A double-blind randomised clinical trial of a device aimed at silencing the phantom sounds of tinnitus has yielded promising results for a condition that affects up to 15% of all adults in the United States.
Tinnitus, the ringing, buzzing or hissing sound of silence, varies from slightly annoying in some to utterly debilitating in others, with almost 40% of sufferers having the condition chronically and actively seek relief.
Now, the recent study from researchers at the University of Michigan’s Kresge Hearing Research Institute, suggests relief may be possible.
Susan Shore, Professor Emerita in Michigan Medicine’s Department of Otolaryngology and U-M’s Departments of Physiology and Biomedical Engineering, led research on how the brain processes bi-sensory information, and how these processes can be harnessed for personalised stimulation to treat tinnitus.
Her team’s findings were published in JAMA Network Open.
The study recruited 99 people with somatic tinnitus, a form of the condition in which movements such as clenching the jaw, or applying pressure to the forehead, result in a noticeable change in pitch or loudness of experienced sounds. Nearly 70% of tinnitus sufferers have the somatic form.
According to Shore, candidates with bothersome, somatic tinnitus, as well as normal-to-moderate hearing loss, were eligible to participate.
“Participants received a portable device developed and manufactured by in2being, LLC, for in-home use,” she said. “The devices were programmed to present each person’s personal tinnitus spectrum, which was combined with electrical stimulation to form a bi-sensory stimulus, while maintaining participant and study team blinding.”
Study participants were randomly assigned to one of two groups. The first group received bi-sensory, or active, treatment first, while the second received sound-alone, or control, treatment.
For the first six weeks, participants were instructed to use their devices for 30 minutes daily. The next six weeks gave them a break from daily use, followed by six more weeks of the treatment not received in the beginning of the study.
Shore notes that every week, participants completed the Tinnitus Functional Index, or TFI, and Tinnitus Handicap Inventory, or THI – questionnaires that measure the impact tinnitus has on people’s lives. They also had their tinnitus loudness assessed during this time.
When participants received the bi-sensory treatment, they consistently reported improved quality of life, lower handicap scores and significant reductions in tinnitus loudness. However, these effects were not seen when receiving sound-only stimulation.
Further, more than 60% of participants reported significantly reduced tinnitus symptoms after the six weeks of active treatment, but not control treatment. This is consistent with an earlier study by Shore’s team showing that the longer participants received active treatment, the greater the reduction in their tinnitus symptoms.
“This study paves the way for the use of personalised, bi-sensory stimulation as an effective treatment for tinnitus, providing hope for millions of tinnitus sufferers,” said Shore.
Auricle, the exclusive licensee of the patents related to the bi-sensory stimulation, was launched with the help of Innovation Partnerships, the central hub of research commercialisation activity at the University of Michigan. Auricle will work towards gaining regulatory clearance and then commercialising the treatment.
Study details
Reversing synchronised brain circuits using targeted auditory-somatosensory stimulation to treat phantom percepts
Gerilyn Jones, David Martel, Travis Riffle, Josh Errickson, Jacqueline Souter, Gregory Basura, Emily Stucken, Kara Schvartz-Leyzac, Susan Shore.
Published in JAMA Network Open on 2 June 2023
Key Points
Question Does precisely timed bisensory (auditory and somatosensory) stimulation reduce tinnitus in humans with somatic tinnitus and does extended treatment lead to longer-lasting reductions in tinnitus symptoms?
Findings In this randomised clinical trial involving 99 participants with somatic tinnitus, statistically significant reductions in tinnitus loudness level as well as statistically significant and clinically meaningful reductions in Tinnitus Functional Index and Tinnitus Handicap Inventory scores were observed after bisensory treatment but not after auditory-only treatment. Bisensory treatment effect outlasted the treatment phase through the washout phase.
Meaning Findings from this trial suggest that 6 weeks of precisely timed bisensory treatment provides a lasting decrement in tinnitus for adults.
Abstract
Importance
Animal models have shown altered dorsal cochlear nucleus circuitry in animals that develop tinnitus; however, precise treatment using bisensory (auditory and somatosensory) stimuli can reverse altered neural patterns and lessen tinnitus.
Objective
To confirm and extend the findings of a pilot study, which suggested an increased efficacy of bisensory stimulation, to a clinical trial with a greater duration and greater number of participants.
Design, Setting, and Participants
This double-blind, crossover, single-centre randomised clinical trial was conducted from March 2019, with a 3-month follow-up per participant ending in July 2022. Eligible adults were recruited from the University of Michigan Health System in Ann Arbor, Michigan. Eligibility criteria included bothersome tinnitus (Tinnitus Functional Index [TFI] score, ≥17 points), somatic tinnitus, normal to moderate hearing loss, and no other tinnitus treatments in the 6 months prior to the trial. Included participants were randomised to either treatment group 1, which received active (bisensory) treatment, or group 2, which received the control (auditory-only) treatment. Results were analysed using intent-to-treat (ITT) and per protocol (PP) populations.
Intervention
Precisely timed bisensory (combined auditory and somatosensory) treatment was delivered through a portable, custom, take-home device that was provided to each participant for daily, at-home treatments. Group 1 participants received 30 minutes per day of the bisensory treatment for 6 weeks, followed by a 6-week washout phase, and then 30 minutes per day of the auditory-only treatment followed by a second 6-week washout phase. Group 2 participants received the auditory-only treatment first, followed by a washout phase, and then the bisensory treatment followed by a second washout phase.
Main Outcomes and Measures Primary end points were changes in TFI score and tinnitus loudness level from baseline through week 6 and week 12.
Results
Of 337 screened individuals, 99 (mean [SD] age, 47 [12.7] years; 59 males [60%]; 85 with non-Hispanic white [86%] race and ethnicity) were enrolled into the study and randomized to treatment group 1 (n = 49) or group 2 (n = 50). The active but not the control treatment resulted in clinically significant decreases in TFI scores at week 6 of phase 1 (ITT population: –12.0 [95% CI, –16.9 to –7.9] points; P < .001; PP population: –13.2 [95% CI, –16.0 to –10.5] points; P < .001). Decreases in tinnitus loudness level were greater than 6 dB sensation level (SL; >half as loud) at week 6 for the bisensory treatment group, with little effect for the auditory-only treatment control group at week 6 of phase 1 (ITT population: –5.8 [95% CI, –9.5 to –2.2] dB; P = .08; PP population: –7.2 [95% CI, –11.4 to –3.1] dB; P = .03), and up to 11 dB SL at week 12 of phase 2 (ITT population: –10.9 [95% CI, –15.2 to –6.5] dB; P = .001; PP population: –14.1 [95% CI, –18.4 to –9.8] dB; P < .001). Decreased tinnitus loudness level and TFI scores extended into the washout phase, indicating a prolonged treatment effect.
Conclusions and Relevance
This trial found that precisely timed bisensory treatment using stimuli and timing developed in a validated animal model was effective for adults with somatic tinnitus. Prolonged reduction in tinnitus symptoms can result from using an extended treatment duration.
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