Auditory Mirror Therapy for Treatment of Tinnitus

There's some pretty cool stuff happening at the Spaulding Neuroimaging Laboratory in Massachusetts. Dr. Clas Linnman and his team have developed a specific kind of mirror therapy for tinnitus. They have already conducted a pilot study and the results are quite positive to say the least.

The project has recently received financial backing from the Mass General Brigham Hospital, which is one of the most prestigious health care institutions in the US. Thanks to the financial aid, they are planning to conduct a larger, placebo-controlled trial.

Here's a summary of what Auditory Mirror Therapy (AMT) exactly entails:

Auditory Mirror Therapy for Tinnitus -- Clas Linnman, PhD, Spaulding Rehabilitation Network. Current healthcare cost for tinnitus (ringing in the ears) in the U.S. is estimated at $17 billion. About one in ten adults suffer from tinnitus, yet there are no FDA approved drugs or devices. The proposed technology provides a new type of treatment for tinnitus that is non-invasive, affordable, and low risk. This neuromodulatory therapy is based on disruption of multi-sensory integration. Like mirror box therapy for phantom pain, in this therapy, sound at the left ear is transmitted to the right ear canal, and sound at the right ear is transmitted to the left ear canal. Implemented in a wearable pair of headphones, a pilot trial of "auditory mirror therapy" (AMT) indicates that brief use of the headphones significantly and substantially reduced tinnitus. The effects of AMT will be verified in a larger, placebo-controlled study of persons with tinnitus. The technology can be implemented as a separate device, added to current hearing aids, or as a software application for microphone-equipped wireless earbuds, with the potential to help many with tinnitus.

Link:
Mass General Brigham Awards $1 Million to Biotech Breakthroughs

 

Auditory mirror therapy for tinnitus, a pilot study (Linnman, 2022)

Abstract
Background: Tinnitus, the phantom perception of sound, shares many properties with phantom limb pain, in that both may arise as a consequence of sensory deprivation. Prediction errors in multisensory integration, such as induced with mirror box therapy in phantom pain, can reduce phantom percepts.

Purpose: We evaluated if a device that swaps sound from the right pinna to the left ear canal, and from the left pinna to the right ear canal, can reduce tinnitus. We call this auditory mirror therapy (AMT).

Research design: Uncontrolled trial Study sample: 20 subjects with chronic tinnitus Intervention: An AMT devise consisting of a modified ear defender device with microphones that swaps sounds from left pinna to the right ear canal and from the right pinna to the left ear canal. Participants used the device at home for two weeks.

Data collection and analysis: Tinnitus Handicap Inventory , Tinnitus Reaction Questionarie, and VAS ratings of symptoms were collected at baseline and post-tratment. Repeated measures t-test were performed, Bonferroni corrected for multiple comparisons.

Results: There was a significant reduction in Tinnitus Handicap Inventory and in awareness of tinnitus after the AMT intervention.

Conclusions: Exposing the audio-visual integration system to prediction errors can help retrain phantom percepts and reduce tinnitus handicap.

 

Ramachandran's mirror box therapy for phantom limb pain is just such a superbly simple concept but incredibly powerful I think. I often imagine the patient almost feeling the neuroplastic changes occurring.

I scratched my head for ages wondering how a mirror box type therapy might be applied to tinnitus patients but ended up believing, to some dismay it has to be said, that perhaps it already had in the form of masking that leaves a lot to be desired.

The method of channeling audio perception between ears, however, is bloody brilliant. Actually it makes perfect sense and with the right development could be an extremely important step forward for us. What was it da Vinci said; something about elegance in simplicity? Anyhow, great find!

 

Easy enough to test at home - get a pair of noise blocking headphones with ambient listening feature and swap the microphone connections!

 

Great idea @ploughna! Your efforts will be greatly appreciated by the Tinnitus Talk community if you go down the DIY road, you daredevil

But all kidding aside, I'm wondering what kind of sound stimulus they've used in the pilot study. Using white noise, pure tones or something like notched sound stimulation could entail completely different results for tinnitus perception. I think I'll write them an e-mail about this matter.

 

Agreed. There could be any combination of tone/volume matched data thrown into the mix so although a DIY project could be interesting I'd be inclined to tread quite cautiously with something like that at this stage.

I did a quick search on Clas Linnman today and it looks like he's got a patent pending for the AMT 'device'. Not sure if the patent data would detail anything further regarding the mechanism of action.

 

Sounds like a plausible solution and now I have many questions. Primarily, how could this be such a simple concept that we've overlooked?

 

This is really cool.

Reminds me of a video I saw (having trouble finding it with TikTok's terrible search feature) of a college experiment where they would hide a subject's arm and replace it with a fake arm. Then they started rubbing the hand on the fake arm with different objects and the person reported feeling the object being rubbed on their hand. They then stabbed the fake hand and the person briefly felt the pain.

 

You could ask that question anytime a legitimate treatment is created for any condition or disease. Researchers have been circling around a bunch of possible ideas for a while, some of them are bound to work once the right protocols are figured out.

