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| TINNITUS OVERVIEW |
Introduction and Definition of Tinnitus
It may seem odd to define a disorder by exclusion, but with tinnitus it can often help. It is highly
common for people to experience particular noises in their ear(s) briefly when there is not sound actually
present. Often this is a ringing sound that lasts several seconds and is associated with the perception of
hearing loss (Kiang, Moxon & Levine, 1970). This is not tinnitus. Nor is it pathological. Also, tinnitus
does not include perceived sounds (without the actual presence of such sound) that have intelligible content,
like speech. That would be an entirely separate category of disorders, not specifically related to hearing.
Tinnitus, or “ringing in the ears,” could be more accurately defined as an “internal sound” (one that has no
external generator). Furthermore, to be classified as tinnitus, this sound would be perceived most or all of
the time. Such perceived sounds have been often described in many ways, including ringing, buzzing, humming,
whooshing, and so on. Click here to listen to a sampling of the most common tinnitus sounds.
Tinnitus isn’t a disease; it’s a symptom that can be the result of a number of medical conditions. Tinnitus is
therefore common; it affects over 50 million people in the United States. Of this number, it has been reported
that over 13 million have sought treatment from a healthcare provider for their tinnitus and 3 million are so
severely debilitated by their tinnitus that they have difficulty managing their day-to-day lives.
Signs and Symptoms of Tinnitus
Tinnitus is a perceived noise in one or both of your ears that exists without an external stimulus. This noise
may sound like a ringing, buzzing, whooshing, or hissing. The volume of the tinnitus can range from mild to
severe; likewise, noise may vary in pitch from a low roar to a high squeal. In some cases, the tinnitus may be
so loud or annoying that it may interfere with your ability to concentrate or hear properly.
Click here to listen to a sampling of the most common tinnitus sounds.
Causes of Tinnitus
Two separate classifications of tinnitus exist, each with its own causes. While subjective and objective
tinnitus have similar symptoms, the vast majority of tinnitus cases are classified as subjective.
In subjective tinnitus, only the patient can hear the annoying sound of tinnitus; a doctor examining the patient
cannot hear the noise. This type of tinnitus is typically caused by malfunctioning auditory cells, which
inappropriately send electrical signals. These electrical impulses are is interpreted by the brain as sound.
Subjective tinnitus most commonly results from:
- Noise-related damage to your inner ear. This erosion of your hearing ability may result from a single loud event or excessive exposure to loud noise over a long period of time. Loud devices such as tractors, chain saws and weapons are common sources of noise-related tinnitus. Portable music devices, such as MP3 players or iPods, may become a common source of noise-related tinnitus in the future if people play these devices loudly for long periods.
- Presbycusis. Age-related hearing loss usually begins around age 60, and can be associated with malfunctioning auditory cells.
Other causes of subjective tinnitus may include:
- Medication. Aspirin used in large doses and certain types of antibiotics can affect inner ear cells. Often the unwanted noise disappears when you stop using these drugs.
- Otosclerosis. Stiffening of the bones in your middle ear may affect your hearing.
- Injury. Trauma to your head or neck can damage your inner ear.
In objective (or pulsatile) tinnitus, both the patient and a doctor can hear an audible noise. Causes of objective tinnitus may include:
- Atherosclerosis. With age and buildup of cholesterol and other fatty deposits, major blood vessels close to your middle and inner ear lose some of their elasticity — the ability to flex or expand slightly with each heartbeat. That causes blood flow to become more forceful and sometimes more turbulent, making it easier for your ear to detect the beats.
- High blood pressure. Hypertension and factors that increase blood pressure, such as stress, alcohol and caffeine, can make the sound more noticeable. Repositioning your head usually causes the sound to disappear.
- Turbulent blood flow. Narrowing or kinking in a carotid artery or jugular vein can cause turbulent blood flow and head noise.
- Malformation of capillaries. A condition called A-V malformation, which occurs in the connections between arteries and veins, can result in head noise.
- Head and neck tumors. Tinnitus may be a symptom of a tumor in your head or neck.
Seeking Medical Advice for the Treatment of Tinnitus
Most cases of tinnitus itself aren't harmful to your health. However, if tinnitus persists, worsens, or distracts you from
daily activities, see your doctor. Your physician may be able to suggest treatments that might reduce the noise and techniques
to help you better cope with the noise.
Common treatments for tinnitus are varied and include sound therapies, amplification, cochlear implants, cognitive therapy,
biofeedback, TMJ treatment, drug therapy, and alternative treatments. Based on scientific studies, sound therapies are the
most effective tinnitus treatment, reducing severe tinnitus to a mild discomfort in over 80% of patients. To learn more about
tinnitus treatments and tinnitus treatment providers, please visit our
Tinnitus Treatments Section.
Coping with Tinnitus
Sometimes symptoms of tinnitus improve with time. Improvement isn't the result of physical changes, because any damage that
has occurred to your ears is permanent and irreversible. Instead, many people learn to make adjustments to lessen the symptoms.
Some techniques and lifestyle adjustments which may help to relieve your tinnitus include:
- Join a support group. Sharing your ideas with others may help you to learn how to better cope with your tinnitus. Support groups are available both in person and online. Click here to view helpful tinnitus Internet links, including those to online support groups.
