Pneumatization of Sphenoid Sinus in a South African Population: An Investigation using Computed Tomography scans.

Abstract

Introduction Sphenoid air sinuses (SS) are a popular site for surgical entry when treating diseases such as intrasella and cranial base tumours. The transsphenoidal approach is more efficient and associated with lower morbidity and death compared to the standard transcranial technique. Extensive pneumatization of the SS is regarded as a prerequisite for the transsphenoidal approach. However, extensive pneumatization can endanger the optic nerve (ON) or internal carotid artery (ICA) during surgery. Understanding local anatomy is crucial for effective preoperative planning and treatment. Anatomical variations in the SS across different populations make it essential to know the anatomical details for different population groups. This study aimed to explore the pattern and extent of pneumatization, volume, and pneumatized extensions of SS in a South African population using radiological images. Materials and Methods This was a retrospective radiological study of an adult population (≥18 years). Computed tomography (CT) scans of 63 patients were analyzed bilaterally (n =126 SS). The sample comprised of 30 males and 33 females. The sphenoid sinus volume (SSV), pneumatization patterns, lateral extensions, posterior pneumatization and protrusion of the ON or/and ICA were assessed. Results The post-sella type was frequently observed (44.4%), the conchal type was the least prevalent (4%). The post-sella type was predominant in females on the left SS (58.9%). The conchal type was mainly observed in black South Africans (4.2%). The body type was frequently observed (33.3%), followed by pneumatization of greater wings of the sphenoid bone (26.7%), full lateral (23.3%) and pneumatization of pterygoid process (11.7%). Pneumatization of the lesser wing of sphenoid was least prevalent (5.0%). Statistically significant differences in different population groups were identified, with pneumatization of the greater wings of the sphenoid bone only observed in black South Africans (30.8%). The most prevalent type of posterior pneumatization was the dorsal type (60.0%). Clival type was more prevalent in Indian/White South Africans (37.5%). Subdorsal type was only observed in black South Africans. Statistically significant differences in terms of laterality and sexual dimorphism were identified. Group 1 (no protrusion of ICA/ON) was frequently observed (54.2%), followed by group 4 (protrusion of ICA & ON) (19.2%). Group 3 was more prevalent in males (13.0%) and females accounted for only 4.5%. Females presented a higher SSV 243 (72.5-837) cm3 and 98.5 (21.0-456) cm3 in males (p > 0.05). Black South Africans presented a higher SSV compared to other South African populations. Discussion and Conclusion The prevalence of the different patterns of pneumatization varied within the diverse South African population, with pneumatization of the greater wings of the sphenoid bone mainly prevalent in black South Africans. Pneumatization of the clivus exhibited a higher prevalence, on the right SS, and in females as compared to other populations. Protrusion of the ON into the SS in South African patients was very low when compared to other populations. Female patients in the South African population presented with higher SSV than males, which varied from other populations. Anatomical knowledge obtained from this study can be applied in transsphenoidal surgery and in treatment of other cranial base pathologies related to SS to ensure effective preoperative evaluations and favorable postoperative outcomes.