Investigation of the cochlear effects of intratympanic steroids administered following acoustic trauma
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Date
2012
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Abstract
Objectives/Hypothesis: To electrophysiologically and histomorphologically demonstrate the effects of intratympanic corticosteroids administered following an acoustic trauma on cochlear hair cells. Methods: The trial was performed on 16 Wistar albino rats. The rats underwent distortion product otoacoustic emissions (DPOAE) measurement before the acoustic trauma, and subsequently rats were exposed to noise. Following acoustic trauma, the otoacoustic emission measurement was repeated. The rats were divided into two groups, a study group and a control group. The study rats were injected with methylprednisolone via the intratympanic route throughout the study. In the control group, the rats were injected daily with saline. After performing repeated otoacoustic emission measurements, one rat in each of the groups was sacrificed and their cochleae isolated. Results: The histological investigation performed after the 1st week revealed a statistically significantly higher rate of apoptotic cells in the inner and particularly the outer hair cells of the rat cochleae in the control group compared to the study group. Early measurement of DPOAE within the 1st week demonstrated significantly better amplitudes in the study group compared to controls. The otoacoustic emission assessment performed on the 14th day demonstrated statistically similar DPOAE values between the two groups. Conclusions: Intratympanic methylprednisolone injection administered following an acoustic trauma appears to reduce cochlear outer hair cell loss. The impact on hearing loss is less certain. Early measurement of DPOAE within the 1st week shows significantly better amplitudes in the study group compared to controls. However at 2 weeks, there is no statistically significant difference in DPOAE amplitudes between the study and control group. © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.
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Animals , Cochlea , Disease Models, Animal , Follow-Up Studies , Glucocorticoids , Hearing Loss, Noise-Induced , Injections , Otoacoustic Emissions, Spontaneous , Rats , Rats, Wistar , Tympanic Membrane , methylprednisolone , animal cell , animal experiment , animal model , animal tissue , apoptosis , article , basilar membrane , cell loss , cochlea , cochlea spiral canal , controlled clinical trial , controlled study , corticosteroid therapy , distortion product otoacoustic emission , drug efficacy , electrophysiology , external ear , hair cell , hearing loss , inner ear , male , noise injury , nonhuman , otoscopy , priority journal , rat , spiral ligament , white noise