Structural Analysis of Tensor Tympani Muscle, Tympanic Diaphragm, Epitympanum, and Protympanum in Menières Disease: A Human Temporal Bone Study

Hypothesis:We hypothesized that there would be significant anatomic differences of the tensor tympani muscle (TTM), tympanic diaphragm, epitympanum, and protympanum in patients with versus without Menières disease.Background:The effects of tenotomy on Menières disease suggested it relieves the pressure on the inner ear of the contraction of the TTM and of negative middle ear pressure.Methods:Using human temporal bones from patients with Menières disease, two studies were conducted. We examined the presence of otitis media, cholesteatoma, and endolymphatic hydrops, the length, diameter, configuration, the volume of the TTM and tendon, and the area of the tympanic isthmus (Study 1). We examined the presence of otitis media, cholesteatoma and endolymphatic hydrops, and the area and volume of the protympanum (Study 2).Results:In study 1, we observed no significant differences between the two groups. In study 2, we did not observe a small and narrow protympanum in the Menières disease group. None of the ears in the Menières or control groups had otitis media or cholesteatoma in either study. We observed hydrops in all the temporal bones of the Menières disease group and none in the control groups.Conclusion:The position, configuration, and size of the tensor tympani muscle and tendon do not seem to play a role in the pathogenesis of Menières disease. Because the tympanic isthmus and protympanum in Menières disease are not smaller than controls and that none of the temporal bones had otitis media or cholesteatoma, it is unlikely that there was dysventilation in the middle ear.