Critical anatomical variants in preoperative computed tomography of paranasal sinuses in a tertiary care center: a cross-sectional study

Background:Certain anatomical variants of the paranasal sinuses (PNS) predispose to injury of surrounding critical structures during functional endoscopic sinus surgery (FESS) and the occurrence of common pathologies like sinusitis. However, they are often not reported in preoperative computed tomography (CT). Methods:The CT scan of PNS and head of 360 adults (age > 13 years) were retrospectively evaluated for variants of cribriform plate, olfactory fossa, lamina papyracea, uncinate process, sphenoid pneumatization, and anterior ethmoid artery by 4 radiologists with experience of 3 to 6 years. The prevalence of each variant was obtained. Chi-squared and independent sample t-tests were used to analyze relationships between variables, with significance set at P < .05. Results:The prevalence of Keros Type 1, Type 2, and Type 3 olfactory fossa was 24.4%, 66.9%, and 8.6%, respectively, in the right side and 20.6%, 69.2%, and 10.3%, respectively, in the left side. Mean depth of right and left olfactory fossa was 4.9 mm (+/- 1.9) and 5.2 mm (+/- 1.8), respectively. Dehiscence/remote fracture of anterior skull base was observed in 1.9% cases. Dehiscence/remote fracture of lamina papyracea was present in 2.8% cases. Haller cells were observed in 13.9%. Conchal, presellar, incomplete sellar, and complete sellar pattern of pneumatization of sphenoid sinus had prevalences of 2.5%, 6.4%, 26.7%, and 64.4%, respectively. The prevalence of dehiscence of carotid canal in sphenoid sinus was 7.2%. The prevalence of bony septa insertion into carotid canal was 37.8%. The prevalence of supraorbital pneumatization was 51.4%. The prevalence of agger nasi cell and pneumatization of crista galli were 82.2% and 16.7%, respectively. Conclusion:Preoperative CT provides an opportunity to look for critical structures in relation to the PNS. Radiologists should report these findings to prevent potential complications during FESS.