Tinnitus Treatment Using Noninvasive and Minimally Invasive Electric Stimulation: Experimental Design and Feasibility

Abstract

Noninvasive transcranial or minimally invasive transtympanic electric stimulation may offer a desirable treatment option for tinnitus because it can activate the deafferented auditory nerve fibers while posing little to no risk to hearing. Here, we built a flexible research interface to generate and control accurately charge-balanced current stimulation as well as a head-mounted instrument capable of holding a transtympanic electrode steady for hours. We then investigated the short-term effect of a limited set of electric stimulation parameters on tinnitus in 10 adults with chronic tinnitus. The preliminary results showed that 63% of conditions of electric stimulation produced some degree of tinnitus reduction, with total disappearance of tinnitus in six subjects in response to at least one condition. The present study also found significant side effects such as visual, tactile, and even pain sensations during electric stimulation. In addition to masking and residual inhibition, neuroplasticity is likely involved in the observed tinnitus reduction. To translate the present electric stimulation into a safe and effective tinnitus treatment option, we need to optimize stimulation parameters that activate the deafferented auditory nerve fibers and reliably suppress tinnitus, with minimal side effects and tolerable sensations. Noninvasive or minimally invasive electric stimulation can be integrated with sound therapy, invasive cochlear implants, or other forms of coordinated stimulation to provide a systematic strategy for tinnitus treatment or even a cure.

Systematic Review on Intra- and Extracochlear Electrical Stimulation for Tinnitus

“…Tinnitus reduction has been reported as a positive effect of intracochlear electrical stimulation in studies on cochlear implantation in hearing-impaired people [ 89 , 90 ]. Some of these studies demonstrated therapeutic suppression of tinnitus symptoms, but there is no consensus on the most effective type of stimulus [ 7 , 8 ]. In this systematic review, we aimed to provide a comprehensible overview of the electrical intra- and extracochlear stimulation patterns studied and their effect on tinnitus.…”

“…Intracochlear stimulation through a CI is already highly developed for speech recognition in deafened patients. This technology could combine electrical stimulation to optimize both speech recognition and tinnitus suppression [ 7 , 8 ]. Nevertheless, due to its invasive approach, cochlear implantation can induce residual hearing deterioration in the ear implanted.…”

“…An overall risk of bias judgment was determined based on the total score: • high risk of bias (0-3), ◐ medium risk of bias (4-6), ○ low risk of bias (7)(8)(9). Any discrepancies were resolved through discussion between the two reviewers and then by consulting with two additional reviewers (A.L.S.…”

“…So far, several electrical stimulation patterns of the auditory nerve have been described for tinnitus relief, but no consensus on the most effective type of stimulus exists [ 7 , 8 ]. Therefore, in this paper, we aim to systematically review the literature on the effectiveness of intra- and extracochlear electrical stimulation techniques and patterns as a treatment option for patients with tinnitus.…”

Input–Output Functions in Human Heads Obtained With Cochlear Implant and Transcranial Electric Stimulation

“…To date, non-invasive deep brain stimulation has not been achieved in humans. However, remote activation of the auditory nerve through tES has been shown to produce auditory sensations 26,52 , suppress the loudness of tinnitus 25,26,52,53 , and reduce the annoyance of the tinnitus 53 . Optimizing stimulation parameters with the methods introduced here, could aid the development of viable treatment or therapy options for a wide variety of neurological disorders.…”