Stress and tinnitus.

Emotional stress is a constant companion of tinnitus patients, since this phantom sound can unfortunately be a very effective stressor. However, the mechanism of stress contribution to the onset or progression of tinnitus remains unknown. Here, we review the pathways induced by emotional stress and the outcome of their induction: corticosteroid-dependent changes in gene expression, epigenetic modulations, and impact of stress on neuronal plasticity and neurotransmission. Using clinical examples, we demonstrate the presence of emotional stress among tinnitus patients and we present methods to measure the degree of stress. The evidence causally linking emotional stress with tinnitus is still indirect-the main difficulty lies in the inaccessibility of human auditory tissues and the inability to directly measure tinnitus-induced psychological distress in animal models. However, we believe that translational research is the future way of filling this gap, finding the answers, and thereby improving both the diagnosis and treatment of tinnitus patients.