[Anatomical relationship between the frontal sinus ostium and the anterior ethmoidal artery: surgical implications]

The anterior ethmoidal artery represents a major danger in the dissection of the anterior ethmoid roof. In addition to hemorrhage, its injury exposes the patient to the risk of orbital haematoma and requires intraoperative and postoperative vigilance. The goal of this study was to describe the anatomical relationship between the frontal sinus ostium and the anterior ethmoidal artery, such as they are observed with the endoscope during nasalization.

Consecutive patients with no surgical history or agenesia of the frontal sinuses, with an indication for ethmoidal complete exenteration with ablation of the mucous membrane (nasalization), were included in a prospective descriptive study. When dissection of the anterior ethmoidal roof was finished, the relationship between the frontal sinus ostium and the anterior ethmoidal artery were filmed and drawn on a diagram during surgery. A photograph of the relationship between the frontal sinus ostium and anterior ethmoidal artery was selected afterward from the film.

Sixty-eight ethmoids were operated (30 bilateral, eight unilateral) with no complications. The anterior ethmoidal artery was visible in 60 cases (88%), 31 out of 34 cases on the left side (45%) and 29 out of 34 cases on the right side (43%); it was not visible in eight cases (12%), three cases on the left (4.5%) and five cases on the right (7.5%). In the most frequent anatomical configuration (45 cases, 66%), the frontal sinus ostium was separated from the anterior ethmoidal artery by a single ethmoidal cell. The other anatomical configurations were: presence of two cells between the frontal sinus ostium and the anterior ethmoidal artery in 11 cases (16%), and three cells in one case (1%) or absence of the ethmoidal cell between the frontal sinus ostium and the anterior ethmoidal artery (the anterior ethmoidal artery was located on the posterior wedge of the frontal ostium) in three cases (4%). The comparison of the 30 bilateral cases showed a symmetrical relationship between the frontal sinus ostium and the anterior ethmoidal artery in 20 cases (67%).

These data are addressed to surgeons seeking the anterior ethmoidal artery starting from the frontal sinus ostium. Localization of the frontal sinus ostium, which can be achieved by retrograde cannulation of the frontal sinus or using a transcutaneous frontal drain, appears to be a reliable technique to dissect the roof of the anterior ethmoid and locate the anterior ethmoidal artery.