Dr. Nagler's Tinnitus Site

Dr. Nagler’s Tinnitus Site

Hyperacusis, Retraining, Cocoons, and Vegetables

Tinnitus Retraining Therapy¹ is an effective treatment modality for many individuals with hyperacusis, even in some of the most severe cases. I would like to explore the characteristics of hyperacusis (sensitivity to sounds usually well-tolerated by others) that lend this affliction to retraining approaches, and I would also like to examine some of those issues that might adversely affect success rates.

Although some prefer for the purposes of hyperacusis to call the process discussed in this article "Hyperacusis Retraining Therapy," I prefer the original name, "Tinnitus Retraining Therapy," a term which is historically more accurate. Tinnitus Retraining Therapy(TRT) is a treatment initially designed for tinnitus, but subsequently found to be successful for hyperacusis treatment as well - when applied using Dr. Jastreboff's Category III protocol.

It has been my experience that most of the errors in medicine are errors of communication - not errors of ignorance, malice, negligence, or insensitivity. Essential in minimizing errors of communication is the development of simple yet practical definitions. In that vein, a brief discussion of the nature of hyperacusis and the principles of TRT is appropriate before addressing the specific role of this type of desensitization in the treatment of individuals affected by hyperacusis.

I clearly understand that some hyperacusis sufferers might disagree with various elements of the views on this often debilitating malady expressed below; however, crucial in this review is acceptance of the concept that hyperacusis is primarily a disorder of central auditory processing rather than a direct reflection of cochlear pathology. In other words, hyperacusis represents a decreased threshold for discomfort, but there is no evidence that it represents a decreased threshold for damage. Man (generic) is blessed with a very elegant yet simple protective feedback mechanism to minimize damage and maximize the chance for survival. In the kitchen, for instance, if he accidentally touches a red-hot element on the electric range, he immediately withdraws his hand in pain. The pain is thus an appropriate sign of impending harm; if for some reason he does not withdraw his hand, damage (i.e., the burning and destruction of the finger tips) will immediately ensue. When he grasps a warm glass of water, however, he does not withdraw his hand, of course, because there is no discomfort - the protective feedback mechanism is working appropriately. There is no impending damage to the hand from a warm glass of water. Now what happens if there is a mismatch in the feedback mechanism? He rapidly withdraws his hand from the glass of warm water because he experiences discomfort, discomfort in the absence of impending damage. So this mismatch in the feedback mechanism results in a decreased threshold for discomfort, but not a decreased threshold for damage. In the case of hyperacusis, there is no evidence that there is a decreased threshold for cochlear damage, only that a sound well-tolerated by some is uncomfortable or even painful to others. I do not mean in any way to underestimate the magnitude of what can be a very serious - even incapacitating - problem; I wish only to clarify its nature.

Two observations should be made at this point:

First, there is some opinion that in the case of acute hyperacusis induced by a sudden exposure to a loud sound, the hair cells of the cochlea may, indeed, be temporarily "hyper-sensitive" to damage. There is disagreement on this issue, but I think that might be prudent for an individual who first develops onset of hyperacusis after exposure to, for instance, an unexpected gunshot near his head to purposely avoid sounds he finds uncomfortable for a couple of weeks to minimize the possibility of causing permanent damage to "shocked" hair cells, which might otherwise recover. I know of no authoritative opinion that this period of increased susceptibility to damage - if it exists at all - lasts more than a few days.
Second, and very important, what happens if I am wrong? What happens if, in spite of the fact that there is no evidence to support it, sometime in the future we discover that individuals with hyperacusis do, indeed, have long-term decreased threshold to damage? What happens if there is no mismatch in the feedback mechanism? What happens if (in the analogous case) the glass of warm water really can damage the fingers, and if the automatic withdrawal of the hand from the glass does, indeed, serve an essential protective function?

Did you know that eating vegetables causes hearing loss? It just might! Twenty years from now a researcher may find incontrovertible evidence that eating vegetables results in irreversible cochlear damage. Twenty-five years from now parents might be saying to their children, "Can you believe it? Way back in around the turn of the millennium kids were actually forced to eat their peas and carrots. What in the world were they thinking?"

In 2006 there is no evidence that vegetables are deleterious to one's health, and in 2006 there is no evidence that exposure to 80db of noise, however unpleasant it may be, causes any damage whatsoever to the cochlea of an individual with hyperacusis. If we parents choose to live in fear of what unexpected knowledge the future might bring, then our children will never experience the nutritional benefit of eating a well-balanced diet; if hyperacusis sufferers choose to live in fear of what unexpected knowledge the future might bring, then they will never experience the audiological benefit of gradual, purposeful, step-wise exposure to a normal, sound-rich environment - especially since that gradual, purposeful, step-wise exposure need not be at all unpleasant. Moreover (as we shall see shortly) in addition to assisting hyperacusis sufferers out of their self-imposed "sound cocoons" and offering effective treatment, TRT can actually CURE hyperacusis in some instances.

