Keywords
polysomnography - tinnitus - sleep
Introduction
Tinnitus has been defined as an “auditory phantom perception,” meaning that tinnitus
results from an abnormal activity within the nervous system, in the absence of any
internal or external acoustic stimulation. Tinnitus is very common, and ∼ 10 to 15%
of the adult population is affected by it. Most studies indicate that the prevalence
in adults, with a greater prevalence at higher ages, occurs during the sixth or seventh
decades of life. Gender distinctions are not consistently reported across studies,
but tinnitus prevalence is significantly higher in pregnant than in non-pregnant women.[1]
[2]
A relevant percentage of tinnitus sufferers experience symptoms severe enough to significantly
affect quality of life, including sleep disturbances, work impairment, and, in some
cases, psychiatric distress.
The severity of tinnitus varies from an occasional awareness of a noise ( ringing,
hissing, buzzing, roaring, clicking, or rough sounds, for example) in one or both
ears, to an unbearable sound that drives some persons to contemplate suicide. People
with similar psychoacoustic descriptions of tinnitus may differ radically in their
level of annoyance and sense of its impact on daily life. Epidemiologic data reveal
that approximately one fourth of persons with tinnitus are discomforted by it, whereas
the remaining three fourths experience the condition without significant symptoms.[3]
[4] There are reports that tinnitus has led to suicide, although it is probable that
other psychological factors play a more important role in suicide than tinnitus.[5]
Tinnitus, as a result of sudden sensorineural hearing loss (SSHL), is widely believed
to be a neurological phenomenon. Increased bursting and synchronicity in the central
auditory structures, as a result of cochlear pathology, have been implicated in the
generation of tinnitus. A prevailing theory is that tinnitus is a reaction to reduced
information in the frequency bands damaged by hearing loss. This has led researchers
to investigate methods of acoustically stimulating the damaged frequency bands as
a means of alleviating symptoms.[6]
[7]
Tinnitus can result in mood changes, fear, anxiety, depression, sleep disorders, concentration
problems, and several other psychological/emotional issues, which can severely affect
a person's quality of life. As a consequence, more and more patients find their way
to the Otorhinolaryngology–Head and Neck Surgery Department with tinnitus as their
main complaint. Therefore, an extensive audiologic assessment is necessary as part
of the diagnosis and in order to prescribe the proper therapy.[8]
The tinnitus sensation may occur before and during sleep because of the masking effect
of reducing outside noise, resulting in an increased awareness of the tinnitus sensation.[9]
Several studies have found that sleep was listed as the most difficult action in tinnitus
patients. Insomnia was classified as the main complaint in 50% of severe tinnitus
patients, and the severity of tinnitus correlated with the incidence of sleep disturbances.[9]
[10]
The prevalence of sleep disturbances in tinnitus patients varies from 25 to 77% (overall
prevalence of sleep disturbances).[11]
Sleep disorders affect a great percentage of the population. The diagnosis of these
disorders is usually made by polysomnography.[12] Sleep complaints are among the most prominent complaints accompanying tinnitus,
but objective data are rare.
The objective of this review is to identify studies that evaluated tinnitus using
polysomnography.
Review of Literature
The search strategy employed in this literature review was guided by the combination
of two descriptors indexed in the Medical Subject Headings (MeSH): tinnitus and polysomnography. Therefore, we performed a systematic review using the same descriptors in the PubMed
library, and analyzed all articles published. The last manual search conducted in
electronic databases occurred in May 2016.
The entire search process, the selection of the articles and data extraction, was
conducted in pairs. After the search, the articles were selected based on their titles
and abstracts. Subsequently, the texts of all articles were obtained in full.
A systematic literature search was performed using the Medline database, including
hand-searching reference lists from original articles. We identified four studies.
Each study was reviewed by two separate authors (L.S.T and I.B.O) who independently
screened abstracts and titles using the following inclusion criteria:
-
articles written in the English;
-
studies that used polysomnography to assess patients with tinnitus;
-
studies on the topic of tinnitus and polysomnographic assessment.
During the investigation of the articles, we found four studies that used polysomnography
in the analysis of patients with chronic tinnitus. The results are shown in [Table 1].
Table 1
Characterization of the studies
|
Author
|
Number of individuals
|
Study design
|
Instrument
|
|
Hébert et al[13]
|
22 with tinnitus and 22 controls without tinnitus
|
Prospective study
|
Pittsburgh Sleep Quality Index (PSQI)
|
|
Attanasio et al[14]
|
18 with chronic tinnitus and a control group consisting of 15 healthy subjects.
|
Prospective, case-control, nonrandomized study
|
Tinnitus Handicap Inventory (THI)
|
|
Folmer and Griest[10]
|
164 patients returned the follow-up questionnaires
|
Retrospective study
|
Detailed questionnaires were mailed to the patients with information about their medical,
hearing, and tinnitus histories.
|
|
Burgos et al[15]
|
10 patients with tinnitus who were compared with 20 patients with insomnia and 20
healthy controls
|
Prospective, case-control study
|
Beck Depression Inventory (BDI)
|
Discussion
Few studies used polysomnography to analyze the sleep of patients with tinnitus. Aside
from being a difficult exam, it is considered expensive. As a result, the vast majority
of studies use only sleep questionnaires because of the ease of administration and
lower cost.
