Tinnitus

Tinnitus is the perception of sound when no corresponding external sound is present. 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 some degree of hearing loss and with decreased understanding in noise. 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 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 can 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, exposure to certain medications, a previous head injury, earwax, and sometimes, the tinnitus is suddenly perceived 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 counseling as talk therapy. Sound generators or hearing aids may help some. However, there is no medication existing which can target the tinnitus directly.

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.

Associated factors

Factors associated with tinnitus include:

• ear problems and hearing loss:
  • conductive hearing loss
    • acoustic shock
    • loud noise or music
    • middle ear effusion
    • otitis
    • otosclerosis
    • Eustachian tube dysfunction
  • sensorineural hearing loss
    • excessive or loud noise; e.g. acoustic trauma
    • presbycusis (age-associated hearing loss)
    • Ménière's disease
    • endolymphatic hydrops
    • superior canal dehiscence
    • acoustic neuroma
    • mercury or lead poisoning
    • ototoxic medications
• neurologic disorders:
  • Arnold–Chiari malformation
  • multiple sclerosis
  • head injury
  • giant cell arteritis
• temporomandibular joint dysfunction
• metabolic disorders:
  • vitamin B₁₂ deficiency
  • iron deficiency anemia
• psychiatric disorders
  • depression
  • anxiety disorders
• other factors:
  • vasculitis
  • Some psychedelic drugs can produce temporary tinnitus-like symptoms as a side effect
    • 5-MeO-DET
    • diisopropyltryptamine (DiPT)
  • benzodiazepine withdrawal
  • intracranial hyper or hypotension caused by, for example, encephalitis or a cerebrospinal fluid leak

Objective tinnitus

Objective tinnitus can be detected by other people and is sometimes caused by an involuntary twitching of a muscle or a group of muscles (myoclonus) or by a vascular condition. In some cases, tinnitus is generated by muscle spasms around the middle ear.

Spontaneous otoacoustic emissions (SOAEs), which are faint high-frequency tones that are produced in the inner ear and can be measured in the ear canal with a sensitive microphone, may also cause tinnitus. About 8% of those with SOAEs and tinnitus have SOAE-linked tinnitus, while the percentage of all cases of tinnitus caused by SOAEs is estimated at about 4%.

Pulsatile tinnitus

Some people experience a sound that beats in time with their pulse, known as pulsatile tinnitus or vascular tinnitus. Pulsatile tinnitus is usually objective in nature, resulting from altered blood flow, increased blood turbulence near the ear, such as from atherosclerosis or venous hum, but it can also arise as a subjective phenomenon from an increased awareness of blood flow in the ear. Rarely, pulsatile tinnitus may be a symptom of potentially life-threatening conditions such as carotid artery aneurysm or carotid artery dissection. Pulsatile tinnitus may also indicate vasculitis, or more specifically, giant cell arteritis. Pulsatile tinnitus may also be an indication of idiopathic intracranial hypertension. Pulsatile tinnitus can be a symptom of intracranial vascular abnormalities and should be evaluated for irregular noises of blood flow (bruits).

Pathophysiology

It may be caused by increased neural activity in the auditory brainstem, where the brain processes sounds, causing some auditory nerve cells to become over-excited. The basis of this theory is that many with tinnitus also have hearing loss.

Three reviews of 2016 emphasized the large range and possible combinations of pathologies involved in tinnitus, which in turn result in a great variety of symptoms demanding specifically adapted therapies.

Diagnosis

The diagnostic approach is based on a history of the condition and an examination of the head, neck, and neurological system. Typically an audiogram is done, and occasionally medical imaging or electronystagmography. Treatable conditions may include middle ear infection, acoustic neuroma, concussion, and otosclerosis.

Evaluation of tinnitus can include a hearing test (audiogram), measurement of acoustic parameters of the tinnitus like pitch and loudness, and psychological assessment of comorbid conditions like depression, anxiety, and stress that are associated with severity of the tinnitus.

One definition of tinnitus, as compared to normal ear noise experience, is lasting five minutes at least twice a week. However, people with tinnitus often experience the noise more frequently than this. Tinnitus can be present constantly or intermittently. Some people with constant tinnitus might not be aware of it all the time, but only for example during the night when there is less environmental noise to mask it. Chronic tinnitus can be defined as tinnitus with duration of six months or more.

