Inhibiting Tinnitus with a Computer-Based Audiological Approach (2013)

Figure: © iStock/Stockphoto4uWhile 10 percent of the United States population has tinnitus, current treatments for the condition lack a standardized methodology (J Eval Clin Pract 2012;18[2]:326-334; tinnitus prevalence data from the Better Hearing Institute, University of Iowa, and American Tinnitus Association. ) http://www.ata.org/blog-BHI In addition, the cost in time and money of current tinnitus therapies is no small matter ( J Am Acad Aud 2012;23[2]:126-138http://www.ncbi.nlm.nih.gov/pubmed/22353681). Tinnitus retraining therapy (TRT) depends on sound therapy. Treatment success is determined by standardized questionnaires, such as the Tinnitus Handicap Inventory (THI), with three months elapsing between baseline and the first treatment probe. In comparison, cognitive behavioral therapy (CBT) depends on the same procedures but claims to be a superior treatment, with little hard evidence to substantiate that assertion (Lancet 2012;379[9830]:1951-1959http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)60469-3/abstract). Iconic memory studies reveal cognitive loss with the passage of time between stimulus presentation and subsequent recall of the stimulus content (Perception & Psychophysics 1974;16[3]:575-596http://link.springer.com/article/10.3758%2FBF03198590). This article discusses an approach to tinnitus diagnosis and treatment that can be delivered over the Internet to a number of devices, including the iPad and the Samsung Android. The patient can access the program at will, and progress is displayed as an ongoing, hard-data baseline. TRT: NOT AN AUDIOLOGICAL APPROACH Philosophically, it's our view that tinnitus retraining therapy is not an audiological paradigm. Audiology has its roots deeply attached to psychophysics and psy-choacoustics. It appears incongruous that we have not sought a solution to the problems of tinnitus by adding a paradigm that applies immediate repeatability, reliability (accuracy), and validity (results intended). Audiologists are careful in the determination of hearing threshold and are fully indoctrinated to the concept of the invariance of the audiogram as defined by psychophysics. Also, calibration of the instrumentation and the qualifications of the audiologist assure the reliability of the audiogram. No such rigid framework exists in dealing with tinnitus. Since the introduction of the basic tinnitus retraining therapy program 22 years ago, technology has changed, and neurological biomarkers are now available (Front Syst Neurosci 2012;6:53http://www.frontiersin.org/Systems_Neuroscience/10.3389/fnsys.2012.00053/full). Cortical coherence associated with tinnitus has been measured using magnetoencephalography (MEG; Proceedings of the 16th International Conference on Biomagnetism). That report showed only static tinnitus. In the present study, we compared pre- and per-stimulation trials. These studies continue. ALOGORITHM DELIVERED AT PARATHRESHOLD Since the early 1970s, Dr. Dalton and colleagues have presented a series of audiological apparatus and procedures, culminating in several US patents—3,898,382 (1975), for an audiometric signal and apparatus for producing such a signal; 4,556,069 (1985), for a method and apparatus for measuring the differential auditory system; and 8,313,441 (2012), for a neuroaudiological central auditory test apparatus and method of differentiation of the neural correlates in post-traumatic stress disorder, traumatic brain injury, autism, attention deficit hyperactivity disorder, and other conditions. This work led to the development of the heterodyning algorithm used in the study. The most important aspect of the algorithm is that it is delivered at parathreshold, centered on the behavioral threshold, as observed by Eberhard Zwicker and G. Bruce Henning ( Hear Res 1991;53[1]:141-152http://www.sciencedirect.com/science/article/pii/037859559190221T). Hence, when the process is successful, the subject reports “silence,” otherwise defined as neural habituation of negative plasticity. The algorithm consists of a complex of auditory stimuli, with foci seeking a central zero-point. The search for parathreshold in each subject led to the use of double-judgment psychophysics (J Opt Soc Am A 1985;2[9]:1560-1585http://invibe.net/biblio_database_dyva/woda/data/att/f2f3.file.pdf), which allowed for string concatenation of four threshold components. The detection of barely detectable parathreshold stimuli has provided a challenge in sensory research. This psychophysical process offers a solution (Atten Percept Psychophys 2009;71[6]:1426-1433http://link.springer.com/article/10.3758%2FAPP.71.6.1426). The purpose of this paper is to present a neural parathreshold heterodyning paradigm that significantly reduced tinnitus in 17 subjects in one session of 60 minutes or less. A