Article: Tinnitus

Tinnitus, "ringing ears" or ear noise is a phenomenon of the nervous system connected to the ear, characterised by perception of a ringing, beating or roaring sound (often perceived as sinusoidal) with no external source. According to the American Tinnitus Association, tinnitus is pronounced two distinctly different ways, with both being acceptable: ti-NIGHT-us, or TIN-it-us.

Explanation

Tinnitus can be objective (the sound, e.g., a bruit, can be perceived by a clinician) or subjective (perceived only by the patient). The sound may be a quiet background noise, or loud enough to drown out all outside sounds. While the term 'tinnitus' usually refers to more severe cases, a 1953 Heller and Bergman found in a study of 80 tinnitus-free university students that 93% reported hearing a buzzing, pulsing or whistling sound. An increasing number of young people are developing tinnitus; as a result, it is sometimes referred to as "the club disease" as many people experience tinnitus or "ringing ears" after attending loud clubs or concerts or using personal stereos at unsafe volumes.

Causes

Causes of tinnitus include:

• A sudden loud noise such as an explosion or a jet engine exhaust
• Prolonged exposure to environmental noise, including loud music through PA systems (in nightclubs or at concerts) and personal stereos, noisy work environment without ear protection, (eg industrial, motorsport)
• Hearing loss (20 per cent of cases: chronic noise damage and presbycusis)
• Head injury (especially basal skull fracture)
• Drugs: aspirin overdose, loop diuretics, aminoglycosides, quinine, welbutrin
• Temporomandibular and cervical spine disorders
• Suppurative otitis media (also chronic infection and serous OM)
• Otosclerosis
• Earwax
• Ménière’s disease
• Impacted wisdom teeth
• Hypertension and atherosclerosis
• Acoustic neuroma
• Palatal myoclonus (objectively detectable)
• Arteriovenous fistulae and arterial bruits (objectively detectable)
• Severe anemia and renal failure
• Glomus jugulare tumours (objectively detectable)
• Lyme Disease
• Stress and depression
• Thyroid disorders, such as hyperthyroidism or hypothyroidism
• Secretory otitis media (an ear infection often known as 'glue ear') in children
• Fluid in the ear
• Eardrum perforation

Tinnitus can also be exacerbated by severe emotional or physical stress and brought on by loud noises (especially when heard in an otherwise quiet environment) and by physical damage occurring to the ear drum, cochlea or nerve.

Mechanisms of subjective tinnitus

The inner ear contains many thousand minute hairs which vibrate in response to sound waves. These hairs in turn send signals to the brain which are interpreted as sound. If these hairs become damaged, through prolonged exposure to excessive volume, for instance, then deafness to certain frequencies occurs. In this case, they 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's 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.

Prevention

Since there is no tinnitus cure, only treatment, it is wise to take precautions to prevent it occurring. If a ringing in the ears is audible after exposure to a loud environment such as a concert or work place, it means damage is being done. If it is not possible to limit exposure, wearing earplugs or ear defenders can be advantageous. For musicians and DJs, special musicians' earplugs can lower the volume of the music without distorting the sound and can prevent tinnitus developing in later years.

Tinnitus treatment

Many types of tinnitus are temporary and will cease spontaneously while others are permanent in nature. 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. The affected individual may have to generate artificial noise that masks the tinnitus sound. White noise is particularly effective in masking tinnitus. In terms of tinnitus treatment a combination of external masking and psychological counseling known as tinnitus retraining therapy is widely practiced. While it does not actually cure the tinnitus, many report that it becomes much less disturbing and in some cases the offending sound is no longer heard at the conscious level (Habituation of Perception).

See also

• Absolute threshold of hearing
• Auditory system
• Ear
• Hearing impairment
• Hyperacusis
• Noise health effects