Margaret M. Jastreboff, Ph.D.
Associate Professor
Tinnitus & Hyperacusis Center
Department of Otolaryngology
Emory University School of Medicine
Over the years, many methods of tinnitus treatment have been introduced, but very few survived the test of time. Even now, in the year 2000, we do not have a mechanism-based method to provide a cure for tinnitus. More than a decade has passed since the introduction of the neurophysiological model of tinnitus and Tinnitus Retraining Therapy (TRT) [1]. Despite the controversies and criticism surrounding this approach, the number of patients helped is growing constantly, not only in the USA, but around the word. In fact, TRT is used successfully now in more than 20 countries.
What is TRT? TRT reflects the practical implementation of the neurophysiological model of tinnitus. The main principles of the neurophysiological model of tinnitus form the basis for TRT. Specifically, 1) the limbic (emotional) and autonomic nervous systems are the primary and dominant systems for the development of tinnitus annoyance while surprisingly, the auditory system plays a somewhat secondary role in tinnitus manifestation, 2) the brain demonstrates high levels of plasticity and is capable of habituating to any neutral signal, once negative associations with the signal (i.e. tinnitus) are neutralized, 3) hypersensitivity to sound (hyperacusis) should, and frequently does, coexist with tinnitus.
In practical terms, TRT is a method aimed primarily at habituating tinnitus-evoked reactions of the brain and body, and secondarily, at habituation of tinnitus perception. Consequently, successful TRT patients are not bothered by their tinnitus, even though they are aware of it. Additionally, the amount of time the successful TRT patient perceives tinnitus is decreased.
Tinnitus habituation is achieved by inducing plastic changes within the patients' brain. Specifically, conditioned reflex arcs, which connect the auditory, limbic, and autonomic nervous systems, are retrained, as well as neuronal networks at the subconscious level of the auditory pathways are modified. It is important to understand that majority of these connections are at the subconscious level and TRT procedures take this into account.
The two main components of TRT are; 1) educational counseling (which is intensive, individualized and interactive) and, 2) sound therapy.
Counseling sessions are aimed at the reclassification of tinnitus into a category of neutral signals. During the sessions, tinnitus is demystified and patients are taught about physiological mechanisms of tinnitus and its distress, as well as the mechanisms through which tinnitus habituation can be achieved.
The second element of TRT is sound therapy. Constant low level broad band sound decreases the difference between tinnitus-related and background neuronal activity. Consequently, the strength of activation of the limbic and autonomic nervous systems, which at the behavioral level is reflected by a decrease in tinnitus-evoked annoyance, is reduced. This in turn decreases the negative reinforcement in the conditioned reflex arcs and permits blockage of the tinnitus signal within the subconscious part of the auditory pathways, i.e., habituation of tinnitus perception.
Increased background noise creates a situation essentially in opposition to the typical, quiet environment which may induce or enhance tinnitus. Specifically, all patients are advised to avoid silence and to enrich background sounds using nature or music. Moreover, they should not over protect their ears in the normal, everyday situations. For hearing impaired patients, background sounds are amplified via hearing aids.
Many patients can benefit from the use of broad-band noise sound generators. This facilitates tinnitus habituation and helps remove/reduce hyperacusis which frequently accompanies tinnitus. While specific protocols are different for various categories of patients (based on degree of hearing loss, presence of hyperacusis, duration of worsening of the problems after noise exposure), these general rules are the same for all patients.
To help illustrate the popularity and acceptance of TRT, it is interesting to note that during last year's 6th International Tinnitus Seminar in Cambridge, U.K., there were 132 publications. Twenty-five percent of these addressed TRT directly, or indirectly. Considering that at the 5th Seminar (1995) there were no papers on the topic of TRT, it is clear that TRT has achieved a high level of recognition in a very short time.
A major, and as of yet unresolved, issue in TRT deals with assessing the validity of this method. Unfortunately, due to the nature and popularity of TRT, it is impossible to conduct a double blind study. Presently, there are no results from scientifically designed studies evaluating the outcome of TRT. However, the results from clinical practice were extensively reported during 6th International Tinnitus Seminar, Cambridge, U.K., 1999, and published in Proceedings of the Seminar [2].
