Anatomical Variation of the Olfactory Fossa According to Keros and Yenigun Classifications in Karachi, Pakistan

The goal of our research is to assess the olfactory fossa anatomical variation through Keros and Yenigun classification by computed tomography (CT) scan of paranasal sinuses (PNS), as in order for surgeons to prevent major complications, they must be familiar with its variations in anatomy during functional endoscopic sinus surgery (FESS) related to anterior ethmoidal artery injury, as its course varies with depth and length of the olfactory fossa.

At Karachi's Dow University of Health Sciences (DUHS), retrospective research was carried out. From anterior to posterior, sequential coronal and axial pictures were examined, and the existence and location of further anatomical characteristics were documented. A consultant radiologist used the picture archiving and communication system (PACS) software to do the review. The depth of the olfactory fossa and anterior-posterior length were measured. We utilized OpenEpi version 3 to compute the sample size findings. The estimated sample size was calculated as 249 by taking the prevalence of 63.5% for type 2 Keros classification, with a margin of error of 6% and a confidence level.

The median length for the olfactory fossa depth (Keros) for the left and right sides were 6.2 (2.2-10.9) mm and 6.0 (2.8-10.4) mm, respectively. The median anteroposterior length of the cribriform plate (Yenigun) for the left and right sides were 11.4 (6.1-19.2) mm and 11.2 (6.0-18.0) mm, respectively. According to Keros Classification, type 2 was observed as the most prevalent category on the right side for both females and males, with 97/122 (79.5%) and 106/127 (83.5%) individuals, respectively. The chi-square test was applied for the analysis of gender and classification. Keros type 2 was observed to be the most prevalent in both males and females. Similarly, type 2 was also seen to be the most prevalent in the Yenigun classification in both genders. No statistical difference was found in both classifications (p = 0.39). In most of the literature, type 2 has been the most commonly dominated type. The reason seems due to the variation in genes and anatomy of the human PNS.

Preoperative planning should take the morphological characteristics of the ethmoidal roof into account. Understanding the ethmoidal roof morphology among populations may be improved by looking at bigger patient groups and meta-analyses that compile different study findings on this topic.