BLAST OVERPRESSURE INDUCED STRUCTURAL AND FUNCTIONAL-CHANGES IN THE AUDITORY-SYSTEM

Blast overpressure of sufficient intensity can produce injury to vario us organ systems. Unprotected ears result in the auditory system being the most susceptible. The injuries to the auditory system include: ru pture of the tympanic membrane, dislocation or fracture of the ossicul ar chain, and damage to the sensory structures on the basilar membrane . All these injuries can be characterized as a form of mechanical dama ge to the affected structure. Injury to the sensory structures on the basilar membrane leads to temporary and permanent loss of hearing sens itivity. The temporary component of the hearing loss shows a time cour se after removal from the noise which frequently will include an initi al increase in hearing loss followed by a recovery period during which threshold may return to preexposure levels or stabilize at a higher l evel which represents a permanent loss of hearing sensitivity. This ty pe of recovery function suggests that there are damage processes which continue after the traumatic event and that intervention might mitiga te some of the damage and hearing loss. (C) 1997 Elsevier Science Irel and Ltd.