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Last edited: 10/2008
What is Tinnitus?Tinnitus (pronounced “tin-it-us”) is a noise heard by the patient which is not caused by any sound in the environment. Tinnitus is common — nearly 36 million Americans have tinnitus and more than half of the normal population has intermittent tinnitus. About 6% of the general population has what they consider to be severe tinnitus. Tinnitus can come and go, or be continuous. It can sound like a low roar, or a high pitched ring. Tinnitus may be in both ears or just in one ear. Seven million Americans are so severely affected that they cannot lead normal lives. Tinnitus is commonly accompanied by hearing loss. Less commonly, it may be accompanied by hyperacusis (an abnormal sensitivity to sound).
The most common types of tinnitus are ringing or hissing ringing and roaring (low-pitched hissing). Some persons hear chirping, screeching, or even musical sounds. Tinnitus always consists of fairly simple sounds; for example, hearing someone talking that no one else can hear would not ordinarily be called tinnitus: this would be called an auditory hallucination. There is also a specific type of tinnitus known as pulsatile tinnitus. With pulsatile tinnitus, people hear something resembling their heartbeat in their ear. The cause is usually vascular, tumor-related, or muscular in nature. A blood vessel may be close to the eardrum, a vascular tumor such as a glomus tumor may fill the middle ear, or a vein similar to a varicose vein may make enough noise to be heard. Other possibilities include dehiscence of the jugular bulb, and an aberrantly located carotid artery. An enlarged jugular bulb on the involved side is common in persons with venous type pulsatile tinnitus.
What Causes Tinnitus?Tinnitus is usually static noise in the auditory system that is associated with loss of sound from the external environment. Therefore, tinnitus is common and in most, but not all, cases it is associated with some degree of hearing loss. The most common causes of tinnitus are damage to the high frequency hearing by exposure to loud noise or elevated levels of common drugs that can be toxic to the inner ear in high doses. For example, after you have been to a loud rock concert you may experience tinnitus for a while in association with dulling of hearing. If the tinnitus goes away and hearing seems to come back, this is called a temporary threshold shift. Some permanent damage to the delicate hair cells in the inner ear has probably occurred from the noise trauma, so it is important that you prevent further injury from noise exposure. People who take large amounts of aspirin may experience tinnitus which goes away if they stop the aspirin. This also is usually a temporary hearing loss. Also, other medications have been known to cause tinnitus. Tinnitus may be heard when there is a temporary conductive hearing loss due to ear infection or due to blockage of the ear with wax, or may be associated with any other cause of conductive hearing loss. Tinnitus is typically associated with the fluctuation in hearing that occurs with Meniere’s disease. Therefore, diagnosis is important to identify the cause and determine if treatment is indicated Most tinnitus comes from damage to the inner ear (see Figure 1), specifically the cochlea. Tinnitus can also arise from damage to the nerve between the ear and brain (8th nerve, also called the vestibular nerve); from injury to the brainstem (Lanska et al, 1987); and, rarely, to the brain itself. Pulsatile tinnitus (tinnitus that beats with your pulse) can be caused by aneurysms, increased pressure in the head (hydrocephalus), and hardening of the arteries. Anything that increases blood flow or turbulence such as hyperthyroidism, low blood viscosity (for example, anemia), or tortuous blood vessels may cause pulsatile tinnitus. Vitamin B12 deficiency is common in tinnitus patients. Drugs that Commonly Cause or Increase TinnitusMany medications can cause tinnitus. Generally this is thought to arise from their effect on the cochlea (ear). The following is a list of some common medications that may contribute to tinnitus:
How is Tinnitus Diagnosed?Because tinnitus is a symptom rather than a disease, it is important to evaluate the underlying cause. Persons who experience tinnitus should be seen by a physician expert in ear disease, typically an otolaryngologist. The ears need to be examined and a hearing test obtained. Be sure to tell your doctor what medications you have been taking. Other tests may also be indicated. There are some causes for tinnitus which need to be treated. For example, tinnitus may be the earliest sign of pressure on an auditory nerve. Or, tinnitus which pulsates in time with your blood pulse may be due to a vascular problem that can be corrected. Steady, constant tinnitus is usually due to some cause of hearing loss, but people with no measurable hearing loss may hear tinnitus if they are in a totally quiet environment in which little sound is coming into their auditory system from the outside. The eyes should be examined for papilloedema (swelling of a portion of the back of the eye called the optic disk). The temporomandibular joints (TMJ) of the jaw should also be checked, since about 28% of persons with TMJ syndrome experience tinnitus. The doctor may also request a brainstem auditory evoked responses (BAER) test (clicks in ears), an electrocochleography (ECOG), and a magnetic resonance angiography/magnetic resonance imaging (MRI/MRA) test (scan of the brain). In addition, several blood tests may be performed:
In persons with pulsatile tinnitus, additional tests may be proposed to study the blood vessels and to check the pressure inside the head. MRI/MRA or computed tomography (CT) is often suggested in younger patients with unilateral pulsatile tinnitus. In older patients, pulsatile tinnitus is often due to atherosclerotic disease and it is less important to get an MRI/MRA. Based on these tests, tinnitus can be separated into categories of cochlear, retrocochlear, central, and tinnitus of unknown cause.
