Neuromodulation for Treating Tinnitus

 

by Neil Bauman, Ph.D.

© February, 2021

 

A man in the UK wrote:

Would you know anything about Neuromod in Ireland for treating tinnitus? We’ve looked at independent reviews but are still unsure. It’s £2,500 non-returnable and they say 81% get relief within a few weeks. 16% can get worse which is worrying.

At this time, there’s not a lot of information available about this Neuromod treatment by practitioners or by those that have used it so there is not a lot of independent post-study data on the results of this device to draw on. As a result, I went back to the original study to learn more about this emerging tinnitus treatment.

What Is Neuromodulation?

Neuromodulation is a fancy word that, in the case of tinnitus, describes the use of electrical or magnetic stimulation (often specialized sound therapy) to calm down aberrant neurons in the auditory cortex in your brain that have become both hyperactive and synchronized thus producing tinnitus. Modulating the neurons (changing how these neurons behave) in your auditory cortex can sometimes decrease your tinnitus.

One widely-used neuromodulation approach to treat various conditions, including tinnitus, is to apply surface electrical stimulation to your scalp or body, or even to your tongue, which typically includes activating your trigeminal or vagus nerves. (1, p. 1)

When applied to tinnitus, most forms of neuromodulation use some form of sound therapy as their sole neuromodulation agent. The goal is to calm down and de-synchronize this excess neuronal activity. Although this single-agent neuromodulation shows promise and works for some people, it does not work for the majority of people with tinnitus by any means.

In an effort to make neuromodulation more effective for more people with tinnitus, researchers are now trying multi-modal stimulation—typically stimulating, not one, but two senses at the same time, typically your tactile sense (touch/feel) in addition to your auditory sense. This is known as bimodal neuromodulation.

Bimodal neuromodulation has recently shown some promise for more-effectively treating tinnitus than just stimulating the auditory pathways. This is because electrical somatosensory stimulation can broadly activate or modulate neurons throughout the auditory pathways from the brainstem to the auditory cortex. As a result, greater, or more consistent, efficacy may be achieved through electrical stimulation paired with a targeted auditory input to modulate specific brain regions than just using auditory input alone. (1, p. 1)

This means that pairing specific sound therapy with electrical somatosensory stimuli can drive enhanced plasticity within brain regions linked to tinnitus, thus normalizing neuronal hyperactivity. Research has shown that repeatedly stimulating these two sensory inputs can result in long-term therapeutic changes in the brain and thus presumably permanently decrease your tinnitus. (1, p. 1)

The Bimodal Neuromod Device

To determine how well bimodal neuromodulation actually works, researcher Brendan Conlon and associates conducted a study (1) using a newly-developed Neuromod device.

The Neuromod company, founded in 2010 and located in Dublin, Ireland developed the “Lenire”, to provide bimodal stimulation to ultimately produce neuromodulation of tinnitus.

Their product consists of three basic components. The controller (“Lenire”) is a pocket-sized device that controls the timing, intensity and synchronization of the auditory and tongue stimuli. Bluetooth headphones deliver the customized, paired, sound stimuli to the ears. The 32-electrode tongue stimulator (called the “Tonguetip®”), hard-wired to the controller, sits in your closed mouth and provides the tactile (somatosensory) input (mild electrical pulses) to your trigeminal nerve via the surface of your tongue. (2)

Screening Process

In order to better understand the results of this study, it is instructive to look at the screening process all applicants went through because prospective participants underwent a rigorous screening process that eliminated most of them. Thus, the results of this study reflect only a very limited subset of the various factors associated with tinnitus.

In fact of the 5,826 people that completed the on-line assessment application for this study, initial screening quickly eliminated 5,128 of them! Of the remaining 698 that were invited for a clinical screening, the second screening eliminated another 372, leaving only 326 that participated in this study. (1, p. 2)

Note that the screening process eliminated 5,500 applicants—94.4% of all the people that applied! In other words, this study just accepted 5.6% of the applicants. Remember, they all had tinnitus. That’s how narrow the criteria were for being accepted. Obviously, this small sub-set of accepted applicants is not representative of all people with tinnitus. You can assume that the 5,826 people that filled out on-line applications for this study were reasonably representative of all the people in the general population that have bothersome tinnitus. Thus, by rejecting so many from this study, it appears that bimodal neuromodulation likely won’t help the vast majority of people with tinnitus.

It’s quite informative to look at all the kinds of people with tinnitus that were excluded from taking part in this study. Here are some of the exclusion factors listed.

