The understanding and treatment of intrusive tinnitus have changed over the past 15 years. The disorder used to be viewed simply as a problem of the ear. Now any discussion of intrusive tinnitus must consider how the brain processes input from the auditory system. Evaluation and treatment have developed into a neurophysiologically based protocol that has as its goal habituation to the tinnitus.
A crucial feature of this model is that a number of systems in the brain are involved in the emergence of tinnitus. The cochlea and auditory periphery play only a secondary role. These concepts were first proposed in the 1980s by Pawel Jastreboff, and the clinical protocol for evaluation and treatment based on the neurophysiological model was implemented at The University of Maryland Medical Center in 1990. As this treatment was refined, it became known internationally as Tinnitus Retraining Therapy (TRT).
TRT offers an individualized, noninvasive treatment that is effective for patients with intrusive tinnitus. The protocol is targeted to work above the source of the tinnitus; therefore, the etiology of the tinnitus is irrelevant. Whether a patient associates the onset of the tinnitus with noise trauma, medication, surgery, medical problem, motor vehicle accident, or does not associate onset with any known incident has little predictive value for success in a habituation-based protocol. In addition, factors such as maskability, whether tinnitus is bilateral or unilateral, constant or intermittent, pitch or other psychoacoustic characterizations, or level of hearing ability do not preclude treatment with TRT.
Habituation and Sound Sensitivity
Habituation to the tinnitus signal is most effectively achieved by the combined application of two components:
- directive counseling, which attempts to neutralize the negative emotional associations with the tinnitus (habituation of reaction or annoyance)
- sound therapy, which interferes with the detection of the tinnitus signal (habituation of perception or awareness)
Both elements of the treatment must be incorporated to result in the “chicken/egg” effect necessary to achieve complete habituation. When this occurs, the tinnitus, although still present, is no longer an issue in the patient’s life. Patients can go for long periods of time without thinking about it as the tinnitus becomes more like the refrigerator noise that you tune out, unless you stop to listen for it.
The introduction of the concept of habituation to the tinnitus signal was a turning point in tinnitus treatment. A second important clinical contribution by Jastreboff was the assessment of sound sensitivity. When the program was first established, the primary emphasis was on tinnitus. However, measurements of loudness discomfort levels (LDLs) for live voice and pure tones always were performed as part of the evaluation. As reported by Jastreboff and Hazell in 1993, patients treated with sound therapy using low-level, broadband sound exhibited improved LDLs. Patients with initially reduced LDLs generally reported discomfort when exposed to moderate or even soft sounds in their environment. When LDLs improved and dynamic range increased, they reported subjective improvements in their ability to tolerate normal sounds in their environment. As these response patterns emerged, patients with reduced tolerance levels and complaints of discomfort were evaluated and treated in a more specific way, implementing a variant of the basic TRT protocol.
Approximately 40% of the tinnitus patients evaluated in our center have at least some degree of hyperacusis (decreased sound tolerance). This category also includes patients exhibiting phonophobia (fear or emotional reaction to certain sounds) and misophonia (dislike of certain sounds). The aspect of decreased sound tolerance has become an increasingly important part of our evaluation and treatment protocol.
TRT, as it is implemented at the University of Maryland Tinnitus & Hyperacusis Center, usually lasts about 1-2 years. Initial treatment begins with four main components:
- audiological/tinnitus/hyperacusis evaluation
- otolaryngology evaluation
- directive counseling
- sound therapy instruction
Audiological/tinnitus/hyperacusis evaluation is performed to separate the status of tinnitus, hearing, hyperacusis, phonophobia, and misophonia. A detailed history includes specific questions to determine the effect of noise on tinnitus, whether tinnitus and/or ear discomfort is exacerbated in noise and, if so, for how long.
During testing, in addition to establishing audiometric thresholds, pitch and loudness of tinnitus are matched. It also is imperative to establish LDLs for live voice and pure-tone frequencies of, minimally, 500, 1k, 2k, 4k, 8k, and 12k Hz. Spontaneous otoacoustic emissions tests are performed to rule out objective tinnitus. Distortion product otoacoustic emissions tests assess the function of outer hair cells. No test is performed that will exceed the levels of the LDLs. Tests such as tympanometry, acoustic reflex thresholds, reflex decay, or auditory brainstem response may have to wait until LDLs improve. Two hours are scheduled for this evaluation.