- Avoid possible irritants. Tinnitus may be aggravated by loud noises, nicotine, caffeine, tonic water, which contains quinine (the same substance as the medication used to treat malaria), alcohol and excessive doses of aspirin. Nicotine and caffeine constrict your blood vessels, increasing the speed of blood flow through your veins and arteries. Alcohol increases the force of your blood by dilating your blood vessels, causing greater blood flow, especially in the inner ear area.
- Manage stress. Stress can make tinnitus worse. Stress management, whether through relaxation therapy, biofeedback or exercise, may provide some relief.
Why Isn’t There a Cure for Tinnitus?
The question many ask, and reasonably so, is "why isn't there a cure for tinnitus?" The problem is that there is no single cause
of tinnitus. Or, more specifically, the tinnitus perception can arise from different parts of the auditory system
(Bauer, 2004; Kaltenbach, 2000).
In a review article, Kaltenbach (2000) describes a number of potential mechanisms, any one of which can lead to tinnitus. A few
will be described here, but with the varying ways in which tinnitus can arise, it becomes clear that the concept of a "cure" is
not appropriate, and the concept of “treatment”, or better, “therapy” is better suited to help with tinnitus.
Generally, the "mechanisms", or the manner in which the tinnitus disorder manifests physiologically, have generally been categorized
as being peripheral or central. The peripheral auditory system consists of the outer ear (auricle, ear canal), middle ear (ear drum,
the malleus, incus and stapes) and the inner ear (cochlea). The central auditory system consists of the auditory nerve (cranial nerve
VIII) and the neural processing stations all the way up to the cortex. The following is summarized from Kaltenbach (2000):
Peripheral Mechanisms
- Inner Hair Cell – these cells are critical in taking acoustic sounds and translating them into a neural signal. Without these cells you be deaf. It has been suggested that tinnitus can arise from these cells as a consequence of the physical changes in the cells and changes in the blood supply resulting from loud noise.
- Outer Hair Cell – these cells also code sound from the acoustic signal to the neural signal. Without these cells you would have a significant hearing loss and have trouble understanding speech, especially in noisy situations. Incidentally, loss of outer hair cells is often the reason for the hearing loss that is associated with age. While it is thought to be extremely rare, it has been theorized that tinnitus can arise when outer hair cells have increased spontaneous activity leading to increased inner hair cell activity.
Central Mechanisms
- Auditory Nerve – based on surgical and other evidence, it is thought that compression (literal pressure) on the auditory nerve can lead to tinnitus. Surgical decompression surgery has been used with some success, especially on those who have had tinnitus for a short period of time (as cited in Kaltenbach (2000): Moller et al., 1993; Jannetta, 1997).
- Increased spontaneous activity of nerve fibers – all nerve fibers in the body “fire” when there is input. Typically, the greater the input, the more often these fibers fire (faster rates). Even without an input, all nerve fibers fire, the so-called spontaneous rate. It is thought that tinnitus can arise when damage, often due to noise or certain drugs, leads to increased spontaneous nerve activity. Studies have described this as increased spontaneous rates in certain populations of nerves in the auditory brainstem, inferior colliculus, and cochlear nucleus.
- Changes in temporal discharge patterns – as inputs to a nerve increases, they fire faster, but there is a pattern to the firing. That is, like a metronome, some nerve fibers fire “in time” or “in phase” with sound inputs. This example is called neural synchrony. There has been some suggestion that tinnitus manifests as an increase in synchronous dishcharges. Similarly, it has been suggested that bursting can occur. Bursting is when a nerve fires, it fires multiple (two or more) times and at consistent intervals.
- Changes in the cortical map – Our brain is like a map; different areas do different things. A certain area is dedicated to the processing of sound. It has been discovered that when tinnitus may be related to changes in how the cortical map for auditory processing is laid out (as cited in Kaltenbach 2000: Meikle, 1995). There has been suggested that damage to the cochlea (part of the inner ear) can lead to changes in the cortical map for sound.
Kiang, NYS, Moxon, EC, & Levine RA (1970). Auditory-nerve activity in cats with normal and abnormal cochleas. In G.E.W Wolstenhome & J. Knight (Eds.) Sensorneural hearing loss (pp.241-273). London: Churchill.
Bauer CA. (2004). Mechanisms of tinnitus generation. Curr Opin Otolaryngol Head Nech Surg 12: 413-417.
Kaltenbach JA (2000). Neurophysiologic mechanisms of tinnitus. J Am Acad Aud, 11:125-137.
Meikle MB. (1995). The interaction of central and peripheral mechanisms of tinnitus. In: Vernon JA, Moller AR, eds. Mechanisms of Tinnitus. Boston: Allyn and Bacon, 181-206.
Moller MB, Moller AR, Jannetta PJ, Jho HD. (1993). Vascular decompression surgery for severe tinnitus: selection criteria and results. Laryngoscope 103: 421-427.
Jannetta PJ. (1987). Microvascular decompression of cochlear nerve as a treatment for tinnitus. In: Feldmann H, ed. Proceedings of the 3rd International Tinnitus Seminar. Karlsruhe, West Germany: Harsh Verlag, 348-352.
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