Transorbital Endoscopic Identification of Supernumerary Ethmoid Arteries

Abstract

Background:Anterior and posterior ethmoid arteries supply the paranasal sinuses, septum, and lateral nasal wall. Precise identification of these arteries is important during anterior skull base procedures, endoscopic sinus surgery, and ligation of ethmoid arteries for epistaxis refractory to standard treatment. There is controversy in the literature regarding the prevalence of supernumerary ethmoid arteries.Objective:This study examined the prevalence of supernumerary ethmoid arteries by using direct visualization after transorbital endoscopic dissection.Methods:Nineteen cadaveric specimens were evaluated by using a superior lid crease (blepharoplasty) incision and an endoscopic approach to the medial orbital wall. Ethmoid arteries were identified as they pierced the lamina papyracea coplanar with the skull base and optic nerve. The distances from the anterior lacrimal crest to the ethmoid arteries and optic nerve were measured with a surgical ruler under endoscopic guidance.Results:Thirty-eight cadaveric orbits were measured. Overall, there were three or more ethmoid arteries (including anterior and posterior arteries) in 58% of orbits, with 8% of the total sample that contained four or more ethmoid arteries. The average number of ethmoid arteries was 2.7. Bilateral supernumerary ethmoid arteries were noted in 42% of the specimens. The distance between the anterior lacrimal crest and the anterior ethmoid, posterior ethmoid, and optic nerve averaged 20, 35, and 41 mm, respectively. The average distance to the supernumerary or middle ethmoid artery was 29 mm.Conclusion:This study found supernumerary ethmoid arteries in 58% of cadaveric specimens, a prevalence much higher than previously reported. Recognition of these additional vessels may improve safety during endoscopic sinus surgery and skull base surgery, and may permit more effective ligation for refractory epistaxis originating from the ethmoid system.

Osteologic analysis of ethnic differences in supernumerary ethmoidal foramina: implications for endoscopic sinus and orbit surgery

“…The previously reported finding of accessory foramen in North American Caucasians (35%) is higher than in our Icelandic cohort. One study reported a 42% bilateral prevalence in an ethnically heterogeneous group . Because these nonmatching data sets were extracted from studies analyzing different ethnic groups, a direct comparison cannot be made.…”

“…However, recent anatomic studies have suggested that up to 6 branches can be present within a single orbit. A number of studies have described osteometric quantification of the ethmoid foramina as a surrogate for the number of actual ethmoidal arteries, with most studies analyzing heterogeneous ethnic cohorts. However, established ethnic differences in orbital morphology suggest that there may be concomitant significant differences in the presence and symmetry of supernumerary ethmoidal vessels across patient groups.…”

Orbital Fractures

“…The classic teaching is that the anterior ethmoid artery located 24 mm posterior to the anterior lacrimal crest and the posterior ethmoid artery located 12 mm further posterior and 6 mm from the optic canal. In reality, the ethmoid arterial system is variable in number and location of its branches, most often with 3 arteries in unpredictable positions, 10 but can be visualized on CT. Other important structures in the medial orbit are the medial rectus muscle, the medial canthal tendon, the trochlea, and the nasolacrimal sac.…”

“The Accessory Ethmoidal Canal Does Not Necessarily Contain an Arterial Structure”

“…The authors refer to it in different terms, such as supernumerary, tertiary, intermediate, accessory, or middle ethmoidal artery. 1,2 The European position paper on the anatomical terminology of the internal nose and paranasal sinuses suggests the term of accessory ethmoidal artery (AcEA) and it refers a prevalence of 40% according to the Lang J's study. 3,4 However, neither the international anatomical terminology nor the classical anatomy books make reference to AcEA, [5][6][7][8] which creates serious doubts about its existence and if so about its true anatomical origin.…”

“…These arteries are responsible for the nose bleeding in approximately 20% of cases. 1,2 Exceptional intractable epistaxis can involve other different arteries. These reports mention posterior ethmoidal artery, the palatovaginal artery, or branches from facial artery as possible causes.…”