Progression of Peripheral Vestibular System Degeneration Secondary to Otitis Media in the Chinchilla Model

Hypothesis: Untreated otitis media (OM) may associate with progressive histopathological changes in the peripheral vestibular system structures in the chinchilla model. Background: Previous studies have suggested a link between OM and vestibular pathology. However, the mechanisms underlying this relationship are not well understood. Objectives: To evaluate the progression of peripheral vestibular pathology in chinchilla temporal bones with OM. Methods: Chinchilla temporal bones, both control and Streptococcus pneumoniae-inoculated, were obtained from the Paparella Otopathology & Ear Pathogenesis Laboratory and evaluated at 3, 7, 14, 21, and 28 days. Peripheral vestibular pathology was assessed by evaluating organ-specific cell densities in the sensory epithelia and quantifying vestibular ganglion cells for potential pathologies. Results: Compared with controls, S. pneumoniae-inoculated specimens exhibited significantly lower densities of type I and II cells starting from 7 days postinoculation. The exceptions were in the utricle for both cell types and the posterior semicircular canals for type II cells, where the decrease first became noticeable on day 14 (p < 0.05). Loss of transitional cell and dark cells was initially identified in the 14-day and 21-day groups, respectively. The density of vestibular ganglion cells were decreased only in the 28-day group. Conclusion: Our results revealed progressive loss of peripheral vestibular cells and ganglion neurons in cases with persistent OM, which closely aligns with the findings from human otopathology studies. This supports the chinchilla as a reliable model for vestibular pathology research.