Cochlear Neural Degeneration Is Widespread in Ménière's Disease: A Temporal Bone Study

Ménière's disease presents with endolymphatic hydrops and disproportionately poor word-recognition compared to other forms of sensorineural hearing loss, yet the underlying patterns of cochlear degeneration are not well defined. This study aimed to characterize cochlear pathology in Ménières, compare it to age-matched controls and clinically unaffected contralateral ears, and evaluate how hydrops severity and clinical endotypes relate to tissue degeneration.

We analyzed 97 human cochleas, including 43 Ménière's ears, 10 contralateral (clinically unaffected) ears, and 44 age-matched controls. Quantitative histopathology assessed survival of hair cells, spiral ganglion cells, auditory-nerve peripheral axons, stria vascularis, and spiral ligament fibrocytes, along with the degree of endolymphatic hydrops. We also examined the effects of disease duration and endolymphatic sac phenotype (hypoplastic vs degenerative).

Ménière's ears displayed consistent cochlear hydrops and more severe saccular hydrops. They showed roughly half the normal complement of cochlear hair cells but only 25% of the normal complement of auditory-nerve peripheral axons, despite preservation of most spiral ganglion cells. The degree of hydrops was most strongly correlated with cochlear neural degeneration. Ménière's ears also exhibited significant strial atrophy and fibrocyte loss, with strong correlations between these measures. Contralateral ears showed no hydrops but similar strial and fibrocyte degeneration with normal hair and neural populations. Disease duration and endolymphatic sac phenotype, i.e. hypoplastic vs degenerative, produced only modest differences in cochlear histopathology, suggesting that profound neural degeneration is a common endpoint across clinical subtypes.

Profound cochlear neural degeneration is likely the key driver of poor word-recognition scores associated with Ménière's disease. The presence of strial and spiral ligament atrophy in the clinically unaffected ears suggests lateral wall histopathology may be the earliest site of cochlear damage in this disease.