Damage of the Auditory System Associated with Acute Blast Trauma

Abstract

This paper reviews the results of several studies on the effects of blast wave exposure on the auditory system of the chinchilla, the pig, and the sheep. The chinchillas were exposed at peak sound pressure levels of approximately 160 dB under well-controlled laboratory conditions. A modified shock tube was used to generate the blast waves. The pigs and sheep were exposed under field conditions in an instrumented hard-walled enclosure. Blast trauma was induced by the impact of a single explosive projectile. The peak sound pressure levels varied between 178 and 209 dB. All animals were killed immediately following exposure, and their temporal bones were removed for fixation and histologic analysis using light microscopy and scanning electron microscopy. Middle ears were examined visually for damage to the conductive system. There were well-defined differences in susceptibility to acoustic trauma among species. However, common findings in each species were the acute mechanical fracture and separation of the organ of Corti from the basilar membrane, and tympanic membrane and ossicular failure.

Urban Bombing: A Trauma Surgeon's Perspective

“…More extensive injuries to the auditory system may involve discontinuity or dislocation, as well as bleeding, within the middle ear. The internal ear is rarely damaged from the blast injury mechanism (20). Casualties with eardrum perforation are usually admitted overnight for observation, because of concerns for insidious respiratory deterioration due to blast lung.…”

The Effects of Underwater Blast on Divers

“…Chinchillas exposed to repeated 166 dB re 20µPa impulse stimuli developed altered tympanic compliance, returning to normal within two weeks (Eames et al, 1975). However, inter-species differences (Roberto et al, 1989) make application to humans unreliable.…”

“…Chinchillas exposed to repeated 166 dB re 20µPa impulse stimuli developed altered tympanic compliance, returning to normal within two weeks (Eames et al, 1975). However, inter-species differences (Roberto et al, 1989) make application to humans unreliable.In summary, tympanic membrane damage observed includes: a. injection of blood vessels b. subepithelial hemorrhages c. small split like perforations (often parallel to the fibers of the lamina propria) d. multiple or total perforation …”

Disaster Medicine: Conventional Terrorist Bombings

“…24 Hemorrhage in the tympanic membrane is often around the periphery of the pars tensa or immediately below the anterior or posterior malleal folds. 25 Most perforations heal spontaneously without sequelae; cholesteatoma is a reported complication that is confined to patients in whom the membrane did not heal within 10 months and in whom tympanoplasty was not subsequently performed. 24 Ossicular damage includes medial displacement of the malleal handle with disruption of the incudomalleal joint, and incudostapedial joint separation with and without stapes fracture.…”

“…Continuous positive pressure ventilation (CPPV) should not be withheld if the clinical situation deteriorates, but patients should be continuously re-evaluated for the development of a tension pneumothorax. 17,25 Airway pressures should be kept as low as possible. To promote good bronchial hygiene by using bronchodilators, removing of blood and secretions from the tracheobronchial tree by frequent suctioning, and frequently changing the patients body position.…”