Assessment of depth of olfactory fossa in pre-functional endoscopic sinus surgery computed tomography scan of paranasal sinuses

Background: To evaluate the olfactory fossae depth according to the Keros' classification on pre functional endoscopic sinus surgery (pre-FESS) and determine the incidence and degree of asymmetry in the height of the ethmoid roof in the population of western Maharashtra. Methods: Retrospective analysis of 200 multidetector CT studies (400 sides) of paranasal sinuses performed in between January to August, 2017. Results: According to the Keros’ classification, the incidence of different types of olfactory fossae was as follows: type I: 18.5%, type II: 74.5% and type III: 7%. Asymmetry in the ethmoid roof height was found in 11.5% of cases. Conclusions: Keros’ type II was the commonest followed by type I and type III. There was asymmetry in the depth of the olfactory fossae in 11.5% cases. There was no significant gender predilection as far as type and asymmetry were considered.