The second component is an otolaryngology or neurotology evaluation to rule out any medical problem or disease process such as acoustic neuroma, glomus tumor, superior canal dehiscence, vascular bruit, Eustachian tube dysfunction, cochlear malformation, Lyme disease, autoimmune disorders, syphilis, and others. Past medical records and current test results are reviewed by the physician. Referrals may be made by the otolaryngologists to other medical specialties. MRI/CT scans or other tests may be requested. If any medical treatment is indicated, further tinnitus treatment is suspended until the results are determined.
After consultation with the otolaryngologist, the audiologist places the patient in one of the five general categories described by Jastreboff (1998):
- Category 1 patients are significantly affected by tinnitus, but do not have hyperacusis or subjective hearing loss.
- Category 2 patients are affected by tinnitus and have significant hearing loss, but no hyperacusis.
- Category 3 patients have hyperacusis, but no prolonged ear discomfort or exacerbation of tinnitus when exposed to noise. Exacerbation of ear discomfort and/or tinnitus is usually brief, and, if present, resets itself by the next morning. Hearing loss, if present, is irrelevant because hyperacusis must be addressed first. Amplification may be considered after the hyperacusis problem is resolved.
- Category 4 patients have tinnitus and hyperacusis, but have prolonged (day or weeks) worsening of ear discomfort and/or exacerbation of tinnitus after being exposed to noise. This category must be treated very cautiously and requires careful monitoring.
- Category 0 patients have tinnitus, but are not seriously distressed by it. They are generally seeking information and reassurance, and typically do not require sound therapy. This category of patient is more frequently seen in an otolaryngology or audiology practice. It should be noted that negative (and often incorrect) information at this point, such as “there is nothing you can do about it, just learn to live with it,” or “perhaps you are going to lose your hearing,” can push a patient into Category 1.
The categorization determines the emphasis for directive counseling and the course of sound therapy. Patients can change categories as they progress through treatment.
During the third component, which consists of at least two hours of directive counseling, family members or friends are encouraged to participate. This session is designed to demystify the tinnitus and neutralize the negative emotional association. The audiologist reviews test results with the patient so there is a clear understanding of the status of hearing, tinnitus, hyperacusis and phonophobia, or misophonia. The anatomy and physiology of the auditory system is explained in detail, with special emphasis on the cochlear structures. Dialogue includes how the brain handles the input from the auditory system, as well as how this relates to the patient’s individual case. If hyperacusis is present, discussion also includes how the brain increases the gain or sensitivity in the auditory structures and subsequent limbic and autonomic nervous system response. Tinnitus and hyperacusis are thought to be two separate but related issues.
An important contribution of TRT counseling is that intrusive tinnitus is the result of a dynamic relationship between the ear, brain, emotions, biochemistry, neurophysiology, what you eat, what you drink, the stresses you are under, how much sleep you get, and more. It is frequently the inability to control the tinnitus that results in issues such as significant intrusiveness and subsequent anxiety, muscle tension, and sleeplessness. Further discussion relates to an in-depth explanation of the neurophysiological model developed by Jastreboff. Factors such as the role of the limbic and autonomic nervous system, relationship to hearing ability, pitch and loudness of the tinnitus, and assessment of outer hair cell activity are discussed.
Options for sound therapy are introduced, and the patient and clinician make decisions together. Most importantly, patients need to understand why a specific course of sound therapy is necessary. Sound therapy is designed to both interfere with the brain’s ability to detect the tinnitus signal and to reset the neuronal networks. TRT does not employ traditional masking techniques, which are felt to be short-term and counterproductive to the habituation process.
For patients in Category 1 with tinnitus but no significant hearing loss or hyperacusis, sound-generating instruments are the most direct and convenient way to proceed. These instruments emit a broadband sound and allow an open ear canal so the patients can hear easily. They must have a zero noise floor because the volume setting tends to be just slightly above the threshold of hearing. Both ears are fit with instruments even if tinnitus is unilateral, and patients are given specific instructions regarding volume settings and schedule of use.
Patients in Category 2, who have tinnitus and significant hearing loss but no hyperacusis, are fit with amplification to amplify sounds in their environment. Patients are taught that, to use amplification as sound therapy for tinnitus, they must wear the hearing aids all their waking moments, avoid silence, and keep neutral sound on in their environment at all times. This amplified sound does not have to mask the tinnitus. As with other forms of sound therapy, habituation of the tinnitus is a slow, gradual process.
