RADIOLOGICAL OBSERVATION OF ETHMOID ROOF ON BASIS OF KEROS CLASSIFICATION AND ITS APPLICATION IN ENDONASAL SURGERY

Abstract

Introduction: The most complex structure of paranasal sinus or skull base is ethmoid bone or sinus. The Fovea ethmoidalis (FE) and lateral lamella of the cribriform plate (LLCP) is most vulnerable parts or region in the skull base which is most likely to be injured during endoscopic sinus surgeries (ESS). Keros first proposed a three category classification of ethmoidal fovea based on the length of the lateral lamella of the cribriform plate (LLCP). The aim of the present study is to describe the distribution of Keros classification on the basis of gender and laterality among Bengal population. Material and Methods: We did a cross sectional study on computed tomography (CT) scan of paranasal sinuses in 100 patients. We excluded patients with sinonasal tumours, nasal polyposis, previous trauma or surgery either to base of skull or to ethmoid roof. The depth of the olfactory fossa was determined by the height of the lateral lamella. The measurement of both right and left lateral lamella in the CT scan was obtained. The results were grouped according to the Kreos classification and their distributions were analyzed according to gender and laterality. Results: Out of 200 sides CT images studied, the most frequent Keros type was type II (59%) followed by type I (39%) and type III (2%). There is significant difference in the gender. In our study Keros type II (70.34 %) was the most common configuration among males and type I (52.63%) among females. Conclusion: Considering the significant implication of knowing depth of olfactory fossa for the ENT surgeons, radiologist should specifically include this in their routine tomographic reports.