Effects of Intratympanic Dexamethasone on High-Dose Radiation Ototoxicity In Vivo.

Background: Stereotactic radiosurgery for lateral skull base tumors can cause hearing loss when the cochleae are exposed to high doses of single-fraction radiation. Currently, there are no known nondosimetric preventative treatments for radiation-induced ototoxicity. Hypothesis: Intratympanic (IT) dexamethasone (DXM), a synthetic steroid, protects against radiation-induced auditory hair cell (HC) and hearing losses in rats in vivo. Methods: Seven rats received radiation (12 Gy) to both cochleae. In irradiated rats and six nonirradiated rats, IT DXM was randomized to one ear, while tympanic puncture without DXM was performed on the contralateral ear. Baseline and 4-week postradiation auditory-evoked potential tests were performed. The cochleae were processed for HC viability. Results: Cochleae exposed to radiation demonstrated more outer HC (OHC) loss in all turns than nonirradiated ears (p

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