Starkey Research & Clinical Blog

Do the benefits of tinnitus therapy increase with time?

Parazzini, M., Del Bo, L., Jastreboff, M., Tognola, G. & Ravazzani, P. (2011). Open ear hearing aids in tinnitus therapy: An efficacy comparison with sound generators. International Journal of Audiology, 50(8), 548-553.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

Tinnitus management can include a variety of treatment approaches but the most effective usually include a combination of counseling and sound therapy (Jastreboff, 1990; Jastreboff & Hazell, 2004). For many individuals with hearing loss and tinnitus, hearing aids may be the only tinnitus treatment they participate in. Specific treatment recommendations vary depending on a number of patient characteristics, such as degree of hearing loss and severity of the tinnitus disturbance.

Tinnitus Retraining Therapy (TRT; Jastreboff, 1995; Henry et al., 2002, 2003; Jastreboff & Jastreboff, 2006) is a widely known therapeutic approach using counseling and sound therapy, based on the neurophysiological model of tinnitus, that stresses the importance of helping individuals understand their condition, reducing awareness and attention to the tinnitus, providing or restoring appropriate auditory input and eventually training the auditory system to habituate to the tinnitus. Jastreboff & Hazell (2004) have proposed a classification system in which patients are assigned to one of five categories: 0 = mild or recent tinnitus, 1 = normal hearing and severe tinnitus, 2 = significant hearing loss, 3 = hyperacusis and 4 = prolonged worsening of tinnitus or hyperacusis following sound exposure. A patient’s classification on this scale can guide treatment recommendations thereafter. Counseling educates patients about their hearing loss and tinnitus, helping them cope with the stress and annoyance of tinnitus in their everyday lives. Sound therapy treatment aims to help patients habituate to their tinnitus, employing ear-level sound generators for individuals without hearing loss (category 1; described above) whereas hearing aids are recommended for tinnitus sufferers with significant hearing loss (category 2).

Individuals who fall into the borderline area between categories 1 and 2 could theoretically be treated with either sound generators or hearing aids. Presently, there is little evidence to suggest that one of these approaches is superior to the other. Therefore, the purpose of Parazzini et al.’s study was to compare the efficacy of sound therapy treatments with sound generators versus open-fit hearing aids for tinnitus patients whose characteristics fall between categories 1 and 2.

91 participants completed the study. All participants met the requirements for tinnitus categorization between Jastreboff categories 1 and 2, with pure tone thresholds equal to or less than 25dB HL at 2kHz and greater than or equal to 25dB at frequencies higher than 2kHz. None of the participants had used hearing aids or been treated with tinnitus retraining therapy prior to the study. Participants were randomly assigned to one of two treatment groups: those fitted with small, ear-level sound generators (SG group) and those fitted with binaural open fit hearing aids (HA group). All participants used the devices for at least 8 hours per day. Participants completed the Tinnitus Handicap Inventory (THI; Newman et al., 1996) at each of four appointments scheduled at three-month intervals over a year. Structured interviews were completed at each visit. During these interviews the following variables were examined: the effect of tinnitus on life, tinnitus loudness and tinnitus annoyance.

Analysis revealed that participants showed a marked reduction in scores over time, beginning at the first session three months after initiation of therapy and continuing progressively over subsequent measurements every three months up to the last visit at 12 months.  Results with ear-level sound generators and those with hearing aids were essentially identical. All three variables decreased by approximately 50% from the initial assessment to the final session at 12 months. The mean THI score decreased 52% from 57.9 to 27.9, the effect of tinnitus on life decreased 51% from 6.5 to 3.2, and tinnitus loudness ratings decreased from 7 to 3.6, a reduction of 48%. The common clinical criteria for significant improvement on the THI is 20 points (Newman et al., 1998) and 62% of the participants in the current study reached this goal by 6 months and 74% reached it by 12 months. Applying a criterion of 40% improvement to reflect a reduction in tinnitus disturbance—as proposed by P.J. Jastreboff—51% of the subjects achieved the goal by 6 months and 72% reached it by 12 months.

For all recorded variables, the time of treatment was always statistically significant, indicating that subjects were improving steadily over time. There was never a significant difference based on the type of device, indicating that sound generators and open-fit hearing aids were equally successful at alleviating tinnitus symptoms and reactions, at least for the subjects in this population, whose characteristics fell between categories 1 and 2 in Jastreboff & Hazell’s classification system.

