New research findings suggest mild blast trauma suffered by military personnel affects portions of the auditory system that have not been extensively studied after injuries occur, and this impairment might be diagnosed using well–established testing methods.

“Advances in military protective equipment have increased the survival rate of personnel exposed to blasts, permitting exposure to higher intensity shock waves,” said Riyi Shi, a professor of neuroscience and biomedical engineering in Purdue University's Department of Basic Medical Sciences, College of Veterinary Medicine and Weldon School of Biomedical Engineering. “Due to increased blast survivability, new organ systems have emerged as vulnerable to blast trauma, particularly the brain and auditory system. The vast majority of victims suffer what we refer to as mild blast injury, which is asymptomatic and difficult to detect, yet can produce lasting hearing impairment and may be associated with additional damage to the brain.”

For U.S. military veterans with service–connected disabilities, the two most prevalent conditions are tinnitus, or ringing in the ear, and hearing loss. Researchers are using various tests based on the electrophysiology of the nervous system to record “auditory evoked potentials,” or small voltage changes at the surface of the skull that are picked up with electrodes.

“One of the promising aspects of this approach is that it’s non–invasive,” said Edward Bartlett, an associate professor in Purdue' Department of Biological Sciences and Weldon School of Biomedical Engineering. “We have demonstrated that auditory evoked potential recordings possess strong prospects for future diagnostic utility in identifying blast–injured individuals who are otherwise asymptomatic. While the techniques themselves are not new, their application to blast injury is.”

New findings appeared online in the Journal of Neurophysiology.