Tinnitus and hyperacusis/phonophobia

Abstract

Keypoints: 1. Hyperacusis is a decreased sound tolerance. 2. Prevalence of the disease is described in 9-15% of the population, but increases among tinnitus patients. 3. Pathophysiological mechanisms involve some disruptions in the amplification and regulation processes of the external hair cells, disorders of the efferent system (medial and lateral olivocochlear pathways), or effects to the central sound -processing at the subcortical level. 4. The role of some neurotransmitters (serotonin, GABA), which are also involved in other hyperacusis-related diseases (migraine, depression), can be relevant in this disorder. 5. Other theories confirm the effect of the endorphins that activates the excitatory function of the glutamate, the main auditory neurotransmitter, increasing its toxicity. 6. The activation of the limbic and autonomic nervous systems produces the emotional reaction of the hyperacusis (anxiety, fear, and depression). 7. Proposed treatments are based on acoustic stimulation: progressive introduction of white sound (tinnitus retraining therapy TRT) and customized sounds based on the damaged hearing frequencies. 8. Noise generators and hearing aids can be fitted in severe cases. 9. The role of some drugs involved in the metabolism of serotonin and GABA opens new approaches for the management of hyperacusis. © Springer Science+Business Media, LLC 2011.