Cochlear bone erosion: Effects on cochlear hair cells: A scanning electron microscopy study

Cochleae from gerbils with normal middle ears were compared with cochleae from gerbils with experimentally induced cholesteatomas that were in contact with the cochlear wall (stage III cholesteatomas). Cochleae from gerbils with stage III cholesteatomas were further divided into two groups: one without erosion of cochlear bone, and one with cholesteatoma-induced bone erosion but without cochlear fistulae. The cochleae with bone erosion showed significant loss of outer hair cells in the middle and apical turns, but not in the basal turn. The cochleae with stage III cholesteatomas but without bone erosion did not differ from normal controls. These results suggest that an ototoxic agent, involved in the process of bone erosion, acts through the bony cochlear wall.