This presentation steps the reader through the
fundamentals of one of the most effective tinnitus
treatment programs in the world today, and compares the
underlying physiological model to Dr. Chartrand's
current methodology.
Reader inquiries may be directed to digicare@aol.com, or
faxed to 719-676-6882. All inquiries must be accompanied
with name, address, and phone number to receive a
personal reply.
Prepublication Draft
TRT: Pioneering Research into the
Mind of the Tinnitus Sufferer
A report on the relevance of TRT in current
amplification strategies in patients for whom tinnitus
is also a complaint
By Max Stanley Chartrand, BC-HIS
In 1993, the author published an article in this journal
titled “Tinnitus Management in the Dispensing
Practice”1. Its purpose was to help define the role of
dispensing professionals in the management of their
patient’s tinnitus as an adjunct to fitting hearing aids
under best practice standards.
Also, in that article, was cited the groundbreaking work
of several tinnitus research pioneers as foundational to
some of the benefits that were reported as a result of
appropriate amplification strategies: 1)Residual
Inhibition (RI), Environmental Masking (EM), Auditory
Reattention (AR), and Stress Relief (SR).
In retrospect, it turns out that eclipsing the author’s
study of the above benefits was an even more profound
work under development by Pawel Jastreboff, Ph.D., D.Sc.
and associates at the University of Maryland, and by
Jonathan Hazell, FRCS, and associates at the Tinnitus
and Hyperacusis Centre in London, England. This work has
been titled Tinnitus Retraining Therapy (TRT).
Dr. Jastreboff has since transferred the TRT project to
Emory University in Atlanta, where he and his colleagues
continue its development and worldwide implementation. A
recent visit between the author and Dr. Jastreboff
helped bring us up to date on TRT principles as they
correlate to the tinnitus management principles promoted
in the 1993 article.
Because tinnitus is often a multidisciplinary,
multifaceted effort2,3 Hearing Instrument Specialists®
represent an important team player in the community
healthcare team. For appropriate fitting of hearing aids
may constitute the single most important component of
remediation for patients who suffer from tinnitus and
hearing loss simultaneously.4 However, understanding the
foundational principles behind TRT and when to refer
patients for such therapy can add an important dimension
to tinnitus management within a multidisciplinary
framework.
Patient Classifications
The Jastreboff neurophysiological model5 helps us
understand first, how the perception of subjective
tinnitus develops in most patients, and secondly, why
hearing aids are so vital in hearing impaired cases for
the management of tinnitus. He also describes
accompanying hyperacusis, which, in the hearing aid
patient, is manifested as recruitment, or the recruiting
of a larger than the usual number of cochlear hair cells
and more neural involvement at the cortical level.
Hyperacusis is suspected to afflict, to widely varying
degrees, the vast majority of sensorineural cases6, so
addressing recruitment complaints in the course of
hearing instrument dispensing becomes a related issue to
the remediation of tinnitus complaints, as well.
Jastreboff classifies tinnitus patients at his clinic
into five specific treatment categories7, according to
manifestations of hearing loss, hyperacusis, and
tinnitus:
0. Minimal symptoms, not requiring prolonged
intervention
1. Significant tinnitus without significant hearing loss
2. Significant hearing loss with tinnitus
3. Hyperacusis
4. Hyperacusis with prolonged symptom enhancement by
environmental sound exposure
For our purpose here, we will focus on classification #2
patients: Tinnitus patients who also suffer from
significant hearing loss, and for which amplification
can be a requisite part of their treatment regimen. This
would, of course, include many patients that
Specialists® see routinely in their practice. It would
also include tinnitus sufferers seen by other health
professionals, and who’ve not yet been referred for
auditory testing.
Figure 1 Here
Figure 1 The Jastreboff neurophysiological model used in
his Tinnitus Retraining Therapy (TRT)
Tinnitus Retraining Therapy (TRT) Explained
According to the Jastreboff model, the goal is not
necessarily to eliminate the tinnitus, but through
practiced exposure to “environmental sound enrichment”8
and rehabilitative counseling, the patient is able to
develop habituation or acceptance of the tinnitus sound
until it no longer disrupts their quality of life. Of
course, for hearing impaired patients who meet criteria
for amplification, part of the sound enrichment process
involves wearing hearing aids.
