This article presents an overview of the tinnitus-management procedures most frequently used by non-physician hearing healthcare providers (HHPs).
Subjective tinnitus is a symptom associated with practically every known otologic disorder. Evidence suggests that when there is a peripheral attenuation of acoustic stimulation (as would be caused by hearing loss) there is also an increase in central auditory nervous system activity at numerous anatomical sites, including the dorsal cochlear nucleus, inferior colliculus, and auditory cortex.1,2 This has been verified via neuroimaging.3 Further support for a central model of tinnitus is that patients whose symptoms are presumably caused by cochlear damage from noise exposure may still “hear” tinnitus following the surgical destruction of the auditory nerve.
While the vast majority of tinnitus sufferers have some degree of sensorineural hearing loss, there are non-auditory pathologies that may be related. Moller speculated that ephaptic transmission, or phase-locked spontaneous activity between damaged neurons could account for some of the non-auditory contributors such as temperomandibular joint disorders and cervical injuries.4 More recently, Cheung and Larsen have proposed that the basal ganglia might be a focal point of integration for this phantom perception.5 There are many anecdotal reports regarding tinnitus secondary to a host of systemic diseases. In addition, physical injuries, obesity, allergies, (including food allergies), stress, dietary deficiencies, and intake of stimulants such as nicotine and caffeine have been cited as exacerbating factors.6
Obviously, if the underlying source of tinnitus is identified and treatable, medical or surgical treatment to rectify the cause is the preferred course of action. Thus, it is essential that all tinnitus patients receive a thorough medical evaluation by a qualified otolaryngologist prior to other tinnitus-management intervention. However, since the vast majority of subjective tinnitus sufferers do not have “curable” tinnitus, the next best course of action may be to provide a program addressing the three aspects of tinnitus—auditory, attentional, and emotional—that may be bothersome.
All patients reporting tinnitus have the auditory aspect. For many, attention is focused so much at the tinnitus that it negatively affects daily life, for example, by disrupting one's ability to concentrate or work efficiently. The third and most troubling aspect is when the emotional well-being of a patient is impacted, leading to anxiety, hopelessness, depression, and even suicidal thoughts.
The primary management strategies employed by HHPs are Tinnitus Retraining Therapy (TRT), acoustic desensitization (Neuromonics), sound enrichment (including amplification), and cognitive-behavioral therapy (CBT). The first two of these approaches emphasize the extensive use of counseling to help control the emotional and, to some degree, the attentional aspects of tinnitus. Amplification does not require counseling, but will likely be more effective when it is provided. CBT does not require sound enrichment, but its success may be enhanced by amplification.
There is no clear evidence for the superiority of any one of these approaches over the others. Regardless of the treatment chosen, it is vital to be honest and to set realistic expectations at the outset of the professional relationship. The patient must understand that the logical outcome of the intervention is not going to be a disappearance of the tinnitus. Rather, the objective should be to minimize disruption in the patient's quality of life related to the tinnitus. Detailed explanations are beyond the scope of this article, but we have provided brief descriptions of each approach.
Tinnitus Retraining Therapy
TRT, popularized by Jastreboff and Hazell,7,8 uses a combination of directive counseling and auditory (low-level sound) therapy to initiate and facilitate habituation to the tinnitus perception. According to their neurophysiological model, there is an initial trigger or specific event that creates the tinnitus signal. The actual site of generation for the tinnitus is irrelevant.
Following detection of the signal at sub-cortical levels, perception and evaluation are made at the auditory cortex. Frequently an association is made by the limbic system (the emotional control center of the brain) that subsequently triggers release of neurotransmitters activating the autonomic nervous system. This process creates a gradual accumulation of plastic changes within the nervous system that help maintain both the perception and the negative emotional reaction via a feedback loop. When the limbic system associates tinnitus with fear or threat, attention is directed toward “salient” or information-bearing stimuli.
The counseling aspect of TRT is designed to educate the patient so that the limbic system does not interpret the tinnitus as a threat. This “retraining” can occur because the brain can sort out meaningful stimuli from irrelevant stimuli. But this will occur only if the tinnitus perception no longer carries a negative emotional association. So, the goal is for the brain to adopt a pattern that de-emphasizes the importance of the tinnitus.
Coupled with the directive counseling is the use of low-intensity sound therapy, or “sound enrichment.” To minimize increased central gain in the auditory system, silence should be avoided. Various methods can be used to provide acoustic stimulation. If hearing loss is present, hearing aids can be very helpful, as discussed below. If the patient's hearing acuity is such that amplification is not appropriate, a broadband noise generator coupled to the ear via an open fitting may facilitate habituation. TRT emphasizes that this noise is not meant to be used as a masker to completely cover up the tinnitus perception. In fact, the notion is underscored that initially the tinnitus should be audible along with the low-intensity noise signal.