Parazzini and colleagues evaluated tinnitus sufferers with mild high frequency hearing loss and measured their responses for up to 12 months. Though there was no evidence of plateaus in the data, it remains unknown whether improvements would continue if treatment were to continue beyond this point. Longer term studies would be valuable to determine at what point improvements plateau and if longer measurement periods yield differences between hearing aids and sound generator devices.

The instruments used in Parazzini’s study were either sound generators or hearing aids; none of the devices had both features. Many hearing aids available today offer tinnitus masking stimuli along with traditional amplification features. A similar paradigm examining hearing aids as well as combination devices could offer practical insight into tinnitus treatment options with currently available hearing instrument product lines. Because a goal of tinnitus retraining therapy is to restore auditory inputs to reduce awareness of the tinnitus, hearing aids could have particular benefits over sound generators, because they stimulate the auditory system with meaningful environmental sounds which may more effective at drawing attention away from the tinnitus, in addition to masking the tinnitus with the amplified sound.

Open-fit, behind-the-ear hearing aids appear to be a good solution for tinnitus patients: the ear canal remains open and unoccluded, thereby reducing the likelihood of increased tinnitus awareness. Another consideration is whether receiver-in-canal (RIC) instruments would be an even better choice. RICs are equally as effective as traditional open-fit hearing aids at minimizing occlusion and offer the opportunity to provide a broader high frequency range and more stable high frequency gain than is available when sound is routed thin or standard thickness tubing (Alworth, et al., 2010). This opportunity to provide an extended high-frequency amplification would be expected to increase auditory input in the frequency range where tinnitus is often perceived. Therefore, RICs may more effectively mask the tinnitus via amplification of environmental sounds, reducing tinnitus awareness and potentially, tinnitus annoyance and stress.

Parazzini’s study offers strong support for the use of open-fit hearing aids with tinnitus patients. Advances in hearing aid technology, such as feedback management, automatic signal processing, and the availability of tinnitus masking stimuli may make modern hearing aids even better suited for this purpose. As mentioned earlier, many opportunities exist for research in the treatment of tinnitus with hearing aids: effects of hearing aid style, sound therapy parameters, treatment and counseling strategies, and duration of treatment all remain white space for future researchers.

References

Alworth, L.N., Plyler, P.N., Bertges-Reber, M. & Johnstone, P.M. (2010). Microphone, performance and subjective measures with open canal hearing instruments. Journal of the American Academy of Audiology 21(4), 249-266.

Del Bo, L. & Ambrosetti, U. (2007). Hearing aids for the treatment of tinnitus. Progress in Brain Research 166, 341-345.

Henry J.A., Jastreboff M.M., Jastreboff P.J., Schechter M.A. & Fausti S.A.(2002).  Assessment of patients for treatment with tinnitus retraining therapy. Journal of the American Academy of Audiology, 13, 523 – 44.

Henry J.A., Jastreboff M.M., Jastreboff P.J., Schechter M.A. & Fausti S.A. (2003). Guide to conducting tinnitus retraining therapy initial and follow-up interviews. Journal of Rehabilitation Research and Development 40, 157 – 177.

Jastreboff, P.J. (1990). Phantom auditory perception (tinnitus): Mechanisms of generation and perception. Neuroscience Research 8, 221-254.

Jastreboff, P.J. & Hazell, J.W.P. (2004). Tinnitus Retraining Therapy: Implementing the Neurophysiological Model. Cambridge University Press.

Jastreboff P.J. & Jastreboff M.M. 2006. Tinnitus retraining therapy: A different view on tinnitus. Otorhinolaryngology and Related Specialties 68, 23 – 29.

Newman, C.W., Jacobson, G.P. & Spitzer, J.B. (1996). Development of the Tinnitus Handicap Inventory. Archives of Otolaryngology Head Neck Surgery 122, 143-148.

Newman, C.W., Sandridge, S.A. & Jacobson, G.P. (1998). Psychometric adequacy of the Tinnitus Handicap Inventory (THI) for evaluating treatment outcome. Journal of the American Academy of Audiology 9, 153-160.

Parazzini, M., Del Bo, L., Jastreboff, M., Tognola, G. & Ravazzani, P. (2011). Open ear hearing aids in tinnitus therapy: An efficacy comparison with sound generators. International Journal of Audiology, 50(8), 548-553.