Validation of the Correlation between Keros and Gera Classification in Endoscopic Sinus Surgery in Koreans

Background and Objectives: The lateral lamella of cribriform plate is the thinnest part of the skull base (SB), and there is a possibility of perforation during endoscopic sinus surgery (ESS). Keros and Gera classifications are known for predicting the risk of damage to the SB. The Keros classification is divided into three types according to the depth of the olfactory fossa, and the longer the depth of the olfactory fossa, the more vulnerable it is to damage SB. The Gera classification was divided into three types by measuring the slope of the ethmoid roof as an angle, and the smaller the angle, the more vulnerable it is to damage the SB. Therefore, this study attempted to analyze the correlation between the both classifications in Koreans. Materials and Methods: We analyzed 294 adult patients with sinus computed tomography images (588 sides) performed for diagnosis. We measured the lateral lamella length (LLL, distance between the fovea ethmoidalis and the horizontal cribriform plate in the olfactory fossa) and Gera angle (GA, angle between LLCP and lateral extension of horizontal plane passing through cribriform plate), and classified them into each type. Statistical analysis was performed for using the chi-square test, student t test, paired t test, and Pearson