The anatomical variance of the anterior ethmoidal artery, with relevance to endonasal surgery. Anatomical Society Summer Meeting Glasgow 2021

The anterior ethmoidal artery is a high-risk structure in the paranasal sinuses, with inadvertent injury potentially leading to blindness or cerebrospinal fluid leak. It is a key structure in certain skull base and sinus surgeries. It is a highly variable structure, in part due to its inter-relations with the many discrete variable structures it closely relates to within the paranasal sinuses and nasal cavity. Awareness of the anterior ethmoidal artery is key to safe surgical practice in endonasal procedures. This study aimed to analyse the relationships of the anterior ethmoidal artery to the adjacent anatomical structures of the nose. This will hopefully help surgeons in identifying the anterior ethmoidal artery and make endonasal surgeries safer. EMBASE, MEDLINE and PubMed were performed in June 2020 and identified articles, of which 17 were considered eligible to be included in this study. The anterior ethmoidal artery was found to have an average diameter and average intranasal length of 0.80 ± 0.24 mm and 5.82 ± 1.41 mm, respectively. The course of the anterior ethmoidal artery was found to vary in its relation to the skull base. It can be adherent to the skull base, suspended within the soft tissue or in a thin bony mesentery below the skull base. The relationship between the anterior ethmoidal artery and the lamellae was investigated in this study to avoid injury to this artery during the dissection of the lamellae in Endoscopic Sinus Surgery. The first lamella is considered the uncinate process, the second is the anterior wall of the ethmoid bulla, the third lamella is the basal lamella of the middle turbinate and divides the anterior and posterior air cells of the ethmoid sinus. The fourth lamella corresponds to the superior turbinate and the fifth is considered the supreme turbinate. The anterior ethmoidal artery was found between the second and the third lamella in 75% of cases, and in the third lamella in 12%. It was concluded that the anterior ethmoidal artery is a key structure in the skull base that is important to find and assess pre-operatively to minimise the risk of serious complications post-operatively in this area.