Effect of Topical Dexamethasone on Sensorineural Hearing Loss in Endotoxin-induced Otitis Media

Abstract

Sensorineural hearing loss, which is limited to the cochlear basal turn, due to acute or chronic otitis media has been reported in clinical and experimental studies. In the present study, the effect of intratympanic dexamethasone on endotoxin-induced cochlear damage was investigated by measuring the cochlear blood flow and hearing. Materials and Methods: Ten male Sprague-Dawley rats were inoculated with lipopolysaccharide (LPS), and divided into 2 groups of five rats each. One hour after intratympanic inoculation, the group A received 40 μl of phosphate-buffered saline (PBS) in the right middle ear cavity, group B received 40 μl of dexamethasone. The treated animals were examined 24 h after inoculation using auditory brainstem response (ABR) and cochlear blood flow (CBF). Results: The elevated threshold decreased significantly after intratympanic dexamethasone administration compared to the PBS-treated group. Intratympanic dexamethasone administration to the round window of rats led to a statistically significant increase in CBF compared to the PBS-treated group (p<0.05). The response to round window application of prostaglandin E₁ (PGE₁) in the dexamethasone-treated group was better than in the PBS-treated group. Conclusion: Our results showed that intratympanic dexamethasone treatment was effective in protecting the function of the cochlea against endotoxin-induced otitis media.