Meniere's disease and endolymphatic hydrops without Meniere's symptoms: temporal bone histopathology.

We studied temporal bone histopathology in 21 ears with Meniere's disease and 24 ears with endolymphatic hydrops without Meniere's symptoms and compared the findings to those in 10 ears with presbycusis and 11 ears with normal hearing. Normal hearing ears showed less degeneration of cochlear structures than the other ears. In ears with endolymphatic hydrops without Meniere's symptoms, the degeneration of spiral ligament, hair cells, dendrites (peripheral processes) and apical spiral ganglion cells was more severe than in the other three groups. In ears with Meniere's disease and endolymphatic hydrops without Meniere's symptoms, the hair cells and dendrites were more affected than ganglion cells and there was no correlation between hair cell and ganglion cell degeneration. These findings suggest that a permanent threshold shift in late stage endolymphatic hydrops is not related to ganglion cell loss but rather to degeneration of sensory elements.