A randomized, blinded study of canal wall up versus canal wall down mastoidectomy determining the differences in viewing middle ear anatomy and pathology

Hypothesis: Canal wall down and intact canal wall tympanomastoidectomy repr esent two surgical approaches to middle ear pathology. The authors hypothes ize that there is a difference in the ability to view structures in the mid dle ear between these two methods. Background: Depending on the individual, many surgeons have used the two di fferent techniques of intact canal wall and canal wall down tympanomastoide ctomy for approaching the middle ear. However, opinions conflict as to whic h approach provides the best visualization of different locations in the mi ddle ear. This study prospectively evaluated temporal bones to determine th e differences in visualizing structures of the middle ear using these two a pproaches. Methods: Twelve temporal bones underwent a standardized canal wall down tym panomastoidectomy using a reversible canal wall down technique. All bones w ere viewed in two dissections: intact canal wall and canal wall down prepar ations. Four points previously had been marked on each temporal bone in ran domly assigned colors. These points include the sinus tympani, posterior em s of stapes, lateral epitympanum, and the Eustachian tube orifice. An obser ver blinded to the purpose of the study, color, and number of locations rec orded the color and location of marks observed within the temporal bones. R andomized bones of two separate settings were viewed such that each bone wa s viewed in both the canal wall down and the intact canal wall preparations . Results: A significant difference was noted in the ability to observe middl e ear pathology between the intact canal wall versus canal wall down tympan omastoidectomy, with the latter showing superiority (p < 0.001). Of the fou r subsites, the sinus tympani, posterior crus of stapes, and lateral epitym panum were observed more frequently with the canal wall down. There was no significant difference in the ability to observe the Eustachian tube orific e between the two techniques. Conclusions: Statistical analysis shows good reproducibility and randomizat ion of this study. The canal wall down tympanomastoidectomy allowed for sup erior viewing of the three locations, sinus tympanic, posterior crus of sta pes, and lateral at the tympanum, as they were marked in the study. This st udy shows the potential for improved visualization via the canal wall down tympanomastoidectomy.