Tinnitus is known to be inhibited by stimulation of the auditory system by stimuli such as acoustical, electrical and magnetic. Residual inhibition (RI) is when tinnitus is temporarily eliminated for a period of time lasting seconds, minutes, up to hours or even days in some people. There are various theories to explain tinnitus. Some studies hypothesise that it is a trade-off between a central gain increase and neural noise – which seeks to maintain neural homeostasis. This study sought to investigate tinnitus and RI mechanisms further; in particular alterations in auditory change detection and memory related to RI induced by electrical stimuli. This was done using a novel technique of brain mapping – mismatch negativity focusing on the fact that tinnitus is considered an alteration of neural activity. The study was well designed as a single-blind randomised controlled clinical trial with two groups: auditory electrical stimulation (AES) and placebo electrical stimulation. Thirteen of 28 participants with problem tinnitus (46.42%) indicated RI after receiving AES. All of the comparisons made in this study achieved statistical significance. One of the conclusions to be drawn is that RI induced by AES reflects the temporary reestablishment of auditory change detection in tinnitus sufferers. As tinnitus is not completely understood its treatment is also complicated. This study indicates that inducing RI could potentially provide long term relief. Further research is needed and mismatch negativity mapping is a promising tool.

Alterations in auditory change detection associated with tinnitus residual inhibition induced by auditory electrical stimulation.
Mahmoudian S, Farhadi M, Mohebbi M, Alaeddini F, Najafi-Koopaie M, Farahani ED, Mojallal H, Omrani R, Daneshi A, Lenarz T.
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Cheka R Spencer

MSc, AFHEA, FRCS (ORL-HNS), Royal Free London NHS Foundation Trust, London, UK; Member of the ENT UK Global Health Committee. @ENTUKGlobal

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