Acoustic desensitization (Neuromonics treatment)
An approach combining detailed counseling with stimulation via music was proposed by Davis et al.9 The unique aspect of this approach is that it uses recorded music specifically chosen for its amplitude and tempo characteristics and then filtered in accordance with the patient's hearing thresholds and delivered via a wearable system consisting of a sound processor and high-fidelity headphones. The sound processor provides a background of music mixed with white noise and filtered out to a higher frequency (12,500 Hz) than can be reached with hearing aids.
The recorded music is presented to the tinnitus patient at a relatively soft intensity level (designed to just interfere with the tinnitus perception), and to be listened to passively (as opposed to actively) for 2–4 hours a day to induce relaxation and desensitization. The background white noise, which is employed to mask the tinnitus during the quiet intervals of the music, is used during the first couple of months of treatment and then phased out.
While the Neuromonics approach has met with reported success,10 it does not provide amplification on a full-time basis, something that may be important for a tinnitus sufferer who also has hearing loss. Acoustic stimulation (sound enhancement) may facilitate habituation by increasing neuronal activity, decreasing contrast (between silence and tinnitus) to make tinnitus more difficult to detect, and minimizing increased central auditory gain. Because of the importance of sound therapy, the next section is devoted to a discussion of several methods of delivering appropriate acoustic stimuli.
AMPLIFICATION AND OTHER SOUND THERAPIES
Current sound treatments employ wearable noise generators (preferably coupled to the ears so that the canals are not completely blocked), music, hearing aids, home sound-enrichment approaches such as use of radio, TV, or electrical fans, and commercially available recordings that transmit relaxing sounds, such as ocean waves. The goal is to provide sounds that (1) stimulate and soothe the limbic system, (2) stimulate the neural pathways up through the auditory cortex, and (3) compensate for hearing deficits, when appropriate.
The objective is to have the tinnitus interact with a neutral sound that is easily ignored. One should not actively listen to the chosen sound, as that could activate the limbic system in an unwanted manner. The volume of the sounds should not be so high that it completely masks the tinnitus. Rather, the signal level should mix with the tinnitus in a manner such that both signals may be audible, but neither is particularly distressing. This can be defined as “the tinnitus interference or mixing level.”
This approach differs significantly from the concept of masking, when an external sound (often noise) is intense enough to either cover up, inhibit, or alter perception of tinnitus. Many patients report that daily experienced external sounds effectively mask or diminish tinnitus perception. This, in addition to the fact that attention is more occupied during the daytime, explains why so many patients indicate tinnitus is most noticeable in quiet environments or at night. Unfortunately, many tinnitus sufferers find that after a short period, a masking noise is nothing more than a substitute of one annoying sound for another.
Hearing aids can be enormously effective in assisting tinnitus patients.11 The exact mechanism accounting for the beneficial effects of amplification is uncertain, but is probably related to at least five factors.
One, it is likely that tinnitus is exacerbated by silence, perhaps because the brain seeks out the neural stimulation it is being deprived of by the hearing loss. Amplification increases neural activity and thus may assist in “turning down” the brain's sensitivity control.
Two, it is possible that tinnitus is related to a lack of neural inhibition. Perhaps the greater activity created by amplification allows the inhibitory function to correct itself to a degree.
Three, the auditory system has two primary tasks: to analyze and interpret incoming sound, and to suppress unwanted signals. Since tinnitus is not a sound that is subject to analysis, the brain may be incapable of making the necessary determination to decide whether the signal needs to be analyzed or suppressed. By providing amplification of “true” auditory signals, the brain may have a greater opportunity to remind itself what is true sound and what is pseudo-sound.
Four, hearing aids amplify enough background noise (wanted or otherwise) to partially “mask” the tinnitus or at least reduce its contrast to silence.
Five, if hearing aids assist in reducing the fatigue and stress that accompany having to strain to hear, the ability to cope with tinnitus is improved.
Using musical stimuli
Musical stimuli may be effective with tinnitus not only because they produce neural stimulation, but also because if the music is interpreted as pleasant, it can positively impact the limbic system. Hearing aids may also be used for music.
The most common methods for delivering music via amplification are through the microphone, telecoil, or wireless streaming devices. Telecoils, historically, were not acceptable for music listening, due to inadequate frequency response and gain. However, pre-amplified (active) telecoils have reduced these issues and inductive earhooks are now designed specifically for music and have a stronger signal strength and stereo signal. When using FM or Bluetooth systems, the music source is plugged directly into the accessory, or transmitted to the accessory wirelessly, for example by Bluetooth technology. The signal is then transmitted to the hearing aids either via an FM signal or a proprietary near-field magnetic induction (NFMI) signal.
Sweetow and Henderson Sabes reported on the use of a variety of acoustical stimuli that can be delivered through wearable hearing aids.12 A recent advance that shows considerable potential for assisting tinnitus patients is the presentation of fractal tones that can be programmed for variations in tempo and pitch. The authors found these relaxing tones (which sound like wind chimes) to be preferred over hearing aid amplification alone or over a broadband noise for the majority of tinnitus subjects in their study. They also have a possible advantage over other musical stimuli in that they are not predictable and thus may discourage active listening, which could alter the rate of habituation.
