Endoscopic view of a posterior ostium of the ethmoid bulla
by Eiji Yanagisawa, MD, FACS, Joseph P. Mirante, MD, FACS, and Dewey A. Christmas, MD

A 37-year-old woman presented with recurrent ethmoid sinusitis, which was confirmed on computed tomography. She underwent functional endoscopic sinus surgery to treat her persistent ethmoid disease.During surgery, the left ethmoid bulla was opened anteriorly (figure, A). Inspection of the posterior wall of the left ethmoid bulla revealed a well-defined ostium that extended through the basal lamella (figure, B). A right ethmoidectomy was also performed through the anterior wall of the right ethmoid bulla (figure, C). Visualization of the posterior wall of the right ethmoid bulla also showed a well-defined ostium that extended through the basal lamella (figure, D). As the dissection progressed, both of these ostia were found to open into the posterior ethmoid cells.

A: Telescopic view (0°, 4 mm) of the left nasal cavity shows a microdebrider entering the anterior wall of the ethmoid bulla. B: After the anterior wall of the ethmoid bulla was removed, the telescopic view shows the well-defined ostium in the posterior wall of the left ethmoid bulla that extends through the basal lamella. C: A right ethmoidectomy is performed through the anterior wall of the right bulla with a microdebrider. D: This view also shows a well-defined ostium in the posterior wall of the right ethmoid bulla (basal lamella).

The anterior and posterior ethmoid cells are defined by and separated by the basal lamella of the middle turbinate. Cells that are part of the anterior ethmoid labyrinth drain into the middle meatus, and cells that belong to the posterior ethmoid labyrinth drain into the superior meatus and occasionally into the supreme meatus.1 The ostium of the ethmoid bulla is usually found in the posterior and medial aspect of the bulla draining into the hiatus semilunaris superior; sometimes it is found in the anterior or lateral ethmoid bulla wall, the ethmoid infundibulum, the retrobullar recess, or the hiatus semilunaris inferior. A circumstance in which the ostia of the ethmoid bulla connect through the basal lamella into the posterior ethmoid labyrinth is an unusual finding.

From the Southern New England Ear, Nose, Throat, and Facial Plastic Surgery Group; the Section of Otolaryngology, Hospital of St. Raphael; and the Section of Otolaryngology, Yale University School of Medicine, New Haven, Conn. (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).