FDA Consumer
April 1989
Vol. 23, No. 3
WHEN BELLS ARE RINGING (BUT THERE AREN'T ANY BELLS)
Vern Modeland
It happens. You awaken in the night, then lie reviewing the sounds around you. Breathing. Curtains rustling in a breeze. The rattle of cans while a cat does a garbage inventory. A radio playing somewhere. A jet far overhead. Then, for some of us, there's that other sound in the quiet of the night. Some describe it as the noise a cicada makes, an ocean's roar, a sizzle, or like a transformer's hum. For others it's more like the ringing of bells, and that's where the name for this condition comes. This "other" sound is called tinnitus, from the Latin tinnire, which means to ring or tinkle like a bell.
Tinnitus, pronounced tin -i-tus or tin- night -us, rings continually in the minds of millions of people. It may be in one ear, both, or be perceived as somewhere else in the head or, rarely, as an outside sound.
A sound outside the ears, one that can sometimes also be heard by an examiner with a stethoscope, is described clinically as "objective" tinnitus. Objective tinnitus is usually found to be caused by the movement of joints in the jaws, clogged Eustachian tubes in the middle ear, or repetitive muscle contractions. Sometimes, in a quiet room, someone with objective tinnitus might be hearing the pulse of his or her blood in the carotid artery in the neck, the hum of normal flow of blood through the jugular vein, or movement of bones in the neck.
Ringing, buzzing, blowing, roaring, clanging, popping, or nonrhythmic beating noise that ranges from a small nuisance for most people to a cacophony for others that can dominate life and make it hard to sleep, understand conversations, or concentrate on work is called "subjective" tinnitus. For a few, its torment can be so severe they seek psychiatric help, describing their private sound as like an internal siren. And, more than 200 years after the word made its way into the English language, medical experts have no great insight to report as to the likelihood of breakthroughs in treating tinnitus. For now, they say, no one can guarantee you that there's a cure for this type of sound that is in your head only.
Researchers estimate that 36 million Americans have tinnitus, and the condition is severe enough in 7.2 million that they have sought medical help. Some medical professionals who treat tinnitus say even those figures might be low. Robert Dobie, M.D., a professor in the Department of Otolaryngology at the University of Washington Medical Center in Seattle, estimates 14 percent to 17 percent of Americans have frequent or constant tinnitus. He says that for 1 percent to 2 percent of them, tinnitus is severe enough to affect their everyday life. The American Tinnitus Association (P.O. Box 5, Portland, Ore. 97207) says its studies indicate that as much as 5.3 percent of the population suffers from severe tinnitus.
The percentage of the total population reporting tinnitus is about the same in England, and probably in any other industrialized nation, according to Jack Vernon, now in his 22nd year as director of the Hearing Research Center at The Oregon Health Sciences University in Portland.
Three men have tinnitus for every two women who do--probably because more men than women work in construction, manufacturing, and other very noisy locations, says Vernon.
Sam Hopmeier, a St. Louis audiologist with extensive experience in treating tinnitus, says subjective tinnitus is most frequently related to hearing impairment. But, even if you don't work in overly noisy surroundings and have never experienced tinnitus, there's a good chance it still may someday ring for you. By middle age, the symptom can appear with no particular cause. Dobie says accumulated exposure to noise and age-related changes in the body are principal reasons. Another physician, Max A. Goldstein, once wrote of certain types of tinnitus that "the patient is literally listening to old age sneaking up on him."
Tinnitus is by definition a symptom of something and not itself a disease. A symptom of what? It's been linked to hearing loss and its opposite, hyperacusis (extremely sensitive hearing); hypertension (high blood pressure); hyperglycemia (high blood sugar); arthritis, especially in the neck; tumors; injuries to the head, neck or ears, including whiplash; drugs, including aspirin and other over-the-counter painkillers, alcohol, nicotine, and some antibiotics; Meniere's disease of the inner ear, which also has as its symptoms dizziness, nausea, and progressive hearing loss; and otosclerosis, a disease in which bones in the ear are immobilized by new bone growth. Treatment of any one of these generally results in relief from accompanying tinnitus.
Infection or wax in the ears also has been found to start tinnitus ringing as a signal of the need for treatment.
Tinnitus in younger people most frequently follows injuries to the head or ears, including hearing damage caused by loud music. Loud noise, according to Vernon, is the most prevalent cause of tinnitus and one of the most preventable causes of hearing impairment. A crusader against abuses to our hearing, Vernon promoted an unsuccessful bill in the Oregon legislature that would have required warning signs at the doors of night clubs where loud music is played, to caution those who enter about the risk from the din inside.
Damage to the ear caused by excessive exposure to loud noises has been documented. Our ears contain microscopic hairs as a fringe on the ends of auditory cells in the inner ear. When healthy, these hairs move in response to the pressure of sounds that vibrate the eardrum. The movement leads to chemical changes that in turn produce small electrical signals. The electrical signals excite nerve cells in each of some 30,000 fibers that spiral away from the cochlea, a snail-shaped and fluid-filled compartment in the inner ear. This spiral of fibers comes together to form the auditory nerve and carries stimulation from the ear to the brain. Continued or repeated exposure to loud noises can damage the tiny hairs in the inner ear, sometimes leaving them with the appearance of rows of trees bent or broken before a hurricane's wind. Where there are no healthy hairs, erect and swaying to each sound that reaches the ear, there will be no stimulus to the brain from that particular nerve and nothing more to be heard--from the outside, anyway.
At present, there are no drugs approved by FDA specifically to treat tinnitus and, to date, no major controlled clinical drug studies.
