Acoustic CR Neuromodulation
Last updated on 23 May 2013
Sound therapy has long been recognised as an important part of tinnitus management. Most commonly, ear-level sound generators are used to mask the tinnitus sound when needed, allowing people to adapt to their tinnitus over time. With ever increasing understanding of how tinnitus is generated in the brain, there are growing possibilities that sound can be used to disrupt tinnitus in more targeted ways.
One recent development in this area is a therapy called Acoustic Coordinated RESET (CR) Neuromodulation, from the German company ANM. This therapy specifically targets a mechanism of tinnitus which is thought to involve abnormal levels of synchronous activity in the hearing brain, where large populations of nerve cells repeatedly and spontaneously fire at the same time. The therapy is currently being marketed by the private healthcare sector in Germany and was recently made available in the UK by The Tinnitus Clinic, London.
The CR Neuromodulator delivers a sequence of low-level tones via earphones from a small matchbox-sized device. The tones are selected using a mathematical algorithm, developed by ANM, such that the tones used match the tinnitus pitch and the surrounding range. The set of tones is therefore adjusted individually to each person. In addition, tones are presented in a determined sequence so as to systematically stimulate regions of the hearing brain sensitive to different tones, in a patterned way.
The aim of this patterned sound stimulation is to force nerve cells sensitive to different tones to fire at different times, disrupting abnormal increased synchronous nerve cell firing that may be responsible for the perception of tinnitus. Although it is not clear how this synchronous neuronal activity arises, it is likely a direct result of the loss of input to the brain that results from hearing loss. Adapting to reduced inputs from the ear may cause nerve cells in the brain to begin to “chatter” spontaneously and fire in synchrony with neighbouring nerve cells. This type of abnormal brain activity can be detected and recorded with electroencephalography (the recording of electrical activity along the scalp) and is emerging as a marker of tinnitus-related brain activity.
In a first exploratory study of the CR Neuromodualtion therapy, Prof Peter Tass and his collaborators at Jülich, Germany, tested 63 patients with chronic tonal tinnitus. Patients were asked to wear the CR Neuromodulation device for 4-6 hours per day for 12 weeks, after which tests and questionnaires generally indicated a decrease in tinnitus loudness and annoyance as well as perceived tinnitus severity. These effects persisted during the following 4-week resting period. In addition, the abnormal patterns of brain activity recorded before the therapy using electroencephalography, appeared to normalise after the therapy.
The results of this study (RESET1), published in the journal Restorative Neurology and Neuroscience, are exploratory but encouraging. Assessing the clinical effectiveness of the device however calls for a Phase 2 clinical trial. We will be conducting this trial (RESET2) at the NIHR National Biomedical Research Unit in Hearing (NBRUH), in collaboration with colleagues at the Ear Institute, University College London, with participants joining the trial from May 2012.
The trial will evaluate the effects of this new therapy on 100 participants by measuring changes in the reported severity of tinnitus, changes in the quality (pitch, loudness) of tinnitus, and whether there are changes in the patterns of brain activity associated with tinnitus. For the first part of the trial, a 12 weeks ‘randomised controlled trial’, participants will be randomly allocated to either a treatment group or to a placebo group.
Although all participants will receive a device, initially only one group will receive the therapy as it is intended to be delivered. Participants in the placebo group will receive a random sequence of sounds. This group is very important to estimate those changes in tinnitus that are not specifically related to the device. The device will be fitted individually, as described above, by a specialist audiologist. Participants will then visit the research centre regularly for assessments and to report on their experience of using the device. After the first 12 week phase, participants in the placebo group will be invited to continue for another 24 week period – a ’long term extension’ phase - during which they will receive the formal therapy.
Eligible participants for this trial include adults that have experienced constant tinnitus for at least 3 months. Participants must also be able to hear the tones delivered by the device and therefore should not have too severe a hearing loss. Very importantly, participants should be willing to wear the device for 4-6 hours a day for the duration of the trial.
The RESET2 trial will provide the high level clinical evidence necessary to make informed decisions about the efficacy and feasibility of CR Neuromodulator as a therapy for tinnitus. Our investigation into the effect of the therapy on brainwave activity will also provide further insight into the neurophysiology of tinnitus and help us think about how we might best interrupt it!
A BTA spokesperson commented: “The results of this exploratory first trial are interesting and encouraging. The findings now need to be replicated by the independent NIHR NBRUH randomised-controlled trial to assess whether this new intervention is a viable and effective treatment for tinnitus patients. We look forward to seeing the results of the Phase 2 Trial”.
Tass PA, Adamchic I, Freund HJ, von Stackelberg T and Hauptmann C (2012) ‘Counteracting tinnitus by acoustic coordinated reset neuromodulation.’ Restorative Neurology and Neuroscience 30: 1-23.
Dr Ana Alves Pinto has worked in auditory research for 10 years, having obtained a PhD in Psychoacoustics and Auditory Neuroscience in 2007. Ana is currently a Research Fellow in tinnitus at the NIHR Nottingham Hearing Biomedical Research Unit, working with Specialist Audiologist Holly Thomas, and the trial Principal Investigators Dr Derek Hoare and Professor Deb Hall.
This article originally appeared in the Spring 2012 issue of Quiet
exploratory but encouraging