Risk Factors for Anterior Skull Base Injury in Endoscopic Sinus Surgery

Objectives This retrospective study aimed to investigate the relationships between the Keros classification, the Gera classification, the vertical height of the posterior ethmoid roof (ER), and anterior ethmoidal artery (AEA) types in Japanese patients. Methods We investigated the computed tomography (CT) slices of paranasal sinuses (120 sides) of 60 patients; measured the cribriform plate (CP) depth, lateral lamella CP angle (LLCPA), and vertical height of the lateral ER from the hard palate (LERHP) at the coronal plane of the posterior ethmoidal artery (PEA); and reviewed the AEA types, whether floating or non-floating. Results CP depth was positively correlated with LLCPA (r=0.63; p<0.01) and the height of LERHP (r=0.19; p<0.05). The height of the LERHP in females was significantly lower than that in males. With increased CP depth, floating AEAs became prevalent (p<0.001). Conclusion In females, low height of the posterior ethmoid sinus roof, where cerebrospinal fluid (CSF) leaks occurred while penetrating the basal lamella, often existed; the heights positively correlated with the Keros classification in Japanese patients. The Keros and Gera classifications, AEA type, and posterior ER height do not individually constitute a complete risk assessment but may correlate, preventing major complications, such as CSF leak and orbital hemorrhage.