Radio anatomical analysis of positional relation between anterior ethmoid artery canal and ethmoid skull base in correlation with olfactory fossa

Skull base (SB) injuries happens mostly either in the thinnest or the least resistant part ofskull base. The lateral lamella of cribriform plate is one of the common sites of injury during endoscopicanterior skull base surgeries. The anterior ethmoid artery (AEA) visualization is considered as a significantanatomical landmark in such surgeries. Studies correlating their positional relation with morphology ofolfactory fossa remains limited. This study aims to look into the relation of AEA to that of SB in differenttypes of olfactory fossa morphology.Materials and Methods: A retrospective radiological study was done on 100 coronal CT images frompatients who were subjected to paranasal CT imaging. In bone window of coronal CT scans, the positionof AEA in relation to SB was noted and the vertical distance between them was measured. Based on thedistance of AEA from SB, 3 groups were subdivided as follows: Group A - mm and Group C - > 5 mm. The depth of the olfactory fossa was measured and categorized according toKeros classification.Results: Out of 200 sides, AEA was found below SB in 167 out of 200 (83.5%) with majority belongingto Group A (101 out of 167). Keros type II was commonly observed among all the groups. The position ofAEA below SB was seen at a greater frequency as the height of SB increased with the Keros classificationand was statistically significant (P = .006)Conclusion: The knowledge of presence of anterior ethmoid artery outside the skull base with long laterallamella preoperatively would help the surgeon to avoid intraoperative complications during endoscopicskull base or sinus surgeries.Keywords: Anterior ethmoid artery, Skull base, Lateral lamella, Olfactory fossa, Keros.