Level of complete dissection of the ethmoid sinuses with a computed tomographic image guidance system.

OBJECTIVES: We sought to determine the adequacy of endoscopic total ethmoidectomy with the use of a computed tomographic (CT) image guidance system.
METHODS: Endoscopic ethmoid sinus dissections were performed on cadavers by otolaryngologists. All cadavers were scanned before dissection. On each side of the cadaver, the ethmoid sinuses were examined independently. A complete endoscopic ethmoidectomy was performed with a CT image guidance system. After the endoscopic ethmoidectomy, the cadaver underwent a postdissection CT scan. The postdissection CT images were then evaluated for the level of complete dissection of the anterior and posterior ethmoid sinuses.
RESULTS: There were 18 ethmoid sinuses in the study. One specimen underwent a complete total ethmoidectomy with no residual cells. There were 4 complete anterior ethmoidectomies and 5 complete posterior ethmoidectomies. Overall, the average numbers of residual anterior ethmoid and posterior ethmoid air cells were 1.39 and 1.22, respectively. This difference was not statistically significant. The skull base was dissected more completely than the lamina papyracea, with a significant difference (p = 0.03). There was no difference in terms of residual cells between the left and right ethmoid sinuses (p > 0.05).
CONCLUSIONS: Even with the use of a CT image guidance system, a complete ethmoidectomy was still difficult to achieve. Residual ethmoid sinus cells were more commonly found along the lamina papyracea than along the skull base.