Dissociating Mechanisms of Tinnitus & Hyperacusis: A Survey & Behavioral Study
Jenise Imani Chappell (Student, pictured) and Fatima Husain, Ph.D. (Mentor), University of Illinois at Urbana-Champaign, Urbana, IL
Roadmap to a Cure: Pathways A & D
Tinnitus and hyper- acusis are often co-morbid conditions; past research esti- mates that 40-79% of tinnitus patients also report increased sensitivity to sound. This study will explore whether the two conditions share a common physiological pathway, by compar- ing otoacoustic emis- sions in patients with just tinnitus, patients with just hyperacusis, patients with both tinnitus and hyperacusis, and a control group.
Otoacoustic emissions are sounds that are generated by the hair cells in the inner ear, which are part of healthy, normal hearing. These emissions diminish after inner ear damage, so measuring these sounds is a clinically useful way of assessing inner ear health. Otoacoustic emissions are NOT the cause of tinnitus; these sounds are imperceptible to the human brain and can only be measured by very sensitive microphones.
Through an online survey and in-person patient testing, the researcher will determine whether tinnitus and hyperacusis share similar otoacoustic emission cor- relates. If both conditions show similar physiological dynamics, it would indicate that they both could be treated through similar means.
By focusing on patients with both tinnitus and hyper- acusis, this study will also highlight the particular treatment needs for this population, with a particular emphasis on how to best use and fit hearing aids. While often used for tinnitus management, current clinical practices around hearing aids do not adequately account for the noise-sensitivity of hyperacusis patients. A better understanding of the internal mechanisms of hyperacu- sis would account for the variable efficacy of hearing aids for these patients and point towards clinical prac- tices for improving outcomes.
Tinnitus and Tonotopic Remapping of the Auditory Cortex
Pim van Dijk, Ph.D. (pictured), Emile de Kleine, Ph.D., and D.R.M. Langers, Ph.D., University Medical Center Groningen, Groningen, The Netherlands
Roadmap to a Cure: Pathways A, B & C
Tinnitus is believed to be related to changes in the brain, specifically a process referred to as tono- topic reorganization. (Tonotopy is the organization of how particular sound frequencies are pro- cessed in different areas of the brain.) Reorganization may lead to an overrepre- sentation of particular sound frequencies in the brain, which leads to the perception of tinnitus. Several therapies have been proposed to restore normal tonotopy, and thereby possibly cure tinnitus.
However, the underlying assumption that tinnitus is caused by tonotopic reorganization has never been fully tested in humans. Dr. Van Dijk’s project addresses this gap in the research. For the first time, researchers will use new, state-of-the-art functional magnetic resonance imaging (fMRI) to robustly measure detailed tonotopic maps in subjects with and without tinnitus. By a comparison of these two groups, it will become clear to what extent tinnitus is associated with tonotopic reorga- nization.
If it is affirmed that tinnitus is related to tonotopic reorganization in the human brain, it will strongly stimulate the development of therapies (such as new sound therapies) that aim to restore normal tonotopic representation and potentially eliminate tinnitus.
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Summer 2014 | Tinnitus Today
25
SCIENCE & RESEARCH
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