Hébert et al[13] prospectively examined the subjective and objective sleep parameters of this patient
population to determine the differences in sleep disturbances associated with chronic
tinnitus compared with matched controls. A total of 44 subjects (22 with tinnitus
and 22 controls without tinnitus), unselected with respect to sleep complaints, participated
in this study. The analysis involved 1-week sleep diaries, subjective sleep questionnaires,
and 1 night of polysomnographic (PSG) assessment. Compared with the matched controls,
the tinnitus group showed lower subjective sleep quality as measured with the Pittsburgh
Sleep Quality Index (PSQI) and the sleep diaries, but no significant difference in
objective polysomnographic sleep parameters (that is, sleep latency, efficiency).
However, the quantitative non-rapid eye movement sleep analysis revealed lower spectral
power in the delta frequency band in the tinnitus group compared with the controls,
and this decrease was correlated with subjective sleep complaints (the lower the delta
spectral power, the greater the complaints). This is the first report of an electrophysiological
correlate of sleep difficulties supportive of subjective sleep complaints in the tinnitus
population.
Attanasio et al[14] evaluated the sleep architecture and its possible alterations in chronic tinnitus
patients, and investigated any possible correlation between sleep architecture modifications
and tinnitus perception, adaptation, and the degree of discomfort in these patients.
They performed a prospective, case-control, nonrandomized study, in which 18 patients
affected by chronic tinnitus were compared with a homogeneous control group consisting
of 15 healthy subjects. The experimental group was enrolled at the Tinnitus Ambulatory
at Policlinico Umberto I's Department of Sensory Organs, and the control group was
composed of voluntary subjects. A full overnight polysomnography was performed on
both groups. The tinnitus patients answered two questionnaires: the Tinnitus Handicap
Inventory (THI), and a questionnaire concerning their subjective sleep quality, tinnitus
intensity before bedtime, tinnitus intensity at remembered nocturnal wake-up periods,
and tinnitus intensity at morning wake-up. The controls completed only the sleep quality
questionnaire. All tinnitus patients had a statistically significant alteration in
sleep stages. The average percentage of stage 1 + stage 2 was 85.4% ± 6.3, whereas,
in the control group, the average percentage of stage 1 + stage 2 was 54.9 ± 11.2
(p < 0.001). Stages 3 and 4 and rapid eye movement (REM) sleep were lacking in all tinnitus
patients with an average percentage of 6.4 ± 4.9 of REM sleep, and 6.4 ± 4.9 of stages
3 + 4. The control group showed an average percentage of 21.5 ± 3.6 of REM sleep and
21.5 ± 3.6 of stages 3 + 4 (p < 0.001). No correlation was found between the decrease in REM and the increase in
the THI score in the tinnitus group (r = 0.04). However, a mild correlation was found
between the increase in light sleep (stage 1 + stage 2) and the THI score reported
by the tinnitus group. Therefore, patients with light sleep report a higher THI score
(r = 0.4).
Folmer and Griest[10] investigated the effects of insomnia on tinnitus severity, and determined how this
relationship may evolve with the passage of time. Questionnaires were mailed to patients
before their initial appointment at the Oregon Health Sciences University Tinnitus
Clinic between 1994 and 1997. These questionnaires requested information pertaining
to insomnia, tinnitus severity, and loudness. During their initial appointment, the
patients received counseling, education, and reassurance about tinnitus, audiometric
and tinnitus evaluations, and treatment recommendations. Follow-up questionnaires
were mailed to 350 patients 1 to 4 years (mean 5 ± 2.3 years) after their initial
appointment at the clinic. A total of 174 patients (130 men, 44 women; mean age 55.9
years) returned the follow-up questionnaires. Although many of these patients improved
in both sleep interference and tinnitus severity, a significant number (43) reported
on the follow-up questionnaire that they continued to have difficulty sleeping. The
reported loudness and severity of tinnitus were significantly greater for this group
than for the groups of patients who reported that they never or only sometimes have
difficulty sleeping. The relationship between sleep disturbance and tinnitus severity
became more pronounced with the passage of time. Insomnia is associated with greater
perceived loudness and severity of tinnitus. These findings underscore the importance
of identification and successful treatment of insomnia for patients with tinnitus.
A final study looked at the sleep stages and other variables in 10 patients with tinnitus
who were compared with 20 patients with insomnia and 20 healthy controls. As to the
continuity of sleep, the patients with tinnitus showed decreased sleep efficiency,
shorter sleep time, and greater number of awakenings, and the results were significant.
The patients with tinnitus had a lower percentage of stage 2, higher percentage of
stage 1, and lower latency for REM sleep compared with the controls, but without statistical
significance.[15]
The studies were important to evaluate the stages of sleep in an objective way, especially
the stage of REM sleep, considered the phase of restful sleep.
Final Comments
Polysomnography has proved to be a useful examination in the investigation of patients
with chronic tinnitus.
The work shows that few studies have assessed tinnitus by polysomnography. The vast
majority of studies evaluated the sleep of patients with tinnitus only with questionnaires.
We believe that more studies using polysomnography for the objective evaluation of
tinnitus are necessary.
