Natural history of tinnitus in adults: a cross-sectional and longitudinal analysis

Tinnitus: Clinical Insights in Its Pathophysiology-A Perspective

Tinnitus, the perception of sound without a corresponding external sound source, and tinnitus disorder, which is tinnitus with associated suffering, present a multifaceted clinical challenge due to its heterogeneity and its incompletely understood pathophysiology and especially due to the limited therapeutic options. In this narrative review, we give an overview on various clinical aspects of tinnitus including its heterogeneity, contributing factors, comorbidities and therapeutic pathways with a specific emphasis on the implications for its pathophysiology and future research directions. Tinnitus exhibits high perceptual variability between affected individuals (heterogeneity) and within affected individuals (temporal variability). Hearing loss emerges as predominant risk factor and the perceived pitch corresponds to areas of hearing loss, supporting the compensatory response theory. Whereas most people who have tinnitus can live a normal life, in 10-20% tinnitus interferes severely with quality of life. These patients suffer frequently from comorbidities such as anxiety, depression or insomnia, acting as both risk factors and consequences. Accordingly, neuroimaging studies demonstrate shared brain networks between tinnitus and stress-related disorders shedding light on the intricate interplay of mental health and tinnitus. The challenge lies in deciphering causative relationships and shared pathophysiological mechanisms. Stress, external sounds, time of day, head movements, distraction, and sleep quality can impact tinnitus perception. Understanding these factors provides insights into the interplay with autonomic, sensory, motor, and cognitive processes. Counselling and cognitive-behavioural therapy demonstrate efficacy in reducing suffering, supporting the involvement of stress and anxiety-related networks. Hearing improvement, especially through cochlear implants, reduces tinnitus and thus indirectly validates the compensatory nature of tinnitus. Brain stimulation techniques can modulate the suffering of tinnitus, presumably by alteration of stress-related brain networks. Continued research is crucial for unravelling the complexities of tinnitus. Progress in management hinges on decoding diverse manifestations, identifying treatment-responsive subtypes, and advancing targeted therapeutic approaches.

Greenness, Genetic Predisposition, and Tinnitus

This study aimed to investigate the association between residential greenness and tinnitus and the potential interaction between greenness and genetic predisposition to tinnitus. The normalized difference vegetation index (NDVI) is used to measure residential greenness. The tinnitus is defined based on self-reported. In the cross-sectional analyses, logistic regression models are used for the baseline sample of the United Kingdom Biobank cohort. In the secondary analysis, a Cox proportional hazard model is used for a subsample of participants who completed the tinnitus questionnaire at follow-up. In the cross-sectional analysis including 106471 participants, higher residential greenness is associated with lower odds of tinnitus for each interquartile range increase in continuous NDVI, with an adjusted odds ratio of 0.97 (95% confidence interval: 0.95 to 0.99) for tinnitus. A similar association is observed in the longitudinal analysis, with an adjusted hazard ratio of 0.92 (95% confidence interval: 0.86 to 0.98) for the association of NDVI increased per interquartile range with incident tinnitus. Moreover, there is a significant interaction between greenness and genetic predisposition to tinnitus (P < 0.05). This study suggested that residential greenness is negatively associated with tinnitus. Greenness and genetic predisposition to tinnitus are found to have a significant interaction.

Music therapy for tinnitus: A systematic review and meta-analysis

OBJECTIVE

To evaluate the clinical efficacy of music therapy in the treatment of tinnitus.

METHODS

Three English databases (PUBMED, Embase, Web of Science) and three Chinese databases (CNKI, VIP, and Wanfang) were searched, and eligible articles were selected according to the set inclusion criteria. Clinical efficacy was used as the primary outcome, and each score was used as the secondary outcome. Using RevMan5.3 software for statistical analysis.

