There is much evidence that tinnitus is far more common than most people realize.
A number of years ago, a research group in Sydney, Australia, advertised for volunteers to help test out a device that might offer relief for tinnitus sufferers. The response was so overwhelming that the number of phone calls caused severe problems for the researchers. Some callers seemed to be truly distressed and anxious to seek treatment. It was clear that the incidence of serious tinnitus in the general population was much higher than had been expected by those organizing the study.
PREVALENCE AND DEFINITIONS
Many studies on tinnitus have involved subjects who attended a tinnitus clinic. However, data from representative samples of the general population are not common.
Another problem in estimating the incidence of this condition is that the definition of tinnitus used in any study is probably a significant factor in assessing the results. Definitions vary from study to study, which makes comparisons among studies difficult. For example, Rosenhall merely asked 70-year-old persons, “Do you have buzzing sounds?” without any mention of duration.1 The prevalence was 27.6%.
The same was true of Sataloff's study, in which he asked 57-to-91-year-old persons, “Do you have noises in your ears?” 2 The prevalence reported in this study was 24%. In the National Health Examination study, persons aged 55 to 79 years old were asked, “At any time over the last few years, have you ever noticed ringing (tinnitus) in your ears or have you been bothered by funny noises?”3 Of these, 41.1% said that they had noted this problem, which is much higher than the prevalence in the earlier studies.
As Wigney pointed out, the particular question used almost certainly affects the results.4 For example, Axelsson reported only a 20.1% affirmative response to a question that referred to “suffering” from tinnitus in a group of 50-to-79-year-olds.5 The finding may have been due to the connotation of the word “suffering,” which may have implied a more serious condition.
Quaranta et al. in Italy reported an incidence of tinnitus of only 14.5%, but the age group was much younger (18 years and older).6
In a grant study carried out by the Medical Research Council in the United Kingdom starting in 1978, called the National Study of Hearing (NSH), 37,670 subjects in the age group 17 to 80 years responded to questionnaires concerning hearing status.7 Only 10% of these reported tinnitus of over 5 minutes' duration (not just noted after loud noises). This was referred to as prolonged spontaneous tinnitus (PST).
In contrast, our study's definition assessed only prolonged tinnitus. Thus, our definition would have included people whose tinnitus immediately followed loud noises. However, when we asked these subjects to report the experience of tinnitus of any type, the prevalence was about 34%.
Davis noted an increase in prevalence of PST with age (5.7% at ages 17 to 30 years and 16% at ages 61 to 70 years), which could account for the differences in prevalence among some of the studies quoted.8
BLUE MOUNTAINS HEARING STUDY
In 1997, we began a study in the Blue Mountains area of Sydney, which involved 2015 persons aged 55 and over who lived in two adjacent postal districts, representing over 75% of eligible persons in this age group. The subjects in the Blue Mountains Hearing Study (BMHS) were given an extensive audiologic assessment. A comprehensive hearing and medical questionnaire was also administered, which included questions on tinnitus. The subjects were also involved in an eye study, their diet was assessed, and they were given a test to assess their intellectual ability (Mini-Mental Status Examination), as well as several other tests.
The results showed a very high (30%) incidence of persons reporting prolonged tinnitus (PT), which was defined by the question, “Have you experienced any prolonged ringing, buzzing, or other sounds in your ears or head within the past year, that is, lasting for 5 minutes or longer?” This and the other questions on tinnitus were taken from the American Tinnitus Association (ATA) survey.
Our data did not show that the prevalence of tinnitus increased in older age groups, but our study population contained only those aged 55 and over. The earlier studies seem to indicate that prevalence is lower in younger age groups. There was no gender difference and many of the 602 people who stated that they had experienced prolonged tinnitus (48%) described symptoms in both ears. Surprisingly, 50% of the tinnitus sufferers could hear the noise in the daytime when it was quiet.
It appeared that over half had noted a gradual onset (55%) and had a history of tinnitus lasting from 1 to 10 years (53%). The tinnitus was present in most (64%) of the group “often” to “all of the time,” and 16% of those with persistent tinnitus found it annoying to the highest degree. A similar percentage (15%) found that it interfered with sleep, at least occasionally.
It was perhaps not surprising that 37% of the group with prolonged tinnitus had sought professional help. Over half (64.5%) of these had contacted their family doctor. Only 25.6% had seen an ENT specialist and a mere 5.2% had been seen by an audiologist.
