Surgical Anatomy of Variations in Sphenoid Sinus Pneumatisation using Computerized Tomograph

Background: The cavity of the sphenoid sinus is a natural surgical route for accessing the middle cranial fossa. The extent of pneumatisation of the sphenoid is key to the preoperative evaluation of transsphenoidal, surgical procedures. Aim: To determine the prevalence and variations in the extent of pneumatisation of the body of the sphenoid bone using computerised tomography (CT). Methodology: Head CT scans of 323 patients were studied at the Radiology Department of the Usmanu Danfodiyo University Teaching Hospital, Sokoto, after ethical approval was granted. The CT scans were taken with a GE Bright Speed Multidetector Helical CT Scanner, and viewed with the Digital Imaging and Communication in Medicine (DICOM) viewer, powered by RadiAnt Version 4.2 software. Sphenoid sinus pneumatisation was defined by the anteroposterior extent of the sinus cavity of the sphenoid bone on sagittal images. The extent of pneumatisation was classified into four; conchal, presellar, sellar and postsellar, based on the position of the posterior wall of the cavity in relation to the anterior and posterior walls of the sellar turcica. Results: The predominant type of pneumatisation was the postsellar. The prevalence of the different types of pneumatisation were: postsellar, 50.2%, sellar, 32.0%, presellar, 14.7%, and conchal, 3.1%. There was no statistically significant relationship between pneumati- sation and sex (X2 = 0.585), or age (X2 = 0.076). Conclusion: With the prevalence of the different types of pneumatisation, a pre-operative CT assessment of the sphenoid sinus anatomy is essential, whenever the options for a transsphenoidal access to the sellar is being contemplated.