This study excluded people if they had:

• Objective tinnitus, which includes pulsatile tinnitus, muscle contractions in the middle ear such as Tonic Tensor Tympani Syndrome, gaze-evoked tinnitus, nodding-chime tinnitus, etc.
• Somatic tinnitus caused by head, neck or jaw movements/injuries.
• Conductive hearing loss.
• Tinnitus for less than 3 months or longer than 5 years.
• Tinnitus with a minimum masking level less than 20 dB or greater than 80 dB hearing level (HL).
• Substantial sensorineural hearing loss defined as greater than 40 dB in at least one test frequency in the range of 250 Hz to 1,000 Hz or greater than 80 dB in at least one test frequency in the range of 2 kHz to 8 kHz.
• Begun using a hearing aid within 90 days before their eligibility assessment.
• Used a cochlear implant, heart pacemaker or vagal nerve stimulator.
• A temporomandibular joint disorder.
• A loudness discomfort level (LDL) of less than 30 dB SL (that is, an LDL of less than 30 dB above the faintest sound they could hear at that test frequency). In other words, they had severe loudness hyperacusis.
• A Tinnitus Handicap Inventory (THI) score of less than 28 or more than 76 points. They considered a score less than 28 as being sufficiently mild so as to be less amenable to therapeutic intervention. At the other end of the scale, they considered a score greater than 76 as catastrophic and typically associated with other conditions including depression, anxiety, and suicidal tendencies.
• An anxiety score of greater than 120 on the 160 point State-Trait Anxiety Inventory (STAI). (The STAI is a psychological test that consists of 40 questions answered on a self-reported basis. It measures two types of anxiety—state anxiety, that is, anxiety about an event, and trait anxiety, or anxiety as a personal characteristic.)
• Meniere’s disease.
• A history of auditory hallucinations (which could exclude all those with Musical Ear Syndrome [MES]). (1, p. 12)

In addition, the screening visit included various tinnitus, hearing, oral cavity, and health assessments conducted by designated audiologists, clinicians, and researchers to further stratify and identify participants that satisfied the inclusion and exclusion criteria. (1, p. 10)

Procedures

Before the study began, audiologists fitted each participant with the Neuromod device. They measured each participant’s pure-tone audiometric thresholds between 250 Hz and 8 kHz, then adjusted the intensity of the auditory stimuli to be approximately 10 dB above their hearing thresholds at each tone frequency. (1, p. 11)

In addition, they adjusted the electrical stimulation intensity of the Tonguetip® to match each participant’s tongue sensitivity. (1, p. 5)

Participants were instructed to use the Neuromod device for two 30-minute sessions daily for 12 weeks. To be compliant with the study terms, they had to use the device for a minimum of 36 hours over the 12-week treatment period. (1, p. 11) Participants were clinically evaluated at 6 and 12 weeks. Furthermore, they were assessed at three follow-up visits ending at 12 months after completing the therapy. (1, p. 2)

Results

The results were revealing. The first thing you need to know is that Neuromod therapy doesn’t work for all kinds of tinnitus as is abundantly clear by all the tinnitus factors they excluded in the screening process. Thus, don’t assume that Neuromod therapy will help very many people with tinnitus as they only included those that they felt had a good chance of success.

Therefore, when they conclude that 81% got relief, this was only 81% of the 5.6% of those with tinnitus that were accepted into this study. By extrapolation, this would work out to only 4.5% of the general population with tinnitus. Thus, for the vast majority of people with tinnitus (95.5%), there is no indication whether this device would help them or not.

Second, you need to know that this Neuromod therapy, while helping an impressive 81% of the people in the study, didn’t improve their tinnitus all that much on the average.

Results were based on the Tinnitus Handicap Inventory (THI). “The Tinnitus Handicap Inventory predominantly assesses the emotional and functional impact of tinnitus, in which 25 items are scored 4/2/0 on a categorical scale corresponding to yes/sometimes/no. The global score of the THI (i.e., sum of points across all 25 items has a value of 0 to 100 with a higher score indicating a greater negative impact of tinnitus.” (1, p. 12)

An analysis of the results of the Tinnitus Handicap Inventory scores after completing the Neuromod therapy revealed that this therapy only reduced the tinnitus scores by an average of 14 points (or 14%).

Note that this study did not have a control group. Consequently, there was no estimate of the placebo effect which could have accounted for much of the measured change in tinnitus.

Third, this study did not evaluate tinnitus reduction for any kinds of somatosensory tinnitus. Thus the results only apply to those who have subjective tinnitus.

Note that it was obviously necessary to exclude those with somatosensory tinnitus from this study since this study was using somatosensory inputs to test the efficacy of bimodal neuromodulation. Yet, often the cause of somatosensory tinnitus is hyperactivity of the nerves in those portions of your body enervated by the trigeminal and vagus nerves—the very nerves the Neuromod device was using to try to help reduce tinnitus. Thus, it should be no surprise that some people in this study found their tinnitus getting worse because of this extra activity in their trigeminal nerves when taking the Neuromod therapy.