In keeping with our suspicions, 94% had been offered no treatment at all, only 3.6% had been offered medication, and only 1.2% were offered hearing aids or maskers (although this may be misleading as some already wore hearing aids). Few in the group described their treatment as successful, but one wonders if the 94% of people who were not offered treatment included individuals who would be helped by treatment, since many tinnitus clinics report successful outcomes.
The findings of this study possibly highlight a problem, namely that the “you will just have to put up with it—there is no effective treatment” attitude to tinnitus is still very common. If more than 90% of people presenting with prolonged tinnitus are offered no treatment at all (and, in our group of subjects, at least 16% of the group presenting for treatment found it annoying to the highest degree), it seems fair to say that there is considerable room for improvement in the services offered to sufferers of prolonged tinnitus.
Factors associated with tinnitus
A number of individual risk factors are known to be associated with tinnitus and are listed below. Some of these have been reported in the literature, and we found similar results in our study.
* Measured hearing loss
* Family history of hearing loss
* Noise exposure
* Industrial ototoxic chemical exposure
* Severe neck injury
* Middle ear and sinus infections
* High cholesterol
* Poor health (self-rated)
As expected, we found that men had been exposed to more noise at work than women, and this was one of the strongest risk factors associated with tinnitus. This finding was also reported by Coles in the NSH study,7 and Quaranta in the Italian study.6
Chung examined the prevalence of tinnitus among 30,000 workers exposed to noise over a time-weighted average of greater than 85 dBA for 8 hours.9 Of these, 6.6% had tinnitus that was “more than momentary.” The prevalence increased significantly with increasing age and increasing hearing loss.
McShane et al. found that 49.8% of 3466 persons reporting noise-induced occupational hearing loss had tinnitus, but they found no correlation with hearing loss.10 Coles found that the prevalence of prolonged spontaneous tinnitus was 24% among subjects with a history of noise exposure as compared with 14.4% with no history.7 Coles also identified hearing loss as a very strong risk factor in the NSH study, as it was in the BMHS study. In view of the possible association of tinnitus with damage to the cochlea, this is not unexpected.
Noise exposure can certainly cause cochlear damage, likely resulting in hearing loss and tinnitus. Of course, peripheral damage resulting in hearing loss and tinnitus can lead to changes in the emotional state of the patient.11-13 Emotions are largely represented in the brain.
It might be useful to assume that there are two elements involved as far as a sufferer is concerned.
(1) There seems to be a link between the presence of tinnitus and cochlear damage (although one does not invariably result in the other).
(2) The attitude toward and the distress caused by tinnitus are not linked to the extent of the hearing loss.
It must be said that, although there seems to be significant evidence that tinnitus is often related to damage to the cochlea (which might be predicted from a psychoacoustic model), there are also tinnitus sufferers who have no measurable hearing loss. In a preliminary analysis of BMHS results by Wigney, the annoyance caused by tinnitus did not seem to be linked to several audiologic indicators of hearing loss.4
It also appears that the annoyance caused by tinnitus is rather different from the presence of tinnitus itself. Some individuals clearly have considerable damage to the cochlea and no tinnitus; some have what they describe as loud tinnitus, yet report that it causes no distress; others may be distressed by relatively minor tinnitus.
The presence of tinnitus can be due to a number of causes, which may explain why its relationship to hearing loss varies. The attitude to tinnitus and the annoyance caused by tinnitus do not seem to be closely linked to hearing loss.
Non-audiologic factors are probably involved in tinnitus, which may explain why treatments that target such things as changes of attitude to tinnitus and counseling appear to be fairly successful. Whatever is present is perceived by the listener as a noise. It could be described as a “phantom” in that others cannot hear it (except for rare objective tinnitus cases). But, as far as the tinnitus sufferer is concerned, the auditory system is behaving in the same way as it does when a noise is perceived. The annoyance caused by tinnitus may be influenced by how loud it seems to be and/or how the sufferer reacts to it. The reaction to the tinnitus may be linked to personality, events in the individual's personal life, and other factors.
The Blue Mountains Hearing Study data suggest that prolonged tinnitus is reported by just under a third of older people and can therefore be described as a very common problem. While only 16% of this group found it extremely or very annoying, treatment was sought by only one-third of those reporting tinnitus, and effective treatment regimes were hardly ever offered. There is clearly a significant challenge for audiologists as far as this group is concerned.
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4. Wigney D, Mitchell P, Golding M, et al.: The audiological profile of tinnitus in elderly Australians: Preliminary findings. In Hazell JWP, ed. Proceedings Sixth International Tinnitus Seminar
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10. McShane DP, Hyde ML, Alberti PW: Tinnitus prevalence in industrial hearing loss compensation claimants. Clin Otolaryngol
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