The effects of dexamethasone following an acute acoustic trauma

Abstract

An acute acoustic trauma (AAT) results when the unprotected ear is exposed to very high sound pressure levels, usually as the result of an industrial or military accident. There is no commonly accepted treatment in the U.S. for an AAT. A study was performed to evaluate the effects of a corticoid steroid (dexamethasone) on the hearing loss from a series of blast waves that would simulate an AAT. Dexamethasone is commonly used as an anti-inflammatory agent in veterinary medicine. Groups of chinchillas were exposed individually to ten 160-dB peak SPL reverberant blast waves from a conventional shock tube at a rate of one blast per minute. Immediately following the exposure, the animals were injected with dexamethasone alone (1.0–2.0 mg/kg IV) or in combination with dimethyl sulfoxide (DMSO), a free-radical scavenger. Individual groups of animals showed the well-known extreme variability in hearing losses as noted in earlier studies [e.g., R. P. Hamernik et al., J. Acoust. Soc. Am. 90, 197–204 (1991)]. Examining the median permanent threshold shifts (PTS) of the groups of animals showed a distinct dose-response effect with increasing dosages of dexamethasone associated with lower levels of PTS in the frequency region most affected by the noise exposure.