Since this neuromodulation therapy helps reduce tinnitus in some people, but makes tinnitus worse in others, it seems it would be better if researchers studied neuromodulation therapy using nerves that are not involved in somatosensory tinnitus.

This study revealed some interesting findings.

• Of the 84% of treatment-compliant participants, 74.7% to 88.8% (average 81.7%) demonstrated improvements in their THI or TFI scores during treatment. After 12 weeks of treatment, their scores improved an average of 13.2 to 14.6 points. (1, p. 9) (Note that the Tinnitus Functional Index [TFI] is another way of measuring how much effect tinnitus has on your life. Researchers used both the THI and TFI in this study—thus the two sets of results.)
• There was rapid improvement within the first six weeks of the therapy, but only minimal improvements in the second six weeks of treatment. This may have been because the brain becomes less sensitive in response to repetitive stimuli over time (it habituates to the repetitive stimuli). (1, p. 10) Thus, this kind of treatment is likely only needed for 6 weeks.
• Improvements to tinnitus scores showed that the changes to the brain were probably permanent. (1, p. 5) Bimodal neuromodulation achieved a 14.2 point average improvement in the THI scores at 12 weeks. This improvement lasted for at least 12 months after treatment, only dropping slightly to 12.7 points. This slight 1.5 point drop after a year is very good. Up to now, no other tinnitus treatment has demonstrated such long-term post-treatment effects in a large-scale clinical trial. (1, p. 9)
• There was a trend toward greater improvement in THI and/or TFI scores for those who had worse tinnitus symptoms at the start of the study. Some participants achieved a decrease of between 20 and 30 points. (1, p. 5)
• The above study only looked at bimodal results. In contrast, in a different 4-week study comparing bimodal neuromodulation results with just using auditory neuromodulation results, the bimodal stimulation group achieved an average reduction of 6.3 points in their TFI scores, whereas the auditory only group did not achieve a noticeable improvement in symptoms. (1, p. 10) (This study only went for 4 weeks instead of 12 weeks. Furthermore, the stimulation was only 30 minutes a day vs. 60 minutes per day for the above study. Thus, if this study had been longer, the scores may have been significantly higher.)

Note that tinnitus is a psychosomatic condition—there is a “physical” component and an emotional or psychological component. However, in these studies, researchers only looked at, and treated, the “physical” component. They ignored the psychological component, which is a large part of successful tinnitus treatment. This could also have accounted for the small improvements in the TFI scores. If they had combined neuromodulation therapy with effective counseling or Cognitive Behavioral Therapy (CBT), the results probably would have been much higher.

Not all is good news however. A significant number of participants experienced an increase in their tinnitus, not a decrease. This could be attributed, as mentioned previously, to using the trigeminal nerve for the neuromodulation input, which is known to cause somatosensory tinnitus in numbers of people. This may be the reason some participants had a dramatic increase in their tinnitus while others only had a minor subjective increase. (1, p. 7)

For example, 5 (1.5%) people had a dramatic increase in their tinnitus, 25 (7.7%) had a moderate increase and 29 (8.8%) had a slight increase in their tinnitus for a total of 18%. In addition another 10 people had fluctuating tinnitus. (1, p. 8)

Thus overall, the bad news is that even if you fall into this select group of people with tinnitus, you still have close to a 1 in 5 chance of making your tinnitus somewhat worse if you take this treatment.

In contrast, the good news is that you have a 4 in 5 chance of making your tinnitus somewhat better by an average of 14% if your tinnitus fits the narrow criteria for this Neuromod therapy. This means that considering everyone in the general population with tinnitus, you only have a 4.5% chance of improving your tinnitus.

And to get this 4.5% chance of improving your tinnitus, you have to put out a non-refundable £2,500. Even then, you’ll only get an average of 14% improvement in your tinnitus, while risking an 18% chance you’ll make your tinnitus worse. Is it worth it? That’s for you to decide.

As I see it at this point, bimodal neuromodulation using the Neuromod device definitely shows promise, but it is not there yet.

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(1) Conlon, Bredan, et. al. 2020. Bimodal Neuromodulation Combining Sound and Tongue Stimulation Reduces Tinnitus Symptoms in a Large Randomized Clinical Study. https://stm.sciencemag.org/content/12/564/eabb2830.full. tent-a1-science-paper-2.pdf.

(2) Neuromod. 2021. https://www.neuromoddevices.com/.