The following is an excerpt from the Mayo Clinic Press book Mayo Clinic on Hearing & Balance, 3rd Edition by Jamie M. Bogle, Au.D., Ph.D.
Tinnitus (pronounced either as TIN-ih-tus or tih-NIE-tus) is the perception of sound in your ear caused by no apparent external source. The sound is characterized as a ringing, buzzing, whistling, chirping, hissing, humming, roaring or clicking, among other descriptions. Some people refer to it as music or the sound of boiling water.
Regardless of how it’s described, it’s a sound that’s not produced in your surroundings. Often, the noise seems to originate in your head.
Many people experience brief episodes of tinnitus after being exposed to an extremely loud noise or taking certain medications. But few people are overly alarmed by such episodes, and the sound usually goes away.
According to the American Tinnitus Association, about 50 million people in the U.S. experience tinnitus. For about 20 million of these people, tinnitus is chronic, meaning it’s a long-term issue. And 2% have tinnitus that’s so extreme that it’s almost unbearable.
The impact of tinnitus on people’s lives can range anywhere from annoying to debilitating. At night, the noise may make it difficult to fall asleep. Tinnitus can also make it hard to focus on daily activities and jobs. Frustration with the unexplained sounds can often lead to anxiety, fear and depression.
Tinnitus is a symptom associated with many ear disorders as well as with other diseases, including heart disease, allergies and anemia.
UNRAVELING THE MYSTERY
What triggers tinnitus — which might explain how and why the noise occurs — is unclear. But several theories have been proposed.
One thought is that it’s a phenomenon of the central nervous system, similar to the phantom-like sensations experienced after a limb amputation. A person may feel pain in his or her foot even after the leg has been removed. With tinnitus, the central auditory nervous system may be responding to the loss of hair cells in the inner ear by becoming overactive. In other words, one or more stations in the brain that process what you hear may generate abnormal activity.
In addition to too much activity in these auditory centers, parts of the brain that aren’t involved in processing sounds also may play a role. For some people with tinnitus, for example, there seems to be a link between the auditory system and the limbic system, which is responsible for emotions like fear and anxiety. The auditory system also seems to be influenced by the part of the brain involved with touch (somatosensory system) and by the movement of body parts, like jaw clenching and certain neck movements. These movements can cause changes in the loudness and pitch of tinnitus.
Researchers have learned all of this by studying positron emission tomography (PET) scans, which reveal the parts of the brain that are used to accomplish specific tasks. PET images of the brains of people with tinnitus are leading researchers to think that parts of the brain that process what people hear interact with areas of the brain that aren’t involved in hearing. This may explain why some people with tinnitus perceive the sounds they hear more intensely compared with others who have tinnitus.
Other researchers think the cause of tinnitus may lie with the activity of chemicals in the auditory nerve. These chemicals carry messages from the inner ear to the brain. Finally, for some people, tinnitus may stem from turbulent blood flow through arteries and veins that lie close to the inner ear.
While there are many possible explanations, scientists agree that tinnitus is a complex systemwide problem that involves the parts of the central nervous system that process sounds — and many parts that don’t.
The good news is that tinnitus generally isn’t serious or life-threatening. In a few cases, tinnitus may even be caused by an underlying condition that’s treatable.
While there’s usually no cure for tinnitus, there are many ways to manage it and lessen its effect on your daily life. You may need your doctor and an audiologist, and your participation is critical.
DIAGNOSIS
There’s little doubt that tinnitus can be troublesome. In many cases, tinnitus triggers a cycle of growing discomfort: Annoyance leads to increased attention to the noise, which causes greater frustration. Some people find the distraction so severe that they’re unable to carry on with their regular daily activities.
Several options are available that may allow you to manage tinnitus and still function in life with a reasonable degree of comfort.
First, talk about the condition with your physician or audiologist. He or she can help identify or rule out a treatable cause of your tinnitus. Other specialists may become involved in the diagnosis. If an underlying condition is causing the tinnitus, treating the cause may resolve the tinnitus. Measures such as treating an ear infection or removing impacted earwax also may help reduce tinnitus.
If the cause of your tinnitus is unknown, you and your medical team can decide how best to treat your symptoms. A medical history, physical exam, hearing tests and lab tests may provide vital clues. In addition to making these assessments, an audiologist may try to determine the specific frequency (pitch) and intensity (loudness) of your tinnitus through audiological tests. This information can help you and your medical team select the best treatment for your situation.
Relevant reading
Mayo Clinic on Hearing and Balance, 3rd Edition
Mayo Clinic on Better Hearing and Balance helps readers understand the possible causes of hearing and balance issues and offers solutions aimed at improving not just hearing and balance, but quality of life overall.
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