Helpful as the above described approaches may be, some patients cannot afford the cost of hearing aids or may have minimal hearing loss. There are also some low-cost acoustic strategies that can be personalized and used by tinnitus sufferers. These approaches are not a substitute for professional counseling and examination or for amplification.
Free or low-cost applications available through smart phones and personal computers may allow the user to create or modify sounds or music for sound therapy. Music players, like the iPod, may have settings that allow for basic adaptations, like a high-frequency boost. Some apps for smart phones and iPod Touch allow the user to modify the signal.13
Voice over Internet protocol (VOIP) phone calls may lend themselves to similar processing schemes.14 Headphones should be selected with care; optimal headphones should have a broad frequency range, while still allowing the listener to safely hear important sounds from the “outside world.”
Another method for creating personalized acoustic stimuli is audio-editing software. Audio-editing programs allow the user to record, generate, or edit sounds.15 For example, a favorite musical piece may be filtered to compensate for the individual's hearing loss or low-level white or filtered noise may be added to the background. Additionally, right and left channels of the audio track may be adapted independently, the dynamic range of the track may be compressed, and the tempo of the track may be modified without changing the pitch.
If a patient obtains significant relief from residual inhibition, individual sine waves may be generated to listen to alone or to add to other audio tracks, like music. The tone generator and audio effects available in sound-editing software also can be counseling tools. Sounds may be created to allow the partners of tinnitus patients to experience a simulation of the tinnitus experience.
ADDRESSING PATIENT REACTION
Regardless of the cause of tinnitus, the determination of whether or not the patient will require tinnitus patient management is ultimately a function of how the patient reacts to the tinnitus. If a person is not bothered by the tinnitus, it ceases to be a problem. This is not to suggest that attempts should not be made to identify and, if possible, rectify the underlying disease process. But, given the reality that most cases of subjective tinnitus are idiopathic in nature, psychological intervention aimed at reducing the stress, distress, and distraction associated with the tinnitus can be very productive and often will produce the most attainable goals. Many of the techniques reported to have produced success with the management of tinnitus patients have been borrowed from chronic pain management.
Drawing on the finding that the correlation between tinnitus loudness match and tinnitus annoyance is not particularly high (r = <0.5),16 Sweetow proposed that it is the patient's reaction to the tinnitus, rather than the mere presence of tinnitus, that produces the problem.17 In fact, one's reaction to tinnitus is not necessarily related to its loudness. For example, a very soft signal that carries a warning of potential danger (such as the squeak of a floorboard in an adjacent room when no one is supposed to be there) will gain attention and place the autonomic nervous system even more on alert than would louder sounds, such as external traffic, that do not signal a potential negative outcome.
Because of the many similarities of subjective tinnitus to pain (both are subjective, both are invisible, and both are effected by extraneous events), Sweetow advocated cognitive-behavioral therapy as an approach to managing the tinnitus patient.17 Extensive reviews can be found of the principles and practices of cognitive-behavioral therapy as they apply to the tinnitus patient.18,19 The goal of CBT is to modify maladaptive thoughts and behaviors by applying systematic, measureable implementation of strategies designed to alter unproductive actions. A reaction is a behavior, and all behaviors are subject to modification. CBT is most effective when combined with attention control, imagery training, and relaxation.
All of these treatments have been reported successful in the majority of patients receiving them. CBT is designed to take approximately 2–3 months of intensive therapy, TRT requires as much as 18 to 24 months of less active participation, and the Neuromonics acoustic desensitization protocol is intended to be done over 6 months. Hearing aids, including the use of fractal tones, may produce immediate relief, or may require an acclimatization period.
Critics claim that a shortcoming of TRT approach is that it does not consider depression and anxiety disorders, even though as many as 40% of tinnitus patients may suffer from depression and anxiety. Psychologists also have claimed that the interactive and collaborative aspects of CBT are more important than directive counseling and that TRT does not teach coping strategies. TRT and Neuromonics advocates argue that sound therapy (which is not a part of CBT) is essential to minimizing increased central auditory gain and promoting relaxation.
Despite the lack of a tinnitus “cure,” it is unethical and immoral for audiologists or hearing aid dispensers to tell a tinnitus sufferer, “There is nothing that can be done for you. Just learn to live with it.” Although not every practitioner will want to (or, realistically, should) become immersed in comprehensive and detailed tinnitus patient management, all practitioners owe it to their patients and their profession to have a basic knowledge of the effects of tinnitus and how basic counseling techniques and simple acoustic therapies can minimize its negative impact on many patients.
Any of the approaches discussed above can help tinnitus patients, though the choice of which is likely to work best depends on the characteristics and needs of the patient and the comfort level and skills of the practitioner.
© 2010 Lippincott Williams & Wilkins, Inc.