Major discoveries of drugs or devices that seemed to have an effect on tinnitus have frequently been serendipitous. In the mid 1930s, a physician injected Novocain (procaine hydrochloride, a nerve-blocking anesthetic of short duration) into a surgical patient's nose. The patient also had tinnitus and remarked that the tinnitus cleared temporarily after the injection. A New Zealand pain clinic, in early tests of another local anesthetic, lidocaine hydrochloride, found that drug also temporarily stopped tinnitus. In a controlled study at the Oregon Hearing Research Center, 23 of 26 people tested said lidocaine either put their tinnitus into remission or turned it off completely. But lidocaine had serious side effects, and its impact on tinnitus only lasted for a half hour or so, Vernon says.
Paul Guth, a pharmacologist who researches hearing and balance mechanisms at the Tulane Medical School, New Orleans, says side effects of lidocaine in tests to treat tinnitus included amnesia, slurred speech, and fainting. Guth's research has been into medications that target the hearing system. One such drug, aminooxyacetic acid (AOAA), had reached clinical trials in controlling epileptic seizures and seemed to be safe in humans. A former student, Richard Bobbin, reported to Guth he found AOAA also had a measurable effect on endocochlear potential, an electrical voltage output essential to the function of the inner ear. A reduction in the endocochlear potential reduces activity in the auditory nerve, studies showed. Bobbin reported AOAA lowered endocochlear voltage potential in laboratory animals, so Guth tested it on 70 people with tinnitus. Fourteen patients reported some relief, he found. However, 10 of those who were helped also reported side effects that led Guth to search for other drugs that also could reduce endocochlear potential.
Furosemide, a potent diuretic prescribed for people who have very severe kidney damage, also was tried on tinnitus patients. Reported side effects for kidney patients included tinnitus and transitory hearing impairment, but Guth found that when furosemide was given in reduced dosages intravenously to 37 volunteers with tinnitus, half of them reported they believed it helped, so Guth continued testing furosemide in oral doses on nine patients. Seven of the nine volunteered to continue taking the medication, an indicator that they must be getting some relief, he said.
Alprazolam (trade name Xanax), a central nervous system depressant prescribed for anxiety disorders, has been reported to have helped a small number of tinnitus patients. And it introduced another line of questioning. What is the relationship between depression and tinnitus? Is tinnitus a cause or result? Dobie's research indicates that antidepressant medications, particularly tricyclic antidepressants, have helped convert people who are suffering from tinnitus into people who are dealing with it. Dobie adds that other patients referred to him have benefited from relaxation techniques, biofeedback (conscious effort to control involuntary body functions such as breathing and heartbeat), and other forms of therapy that show them how better to live with tinnitus. Hypnotism has been tried for relief of the mental stress caused by tinnitus, but no positive results are documented.
Technology also may have some answers for tinnitus sufferers. Directing a small charge of electricity into the auditory nerve has shown some promise in silencing tinnitus. Of 20 persons tested with electrical nerve stimulation at the Washington Medical Center in Seattle, only one was helped, but that person was helped dramatically, according to Dobie.
If electrical nerve stimulation continues to show promise, surgically implanted stimulators may become a technology for the future in tinnitus treatment. Meantime, a more elementary electronic device is already helping some. It's the tinnitus masker. Using an external noise source to mask the rush, the ringing, or the roar of tinnitus has been effective for about 70 percent of the 500 people that St. Louis audiologist Hopmeier has treated for tinnitus during the past 10 years.
The principle in masking is much the same as when you realize you are no longer bothered by routine office noises, ventilator fans, or traffic sounds. Masking is based on the mind's ability to ignore external noises that become familiar or monotonous. It's easier to ignore an external sound than an internal one, Hopmeier points out.
Vernon became interested in masking in 1977 after the chance discovery by a patient that he could not hear his tinnitus when he stood near a waterfall, and that the water's sound was an acceptable and welcomed substitute for tinnitus. But the best masking sound is not the "white noise" of a waterfall, according to audiologist Hopmeier. That would interfere with the wearer's ability to understand speech, he says. So, following a hearing and perception test that Hopmeier describes as his way to determine a "sensation level," to indicate the amount of stress the person is experiencing due to his or her tinnitus, a masking device is customized that is most pleasing and helpful for the wearer.
More than 90 percent of people who come to Hopmeier with tinnitus also have some impairment to hearing that they either had not recognized or did not think was significant. Their concern had become focused on their tinnitus, he explains. Sixty percent of the tinnitus masking devices he has fitted have been combined with a hearing aid, and for some people the devices are fitted in both ears, depending on the amount of hearing loss and the patient's perception of the tinnitus' location. Dual-purpose hearing and masking devices have separate volume and on-off controls. Hopmeier says most users eventually become less dependent on the masking and more on the hearing aid, which offers a natural masking effect. The hearing aid's own amplification of voices and other sounds in the environment draws the user's attention away from his or her tinnitus, Hopmeier explains.
Some of the relief that masking gives tinnitus patients may be psychological, according to Dobie. For some tinnitus sufferers, just knowing they have their masking device available to use if they want seems to provide reassurance and relief. Dobie, Vernon and Hopmeier agree that the lack of control over this unwanted noise in their heads is the distressing aspect of tinnitus that leads most people to seek help.
Masking devices require FDA approval because they present a potential for risk of injury to the ears or long-term hearing impairment due to overstimulation from the continuous and sometimes loud masking noise. Five brands and nine models of tinnitus masking devices have approval for marketing from FDA.
James L. Parkin, a Salt Lake City otolaryngologist, observes that "tinnitus is an irritating symptom for both the patient and the physician. The patient is annoyed most by the problem during times of fatigue or anxiety. He is concerned that it indicates serious mental or physical illness. The physician is annoyed because his diagnostic efforts may not reveal a well-defined cause for the complaint."
Tinnitus. It . . . happens.
