Correlation Between Keros Classification and the Location of the Anterior Ethmoidal Artery: A CT-Based Study

Background and ObjectivesThe lateral lamella of the cribriform plate (LL) at the ethmoid roof is the most vulnerable site for skull base (SB) injury during endoscopic sinus surgery (ESS).The Keros (K) classification is widely used as a radiologic index to estimate the risk of SB injury.This study aimed to quantitatively evaluate the relationships among the K classification, LL, and the position of the anterior ethmoidal artery (AEA), including the SB-AEA distance and AEA type, in order to assess their clinical relevance for improving ESS safety.Subjects and Method This retrospective study analyzed sinus CT of 294 patients (588 sides).The K classification (types I, II, and III), LL length, and the distance between the SB and AEA (SB-AEA) were measured.The AEA location was classified either as type 1 (located at the SB) or type 2 (low-lying, below the SB). ResultsThe K type II was the most common classification.A significant association was identified between the K classification and the prevalence of AEA type 2 (p<0.001).The SB-AEA distance differed significantly among the different K types (p<0.001), with the K type III demonstrating the greatest distance (2.75±1.86mm), which was significantly longer than that of types I and II.The LL length showed a significant positive correlation with the SB-AEA distance (r=0.323,p<0.001).Conclusion The K type III represents an anatomical configuration that may be more susceptible to the AEA injury than other K types, characterized by a greater SB-AEA distance and a higher prevalence of low-lying AEA.