NIH clinical trials recruitment
The small clinical trial, which is recruiting volunteers, is being conducted at four centers through a cooperative agreement with MicroTransponder, Inc., a medical device company based in Dallas.
Roughly 10 percent of the adult population of the United States has experienced tinnitus lasting at least five minutes in the past year, and approximately 10 million of them have been bothered enough by the condition to seek a doctor. Although tinnitus may be only an annoyance for some, for others the relentless ringing causes fatigue, depression, anxiety, and problems with memory and concentration. Available treatments help some people cope, but current therapies lack the potential to significantly reduce the bothersome symptoms of tinnitus.
The trial, supported by the National Institute on Deafness and Other Communication Disorders (NIDCD), a part of NIH, may mark the beginning of a change in how tinnitus is treated.
“Tinnitus affects nearly 24 million adult Americans, ” said James F. Battey, Jr., M.D., Ph.D., director of the NIDCD. “It is also the number one service-connected disability for returning veterans from Iraq and Afghanistan. The kind of nervous system stimuli used in this study has already been shown to safely and effectively help people with epilepsy or depression. This therapy could offer a profoundly better way to treat tinnitus.”
Most cases of chronic tinnitus are preceded by a loss of hearing as the result of damage to the inner ear from aging, injury, or long-term exposure to loud noise. When sensory cells in the inner ear are damaged, the resulting hearing loss changes some of the signals sent from the ear to neurons in the auditory cortex of the brain. Scientists still haven’t agreed upon what happens to create the illusion of sound when there is none, but the therapy being tested in this new clinical trial attempts to ameliorate the phantom sound of tinnitus by going to its source – the brain.
The auditory pathway is organized by what scientists call the tonotopic map, a structural arrangement in which different tone frequencies are transmitted separately along specific parts of the pathway. Hearing loss is the result of a loss in the ability of the auditory system to process certain frequencies. Earlier studies showed that the loss of the ability to hear these frequencies matched patterns of distortion in the neurons of the auditory cortex’s tonotopic map.
This research suggests that tinnitus might be the result of the brain trying to regain the ability to hear those lost frequencies by turning up the signals of neurons in neighboring frequencies. Because there are too many neurons processing the same frequencies, they fire more strongly, more frequently and in concert with each other, even when the environment is quiet. It is these changing brain patterns that researchers believe could produce the perception of whooshing, ringing, or buzzing in the ear that characterizes tinnitus.
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