The Neuroscience and the Treatment of Tinnitus : The Hearing Journal – Lippincott Williams & Wilkins
Tinnitus, or “ringing in the ears,” is a common audiological complaint that is extremely heterogeneous in presentation, etiology, and severity.1 Tinnitus affects approximately 50 million Americans,2 with a similar worldwide prevalence.3 It is the number one service-related disability among U.S. veterans, affecting more than 2.17 million military members.4 There is also an increased prevalence of tinnitus in elderly populations, with estimates as high as 20% in adults over the…….
Tinnitus, or “ringing in the ears,” is a common audiological complaint that is extremely heterogeneous in presentation, etiology, and severity.1 Tinnitus affects approximately 50 million Americans,2 with a similar worldwide prevalence.3 It is the number one service-related disability among U.S. veterans, affecting more than 2.17 million military members.4 There is also an increased prevalence of tinnitus in elderly populations, with estimates as high as 20% in adults over the age of 50.5 Tinnitus has many societal and economic impacts, with some studies estimating the annual tinnitus-related health care cost to be between $700 and $2,000 (USD) per individual.6,7
Shutterstock/Axel_Kock, tinnitus, neuroscience, hearing loss.
In addition to its high prevalence, the heterogeneity of tinnitus has complicated both research and clinical management of the disorder.1 Many documented causes of tinnitus include conductive and sensorineural hearing loss, ototoxicity, head and neck injury, and others.8 Tinnitus severity exists on a wide spectrum ranging from mildly bothersome to severely debilitating. The percept itself is also incredibly variable as some patients report a buzzing, whooshing, pure tone, or other indistinct sounds. Yet it remains unclear whether common or different mechanisms underlie tinnitus with different causes and clinical presentations.1 Importantly, there is neither a cure nor FDA-approved drugs for tinnitus. Many current clinical strategies are focused on alleviating the negative emotional effects of tinnitus without addressing the biological processes that underlie the phantom percept. Our review describes the current basic and clinical research of the physiological correlates of tinnitus and mechanism-driven drug development efforts.1
TINNITUS RESEARCH UPDATE
Tinnitus is the persistent, involuntary, subjective phantom percept of internally generated, indistinct, nonverbal noises and tones. In most cases, tinnitus is initiated by acquired hearing loss and maintained only when this loss is coupled with distinct neuronal changes in auditory and extra-auditory brain networks.1 The exact geometry of the electrical patterns of activity that are necessary and sufficient for the generation and maintenance of tinnitus lies within these networks, but the precise patterns and mechanisms remain unclear.1
In the last 30 years, tinnitus has gained more research attention. Recent progress in tinnitus research can be largely attributed to the development of tinnitus behavioral models in rodents beginning in the 1980s. Animal models are either operant or reflexive; both types are predicated on the idea that tinnitus alters the perception of silence. Operant models are based on the training of animals to behave differently in silence vs. noise. Reflexive models are based on differences in innate reflexes in response to acoustic stimulation or silence. While both models have significantly advanced tinnitus research, we propose that operant …….
