Vertical insertion of the middle turbinate: a sign of the presence of a well-developed agger nasi cell. (Rhinoscopic Clinic).

A 35-year-old man was evaluated for facial pressure and discomfort in the right periorbital and bilateral malar areas of several months' duration. He also complained of difficulty in nasal breathing. Computed tomography (CT) of the sinuses showed opacification of both maxillary sinuses, a large and well-developed right agger nasi cell, and a vertical insertion of the right middle turbinate (figure, A). The vertical insertion was also visible on nasal endoscopy (figure, B). The patient underwent endoscopic sinus surgery, and a microdebrider was used to open the agger nasi cell (figure, C and D). The posterior wall of the agger nasi cell was removed, thereby uncapping the obstruction of the frontal recess. Postoperatively, the patient's facial discomfort resolved.

The middle turbinate, part of the ethmoid bone, overhangs the important and complicated area of the middle meatus. The attachment of the middle turbinate divides the cribriform plate medially and the fovea ethmoidalis laterally. (1) There are many variations of the middle turbinate, some of which are associated with subsequent sinus pathology. A bent or otherwise altered shape can cause obstruction of the middle meatus. (2)

The agger nasi cell appears as a mound or eminence in the lateral wall of the nose, anterior to the origin of the middle turbinate. The middle turbinate generally arises at an angle to the lateral nasal wall. An important variation occurs when the insertion develops in a direct vertical fashion upward. In the presence of an agger nasi cell, the projection of the lateral wall of the nose toward the nasal septum is increased. The projection usually causes the middle turbinate to hang more directly vertical. (3)

Depending on the degree of pneumatization, agger nasi cells can be bounded anteriorly by the frontal process of the maxilla, anterolaterally by the nasal and lacrimal bones, posterolaterally by the lamina papyracea, superiorly by the frontal sinus, inferolaterally by the uncinate process, and posteriorly by the anterior ethmoid complex. (3) The frontal recess is situated behind the posteromedial wall of the agger nasi cell. As pointed out by Kuhn et al, pneumatized agger nasi cells can obstruct the frontal recess and result in frontal sinus disease. (3) An extensively pneumatized agger nasi cell can also displace the insertion of the middle turbinate medially, anteriorly, and superiorly, thereby moving the large agger nasi eminence above the insertion of the middle turbinate.

Avoiding excessive resection of the agger nasi cell medially will minimize the risk of an inadvertent destabilization of the middle turbinate. CT of the area should confirm the presence of an anterior ethmoid cell or agger nasi cell anterior to the attachment of the middle turbinate.

Knowledge of the variations in the anatomy of the middle turbinate is of great value in predicting the outcome of the treatment of pathology in the sinuses. The presence of a vertical insertion of the middle turbinate can alert the surgeon to the presence of an agger nasi cell and thereby assist in preoperative planning.

References

(1.) Lawson W. The intranasal ethmoidectomy: Evolution and an assessment of the procedure. Laryngoscope 1994;104(6 Pt 2):1-49.

(2.) Mirante JP, Christmas DA, Yanagisawa E. Powered endoscopic turbinate surgery. In: Yanagisawa E, Christmas DA, Mirante JP, eds. Powered Instrumentation in Otolaryngology--Head and Neck Surgery. San Diego: Singular Publishing, 2001:163-82.

(3.) Kuhn FA, Bolger WE, Tisdal RG. The agger nasi cell in frontal recess obstruction: An anatomic, radiologic and clinical correlation. Operative Techniques in Otolaryngology--Head and Neck Surgery 1991;2:226-31.

From the Southern New England Ear, Nose, Throat, and Facial Plastic Surgery Group, New Haven, Conn., 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. Christmas and Dr. Mirante).