CBCT).

Main Methods:

• A retrospective analysis of 350 CBCT scans was conducted.
• Two independent observers evaluated the scans for the presence of FNM, CBM (including types), and CPC.
• Interobserver agreement was assessed using Cohen's kappa statistics.

Main Results:

• Fossa navicularis magna (FNM) was identified in 19.4% of cases, and canalis basilaris medianus (CBM) in 9.7%.
• Craniopharyngeal canal (CPC) was not observed in any of the evaluated scans.
• Type 5 was the most prevalent type of CBM. No significant gender or age-related differences were found in prevalence. High interobserver agreement was achieved for FNM and CBM prevalence.

Conclusions:

• FNM and CBM are notable anatomical variations of the clivus, while CPC is rare.
• Knowledge of these variations is crucial for radiologists, anatomists, and surgeons to prevent misdiagnosis.
• Awareness of these anatomical variations can help identify individuals at higher risk for meningitis or skull base tumors.