There are millions of people for whom absolute silence does not exist. When the world grows silent, they still hear a ringing, hissing, roaring, whistling, chirping or clicking. They suffer from tinnitus.
I’m one of them. Most of the time it doesn’t bother me, but if I listen, I can always hear a high-pitched ringing.
Tinnitus (from the Latin word meaning “to tinkle or to ring like a bell”) affects approximately one in five people. About a quarter of those seek medical attention; 15 to 20 percent of those are so debilitated by tinnitus they can’t function normally. That translates to well over two million people in North America.
Many different triggers for tinnitus have been identified. One is loud noise, which can damage or destroy hair cells in the inner ear. Up to 90 percent of all tinnitus patients have some level of noise-induced hearing loss (I’ve always wondered if that very loud England Dan and John Ford Coley concert I attended in universi–I mean, in kindergarten–had something to do with mine.)
Wax build-up can contribute to tinnitus, as can certain medications, ear and sinus infections, jaw misalignment, cardiovascular disease, tumors on the nerves of the ears and head and neck trauma.
Treatments include hearing aids, stress-relieving techniques such as biofeedback, and drugs ranging from anti-anxiety drugs to anti-depressants, antihistamines, anticonvulsants and anesthetics.
A cochlear implant, a receiver implanted just under the skin behind the ear that sends electrical sound signals to the brain, helps some people, either by providing ambient sound to mask the tinnitus or through the electrical stimulation, but because implanting one destroys any healthy hair cells that are left, it’s only prescribed for deaf or near-deaf people.
Other people may be prescribed masking devices, which resemble hearing aids, but produce a constant low-level sound to reduce or even eliminate the patient’s perception of tinnitus. Sometimes masking devices are combined with therapy to teach the patient to overcome his or her negative emotional reaction to the tinnitus.
None of these treatments are very satisfactory–which is why the results of a small study by Herta Flor and a team of researchers at the University of Heidelberg’s Central Institute of Mental Health are exciting.
Flor and her team had previously worked with amputees suffering from phantom limb pain. They discovered that the part of the brain that used to control the amputated limb shrinks as neighboring areas in charge of other body parts begin to take it over for their own use.
Flor wondered if tinnitus might also be a phantom sensation. She and her team looked at the auditory cortex of people suffering from the problem, and discovered changes similar to those found in the brains of amputees. In people without tinnitus, the areas of the auditory cortex that respond to different sound frequencies are all of similar size, while in people with tinnitus, the regions that correspond to the frequencies of the mysterious sounds they hear are much larger than other regions.
Flor and her team successfully treated phantom limb pain by asking patients to recognize the position and frequency of mild electrical shocks applied to their stumps. The shocks stimulated the limbs’ shrinking brain areas, causing them to expand–and reduced phantom limb pain by almost 70 percent.
In tinnitus, the problem seems to be the opposite–the area of the brain producing the phantom sound is too big, not too small–so Flor decided to see if she could stimulate the areas of the brain immediately surrounding the one related to the frequency of the tinnitus, the theory being that as those parts of the brain grew, the tinnitus-producing part would shrink. Her team trained nine people with tinnitus to tell the difference between different pairs of tones at frequencies close to, but not the same as, the frequency of their tinnitus. Two hours a day of training over four weeks produced a 35-percent reduction in the patients’ tinnitus, while a control group using tones unrelated to their tinnitus showed no improvement at all.
The results were so encouraging a full-scale clinical trial is now underway. If the effectiveness of the treatment is confirmed, indicating that tinnitus is indeed a phantom sensation, then it could be possible to prevent tinnitus altogether by giving someone exposed to a tinnitus trigger, such as loud noise, the same drugs given to amputees to prevent phantom limb pain. The drugs block the receptors in the brain involved in its reorganization.
With luck, tinnitus may someday be a far less common problem than it is today.
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