Endoscopic view of the posterior ethmoid artery.

The anterior and posterior ethmoid arteries are important anatomic structures to be recognized during endoscopic sinus surgery. (1,2)

The anterior ethmoid artery, a branch of the ophthalmic artery, leaves the orbit via the anterior ethmoid foramen, crosses the roof of the anterior ethmoid sinus, and supplies the anterior ethmoid cells and frontal sinus (figure, A). The artery then enters the anterior cranial fossa, gives off meningeal branches, and turns downward into the nasal cavity through the slit-like apertures at the side of the crista galli. The anterior ethmoid artery supplies the anterior one-third of the lateral wall of the nasal cavity and a similar portion of the nasal septum. (3)

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The posterior ethmoid artery takes a similar course along the roof of the posterior ethmoid, and it enters the nasal cavity through the cribriform plate. It is normally much smaller than the anterior ethmoid artery. (1-4) The posterior ethmoid artery supplies the posterosuperior portion of the lateral nasal wall (superior turbinate) and a corresponding portion of the nasal septum. Both the anterior and posterior ethmoid foramina are usually situated along the frontoethmoid suture line (figure, A). (4) The distance between the anterior and posterior ethmoid foramina is approximately 10 mm. (4) Kirchner et al reported that the distance from the posterior ethmoid foramen to the anterior portion of the optic foramen ranged between 4 and 7 mm in 84% of the skulls they studied. (4) In most cases, the posterior ethmoid artery is embedded in the bone of the roof of the posterior ethmoid sinus and may not be visible. (2,4)

According to Stammberger, one way to find the anterior ethmoid artery by the endoscopic approach is to follow the anterior surface of the ethmoid bulla in the direction of the roof of the ethmoid sinus. (1) If the bulla lamella extends up to the roof of the ethmoid sinus, the ethmoid artery can usually be found immediately adjacent to this point--usually 1 to 2 mm posteriorly. By following the roof posteriorly, one may be able to see the posterior ethmoid artery crossing the roof.

We evaluated an elderly man who had undergone numerous sinus procedures and polyp removals in his distant past; his most recent surgical procedure had been 29 years earlier. We found that he had extensive recurrent polyposis. The patient elected to undergo revision surgery and polypectomy. Intraoperatively, we found and removed numerous polyps with a microdebrider (figure, B). After removing polyps from the left ostiomeatal complex and the left ethmoid sinus, we observed a posterior ethmoid vessel in the roof of the left posterior ethmoid sinus (figure, C). Closer endoscopic inspection revealed an exposed and well-defined posterior ethmoid artery crossing the roof (figure, D). We observed a protrusion of thin bony walls at the medial (anterior cranial fossa) and lateral (orbit) ends of the posterior ethmoid artery. Injury to these protrusions can lead to orbital hematoma, cerebrospinal fluid leakage, or intracranial infections. (5,6)

Severing the anterior or posterior ethmoid artery can cause serious complications if the artery retracts into the orbit and continues to bleed. It can cause periorbital, intraorbital, or retro-orbital hematoma, resulting in visual disturbances or even blindness. (2,5,6) In the event of rapid protrusion and fixation of the eyeball, the surgeon must be prepared to perform emergency orbital decompression to prevent blindness. Immediate lateral canthotomy is recommended. In addition, opening the orbital septum via an infraorbital approach and control of bleeding via a Lynch-type external ethmoidectomy approach should be considered. (2,5,6)

If recurrent or persistent severe posterior epistaxis should occur following internal maxillary and anterior ethmoid artery ligation, Lander and Terry suggest that the source of the bleeding might be the posterior ethmoid artery. (7) They recommend a transorbital endoscopic ligation or bipolar cautery through a Lynch incision.

Remember that the posterior ethmoid artery runs along the roof of the ethmoid sinus. The surgeon should not go any farther above this artery during ethmoidectomy.

References

(1.) Stammberger H. Functional Endoscopic Sinus Surgery: The Messerklinger Technique. Philadelphia: B.C. Decker, 1991:70-4.

(2.) Ohnishi T, Yanagisawa E. Endoscopic anatomy of the anterior ethmoidal artery. Ear Nose Throat J 1994:73:634-6.

(3.) Hollinshead WH. Head and neck. In: Hollinshead WH. Anatomy for Surgeons. 2nd ed. Vol. 1. New York: Harper and Row, 1968.

(4.) Kirchner JA, Yanagisawa E, Crelin ES, Jr. Surgical anatomy of the ethmoidal arteries. A laboratory study of 150 orbits. Arch Otolaryngol 1961;74:382-6.

(5.) Ohnishi T, Tachibana T, Kaneko Y, Esaki S. High-risk areas in endoscopic sinus surgery and prevention of complications. Laryngoscope 1993; 103:1181-5.

(6.) Stankiewicz JA. Complications of endoscopic sinus surgery and malpractice. In: Stankiewicz J A, ed. Advanced Endoscopic Sinus Surgery. St. Louis: Mosby, 1995.

(7.) Lander MI, Terry O. The posterior ethmoid artery in severe epistaxis. Otolaryngol Head Neck Surg 1992; 106: 101-3.

From the Southern New England Ear, Nose, Throat, and Facial Plastic Surgery Group, New Haven, Conn., the Section of Otolaryngology, Hospital of St. Raphael, New Haven, and the Section of Otolaryngology. Yale University School of Medicine, New Haven (Dr. Yanagisawa); and the Department of Otolaryngology, University of South Florida College of Medicine, Tampa, and the Halifax Medical Center, Daytona Beach, Fla. (Dr. Mirante and Dr. Christmas).