One recent study of TRT, based on her Ph.D. dissertation, was presented by McKinney (U.K.) [3]. She presented results of a randomized trial where 169 patients were assigned to groups with 1) sound generators set to the threshold of hearing, 2) sound generators set to the level where the perception of tinnitus and external sound start to mix/blend together (optimal level for TRT), or 3) counseling alone. Patients with tinnitus and hearing loss were assigned to groups with hearing aids or combination instruments (hearing aid combined with sound generator). The effectiveness of the treatment varied from 64% to 84%; the group treated with sound generators set to the level where the perception of tinnitus and the external sounds blend together had the best (84%) success rate. The results were consistent with predictions of the neurophysiological model of tinnitus and supported the importance of sound therapy. Interestingly, improvement in tinnitus relief was observed in only 6% of the non-treated group of 113 people.
Sheldrake, et al. UK presented results from 483 patients, all treated with TRT. Using the same criteria as McKinney, she reported 84% success rate. Success rates greater than 80 percent have been reported often. Lux-Wellenhof, et al., Germany - 122 patients, success rate about 80%; Bartnik,et al. Poland - 556 patients, success rate 80%; Heitzmann, et al., Spain - 56 patients, success rate 84%; Herraiz, Spain - 172 patients, success rate 88%;Jastreboff, USA - 223 patients, success rate 82% (consistent with previously published data [4]). Furthermore, Hall reported during Cambridge 1999, and the AAA 2000 meeting reported clear improvement during TRT treatment. Additionally, during the 1999 meeting of Academy of Dispensing Audiologist, Bermuda, Nagler, USA reported over 80% success rate on over 500 patients.
Recent studies with functional brain imaging confirmed the prediction of the neurophysiological model that the limbic system is involved in tinnitus [5,6]. Additionally, a study of the changes of minimal masking levels during the treatment [7] supported the existence of treatment-induced modifications of the neuronal networks within auditory pathways reflecting an increased ability to block the tinnitus signal and consequently tinnitus perception.
There are a significant number of papers and book chapters on TRT and the scientific basis of this method [8-10]. Nonetheless, there are still points in need of more extensive explanation. For example, a concise but sufficiently detailed description regarding sound use is needed when presenting TRT to professionals in the field of audiology. Additionally, descriptions of direct interactions with patients and explanations provided to patients to achieve the proper stage for habituation to occur are also needed.
Frequent concerns of tinnitus patients include: 'Is tinnitus a symptom of life threatening disease?', 'Will I go deaf?', 'I am afraid that tinnitus will get Worse', 'No one can understand my tinnitus',and, 'They think I have some mental problems', 'I have problems with concentration', 'I cannot sleep',' I am afraid of losing my job', 'I cannot understand people', 'I cannot participate in many activities', 'I am losing joy and my sense of life', and 'I feel depressed'. The above concerns are indeed common.
Obviously these concerns put tinnitus in the category of important factors which induce negative reactions of the limbic and autonomic nervous systems, starting the vicious circle and preventing spontaneous habituation to occur. After a physician excludes medically or surgically treatable problems and assures the patient there is no basis for future tinnitus-related health concerns, other issues can be discussed.
Tinnitus is a common problem in the USA. Some 50 million people in the USA have tinnitus. Fortunately, less than 25% of those who experience tinnitus suffer from it. It is difficult to determine why some people suffer with tinnitus, while others do not. It may be related to physiological changes (e.g., hormonal changes), a predisposing problem (e.g., pre-existing depression), accidental events in life (e.g., retirement), ototoxic drug exposure, psychological profile or predisposition, limbic system or autonomic system irregularities, or many other etiologies.
Since none of the proposed theories of the mechanisms of tinnitus signal generation have been proven, when discussing tinnitus with patients we choose the Discordant Damage (Dysfunction) Theory (details described in [1,11]) presenting tinnitus as a result of compensation by the auditory system of otherwise irrelevant discordant dysfunction/damage within the auditory pathways.
