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Anatomic misconceptions regarding the agger nasi cell:a preliminary analysis utilizing endoscopic anatomic dissection and 3D-CT.

The agger nasi cell is a key anatomic landmark in endoscopic frontal sinus surgery. However, discord amongst authors regarding anatomic definition and prevalence raises questions of its suitability as a surgical landmark. The purpose of this investigation is to evaluate the agger nasi cell using radiographic imaging correlated with endoscopic anatomic dissection to consider the cell's role as a surgical landmark and to explore if 3D-CT technology can provide enhanced insight into this anatomy.


METHODS
CT scans of 11 cadaveric sinonasal complexes were studied using triplanar CT or 3D CT scanning with stereoscopic 3D imaging (3DSI). Endoscopic dissections were performed and video recorded. Attention was given to identify agger nasi pneumatization and its origin.


RESULTS
Pneumatization of the agger nasi region was noted in 4/11 cases (36.4%). (In two cases the pneumatization arose from the frontal recess, in two from a true agger nasi cell.) The agger nasi region appeared as solid unpneumatized bone in 4/11 cases (36.4%). In 3/11 cases (27.3%) limited pneumatization was noted, bordering on but not pneumatizing the agger nasi proper.


CONCLUSION
It may be confusing for otolaryngologic surgeons in training to rely on the "agger nasi cell" as a surgical landmark due to misconceptions regarding the anatomy, prevalence and anatomic definitions. Using standard CT scans to teach anatomy may have shortcomings as compared to the gold standard of surgical dissection. However, new 3D-CT holds promise to more accurately reflect small microanatomic features and provide an improved road map of a patient's anatomy in surgery.