Figure 1 shows the neurophysiological basis for the
Jastreboff model, while figure 2 demonstrates the
relationship between auditory and sensory pathways, and
the aversive conditioned reflex. Both of these
demonstrate plasticity of the human brain, both as an
aberrant perception of unwanted noise (tinnitus) and the
development of habituation.
Figure 2 Here
Figure 2 Model for describing relationship between
auditory and extra-auditory pathways, and the adversive
conditioned reflex.
While the neurophysiological model and TRT protocols do
not necessarily explain all causal factors and sites of
lesion---which manifestations can be nearly as varied as
the individuals suffering from them---they do illustrate
that:5
§ The “limbic (emotional) and autonomic nervous systems
are involved in contributing to tinnitus annoyance.”
§ When tinnitus is disturbing to the sufferer it
interrupts natural homeostasis (or one’s emotional
balance)
§ After undergoing “sound enrichment” (including wearing
amplification) the regenerative nueroplasticity of the
brain allows one to habituate or neutralize negative
associations of tinnitus
§ Due to recruitment in the central auditory system
hyperacusis frequently accompanies or co-acts with
tinnitus
Remediation pathways for TRT involve: 1) intensive
patient counseling and education, and 2) sound therapy.
Dr. Jastreboff goes on to explain:
“Counseling sessions are aimed at the (patient’s)
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 broadband sound decreases the differences
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.” 9
At the heart of TRT is utilization of sound therapy,
which is the opposite of the quiet environment in which
tinnitus has been provoked10. For the hearing impaired
patient, appropriate amplification can also provide the
needed broadband noise backdrop by introducing
“environmental masking”1. But, also important are the
hours in which amplification is not worn, during sleep
for instance. Since the most desirable environmental
sounds are those that occur naturally, TRT therapists
counsel for various strategies and equipment to be used
during the hours of sleep, such as wind blowing, ocean
waves, sounds of nature, etc.). These are tailored to
each patient’s needs and circumstances.
The hope is that, over time, a round-the-clock
enrichment process satisfies the subconscious (central
auditory and limbic) need to put balance back into the
normal “primitive” backdrop of life, so that the patient
ultimately achieves habituation (or subconscious
acceptance) of the tinnitus sound itself.
Emotional Associations
Hazell refers to the underlying neuromechanics of
tinnitus as “the mechanism of aversive reactions”5. Not
unlike Ramsdell’s auditory model (see figure 3) of three
listening levels in human hearing12--- 1) Primitive, 2)
Signal, and 3) Linguistic Communication---Hazell
describes the subconscious components of hearing that
are controlled primarily by limbic and autonomic nervous
responses to sound in the environment.
Figure 3 Here
Figure 3 Chartrand’s model illustrating a new way to
view Ramsdell’s 3-tier auditory receptive model. In this
way, the symbolic (communication) level is defined at
one extreme by non-verbal background (primitive) and at
the other extreme by alerting (signal) level, which
transcend abstract interpretation and connect with
autonomic (involuntary) responses.
Some aversive reactions affect varying parts of the
brain, the amygdala, for instance, which is involved
with fear, fight or flight, startle, anger, annoyance
and preparation for danger11. Consequently, physical
responses such as muscle tension, sweating, increases in
heart rate, and adrenalin secretion may be incited in
the hearing impaired individual that would not affect a
normal hearing individual in the same way.
While the normal ear is able to detect extremely quiet
sounds (approaching 0 SPL @3-4KHz) and yet tolerate loud
sounds up to an incredible 130dBSPL, an impaired cochlea
loses the ability to hear soft sounds and, conversely,
the ability to tolerate loud sounds (recruitment). This
narrowing of the dynamic range is created primarily by
“abnormal loudness growth”, in some cases increasing in
perceived loudness growth as much as 3, 5 or 10dB per
actual decibel!