dominant feature of the procedure is the potential for therapeutic application. Once the algorithm has been established, the same tablet can be used to maintain residual habituation, moment by moment, day by day, using a Skinnerian operant (instrumental) conditioning paradigm. The data from the therapy protocol will be reported in a subsequent publication. RATING TINNITUS AGGRAVATION Data on 17 subjects age 46 to 77 are reported here. The computer-based program was designed to be carried out by or under the supervision of an audiologist or equally qualified specialist to first ascertain the suitability of tinnitus treatment through a full audiological evaluation. All stimulus parameters were under patient control via a Samsung Galaxy Tab (10.1).Table 1: Tinnitus Severity among Study ParticipantsParticipants were asked to rate tinnitus aggravation level (AGL) five times throughout the procedure, as shown in table 1. 1. The entry-level behavioral baseline (BSLN) was obtained as a single overall aggravation level. This score was calibrated by comparing the single measure with the obtained tinnitus handicap inventory. The aggravation level was determined prior to the fitting of the specially designed headsets. 2. Sham trial (ST): To negate the possibility of a placebo effect, a sham trial was completed prior to the introduction of the modifying algorithm. The earphones were placed on the participant, who was then instructed to rate aggravation level to a sham stimulus. 3. Establishment of the parathreshold parameters (EPP) was accomplished using a double-judgment psychophysical method of adjustment under the control of the participant without the specific heterodyned circuit. The aggravation level was repeated. 4. Heterodyning (H): All parameters of the level three trials were retained, except the heterodyne process was activated and the aggravation level repeated. 5. Residual habituation (RH): Following a stimulation period of five minutes, the headsets were removed. The subject had two tasks to complete: immediately to rate the aggravation level and then to trace the return of tinnitus to the initial aggravation level. EMOTIONAL SIDE NOT MAJOR CONSIDERATION A one-way within-subjects ANOVA was conducted, with the factor defined as the treatment condition and the dependent variable the Tinnitus Severity Index score. The results of the ANOVA indicated a significant treatment effect—Wilks's Λ =.15, F (4, 13) = 18.48, P <.01, multivariate h2 =.85.Figure 1: This graph shows changes in tinnitus aggravation level across baseline (BSLN), sham trial (SHAM), establishment of parathreshold parameters (EPP), heterodyning (HET), and residual habituation (RH).As illustrated in Figure 1, pairwise comparisons revealed no significant difference between baseline tinnitus (AGL) and the sham trial but did show significant differences between these two conditions and all the other conditions—establishment of parathreshold parameters, heterodyning, and residual habituation.Figure 2: The results of magnetoencephalography scans taken before and during the treatment are shown here (coronal-anterior to posterior). A five-minute session of the participant listening only to the tinnitus is shown in scans labeled “BEFORE,” and a five-minute session of the participant being presented the algorithm at parathreshold is labeled “DURING.” The patient in this series reported hearing only silence during the treatment. That is, the subject heard neither the tinnitus nor the stimuli from the algorithm.Figure 3: Pre- and per-stimulation scans are shown on the far left. The diagrams on the right are computer maps of the actual restructuring of the neural pathways caused by the tinnitus cancellation algorithm. Note the changes in the focus at the cortex from one area to another. One major change is seen in the routing of the right middle temporal gyrus (R. Mid. Temp. G.), Brodmann area 21 (top), to the left supramarginal gyrus (L. Supramar. G.), Brodmann area 40 (bottom). Coherence shift (ovals) occurs from Brodmann area 41 to area 6. The coherence scale shows the frequency-power relationship for each wave cycle as a function of time.Magnetoencephalography was carried out on one of the participants in the study. Figures 2 and 3 show the data for that patient. The algorithm used in this investigation evolved from a 20- year progression of integrated neurophysiologic/psychophysical studies of the dichotic auditory system. The emotional side of tinnitus, while not totally ignored, was not a critical consideration of this investigation. While audiology is the logical choice for tinnitus diagnoses and treatment, it has been superseded by less exacting psychological-like behavioral therapies. This study supports the hypothesis that tinnitus can be approached as an audiological rehabilitation continuum rather than a unique psychologicalprocess.