Category 3 patients, those with hyperacusis, may include patients with normal hearing or those with significant hearing loss. In all cases, if hyperacusis is present, it must be addressed first. These patients are fit with sound generators and enter into a variant of the basic tinnitus protocol, which is slightly more conservative. Although appropriate protection from noise is important, patients who overprotect are taught to wean themselves off. Gold, Frederick, and Formby (1999) reported that improvements in sound sensitivity for Category 3 patients typically occur quickly, and patients report subjective improvement in their ability to tolerate sounds that were previously uncomfortable. For example, they become comfortable riding in a car, hearing dishes clatter, and going to church, movies, the mall, or sports events.
Sound therapy continues for about one year until improvements are stabilized. Patients with hyperacusis and significant hearing loss who were previously unable to benefit from amplification frequently make a comfortable transition to appropriate amplification in about eight months to a year. Almost all patients with hyperacusis will exhibit an element of phonophobia, which is discussed in the directive counseling session and at follow-up appointments. For those patients with misophonia and/or phonophobia only, a different approach is indicated.
Category 4 patients exhibit an exacerbation of tinnitus and/or hyperacusis for extended periods of time (days or weeks) as the result of sound exposure. Sound therapy is implemented with extreme caution and close follow-up. These patients are the most difficult to treat successfully.
For all categories, it is essential to monitor progress and systematically reinforce and clarify the concepts introduced during directive counseling. Ideally, periodic follow-up visits occur for 1-2 years until the goals are met. These visits are typically more frequent during the first six months. Change is generally slow, incremental, and subtle with expected rough patches.
Outcome measures for TRT are limited by the inability to measure tinnitus or assess severity objectively. Past inability to perform double-blind studies and low rate of follow-up also have contributed to this limitation. Historically, the success rate has been measured by patient responses on questionnaires related to percentage of time they are aware of tinnitus, number of activities interfered with, and effect on their life.
Improvement in at least two of these areas by at least 20% was required to indicate significant improvement. Early retrospective studies by Jastreboff (1998) indicated significant improvement in about 80% of patients who received full treatment. Data replicating these results were reported in 1999 by Sheldrake, Hazell, and Graham; Bartnick, Fabijanska, and Rogowski; and Heitzman, et al. Berry et al. (2002) reported significant improvement in self-perceived disability following TRT as measured by the Tinnitus Handicap Inventory, a validated, patient-based outcome measure.
Clinically, TRT has not been as effective for patients with short-term memory loss, traumatic brain injury, untreatable psychological or psychiatric problems, or those undergoing litigation related to the tinnitus and/or hyperacusis problem. Controlled studies are necessary to evaluate the efficacy of the individual components, such as directive counseling, sound therapy, and clinician effect. Currently, Henry and Schecter are conducting randomized clinical trials comparing TRT and masking sponsored by Veterans Affairs Rehabilitation, Research and Development Service in Portland, OR.
The University of Maryland Tinnitus & Hyperacusis Center has been awarded a planning grant for a multi-center, double-blind, randomized clinical trial testing the efficacy of TRT and its components. Study participants will include active and retired military personnel at six major medical centers of the U.S. Armed Forces and two civilian centers. Participating clinical centers will include audiology and otolaryngology staff in the U.S. Army, Navy, and Air Force and two universities. In addition, research in adaptive chronic auditory gain and its relationship to sound tolerance is ongoing at the University of Maryland Tinnitus & Hyperacusis Center as a direct outgrowth of our clinical experience with hyperacusis. We are currently recruiting subjects who have hearing loss and are unable to benefit from amplification due to sound sensitivity problems.
This article is presented as an introduction to Tinnitus Retraining Therapy. TRT continues to be adapted and refined by Jastreboff and others all over the world. The concepts of the neurophysiologically based model and habituation-based protocol have opened new areas for both scientific research and clinical applications. The role of audiologists in TRT involves more than performing a battery of tests. They are actively involved in the individual directive counseling process, not as psychologists or psychiatrists, but to educate and empower this group of patients who were previously difficult to manage.
For More Information
Visit the Web site of the American Tinnitus Association at http://www.ata.org/, call 503-248-9985 or 800-634-8978, or e-mail email@example.com.