Now CURE is a very strong word. In the case of Tinnitus Retraining Therapy as conceived by Dr. Pawel Jastreboff and Mr. Jonathan Hazell, we speak of successfully "treating" tinnitus, but not "curing" tinnitus. Tinnitus Retraining Therapy (for tinnitus) is treatment directed at the reason the tinnitus signal persists on a conscious level instead of being naturally habituated like the sound of a fan (filtered out of the brain before reaching the level of conscious awareness).^{2, 3} For a true tinnitus cure to occur, not only would the reason for persistence of the signal need to be addressed, but also the source of the tinnitus - the tinnitus generator - the reason for the emergence of the signal - would need to be addressed. Tinnitus Retraining Therapy is not a cure for tinnitus, since even the successful TRT patient will hear the tinnitus if he or she tries to do so, especially in a quiet environment.

Let us at this point look specifically at hyperacusis. With hyperacusis, in contradistinction to tinnitus, there is no "generator." For that matter there is not even any anatomical structure in need of repair. True, there are often damaged or destroyed cochlear hair cells, but the damaged hair cells do not cause the hyperacusis! What causes the hyperacusis is the physiological (functional) irregularity in central auditory processing that (in most cases) resulted from whatever damaged the hair cells in the first place.⁴ And this central auditory processing irregularity is treatable and in some cases totally correctable! By readjusting the protective feedback mechanism so that the threshold for auditory discomfort approximates the threshold for auditory damage, there would be no hyperacusis! Tinnitus Retraining Therapy is a treatment based upon neurophysiological principles. It deals with brain function, not cochlear anatomy. Since hyperacusis is a disorder of brain function, TRT is well-suited to hyperacusis treatment.⁵

TRT, whether for treatment of tinnitus, hyperacusis, or both, requires two elements: (1) the appropriate application of low level easily habituated sound, and (2) the use of intensive individualized interactive educational sessions (called "directive counseling") to explain (demystify) the entire process and to insure the effective use of low level sound to optimal advantage. With respect to hyperacusis, the low level sound is employed to desensitize the auditory system, a system which is over-sensitive in that there is discomfort out of proportion to damage at various sound levels. (The low level sound may be provided in a variety of ways in TRT, dictated by the severity of tinnitus, the severity of hyperacusis, by whether or not there is any significant hearing loss or recruitment,⁶ and by other factors.) Note that desensitization of an auditory system in which the threshold for discomfort approximated the threshold for damage would be deleterious.⁷ Such is not the case, however, with hyperacusis.

Neurophysiologically, desensitization is extremely complex. For instructional purposes only, I find it convenient to view the process in terms of the following model: Assume that normal environmental background sound levels are approximately 25dB. This level typically is well-tolerated by individuals with and without hyperacusis alike. It might be the sound in a fairly innocuous home setting, the kind of background sound level which would not even be apparent unless one purposely focused attention upon it. Thus, it would be a sound level routinely typically habituated by one and all. Assume now that a person with hyperacusis would have a "loudness discomfort level" of, say, 80dB. An 80dB sound would cause great discomfort to this individual, whereas someone without hyperacusis would typically be able to tolerate a level of 100dB or even possibly greater without difficulty. (Remember, these figures are for illustrative purposes only.) Our desire in treatment would be to push the loudness discomfort level of 80dB towards the "normal" LDL of 100dB. In this case, the hyperacusis LDL of 80dB is 55dB over the easily-habituated background sound level in the home of 25dB. So let us add a very soft constant natural non-threatening broad band ("white noise") level of, for example, 5dB to the background environmental sound of 25dB. The white noise would be supplied by a pair of wearable noise generators with "open molds," meaning that the devices only minimally occlude the openings of the external auditory canals and thus do not in any way block transmission of the sound waves from the variousbackground sources already present (the 25dB). A person who has experimented with such a device would readily report that within a few minutes the 5dB white noise shhhhhh sound is not even detected unless it is purposely sought; the 5dB is rapidly habituated. After several weeks, therefore, that person's brain would equate a level of 30dB with background environmental sound. Within time, then, the LDL would shift to 85dB, maintaining approximately the same interval of 55dB over the (new) background environmental sound level of 30dB. If at this point an additional 5dB of white noise (again easily habituated) is added, within a few more weeks we would expect the LDL to approximate 90dB, not very far from "normal."⁸ Within time - often several months to a year or more - the "retraining" of the brain should be so complete and the resetting of the threshold of discomfort so natural that no wearable devices would be needed at all! The results of this type of desensitization typically will tend to be suboptimal, however, without the second element of TRT, "directive counseling." In fact, without directive counseling the treatment cannot even be called TRT, and while improvement in hyperacusis might be (and often is) seen with desensitization alone, any suboptimal result thus obtained should not and must not be ascribed to some kind of failure of TRT.

