Researchers at the Stanford University School of Medicine recently published a paper that suggests long-term hearing loss caused by loud blasts or explosions may one day be reversible in humans.
The team’s research disproved the previously held belief that a gross membranous rupture of the cochlea, the auditory portion of the inner ear, is an underlying mechanism of blast-induced hearing loss. The finding has particular significance for veterans, among whom damage to the ear is a prevalent condition. More than 60 percent of wounded service members sustain eardrum injuries, tinnitus or hearing loss.
Despite initially setting out to develop an imaging technique to depict such ruptures as induced by blast trauma in mouse models, the researchers changed direction after realizing that loud blasts caused hair-cell and nerve-cell – but not structural – damage.
“When we started doing the experiments we realized we weren’t seeing anything. No [damage] was happening, ” said Professor of Otolaryngology John Oghalai, the study’s senior author. “We were surprised by this finding.”
The study’s findings mark significant progress towards the goals of the Stanford Initiative to Cure Hearing Loss, a broader University endeavor, and may lead to the development of medications that could limit directly blast-induced damage to the ear. The researchers’ efforts may also facilitate the creation of surgical techniques and drugs that could reduce any permanent cochlear damage.
“A major goal is to start human trials within 10 years to cure hearing loss,” Oghalai said.
Reaching that goal, however, will necessitate overcoming the challenge of regenerating lost hair and nerve cells within the cochlea.
“Mammals do not regenerate their hair cells, probably because we developed specializations that allow us to hear much higher frequency sounds,” Oghalai said. “There is a heavy research force working on this problem.”