Arikah Map

Tinnitus

Tinnitus
Classifications and external resources
ICD-10 H93.1
ICD-9 388.3
DiseasesDB 27662
MedlinePlus 003043
eMedicine ent/235 

Tinnitus (ti-NIGHT-us or TIN-i-tus[1], from the Latin word for "ringing"[2]) is the perception of sound in the human ear in the absence of corresponding external sound(s).

Tinnitus can be perceived in one or both ears or in the head. It is usually described as a ringing noise, but in some patients it takes the form of a buzzing, hissing, humming, or whistling sound; or as ticking, clicking, roaring, "crickets," tunes, songs, or beeping. [3]. It has also been described as a "whooshing" sound, as of wind or waves [4].

Tinnitus is not itself a disease but an unwelcome symptom resulting from a range of underlying causes, including ear infections, foreign objects or wax in the ear, and injury from loud noises. Tinnitus is also a side-effect of some oral medications.

The sound perceived may range from a quiet background noise to a signal loud enough to drown out all outside sounds. The term 'tinnitus' usually refers to more severe cases. A 1953 study (Heller and Bergman) of 80 tinnitus-free university students placed in a soundproofed room found that 93% reported hearing a buzzing, pulsing or whistling sound. However, it must not be assumed that this condition is normal -- cohort studies have demonstrated that damage to hearing from unnatural levels of noise exposure is very widespread in industrialized countries.[5] (see noise health effects)

Because tinnitus is often defined as a subjective phenomenon, it is difficult to measure using objective tests, such as by comparison to noise of known frequency and intensity, as in an audiometric test. The condition is often rated clinically on a simple scale from "slight" to "catastrophic" according to the practical difficulties it imposes, such as interference with sleep, quiet activities, or normal daily activities.[6] For research purposes, the more elaborate Tinnitus Handicap Inventory [7] is often used.


Contents

Objective tinnitus

In a minority of cases, a clinician can perceive an actual sound (e.g., a bruit) emanating from the patient's ears. This is called objective tinnitus. Objective tinnitus can arise from muscle spasms that cause clicks or crackling around the middle ear.[8] Some people experience a sound that beats in time with the pulse (pulsatile tinnitus)[9]. Pulsatile tinnitus is usually objective in nature, resulting from altered blood flow or increased blood turbulence near the ear (such as from atherosclerosis or venous hum[10]), but it can also arise as a subjective phenomenon from an increased awareness of blood flow in the ear.[11] Rarely, pulsatile tinnitus may be a symptom of potentially life-threatening conditions such as carotid artery aneurysm[12] or dissection[13] .

Causes of subjective tinnitus

Tinnitus can have many different causes, but most commonly results from otologic disorders - the same conditions that cause hearing loss. The most common cause is noise-induced hearing loss, resulting from exposure to excessive or loud noises. Ototoxic drugs can cause tinnitus either secondary to hearing loss or without hearing loss, and may increase the damage done by exposure to loud noise, even at doses that are not in themselves ototoxic.[14]

Causes of tinnitus include:[15]

Mechanisms of subjective tinnitus

The inner ear contains thousands of minute hairs which vibrate in response to sound waves and cells which convert neural signals back into acoustical vibrations. The sensing cells are connected with the vibratory cells through a neural feedback, whose gain is regulated by the brain. This loop is normally adjusted just below onset of self-oscillation, which gains the ear the spectacular sensitivity and selectivity. If something changes, it's easy for the delicate adjustment to cross the barrier of oscillation and tinnitus results. This can be actually measured by a very sensitive microphone outside the ear.

One of the possible mechanisms how things can change in the ear is damage to the receptor cells. Although receptor cells can be regenerated from the adjacent supporting Deiters cells after injury in birds, reptiles, and amphibians, in mammals it is believed that they can be produced only during embryogenesis. Although mammalian Deiters cells reproduce and position themselves appropriately for regeneration, they have not been observed to transdifferentiate into receptor cells except in tissue culture experiments.[16][17] Therefore, if these hairs become damaged, through prolonged exposure to excessive decibel levels, for instance, then deafness to certain frequencies occurs. In tinnitus, they may falsely relay information at a certain frequency that an externally audible sound is present, when it is not.

The mechanisms of subjective tinnitus are often obscure. While it is not surprising that direct trauma to the inner ear can cause tinnitus, other apparent causes (e.g., TMJ and dental disorders) are difficult to explain. Recent research has proposed that there are two distinct categories of subjective tinnitus: otic tinnitus, caused by disorders of the inner ear or the acoustic nerve, and somatic tinnitus, caused by disorders outside the ear and nerve but still within the head or neck. It is further hypothesized that somatic tinnitus may be due to "central crosstalk" within the brain, as certain head and neck nerves enter the brain near regions known to be involved in hearing.

While most discussions of tinnitus tend to stress physical mechanisms, there is strong evidence that subjective tinnitus is primarily stress-related, and so should be addressed by improving the state of the nervous system generally, using gradual, unobtrusive, long-term treatments.[18]

Prevention

Because tinnitus and hearing loss can be permanent conditions, precautionary measures are advisable. If a ringing in the ears is audible after exposure to a loud environment, such as a rock concert or work place, it means that damage is being done. Prolonged exposure to noise levels as low as 70 dB can result in damage to hearing (see noise health effects). If it is not possible to limit exposure, earplugs or ear defenders should be worn. For musicians and DJs, special musicians' earplugs can lower the volume of the music without distorting the sound and can prevent tinnitus from developing in later years.

It is also important to check medications for potential ototoxicity. Ototoxicity can be cumulative between medications, or can greatly increase the damage done by noise. If ototoxic medications must be administered, close attention by the physician to prescription details, such as dose and dosage interval, can reduce the damage done.[19]

Tinnitus treatment

There are many treatments that are effective for tinnitus resulting from a particular cause, but none are effective in every case. Conversely, tinnitus may resolve without any treatment. Effective treatments include:

Objective tinnitus:

Subjective tinnitus:

A Tinnitus FAQ lists many other potential therapies.

Although there are no specific cures for tinnitus, anything that brings the person out of the "fight or flight" stress response helps symptoms recede over a period of time. Calming body-based therapies, counselling and psychotherapy help restore well-being, which in turn allows tinnitus to settle. Chronic tinnitus can be quite stressful psychologically, as it distracts the affected individual from mental tasks and interferes with sleep, particularly when there is no external sound. Additional steps in reducing the impact of tinnitus on adverse health consequences include: a review of medications that may have tinnitus as a side affect; a physicial exam to reveal possible underlying health conditions that may aggrevate tinnitus; receiving adequate rest each day; and seeking a physician's advice concerning a sleep aid to allow for a better sleep pattern.

Notable sufferers

Notable sufferers of tinnitus include Ludwig van Beethoven, Bono, Betsy Casey, Eric Clapton, Phil Collins, John Densmore, James Hetfield, Guy Kawasaki, David Letterman, Gabe Lopez, Craig Nicholls, Leonard Nimoy, William Shatner, Bedřich Smetana, Sylvester Stallone, Jack Straw, Barbra Streisand, Peter Sun, and Pete Townshend.

See also

References

  1. ^ OHSU Tinnitus Clinic

Categories


Otology

Find

Find

Find