Long-term Outcome of Tinnitus: Many Unknowns.

INTRODUCTION:

Treatment of tinnitus is challenging for all audiologists and associated healthcare professionals and there is an increasing amount of research effort invested into the effects of various treatments.

Unfortunately, given the high standards required in evidence-based medicine, little treatment research on tinnitus can be regarded as evidence-based. This is unfortunate as it leads to lack of enthusiasm and hopelessness among practitioners. Those of us involved in tinnitus treatment know that there is much to be done, and although our perspectives vary, clinical experience suggests that patients can habituate to tinnitus and might even regard it as something unimportant and hardly noticeable. The aim of this brief article is to highlight some features in the literature and to point at some possible ways to go in future research.

OVERVIEW:

Surprisingly, we know very little about the natural history of tinnitus in the general population. It is true that there have been some large-scale epidemiological surveys and a few longitudinal studies, but most of these have been based on clinical samples. Needless to say, with an approximate point prevalence of 15% in the general population, and with a much smaller percentage of "clinical" tinnitus cases (e.g., much disturbed by it), we can say little by studying only the minority who have tinnitus (1).

For one thing, all clinicians know that some people get rid of their tinnitus, but how can we predict who will be successful, or who will be successful following treatment? In a clinical sample we recently found some improvement for an average follow-up duration of 4.9 years (2). Tolerance of tinnitus increased over time overall, and for patients who had received cognitive-behavioral treatment there was a reduction in tinnitus-related distress. One interesting finding was that tinnitus maskability was a significant predictor of distress at follow-up.

Experience of tinnitus cannot be regarded as something stable. One problem with the tinnitus literature is that even if we had access to long-term follow-up data (and we rarely do) there is much to suggest that the time-lag between treatment and follow-up will include periods of either less or more tinnitus (both in terms of distress and
loudness). The ups and downs of tinnitus would be worthy of investigation and the knowledge is indeed needed in the clinic.

In one study Rubinstein et al. (3) found substantial longitudinal fluctuations in tinnitus and a high occurrence of spontaneous remission. The patients were studied at ages 70, 75 and 79 years. Results showed that tinnitus had increased in severity in 25 % of the women, and decreased in 58%, leaving 17% unchanged. For the men, tinnitus increased in 8% and decreased in 39%, with a larger proportion unchanged (53%). Of course, this study can be questioned as it relied on self-report and that other measures (such as maskability) could show a different result. However, the reliability of tinnitus matching is not impressive (4). It can be very hard for patients to remember how bad their tinnitus was a few years back and the anchor points may change over time so that a distress rating of 8 (on a 10-point scale) might mean a different thing five years later.

My hope is that we in the future will know more about the natural history of tinnitus so that we can add booster treatment at the right time to prevent relapse. Such "relapse-prevention" methods are common practice in cognitive-behavioral treatment of tinnitus (5), but even if we prepare the patient for set-backs, it would be much more useful if information was available so that lapses could be predicted.

A cause of confusion in the tinnitus literature is how improvement is defined. It is with envy that we look at the ease by which some medical colleges define weather a patient is cured or not from cancer or whatever condition is under treatment. However, with most forms of tinnitus, as with many other conditions such as chronic pain, we do not have this opportunity readily at hand. As a result, some researchers define improvement as a minor change on a self-reported questionnaire item, whereas others have regarded silence and nothing but silence as improvement from tinnitus. Clinical psychologists define a clinically significant improvement as a major decrease of the total score of a questionnaire summing several items, but even this approach is easy to question. Other useful concepts, not currently endorsed in tinnitus research, includes high end-state functioning, clinical global impression (in structured interview), or return to work following rehabilitation. Another side of the coin is consumption of health care resources and further treatment seeking. To give an example, if treatment "A" and treatment "B" are fairly equivalent in terms of immediate outcome, treatment A might still be more cost-effective if these patients stop seeking additional treatment (necessary consultations excluded).

Tinnitus research would benefit from epidemiological studies investigating natural history and predisposing, precipitating, perpetuating and protective factors.

My belief is that we need to study this in representative samples adopting modern epidemiological concepts (6). Most certainly, audiological variables such as type and degree of hearing loss and higher auditory cortical processes interact with social and psychological factors such as depressive mood and a stimulating environment both from an acoustic as well as psychological point of view.

The cognitive-behavioral approach to tinnitus management seeks to enhance this interaction, by means of multidisciplinary input from audiologists and clinical psychologists and related professionals. (7). The effects of cognitive-behavioral treatment were recently reviewed in a meta-analysis (8).

Overall, the effects were well established and while the strongest effects have been found immediately following treatment, there is evidence that positive treatment effects are maintained at follow-up. However, the effects are mostly seen with regard to tinnitus annoyance and to a lesser extent on the perceived loudness of tinnitus.

CONCLUSION:

In conclusion, the study of tinnitus demands multidisciplinary input from several professionals including audiologists, physicians, psychologists and others. Hopefully, more researchers and clinicians will get involved in the search for knowledge regarding tinnitus.

REFERENCES:

1. Davis A, Rafie EA. Epidemiology of tinnitus. In: Tyler RS, editor. Tinnitus handbook. San Diego: Singular. Thomson Learning; 2000. p. 1-23.

2. Andersson G, Vretblad P, Larsen H-C, Lyttkens L. Longitudinal follow-up of tinnitus complaints. Arch Otolaryngol Head Neck Surg 2001:175-179.

3. Rubinstein B, Österberg T, Rosenhall U. Longitudinal fluctuations in tinnitus as reported by an elderly population. J Audiol Med 1992;1:149-155.

4. Henry JA, Meikle MB. Psychoacoustic measures of tinnitus. J Am Acad Audiol 2000;11:138-155.

5. Henry J, Wilson P. Psychological management of chronic tinnitus. A cognitive-behavioral approach. Boston: Allyn & Bacon; 2001.

6. Rothman KJ, Greenland S. Modern epidemiology. Philadelphia: Lippincott Williams & Wilkins; 1998.

7. Andersson G. Psychological aspects of tinnitus and the application of cognitive-behavioral therapy. Clin Psychol Rev 2002; 22: 977-990.

8. Andersson G, Lyttkens L. A meta-analytic review of psychological treatments for tinnitus. Br J Audiol 1999; 33:201-210.