As Hazell describes8 the phenomenon, “More nerve fibres
are switched on or ‘recruited’.” At the central auditory
level, sound is analyzed to extract meaningful messages
or signals from an otherwise meaningless background of
noise. “Often the signal is relatively weak in strength,
but strong in meaning.” Hence, when ordinary background
(primitive) sounds move into the signal level of hearing
because of hearing loss, even softer (yet audible)
sounds add to the limbic imbalance, with increased
levels of distress.12
In a recent interview13, Jastreboff asserted, “The
natural system works in AGC, not linear mode, with the
central auditory process determining to what degree
one’s subjective sensitivity changes.” Silence, whether
real or caused by loss of hearing, is perceived at the
central auditory level can be interpreted as a signal
for danger, according to Jastreboff and colleagues.
Parallels with Current Dispensing Practice
In light of the above, there appears to be some
parallels between TRT and other tinnitus amplification
management strategies taught dispensing professionals by
this author:
§ Auditory Reattention (AR)14,15,1, or the redirection
of one’s attention away from the tinnitus complaint and
toward actual (amplified) signals from the environment.
This aspect corresponds to the TRT ideal utilization of
“natural” sounds rather than “contrived” sounds, such as
white noise masking or radio static.
§ Environmental Masking (EM)16,17 comparable to the “low
level masking” of TRT, is generated in the hearing aid
circuit by simply amplifying sounds naturally occurring
in the environment. For patients whose complaint is that
tinnitus is heard only in quiet, it is possible to
eliminate most of that complaint by bringing abnormal
thresholds closer to the normal hearing levels.
§ Residual Inhibition (RI)18,1,2-although dependent upon
appropriately fitted amplification, may actually be a
temporary manifestation of the habituation found in TRT.
In such a comparison, the efferent response (which
incites tinnitus or its “phantom hearing effect”) that
results from auditory deprivation of damaged hair cells
in the cochlea would relax. This can bring about at
least a temporary lessening of the tinnitus loudness in
many cases. In this way, TRT habituation might at least
partially be explained along the lines of the Ramsdell
psychoacoustic model of three levels of hearing.7
§ Stress relief (SR)19,20,21- A combination of any of
the above, coupled with patient counseling and
education, can bring about lessened stress over the
tinnitus complaint. This is a central component of TRT,
as limbic involvement is considered primary to the
aversive stress response, while the tinnitus
manifestation itself is considered secondary.
In Summary
Over the past 3 decades, there have been virtually
hundreds of strategies devised for managing, reducing or
eliminating tinnitus. However, because each school of
thought presents a different physiological model, most
have failed to achieve universal application. Hence,
lack of reproducible treatment outcomes has led many
medical and health professionals to conclude that there
is “nothing that can be done” for tinnitus complaints,
often advising patients to “learn to live with it”22.
Certainly, there appears to be inordinate skepticism
that there even exists a viable approach to the problem
of tinnitus23.
But TRT presents a model that can be used almost
universally, in conjunction with other strategies
appropriate to each individual patient including
biofeedback, (environmental) masking, residual
inhibition, allergy remediation, nutritional/medication
therapy, or stress management counseling24. Hence,
remedial protocols that are tailored and work in
combination within a multidisciplinary framework assure
a greater degree of success for larger numbers of
tinnitus sufferers.
About the author…
Dr. Chartrand serves as director of research for
DigiCare® Hearing Research & Rehabilitation and writes
and lectures extensively on topics of hearing health.
Correspondence: www.digicare.org.
References
1. Chartrand, M.S., “Tinnitus Management in the
Dispensing Practice”, Audecibel, Livonia, MI, fall
issue, pp 7-10 (1993)
2. Chartrand, M.S. “Tinnitus & Amplification”, Audecibel,
Fall, Livonia, MI: International Hearing Society, pp.
18-21 (1989).
3. Chartrand, M.S., “Inferential correlates derived from
a survey among hearing health professionals”, Rye, CO:
Aural Rehab Concepts, (1994).