Discussion of the audiologic results and appropriate counseling of the patient is very valuable. In most cases, it is surprising to the patient that there is no correlation between severity of tinnitus and perceived loudness, pitch or 'maskability' of tinnitus. Additionally, there is no difference in psychoacoustical characterization of tinnitus between those who suffer from tinnitus, as compared to those who just experience it.
The problem seems to arise when activation of the limbic and autonomic nervous systems occurs, due to the creation of a conditioned reflex arc, yielding an immediate autonomic reaction, further enhanced by feedback loop, which creates the vicious circle scenario.
At the behavioral level, the activation of the limbic and autonomic nervous systems is manifested by tinnitus evoking annoyance and strong emotions which further enhance annoyance and negative emotions. These reactions serve as a negative reinforcement preventing spontaneous, natural habituation from occurring. This is why it is so important to provide patients with sufficient information about mechanisms of tinnitus and hyperacusis and to answer in a coherent and clear manner all questions while addressing the patients' concerns.
TRT is a useful approach to the management and treatment of tinnitus. TRT is highly effective for both tinnitus and hyperacusis. TRT can be successfully implemented in audiologic practice. Although TRT can be conducted by various health care givers, audiologists are uniquely qualified to perform TRT as they have the background knowledge of auditory physiology and hearing loss, they are allowed to counsel patients, and they are licensed to dispense sound generators and hearing aids (if needed). Therefore, audiologists are in an advantageous position to conduct TRT.
References
1. Jastreboff, P.J. Phantom auditory perception (Tinnitus): mechanisms of generation and perception. Neuroscience Research, 8:221-254, 1990.
2. Proceedings of the 6th International Tinnitus Seminar, Cambridge, UK, J. Hazell, ed, THC, London, pp. 583, 1999.
3. McKinney, C.J., Hazell, J.W.P., Graham, R.L. An evaluation of the TRT method. Proceedings of the 6th International Tinnitus Seminar, Cambridge, UK, J. Hazell, ed, THC, London, pp. 99-105, 1999.
4. Jastreboff, P.J., Gray, W.C., Gold, S.L. Neurophysiological approach to tinnitus patients. American Journal of Otology, 17:236-240, 1996.
5. Lockwood, A.H., Salvi, R.J., Coad, M.L., Towsley, M.L., Wack, D.S., Murphy, B.W. The functional neuroanatomy of tinnitus: evidence for limbic system links and neural plasticity. Neurology. 1998 Jan;50(1):114-20.
6. Langner, G., Wallhäusser-Franke, E. Computer simulation of a tinnitus model based on labelling of tinnitus activity in the auditory cortex. Proceedings of the 6th International Tinnitus Seminar, Cambridge, UK, J. Hazell, ed, THC, London, pp. 20-25, 1999.
7. Jastreboff, P.J., Hazell, J.W.P., Graham, R.L. Neurophysiological model of tinnitus: Dependence of the minimal masking level on treatment outcome. Hearing Research, 80:216-232, 1994.
8. Jastreboff, P.J., Hazell, J.W.P. Treatment of tinnitus based on a neurophysiological model. IN: Tinnitus. Treatment and Relief, ed. J. Vernon, Allyn & Bacon, Massachusetts, Chapter 22, pp. 201-216, 1998.
9. Jastreboff, P.J. Tinnitus. IN: Current Therapy in Otolaryngology-Head and Neck Surgery. Sixth Edition. G. A. Gates, ed. Mosby-Year Book, Inc., St. Louis, pp. 90-95, 1998.
10. Jastreboff, P.J., Gray, W.C., Mattox, D.E. Tinnitus and Hyperacusis. IN: Otolaryngology Head & Neck Surgery, Volume Four, Third Edition, eds. C.W. Cummings et al., Mosby, St. Louis, pp. 3198-3222, 1998.
11. Jastreboff, P.J. Tinnitus as a phantom perception: Theories and clinical implications. IN: Mechanisms of Tinnitus, eds. J. Vernon and A. Moller, Allyn & Bacon, Massachusetts, Chapter 8, pp. 73-87, 1995.
