Identifying non-otologic risk factors for tinnitus: A systematic review.

BACKGROUND: The origin of tinnitus has been attributed to a peripheral auditory lesion, inducing bottom-up changes and resulting in the perception of a "phantom sound." However, non-auditory factors can co-exist as well, and can even lie at the origin of tinnitus development. An increasing body of literature focuses on psychological, (neuro)muscular, cardiovascular and many other influences and their respective associations with tinnitus prevalence. OBJECTIVE OF REVIEW: The purpose of this study was to provide a comprehensive description of these non-otologic risk factors, and to summarise the evidence in literature about their link with tinnitus. TYPE OF REVIEW: A narrative systematic review was conducted, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement. SEARCH STRATEGY: The MEDLINE, Embase and Web of Science databases were systematically searched for eligible articles, supplemented with manual search methods and grey literature search. Epidemiological studies reporting on the relationship between various non-otologic risk factors and tinnitus were included. EVALUATION METHOD: Quality assessment was performed using the Hoy & Brooks tool. RESULTS: Fifty-five studies were included. Studies were of variable quality, with poor tinnitus definitions and evaluations or questionable sampling of the study population as main contributing factors for high risk of bias. Multiple associated factors have been identified, including cardiovascular, psychological, neurological, musculoskeletal and dietary factors. CONCLUSIONS: The current literature review identified multiple risk factors that could be of significant importance for tinnitus development, maintenance or aggravation. While causality remains uncertain, this systematic elaboration of possible tinnitus comorbidities/risk factors can help provide direction for future research, and can direct clinicians to identify patients at risk and treat relevant symptoms accordingly.

Invasive Neuromodulation as a Treatment for Tinnitus: A Systematic Review.

OBJECTIVE: Although the prevalence and burden of tinnitus is high, none of the available tinnitus treatments has been proven to be effective for the majority of tinnitus patients so far. Neuromodulation is currently gaining more interest to explore as tinnitus treatment. Because noninvasive neuromodulation has been shown to be effective in some tinnitus patients in the short term, more invasive techniques have been applied with variable success and without clear clinical applicability. As new insights into the neuropathophysiology of tinnitus arise, it seems essential to recapitulate the current evidence of invasive neuromodulation for tinnitus, to assess the quality of the available studies and identify gaps in this research domain. DATA SOURCES: MEDLINE, Embase, Web of Science and Clinical Trial Register. MATERIALS AND METHODS: We conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Studies since 2005 that reported on adult human subjects with chronic subjective tinnitus, who underwent some form of invasive neuromodulation, were included. Quality evaluation was performed using the modified Downs and Black checklist. RESULTS AND CONCLUSION: Twenty-one studies were included. Studies were often of low quality due to low sample sizes, lack of controlled designs, or investigating tinnitus as a secondary indication of neuromodulation. Current research results provide insufficient evidence to generally recommend invasive neuromodulation as an alternative treatment alternative for intractable tinnitus, although some promising effects are mentioned. Further research must be encouraged to gain more insight in this treatment including optimization of the technique, and standardization of tinnitus evaluation in subgroups.

Test-Retest Reproducibility of Response Duration in Tinnitus Patients With Positive Residual Inhibition.

Purpose Functional imaging is often used to try to elucidate the pathophysiological mechanism of tinnitus. Residual inhibition, the temporary suppression of tinnitus after application of a masking noise, could be an interesting technique to modulate tinnitus perception in functional imaging paradigms. The purposes of this study were to primarily assess reproducibility of the (partial) positive residual inhibition response duration in patients with tinnitus and to explore its utility in experimental designs. Method Patients with tinnitus exhibiting a (partial) positive residual inhibition response or tinnitus reduction after a 1-min white noise presentation were selected from a broad consulting tinnitus population. In 27 patients, this response was tested 4 times: twice during initial testing and twice during a retest of the psychoacoustic tinnitus measures, 4-8 weeks after initial consultation. In 17 patients with stable residual inhibition responses, reproducibility of response duration, the duration of tinnitus reduction up to pretesting state, was analyzed. Results Initial testing showed a residual inhibition duration of 29.5 s on average. Test-retest reproducibility of response duration was shown to be reliable with an ICC(3, 4) of .871 (95% CI [0.733, 0.948]) and a standard error of measurement of 6.64 s. Conclusions This study indicates the good test-retest reproducibility of residual inhibition duration in our subset of 17 patients with stable (partial) positive residual inhibition. Residual inhibition is, therefore, a technique that can potentially be used for temporary tinnitus manipulation in experimental paradigms to unravel tinnitus pathophysiology.

Etiological approach in patients with unidentified hearing loss.

OBJECTIVES: Etiological diagnosis of hearing impairment is of great importance to ensure early and adequate management. Even after thorough history taking, clinical and audiometric evaluation, the cause of hearing loss remains unclear in a majority of patients. Further examinations can imply imaging, ophthalmologic investigations, laboratory tests, electrocardiography and genetic testing. Lately, the latter has taken an increasingly prominent place within this diagnostic work-up. However, clear guidelines about optimal implementation and sequence of these tests are required. METHODS: Records of patients who visited the consultation for otogenetics at Ghent University Hospital (Belgium) during the period 2006-2012 were retrospectively reviewed. In order to optimize the etiological-diagnostic work-up of unidentified hearing loss, application patterns and results of various diagnostic tests, audiometric and etiological data of each patient were collected and analyzed. RESULTS: Data of 191 patients were analyzed. In 81.2% of the patients, a cause of hearing loss could be determined or suspected. In total, 65.4% had a (presumably) genetic etiology, with connexin 26 (GJB2) mutations as the leading cause. Inquiry of risk factors, associated with congenital hearing loss, and pedigree analysis were found to have the highest diagnostic gain (61.3% and 41.8%). Connexin 26 gene mutations were only present in bilateral hearing impairment, whereas CT abnormalities were related to unilateral (P=0.003), profound (P<0.001) hearing loss. An enlarged vestibular aqueduct was present in 42.9% of all CT abnormalities. Ophthalmologic anomalies were detected in 35.7% of the studied patients. CONCLUSIONS: A sequential approach for the etiological diagnosis of unidentified hearing loss could determine or suggest a cause in more than 80% of patients. The approach may vary based on the presenting phenotype.