4. Nodar, R., “Techniques for Tinnitus Mangement”,
Hearing Professional, International Hearing Society,
March-April, pp. 5-8 (2002).
5. Hazell, J.W.P., “The TRT method in practice”, VI
International Tinnitus Seminar, London: Ed Hazell
Publications THC, pp. 92-98 (1999).
6. Hazell, J.W.P. et al, “Hypersensitivity of Hearing”,
www.tinnitus.org, October (2002).
7. Jastreboff, P.J., “Tinnitus as phantom perception:
Theories and clinical implications”, in Mechanisms of
Tinnitus, eds. Vernon, J. and Moller, A., Massachusetts:
Allyn & Bacon, pp. 73-87 (1995).
8. Hazell, J.W.P., “Environmental sound enrichment”,
www.tinnitus,org, June (2001).
9. Jastreboff, P.J., and Jastreboff, M.M., “Tinnitus
Retraining Therapy: An Update”, www.audiologyonline.com,
Archives, (2002)
10. Shedrake, J.B., Hazell, JWP and Graham, RL, “Results
of tinnitus retraining therapy”, VI International
Tinnitus Seminar, London: Ed Hazell Publications THC,
pp. 292-296 (1999).
11. Chartrand, M.S., Audition, Cognition & the Human
Brain, a 12-hour continuation education course, Livonia,
MI: International Institute for Hearing Instruments
Studies (1999).
12. Chartrand, M.S., Hearing Instrument Counseling:
Practical Applications for Counseling the Hearing
Impaired, Livonia, MI: International Institute for
Hearing Instruments Studies, pp. 19-26 (1999).
13. Chartrand, M.S., Notes from telephone/TDD interview
with Dr. Jastreboff for this article, Rye, CO: DigiCare
Hearing Research & Rehabilitation, October 10, 2002.
14. Wilson, J.P., “Evidence for a Cochlear Origin for
Acoustic Re-admissions et al”, Hearing Res 2:233-252
(1980).
15. Kemp, D.T., “Simulated Acoustic Emissions from
Within the Human Auditory System,” Acoust Soc Am
64:1386-91 (1978).
16. Vernon, J., “Advancements in Tinnitus Management
Strategies”, California Hearing Health Practitioners of
California, Annual Seminar, Long Beach, CA (1996)
17. Vernon, J., “Current use of Masking for the Relief
of Tinnitus”, Tinnitus, Pathology and Management,
Kitahara, ed., pp. 96-106 (1988).
18. Vernon, J., “Attempts to Relive Tinnitus”, J Amer
Audiol Soc 2:124-131 (1977).
19. Sweetow, R., “The Tinnitus-Masking Efficiency of
High-Frequency Hearing Aids”, Hearing Journal 44:4, pp.
24-34 (1991).
20. Surr, R.K., Montgomery, A.A., and Mueller, H.G.,
“Effect of amplification on tinnitus among hearing aid
users”, Ear and Hearing, 6:71-75 (1985).
21. Sheldrake, J.B., Jastreboff, P.J., Hazell, J.W.P.,
“Perspectives for total elimination of tinnitus
perception”, Proceedings of the 5th International
Tinnitus Seminar, Portland, Oregon, 1995, eds. Reich, G.
and Vernon, J., Portland, OR: American Tinnitus
Association, pp. 531-537 (1996)
22. Chartrand, M.S., and Chartrand, G.A., “Participant
Prospectus TA2002 Study”, from Tinnitus and
Amplification 2002 Study, DigiCare Hearing Research &
Rehabilitation, Rye, CO (2002)
23. Nagler, S. M., “The First Nail in the Coffin”,
Otology & Neurotology: An International Forum, 22:4, pg.
429 (2001).
24. Gold, S.L., Gray, W.C., Jastreboff, P.J.,
“Audiological evaluation and follow-up”, Proceedings of
the 5th International Tinnitus Seminar, Portland Oregon,
1995, eds. Reich, G., and Vernon, J., Portland, OR:
American Tinnitus Association, pp. 485-487 (1996).
|
|
|
|
