Pathophysiology and treatment of tinnitus: an elusive disease.

Tinnitus is a perception of sound in proximity to the head with the absence of an external source. It is estimated to occur in 15-20% of the world's population, with 1-3% of cases severely affecting quality of life. Severe tinnitus is frequently associated with depression, anxiety and insomnia. Tinnitus has been associated with a variety of risk factors, including prolonged noise exposure, head and neck injury and infection. The most recent pathophysiologic theory of tinnitus suggests that the central nervous system is the source or "generator" of this condition. However, treatment modalities are still aimed at lessening the awareness of tinnitus and its impact on quality of life rather than attaining a definitive cure. Currently, no drug is available that has demonstrated replicable, long-term reduction of tinnitus impact in excess of placebo effects. However, the market value of such an agent is estimated to be $1.1 billion, with a potential for increase with an aging and longer-living population. This review assesses the current developments in the pathophysiology and treatment for tinnitus, which remains a chronic and debilitating condition.