RESEARCH FROM AROUND THE WORLD
Tinnitus Cancelation Verified by Magnetoencephalography
By Leslie W. Dalton, Jr. Ph.D., CCC-A/SLP, FAAA, FADA, Professor, Communication Disorders, West Texas A&M University
To date, the most effective ways of reducing tinnitus symptoms have principally been by masking with audible sounds paired with psychological counseling to reduce the emotional reaction. While treatments like Tinnitus Retraining Therapy (TRT) help, it usually does not remove the offending noise, but rather covers it up with a louder sound.
Here, I present data on a neurological manipulation technique that canceled or significantly reduced tinnitus in 74% of 62 clinical subjects. Twenty-four percent of those subjects reported “silence” while wearing the cancelation device. Furthermore, residual habituation is reported to be as high as 13 hours upon removal of the device.
Research on this computer-driven technique has been ongoing since 1997 with over 200 subjects participat- ing in the diagnosis and treatment protocol. Initially the success rate for the first group tested was less than 50%. However, as the paradigm developed, sub- sequent subject groups showed an increase to 69%, with the latest group showing a 74% success rate. The final group is reported in this paper.
The cancelation procedure requires the wearing of specially-developed earphones that control every aspect of the binaural auditory stimuli input. The auditory system is then “retuned” by a computer in a manner that can be compared to an electronic signal processing circuit resulting in a process called hetero- dyning. A bonus of this procedure is improvement of speech discrimination and general hearing ability in subjects with hearing loss. Patients report the headsets to function as a superior “hearing aid.”
How It Works
For proprietary reasons the exact process will not be described. However it’s important to note that the procedure takes advantage of accepted audiological findings such that tinnitus is the result of neurological discontinuity caused by an abnormal central auditory processing system (CAPS) as reflected in an audiologi- cal diagnosis beyond the audiogram.
Stability of the normal auditory system depends on a “check and balance” feedback loop to keep the entire CAPS network in “tune.” Sounds strike the middle ear structures via the eardrum and are then delivered to the nerve system at the cochlea. At this point an exquisite neural network, focused at the cochlear nucleus, separates the CAPS into a series of proces-
sors that separates the sound-generated neural codes into loudness, frequency, phase, and location. These new sounds are then delivered to the brain by way of binaural interaction of the two ears.
Within the CAPS, there are two distinct networks – the afferent system (delivering the sounds to the brain) and the efferent system (delivering controlling signals from the brain to the afferent input). Homeostasis of the CAPS depends on the entwined interactive signal processing of both ears and the afferent and efferent systems. Simply stated, each ear is controlled by the other one in the CAPS. Yet, this balance is not a static condition since impairment of the CAPS will change the focal area of sensation on the brain because of neural plasticity.
Restoring Equilibrium
Neuroplasticity refers to the brain’s ability to change as a result of sensory input. Research has demonstrated1 that experience actually changes the brain’s anatomy and physiology. In the data collected, it clearly shows this phenomenon in tinnitus sufferers in a magnetoencepha- lography (MEG) study. By forcibly rerouting the input away from the faulty auditory pathways via a complex computer-generated auditory signal, equilibrium of the CAPS is restored to overcome negative plasticity which is causing the tinnitus.
Figure 1-B (before treatment) is a five minute MEG scan of the patient listening only to his tinnitus. Note the large areas of neural activity caused by the tinnitus.
Fig 1-A (during
treatment) is a five minute MEG scan with the patient being stimulated by the cancellation procedure. The MEG data show large reductions in neural activity.
Post-treatment MEG studies of residual habituation will be completed in the future.
Very recent independent studies at a major Veterans Affairs Medical Center have also verified the results using sham trials and blinded techniques. Those data are being prepared for a major audiology journal. 1
Bautista, et al, J Appl Physiol, 2012. Summer 2012 | Tinnitus Today 21
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