How Is Tinnitus Treated?If a specific cause for tinnitus is determined, it is possible that treating the cause will eliminate the noise. If a specific cause is not found, it is unlikely that the tinnitus can be eliminated. In most cases of tinnitus, the sound is an abnormal auditory sense perception of a sound that is really neither in the body nor coming from the outside. Our sensory systems are very adaptable. We get used to all kinds of smells that on first exposure seem intolerable. We also get used to sensations on the skin and in the mouth that, at first, bother us. Actually, we appear to learn to ignore sounds from our body. For example, the carotid artery (the main supply of blood to our brains) runs right next to the inner ear and yet we usually do not hear the pulse or heart sounds that are carried in the artery. Similarly, we have found that tinnitus can be diminished by not listening to it; ignoring the abnormal perception of sound until it is no longer bothersome. For many people with tinnitus, the sound is usually masked, or covered up, when there is a usual level of noise in the environment. For these people, the tinnitus is bothersome only when they are in a quiet environment. Providing some environmental noise with music or “noise machines” may solve the irritation of hearing the tinnitus when you are trying to go to sleep or quietly reading. Masking of the sound by providing noise from the outside was a popular area of focus in the treatment of tinnitus for several years, but has not proven long-term to be the solution to cure that was hoped. However, masking clearly helps some individuals when they are trying to sleep. We do know that individuals who focus on the tinnitus and listen to it constantly seem to aggravate the degree to which it is bothersome and seem to enhance the abnormal perception of the sound. Therefore, it is very important to understand that the individual is very much in control of the degree to which the tinnitus is distracting or annoying. We know of people who have focused on and listened to tinnitus until it dominated their lives. Most people with tinnitus just ignore it after a while. Ignoring the perception is very effective in minimizing disruption of thought and daily life. Studies have shown that there is not a correlation between the loudness or pitch of the tinnitus and the degree to which it bothers the individual. Controlling the perception by ignoring it is such a simple and effective approach for most individuals that it is the first line of coping with tinnitus for the vast majority of people. Medical TreatmentMedicine may occasionally help lessen the noise even though no cause can be found. In general, we are not very enthused about medication treatment as the side effects can be substantial and the results are often unimpressive. The following medications are used in treatment of tinnitus:
Surgical TreatmentOnly rarely is surgical treatment indicated, and even more rarely, is tinnitus relieved. You should certainly consider surgery if your tinnitus is due to a tumor and also if it is due to a venous source (usually pulsatile in this situation). For venous tinnitus, possibilities include jugular vein ligation, occlusion of the sigmoid sinus, or closure of a dural fistula. Surgery may also be an option to consider if your diagnosis is otosclerosis, fistula or Meniere’s disease. Occasionally persons with Meniere’s disease have relief or reduction of tinnitus from transtympanic gentamicin. Microvascular compression syndrome, in theory, may cause tinnitus, but we have had very little success when the few patients we have seen with this syndrome have undergone surgery. DietWe recommend that persons with tinnitus limit salt (no added salt), and refrain from drinking caffeinated beverages, other stimulants (like tea), and chocolate. The salt restriction is intended for those who might have a subclinical form of Meniere’s disease. Caffeine and similar substances increase tinnitus in a nonspecific fashion. Otherwise the diet should be balanced and have normal amounts of fruits and vegetables. Assistive DevicesHearing aids and other devices called “maskers” may also help alleviate tinnitus. If you have tinnitus associated with a hearing loss, a hearing aid is the first thing to try. Be sure that you try the hearing aid before buying one, as tinnitus is not always helped by an aid. Maskers are based on the idea that tinnitus is usually worse when things are very quiet. Listening to the interstation static on the FM radio, tapes of ocean surf, and the like may be helpful. Pillow speakers may be helpful in order to avoid disturbing others. Tinnitus maskers are fitted and sold by audiologists. However, controlled studies of maskers have failed to clearly demonstrate efficacy. Other TreatmentsBecause tinnitus has been linked to changes in neural activity within the brain, stimulation of the nerves within the cortex has been studied as a treatment option. Repetitive transcranial magnetic stimulation (rTMS) has proven effective in several clinical trials (Khedr, 2008; Kleinjung, 2007; De Ridder, 2007; Rossi, 2007; Langgurth, 2006; Folmer, 2006; Pridmore, 2006). Direct intracranial electrical stimulation of the cortex also has positive effects on tinnitus (DeRidder, 2007). Transelectrical nerve stimulation (TENS) is the application of a smal electrical force to the skin near the ear, in an effort to affect the cochlear nerve. Two small trials (Herraiz, 2007; Ayedmir, 2006) found this to be beneficial in some patients. Botulinum toxin (Botox) has been used in some trials, and showed benefit in some patients (Lainez, 2007; Stidham, 2005). Psychological and Emotional HelpTheerapies such as tinnitus retraining therapy (TRT) and cognitive behavioral therapy (CBT) may be helpful in some patients (Jastreboff, 2006; Wilson, 2006; Andersson, 2005; Herraiz, 2005; Martinez Devesa, 2007). TRT or CBT may be used alone or in combination with other therapies. Anxiety or depression that often accompanies tinnitus may be as big a problem as the tinnitus itself. In this instance, consultation with a psychologist or psychiatrist expert in this field may be helpful. Hypnosis may be effective and increase tolerance to tinnitus. If you can ignore tinnitus rather than obsess about it, this may be the best way to handle it. You might consider joining the American Tinnitus Association. (PO Box 5, Portland, OR 97207, 503-248-9985). How Might Tinnitus Affect My Life?Tinnitus is difficult to diagnose and treat. In many cases, you will have to adjust to tinnitus. The following list provides some tips to make the adjustment easier.
Research Studies in TinnitusAs of 3/2008, a visit to the National Library of Medicine’s search engine, Pubmed, revealed more than 6,175 research articles concerning tinnitus published since 1948. At the American Hearing Research Foundation (AHRF), we have funded basic research on tinnitus in the past, and are interested in funding sound research on tinnitus in the future. Click here if you would like more information about contributing to the AHRF’s efforts to diagnose and treat tinnitus. AcknowledgmentsFigure 1 is courtesy of Northwestern University. References
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