Maryam Moradi - Department of Radiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Bahare Dalili - School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.

Introduction: This study aimed to investigate the distribution of ethmoid roof variation and symmetry according to Keros classification.   Materials and Methods: This cross-sectional study assessed the paranasal CT scans of 600 patients over 18 years of age with no history of surgery, trauma, or localized fracture in the ethmoid, nose, and anterior skull base. The lateral lamella of the cribriform plate (LLCP) sizes were measured and classified as Keros type I (1-3 mm), II (4-7mm), and III (8-16mm). Moreover, the symmetry was surveyed in accordance with the LLCP measurements on both sides of the ethmoid roof. These variations were analyzed regarding gender and age.   Results: In total, 600 patients participated in this study out of whom 311 cases were male. According to the results, the mean age of the participants was 37.50±16.63 years. Furthermore, the mean values of the LLCP height for the right and left sides were 4.17±1.69 and 4.93±1.97 mm, respectively. Moreover, the asymmetry was observed in 38.3% of the cases, and they were classified as 36.7% Keros type I, 50.5% Keros type II, and 12.8% Keros type III.   Conclusion: Keros type II and symmetry were the most common variations in this study. In addition, these variations were independent of age and gender.

Anatomy, classification, Ethmoid sinus