In a medical breakthrough that will help tens of millions of Americans at riskfor noise-induced hearing loss, the Naval Medical Center in San Diego hassuccessfully tested a technique that restores hearing loss if administeredwithin hours following exposure to loud noise. It can also "inoculate" usersagainst hearing loss if taken before such exposure.
The technique uses micro-devices or micro-catheters inserted in the earto deliver antioxidant pharmaceuticals that protect the hypersensitive haircells within the ear that are fundamental to sound detection. Thesepharmaceuticals have already been approved by the FDA for other applications; itis anticipated that the antioxidants will be on the fast track for approval forthe clinical trials using human subject of this research.
Although the ear can tolerate an amazing range of sound intensities, aday of 85 dB noise, the equivalent of standing behind a gas lawn mower, canbegin to damage the cochlea. Damage rapidly escalates with sound levelexposures to 120 dB sound pressure level, the equivalent of standing in front ofthe speakers at a rock concert. At around 130 dB sound pressure level,mechanical destruction of the inner ear begins. Excessive noise initiallydamages the inner ear by generating toxic oxygen-containing compounds thatdamage nerve endings and hair cells by chemical means. Although damage beginssoon after noise exposure, actual hair cell loss does not begin for four to fivedays and progresses over the next 40 days. This presents a window ofopportunity in which damaged hair cells may be rescued through theadministration of antioxidant pharmaceuticals.
"The techniques have already been used to treat hearing loss andMeniere's diseases, and have significant implications for treating other hearingand balance disorders in the military and civilian population," saysco-principal investigator, Dr. Richard D. Kopke, Colonel, Army Medical Corps. Sponsored by the Office of Naval Research and the U.S. Navy Bureau ofMedicine and Surgery, this research addresses issues of critical concern to theUnited States military.
- The military spends more than $1.5 billion in compensation, re-training,and equipment replacement each year due to hearing and balance disorders,
- More than 11 percent of individuals in the military are affected bythese disorders,
- Deafness affects 30 million Americans and costs the nation $56 billionper year,
- An additional 40 million individuals work in environments that pose asignificant threat to their hearing,
- 50 percent of individuals suffer a balance disorder at some point duringtheir lifetime.
To further address hearing and balance problems that affect military andcivilian personnel, the Defense Spatial Orientation Center (DSOC) wasestablished. Dr. Michael Hoffer, Lieutenant Commander, Navy Medical Corps,co-principal investigator with Dr. Kopke, explains that the group is "unique inthat it brings together investigators from a number of different centers" tobring medical treatment directly to where military personnel work.
The above story is based on materials provided by Office Of Naval Research. Note: Materials may be edited for content and length.
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