Tinnitus is the perception of sound when no corresponding external sound is present. Nearly everyone will experience a faint “normal tinnitus” in a completely quiet room but it is only of concern if it is bothersome or interferes with normal hearing or correlated with other problems. While often described as a ringing, it may also sound like a clicking, buzzing, hiss, or roaring. The sound may be soft or loud, low or high pitched, and often appears to be coming from one or both ears or from the head itself. In some people, the sound may interfere with concentration and in some cases it is associated with anxiety and depression. Tinnitus is usually associated with a degree of hearing loss and with decreased comprehension of speech in noisy environments. It is common, affecting about 10–15% of people. Most, however, tolerate it well, and it is a significant problem in only 1–2% of all people. The word tinnitus comes from the Latin tinnire which means “to ring”.

Rather than a disease, tinnitus is a symptom that may result from various underlying causes and may be generated at any level of the auditory system and structures beyond that system. The most common causes are hearing damage, noise-induced hearing loss or age-related hearing loss, known as presbycusis. Other causes include ear infections, disease of the heart or blood vessels, Ménière’s disease, brain tumors, acoustic neuromas (tumors on the auditory nerves of the ear), migraines, temporomandibular joint disorders, exposure to certain medications, a previous head injury, earwax; and tinnitus can suddenly emerge during a period of emotional stress. It is more common in those with depression.

The diagnosis of tinnitus is usually based on the person’s description. It is commonly supported by an audiogram, an otolaryngological and a neurological examination. The degree of interference with a person’s life may be quantified with questionnaires. If certain problems are found, medical imaging, such as magnetic resonance imaging (MRI), may be performed. Other tests are suitable when tinnitus occurs with the same rhythm as the heartbeat. Rarely, the sound may be heard by someone else using a stethoscope, in which case it is known as objective tinnitus. Occasionally, spontaneous otoacoustic emissions, sounds produced normally by the inner ear, may result in tinnitus.

Prevention involves avoiding exposure to loud noise for longer periods or chronically. If there is an underlying cause, treating it may lead to improvements. Otherwise, typically, management involves psychoeducation or counselling, such as talk therapy. Sound generators or hearing aids may help. No medication directly targets tinnitus.

Signs and symptoms

Tinnitus may be perceived in various locations, more commonly in one or both ears or more central in the head. The noise can be described in many different ways but is reported as a noise inside a person’s head or ear(s) in the absence of auditory stimulation. It often is described as a ringing noise, but in some people, it takes the form of a high-pitched whining, electric buzzing, hissing, humming, tinging, whistling, ticking, clicking, roaring, beeping, sizzling, a pure steady tone such as that heard during a hearing test, or sounds that slightly resemble human voices, tunes, songs, or animal sounds such as “crickets”, “tree frogs”, or “locusts (cicadas)”. Tinnitus may be intermittent or continuous: in the latter case, it may be the cause of great distress. In some individuals, the intensity may be changed by shoulder, neck, head, tongue, jaw, or eye movements, also tinnitus loudness can vary between patients.

The sound perceived may range from a quiet background noise to one that even is heard over loud external sounds. The specific type of tinnitus called objective tinnitus is characterized by hearing the sounds of one’s own muscle contractions or pulse, which is typically a result of sounds that have been created by the movement of muscles near to one’s ear, or sounds related to blood flow in the neck or face.

Course

Due to variations in study designs, data on the course of tinnitus showed few consistent results. Generally, the prevalence increased with age in adults, whereas the ratings of annoyance decreased with duration.

Psychological effects

Besides being an annoying condition to which most people adapt, persistent tinnitus may cause anxiety and depression in some people. Tinnitus annoyance is more strongly associated with the psychological condition of the person than the loudness or frequency range. Psychological problems such as depression, anxiety, sleep disturbances, and concentration difficulties are common in those with strongly annoying tinnitus. 45% of people with tinnitus have an anxiety disorder at some time in their life.

Psychological research has focussed on the tinnitus distress reaction (TDR) to account for differences in tinnitus severity. These findings suggest that among those people, conditioning at the initial perception of tinnitus, linked tinnitus with negative emotions, such as fear and anxiety from unpleasant stimuli at the time. This enhances activity in the limbic system and autonomic nervous system, thus increasing tinnitus awareness and annoyance.

Types

A common tinnitus classification is into “subjective and objective tinnitus”. Tinnitus is usually subjective, meaning that the sounds the person hears are not detectable by means currently available to physicians and hearing technicians. Subjective tinnitus has also been called “tinnitus aurium”, “non-auditory” or “non-vibratory” tinnitus. In rare cases, tinnitus can be heard by someone else using a stethoscope. Even more rarely, in some cases it can be measured as a spontaneous otoacoustic emission (SOAE) in the ear canal. This is classified as objective tinnitus, also called “pseudo-tinnitus” or “vibratory” tinnitus.

Subjective tinnitus

Subjective tinnitus is the most frequent type of tinnitus. It may have many possible causes, but most commonly it results from hearing loss. When the tinnitus is caused by disorders of the inner ear or auditory nerve it can be called otic (from the Greek word for ear). These otological or neurological conditions include those triggered by infections, drugs, or trauma. A frequent cause is traumatic noise exposure that damages hair cells in the inner ear.

When there does not seem to be a connection with a disorder of the inner ear or auditory nerve, the tinnitus can be called non-otic. (i.e. not otic). In some 30% of tinnitus cases, the tinnitus is influenced by the somatosensory system, for instance, people can increase or decrease their tinnitus by moving their face, head, or neck. This type is called somatic or craniocervical tinnitus, since it is only head or neck movements that have an effect.

There is a growing body of evidence suggesting that some tinnitus is a consequence of neuroplastic alterations in the central auditory pathway. These alterations are assumed to result from a disturbed sensory input, caused by hearing loss. Hearing loss could indeed cause a homeostatic response of neurons in the central auditory system, and therefore cause tinnitus.

Hearing loss

The most common cause of tinnitus is hearing loss. Hearing loss may have many different causes, but among those with tinnitus, the major cause is cochlear injury.

Ototoxic drugs also may cause subjective tinnitus, as they may cause hearing loss, or increase the damage done by exposure to loud noise. Those damages may occur even at doses that are not considered ototoxic. More than 260 medications have been reported to cause tinnitus as a side effect. In many cases, however, no underlying cause could be identified.

Tinnitus can also occur due to the discontinuation of therapeutic doses of benzodiazepines. It can sometimes be a protracted symptom of benzodiazepine withdrawal and may persist for many months. Medications such as bupropion may also result in tinnitus. In many cases, however, no underlying cause can be identified.

Source: Wikipedia.org