Why, then, might TRT fail in some cases to cure, fail in some cases to adequately treat (if not cure), or for that matter fail to even modestly treat hyperacusis? (1) For reasons currently being studied, but not yet well-understood, hyperacusis in individuals with Lyme Disease (and potentially those with various other infectious disorders affecting the central nervous system) do not seem to respond as well to retraining methodology. (2) People with severe underlying psychiatric disorders tend to respond suboptimally. People with reactive depression, however, a condition not infrequently seen in tinnitus and hyperacusis, seem to respond as well as anyone else - especially when the depression is addressed by a therapist willing to work with the TRT clinician. (3) People with pending medical-legal action do less well with TRT. This phenomenon, which is observed more with tinnitus than with hyperacusis, is felt to be unrelated to possible malingering or potential secondary gain. Rather it has to do with the seemingly endless flow of paperwork and monthly justification required by the legal/insurance industry in such cases, paperwork (not to mention interviews) which by its nature causes something we wish to be less of an issue (tinnitus/hyperacusis) ...to be all that more of an issue. (4) People with severe hyperacusis who for whatever reason are unable at some point in their treatment to make that all-important leap to embrace the concept that their condition does not represent a lowered threshold for damage, but rather a lowered threshold for discomfort can in many ways be their own worst enemies when it comes to TRT. (5) Various psychopharmacological agents at least theoretically have the potential to inhibit neuronal plasticity and thereby delay (or remotely prevent) TRT success. (6) The most common cause for treatment failure lies in the crucial element of "directive counseling" - see below. (7) There are in all probability additional factors in treatment failure, which have not yet been identified.

Directive counseling for people affected by hyperacusis, whether or not there is also a component of tinnitus, is typically very intensive - especially if the hyperacusis is severe. The counseling involves a detailed individualized explanation of the central nervous system mechanisms involved with hyperacusis and the role these mechanisms play in the auditory pathway. This detailed explanation often must be re-introduced at intervals - as greater understanding is achieved. The counseling involves tailoring the use of background neutral sound to the specific circumstances of each hyperacusis sufferer. It involves guidelines about gradual exposure to those environmental sounds which heretofore might have caused discomfort, but which represent no danger. And it involves frequent (often weekly at first - in person or by telephone) "tweaking" of the program as thresholds begin to change and as the inevitable challenges arise. These challenges - frustration, fear, impatience, temporary setbacks, miscommunication - are the factors which most frequently result in totally unnecessary abandonment of treatment before it has had a chance to be successful. Counseling must come from a knowledgeable yet compassionate source. It must be conducted according to the guidelines of TRT as described by Dr. Jastreboff and Mr. Hazell, and the individual doing the counseling must be thoroughly versed in the principles of TRT. He or she must also be willing to be reasonably accessible between scheduled appointments, and the patient must be willing to avail himself or herself of that accessibility, to follow through on recommendations, and not to prematurely discontinue the program.

Tinnitus Retraining Therapy represents a landmark development in hyperacusis treatment. With advances such as TRT and other desensitization approaches, individuals with hyperacusis truly have great reason to feel optimistic about achieving what some have considered to a pipe dream, a miracle. To paraphrase David Ben-Gurion, the first Prime Minister of the State of Israel, you cannot be a realist unless you believe in miracles.

Stephen M. Nagler, MD, FACS

1. JastreboffPJ: Tinnitus, in George Gates (ed.) Current Therapy in Otolaryngology - Head and Neck Surgery, Mosby - Year Book, Inc., St. Louis, 1998

2. NaglerSM: Tinnitus Retraining Therapy. Internet posting (www.tinn.com/trt.html), March 25, 1998.

3. NaglerSM: Tinnitus Retraining Therapy and the Neurophysiological Model of Tinnitus. Tinnitus Today 23(1):13-15, 1998

4. Consider the analogy of a motor vehicle accident, in which a passenger suffers a broken arm and a ruptured spleen. The arm injury did not cause the spleen injury; they were both caused independently by the crash. In the case of hyperacusis there is no evidence to support the myth that the hair cell injury caused the irregularity in central auditory processing; indeed, there is compelling evidence to the contrary, not the least of which is the fact that TRT - an often successful hyperacusis treatment - has absolutely no effect whatsoever on hair cells.

5. There are certainly other effective approaches to hyperacusis treatment (e.g., "pink noise" exposure as desensitization).

6. Recruitment is the phenomenon of accelerated growth of perceived loudness within the frequency range of hearing loss.

7. Refer to the "electric range" example.

8. While this model gives one a good feel for desensitization, it is over-simplified. In actuality the values are relative (not absolute), and the intervals are proportionate (not constant); otherwise, much lower LDL's could never be shifted to acceptable levels. Additionally, numerous other factors are involved with the desensitization process.

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