A computed tomography assessment of olfactory fossa depth in relation to Functional endoscopic sinus surgery in a South African population

Introduction: The olfactory fossa is a region of the anterior skull base vulnerable to injury during Functional endoscopic sinus surgery, being at the highest risk if deep or asymmetric. Detailed knowledge and preoperative evaluation of olfactory fossa depth and its anatomical variations are vital to avoid iatrogenic injury and resultant complications, in order to perform successful endoscopic surgery. The present study aimed to explore the depth of the olfactory fossa and its associated variations within a South African population. Materials and methods: Eighty-six olfactory fossae were assessed using computed tomography scans. Depth measurements were taken on coronal images using predefined radiological landmarks before classification using the Keros system (Types I-III). Results: The overall median (Q1–Q3) olfactory fossa depth was 5.75 (4.30–6.50) mm, with statistically significant differences identified according to sex (p = 0.023) and laterality (p = 0.037). Keros Type II was noted most frequently (75.6% of cases), followed by Keros Type I (16.3% of cases). Keros Type III was noted least frequently (8.1% of cases). Conclusions: The Keros classification is of great importance during preoperative assessments of olfactory fossa depth because of the objective, reliable and pre-emptive information it provides. The South African population displays a higher risk of olfactory fossa injury as a result of the deeper olfactory fossae observed in females (compared to females of other populations), on the left side (compared to the left side of other populations), and overall (entire sample compared to other populations).