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Definition: tinnitus from The Chambers Dictionary

a medical condition in which there is constant ringing or other noise in the ears. [L tinnītus, - ūs a jingling, from tinnīre to ring]


Summary Article: Tinnitus
from Encyclopedia of Global Health

Tinnitus is the perception of an abnormal sensation of sound in the ear or head in the absence of acoustic stimulation from external environment, from within body, due to hallucinations or due to mental illness. Spontaneous tinnitus is a significant interdisciplinary therapeutic problem; it is a common condition affecting around one in 10 of the population at any given time. For the majority of people, it is an annoyance rather than a major health issue; however, for approximately 0.5 percent of the population, tinnitus interferes with their ability to pursue a normal life. The effects of tinnitus are vast; some degree of hearing loss is found in the vast majority of tinnitus patients. In elderly patients, it most frequently coexists with sensorineural hearing loss. Tinnitus is also likely to disrupt cognitive functioning.

Tinnitus is divided into two parts: objective and subjective. Objective tinnitus is caused by sounds generated in the body, while subjective tinnitus is caused by abnormal neural activity that is not evoked by sound. Tinnitus may present with symptoms of hyperacusis (condition characterized by oversensitivity to certain frequency ranges of sound). Tinnitus is a common symptom in otosclerosis patients; affective disorders, such as phonophobia (morbid fear of sound including ones own voice), and depression which may accompany severe tinnitus. Tinnitus is thought to be caused by abnormal neural activity, with possible involvement of the nonclassical ascending (extralemniscal, diffuse, or polysensory) auditory pathway that bypass the primary auditory cerebral cortex and provide subcortical connections to limbic structures (e.g., amygdala) among others.

Pathogenesis of tinnitus is related to the ear, functional changes in the central auditory system, and perhaps the peripheral auditory system. The most probable place generating tinnitus in the auditory pathway is outer hair cells (OHC) inside the cochlea. There appears to be a loss of OHC although inner hair cells are intact. The changes in the central nervous system are induced through expression of neural plasticity, some of which may have been caused initially by abnormalities in the ear or the auditory nerve.

The diagnostic approach in children and adolescents includes hearing tests such as pure-tone audiometry which determines hearing sensitivity and speech audiometry which is a functional test of ear-specific speech discrimination performance. There is currently no cure for tinnitus; however, there are several treatment strategies that can alleviate the symptoms in some patients.

Tinnitus of predominantly central origin has been treated successfully with benzodiazepines (although long-term use is not recommended) and GABAergic drugs such as gabapentin. Many studies advocate the use of hyperbaric oxygen (HBO2) therapy for the treatment for tinnitus. Other studies suggest that the therapeutic effects of HBO2 on tinnitus might be merely due to psychological mechanisms triggered by the attitude of the patient toward HBO2 therapy prior to the treatment.

Fitting with hearing aids is an effective way of treatment in the majority of elderly patients with chronic tinnitus. Suppression of tinnitus by electrical stimulation via a cochlear implant has been studied in recent years. Some individuals who undergo cochlear implant surgery report total or partial relief of the symptoms even in the contralateral ear.

Tinnitus patients may seek treatment with acupuncture, although this has not been demonstrated to be efficacious as a treatment for tinnitus. Proposed mechanisms by which antidepressants might be helpful for tinnitus, including treatment of comorbid depression and anxiety have been studied. In cases with severe annoyance, tinnitus counseling is sufficient therapy. Although the overall prognosis of tinnitus is good, it does have an insidious onset, may continue for decades, cause disruption of sleep patterns, and lead to depression.

    SEE ALSO:
  • Ear Disorders; Otology.

BIBLIOGRAPHY
  • B. C.J. Moore; J. Ashmore; M. Hagard, New Developments in Hearing and Balance (Oxford University Press, 2002).
  • Farhana Akter
    King’s College, London
    Copyright © 2008 by SAGE Publications, Inc.

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