Longterm hearing loss from the loud blast of an improvised explosives devices may be treatable. A new study performed on mice by researchers at the Stanford University School of Medicine may provide future hope to people who are threatened with sudden hearing loss in the aftermath of roadside bombings.
The study, “Mechanisms of Hearing Loss After Blast Injury To the Ear”, was published on Monday in the open access science journal PLOS One
The researchers noted that IEDs are commonly used as roadside bombs both in Afghanistan and Iraq, and they can be instruments of terror used anywhere in the world. Because the ear is sensitive to pressure, it is frequently damaged when service personnel or civilians are exposed to a blast. They wrote:
“Among Veterans with service-connected disabilities, tinnitus is the most prevalent and hearing loss is the second-most prevalent condition. Thus besides the obvious disabilities resulting from damage to the ear, there are significant long-term health care costs for society.”
A statement from Stanford added that over 60 percent of service personnel wounded in action have eardrum injuries, tinnitus, hearing loss, or a combination of those conditions that impact hearing.
“Permanent hearing loss from loud noise begins at about 85 decibels, typical of a hair dryer or a food blender. IEDs have noise levels approaching 170 decibels.”
When the researchers looked to see exactly why the loud blasts of noise caused hearing loss, they discovered that it was caused by both hair cell loss and auditory nerve cell loss — at least in the mice that they studied.
Dr. John Oghalai explained:
“With one loud blast, you lose a huge number of these cells. What’s nice is that the hair cells and nerve cells are not immediately gone. The theory now is that if the ear could be treated with certain medications right after the blast, that might limit the damage.”
Earlier studies had suggested that a tiny structure in the inner ear, called the cochlea, was torn apart to cause the longterm hearing loss. If those studies were right, then the damage would indeed be permanent.
However, the Stanford team said that the cochlea was not destroyed in their mice. It’s possible that older research techniques may have destroyed the cochlea — not the blasts of noise themselves.
If they’re right, it represents new hope that medicines can be developed to prevent longterm hearing loss from explosive blasts of sound.
[explosions photo by Jon Sullivan via Wikimedia]