Audiology

Since most persons with tinnitus also have hearing loss, a pure tone hearing test resulting in an audiogram may help diagnose a cause, though some persons with tinnitus do not have hearing loss. An audiogram may also facilitate fitting of a hearing aid in those cases where hearing loss is significant. The pitch of tinnitus is often in the range of the hearing loss.

Psychoacoustics

Acoustic qualification of tinnitus will include measurement of several acoustic parameters like frequency in cases of monotone tinnitus or frequency range and bandwidth in cases of narrow band noise tinnitus, loudness in dB above hearing threshold at the indicated frequency, mixing-point, and minimum masking level. In most cases, tinnitus pitch or frequency range is between 5 kHz and 10 kHz, and loudness between 5 and 15 dB above the hearing threshold.

Another relevant parameter of tinnitus is residual inhibition, the temporary suppression or disappearance of tinnitus following a period of masking. The degree of residual inhibition may indicate how effective tinnitus maskers would be as a treatment modality.

An assessment of hyperacusis, a frequent accompaniment of tinnitus, may also be made. Hyperacusis is related to negative reactions to sound and can take many forms. One associated parameter that can be measured is Loudness Discomfort Level (LDL) in dB, the subjective level of acute discomfort at specified frequencies over the frequency range of hearing. This defines a dynamic range between the hearing threshold at that frequency and the loudness discomfort level. A compressed dynamic range over a particular frequency range can be associated with hyperacusis. Normal hearing threshold is generally defined as 0–20 decibels (dB). Normal loudness discomfort levels are 85–90+ dB, with some authorities citing 100 dB. A dynamic range of 55 dB or less is indicative of hyperacusis.

Severity

The condition is often rated on a scale from "slight" to "severe" according to the effects it has, such as interference with sleep, quiet activities and normal daily activities.

Assessment of psychological processes related to tinnitus involves measurement of tinnitus severity and distress (i.e., nature and extent of tinnitus-related problems), measured subjectively by validated self-report tinnitus questionnaires. These questionnaires measure the degree of psychological distress and handicap associated with tinnitus, including effects on hearing, lifestyle, health and emotional functioning. A broader assessment of general functioning, such as levels of anxiety, depression, stress, life stressors and sleep difficulties, is also important in the assessment of tinnitus due to higher risk of negative well-being across these areas, which may be affected by or exacerbate the tinnitus symptoms for the individual. Overall, current assessment measures are aimed to identify individual levels of distress and interference, coping responses and perceptions of tinnitus in order to inform treatment and monitor progress. However, wide variability, inconsistencies and lack of consensus regarding assessment methodology are evidenced in the literature, limiting comparison of treatment effectiveness. Developed to guide diagnosis or classify severity, most tinnitus questionnaires have been shown to be treatment-sensitive outcome measures.

Pulsatile tinnitus

If the examination reveals a bruit (sound due to turbulent blood flow), imaging studies such as transcranial doppler (TCD) or magnetic resonance angiography (MRA) should be performed.

Differential diagnosis

Other potential sources of the sounds normally associated with tinnitus should be ruled out. For instance, two recognized sources of high-pitched sounds might be electromagnetic fields common in modern wiring and various sound signal transmissions. A common and often misdiagnosed condition that mimics tinnitus is radio frequency (RF) hearing, in which subjects have been tested and found to hear high-pitched transmission frequencies that sound similar to tinnitus.

Prevention

Safety sign from the UK Government Regulations requiring ear protection

Prolonged exposure to loud sound or noise levels can lead to tinnitus. Custom made ear plugs or other measures can help with prevention. Employers may use hearing loss prevention programs to help educate and prevent dangerous levels of exposure to noise. Government organizations set regulations to ensure employees, if following the protocol, should have minimal risk to permanent damage to their hearing.

Several medicines have ototoxic effects, and can have a cumulative effect that can 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.