 

I emailed Dr. Linnman and asked if I could receive the treatment. I live close to the research facility. Hopefully he gets back, with a yes. This looks very safe and the protocol makes sense to me. Seems low risk high reward to me. If this alleviated my tinnitus to any degree I'd be very happy.

 

Personally, a reliable mechanism for some alleviation when needed is all I'm really looking for at this point and I too would be very happy with that. Nice one for emailing Dr. Linnman. Good luck and please do keep us informed!

 

We’ll need to wait for this to be sure it actually works. Let’s hope they can get it done quickly. Sounds promising.

 

This seems like a stroke of genius. I hope it actually works.

Someone posted a comment in a different thread about how one of the causes of tinnitus could be a disruption of the brain mechanism by which the ears are calibrated/aligned/balanced, in terms of audio reception. This would also explain why those of us who developed tinnitus due to a neglected earwax plug developed the noise -- because the plug mimicked deafness to the point that the ear-aligning mechanism was over-extended, and then, when the plug was removed, it could no longer align the ears again, in terms of audio reception.

I know that, after my tinnitus-causing earwax plug was removed from my left ear, for a time the ear that ear picked up ambient noise VERY loudly and was entirely out of balance with the other, in addition to permanently generating tinnitus. To this day, the ears aren't audio aligned, with the left ear being slightly weaker at the higher frequencies than the right.

(I don't know why the Pfizer vaccine therefore seems to have permanently re-spiked my tinnitus after it died down for many years, but that's another matter.)

At any rate, maybe this mirroring approach will overcome the dysfunction of the brain's auditory calibrating mechanism to align the ears. If that is what is causing tinnitus for some people, perhaps it could actually work.

 

Dr. Linnman got back to me. I'll post updates here after I participate in the study.

 

Any chance he would share the entire paper/study result with us? I only find the abstract online and I'm very curious for the rest.

 

This was a worthless trial. No placebo control. Any treatment always produce an effect when it comes to tinnitus. Placebo control is crucial.

Skip.

 

A pilot study sometimes precedes a placebo-controlled trial because it helps to pinpoint which (sub) group of sufferers in a small sample size might benefit from treatment X, to test logistics (e.g. if a test location can accommodate willing participants for future trials based on interest in pilot study), to show that there's a cause and effect relationship between X and Y (e.g. establishing Z variables to verify that X causes Y, not that there's a spurious correlation in which Z has an effect on X, Y or both) & to show that treatment X has clinically significant effect. If the results of the pilot study are positive and there's a cause and effect between X & Y, then it's enough grounds to move on to a placebo-controlled trial.

All these things are pretty well described in the book Social Research Methods (Bryman, 2015), in case you're interested in knowing more about research methods & designs.

 

I've just received Dr. Linnman's answer in regards to the quality/character of the sound stimulus, when the trial might take place and possible test locations.

 

Nice! Good luck and I hope you'll get the real deal in the new trial.

 

It's not under peer review.

https://www.thieme-connect.com/products/ejournals/abstract/10.1055/a-1749-9279#info

Publication date means it is now published and passed peer review.

 

Thanks! That makes sense. I've e-mailed Dr. Linnman to check if he's ok if the paper can be shared with the Tinnitus Talk Community (since you have to pay for it via other means).

 

I agree and, in fairness, the author does acknowledge the lack of placebo in the paper. I went ahead and bought the complete paper (I can't post it due to copyright and it's watermarked with my name but happy to answer questions). There was only a THI score improvement, no change in volume of tinnitus (although I'll happily take genuine THI improvements any day of the week also). And to answer a different question above, there wasn't any special sound stimulus used - participants were fitted with a modified set of headphones and instructed to use them while going about normal activities for a number of hours each day.

 

That's unfortunate. It would appear that this doesn't work.

Volume of tinnitus is, in my experience, the only thing that matters; it makes all the difference between constant suffering versus normality, and every point in between.

 

They should just cancel the trial then.

 

Someone should do a study and write a learned paper on “Placebo effects in tinnitus trials”!

Seems like they would have plenty of material.

 

All I need to know is if the lack of awareness/reduction of tinnitus handicap part is true. As much as I want the sound to go away, if something helps me not notice it, that does count for something. It did said it was to be used with hearing aids if I'm not mistaken...

 

I haven't received an ok from Dr. Linnman but I can confirm @ploughna's remarks that the results show an improvement in THI and tinnitus awareness, but not tinnitus loudness/annoyance.

Another thing is that they haven't specified what kind of sounds & stimulation timing they have applied in the pilot study.

Still, I think they need to do a placebo-controlled trial for reasons of validity and reliability. Perhaps they can also figure out other stimulation parameters to see if it can optimise/change the effect of AMT.

 

They've mentioned in the study paper that the technique can also be applied for in-ear hearing devices, so hearing aids could fall in that category.

 

What does the device look like?

 

From what I understand, the device is based on the 3M Peltor TacticalPro earmuffs.