Management

If a specific underlying cause is determined, treating it may lead to improvements. Otherwise, the primary treatment for tinnitus is talk therapy, sound therapy, or hearing aids. There are no effective medications or supplements that treat tinnitus.

Psychological

The best supported treatment for tinnitus is a type of counseling called cognitive behavioral therapy (CBT) which can be delivered via the internet or in person. It decreases the amount of stress those with tinnitus feel. These benefits appear to be independent of any effect on depression or anxiety in an individual. Acceptance and commitment therapy (ACT) also shows promise in the treatment of tinnitus. Relaxation techniques may also be useful. A clinical protocol called Progressive Tinnitus Management for treatment of tinnitus has been developed by the United States Department of Veterans Affairs. There is some tentative evidence supporting tinnitus retraining therapy, which is aimed at reducing tinnitus-related neuronal activity.

Sound-based interventions

The use of sound therapy by either hearing aids or tinnitus maskers may help the brain ignore the specific tinnitus frequency, but these methods are poorly supported by evidence, there are no negative effects. There are several approaches for tinnitus sound therapy. The first is sound modification to compensate for the individual's hearing loss. The second is a signal spectrum notching to eliminate energy close to the tinnitus frequency. There is some tentative evidence supporting tinnitus retraining therapy, which is aimed at reducing tinnitus-related neuronal activity. There are preliminary data on an alternative tinnitus treatment using mobile applications, including various methods: masking, sound therapy, relaxing exercises and other. These applications can work as a separate device or as a hearing aid control system.

Medications

As of 2018^[update] there were no medications effective for idiopathic tinnitus. There is not enough evidence to determine if antidepressants or acamprosate are useful. There is no high-quality evidence to support the use of benzodiazepines for tinnitus. Usefulness of melatonin, as of 2015, is unclear. It is unclear if anticonvulsants are useful for treating tinnitus. Steroid injections into the middle ear also do not seem to be effective. There is no evidence to suggest that the use of betahistine to treat tinnitus is effective.

Botulinum toxin injection has been tried with some success in some of the rare cases of objective tinnitus from a palatal tremor.

Caroverine is used in a few countries to treat tinnitus. The evidence for its usefulness is very weak.

Bimodal neuromodulation

In 2020, information about recent clinical trials has indicated that bimodal neuromodulation may be a promising treatment for reducing the symptoms of tinnitus. It is a noninvasive technique that involves the paring of an electrical stimulus to the tongue that is associated with sounds. Equipment associated with the treatments is available through physicians. Studies with it and similar devices continue in several research centers.

Other

There is some evidence supporting neuromodulation techniques such as transcranial magnetic stimulation; transcranial direct current stimulation and neurofeedback. However, the effects in terms of tinnitus relief are still under debate.

Alternative medicine

Ginkgo biloba does not appear to be effective. The American Academy of Otolaryngology recommends against taking melatonin or zinc supplements to relieve symptoms of tinnitus, and reported that evidence for efficacy of many dietary supplements—lipoflavonoids, garlic, homeopathy, traditional Chinese/Korean herbal medicine, honeybee larvae, other various vitamins and minerals—did not exist. A 2016 Cochrane Review also concluded that evidence was not sufficient to support taking zinc supplements to reduce symptoms associated with tinnitus.

Prognosis

While there is no cure, most people with tinnitus get used to it over time; for a minority, it remains a significant problem.

Epidemiology

Adults

Tinnitus affects 10–15% of people. About a third of North Americans over 55 experience tinnitus. Tinnitus affects one third of adults at some time in their lives, whereas ten to fifteen percent are disturbed enough to seek medical evaluation.

Children

Tinnitus is commonly thought of as a symptom of adulthood, and is often overlooked in children. Children with hearing loss have a high incidence of tinnitus, even though they do not express the condition or its effect on their lives. Children do not generally report tinnitus spontaneously and their complaints may not be taken seriously. Among those children who do complain of tinnitus, there is an increased likelihood of associated otological or neurological pathology such as migraine, juvenile Meniere's disease or chronic suppurative otitis media. Its reported prevalence varies from 12% to 36% in children with normal hearing thresholds and up to 66% in children with a hearing loss and approximately 3–10% of children have been reported to be troubled by tinnitus.

See also