RESULTS

A total of 14 studies involving 1239 tinnitus patients were included. The results of the meta-analysis showed that music therapy had a certain clinical efficacy in the treatment of tinnitus, but there was no significant difference compared with the control group (OR = 1.00, 95%CI =0.83-1.22; P = 1.00). However, music therapy significantly improved THI score (MD = -6.77, 95 % CI = -9.62 to -3.92; P < 0.00001), TSQ (MD = -2.80, 95 % CI = -3.23 to -2.36; P < 0.00001), tinnitus loudness (MD = -3.90, 95 % CI = -6.58 to -1.23; P = 0.004), VAS score (MD = -1.11, 95 % CI = -2.11 to -0.11; P = 0.03) and TQ score (MD = -8.36, 95 % CI = -11.10 to -5.62; P < 0.001).

CONCLUSION

Music therapy is an effective method for the treatment of tinnitus, which can improve the THI score, tinnitus severity, VAS score, and TQ score and reduce the loudness of tinnitus. Due to the low quality of the included literature, the current conclusions need to be further verified by more and higher-quality studies.

Reporting of auditory symptoms over time: (in)consistencies, expectations and the nocebo effect

Objective: Consistent symptom reporting for conditions like tinnitus that do not have an associated sign is critical for evaluating severity and intervention effectiveness, and for interpreting research findings. There is little research examining reporting of tinnitus and hearing difficulty over time. We address this here by comparing reported hearing difficulty and tinnitus at two time-points.Design: A cross-sectional study comparing symptom reporting in March 2019 and August/September 2021 using data from two online surveys of the same cohort. Although each survey was designed to address a different question, both asked about symptoms of tinnitus and hearing difficulties and enabled this exploratory analysis.Study sample: 6881 members of the UK general public aged 18+ years.Results: Inconsistent reporting was evident - many participants who reported experiencing tinnitus and/or hearing difficulties in 2019, said in 2021 that they had never had such symptoms before. Additionally, reports of new tinnitus/hearing difficulties in 2021 were unexpectedly high, equating to 18-month incidence rates of 13.6% and 11.7%, respectively.Conclusions: Psychosocial factors, expectations and context impact symptom reporting. This should be considered when treating patients and interpreting research findings. Using real-time data collection methods could thus provide a better understanding of experiences of tinnitus and hearing.

Depression, anxiety and brain volume after hearing loss and tinnitus: cohort study in the UK Biobank

BACKGROUND

Hearing loss and tinnitus have been proposed as potential indicators of impaired mental health and brain morphological changes.

AIMS

To assess the associations of hearing loss and tinnitus with the risk of depression and anxiety and with brain volume.

METHOD

We conducted a community-based cohort study including 129 610 participants aged 40-69 years at recruitment to the UK Biobank with a follow-up period during 2006-2021 to estimate the risk of depression and anxiety after detection of hearing loss and reported tinnitus. We also assessed the associations of hearing loss and tinnitus with brain volume in a subsample with available brain magnetic resonance imaging data (N = 5222).

RESULTS

We observed an increased risk of depression among individuals with hearing loss (hazard ratio [HR] 1.14, 95% CI 1.03-1.26), tinnitus (HR 1.30, 95% CI 1.21-1.41) or both (HR 1.32, 95% CI 1.15-1.52), compared with individuals with neither hearing loss nor tinnitus. Similar results were noted for anxiety (HR 1.18, 95% CI 1.07-1.30 for hearing loss; HR 1.32, 95% CI 1.22-1.43 for tinnitus; and HR 1.48, 95% CI 1.30-1.68 for both). Hearing loss was associated with decreased overall brain volume as well as decreased volume of different brain regions. The latter associations disappeared after adjustment for whole intracranial volume. Tinnitus was associated with greater left accumbens and right occipital pole volume after adjustment for the whole intracranial volume.

CONCLUSIONS

Individuals with tinnitus are at increased risk of depression and anxiety. Hearing loss, on the other hand, is associated with both mood disorders and altered brain morphology.

The Associations Between Workplace Noise, Ototoxic Chemicals, and Tinnitus

OBJECTIVE

To investigate the occupational risk factors associated with tinnitus in the Australian working population.

DESIGN

The research was conducted using data collected from the Australian Workplace Exposure Survey-Hearing, a national cross-sectional study of 4970 workers conducted in 2016 to 2017. Workers were asked if they experienced tinnitus and if they answered affirmatively, they were asked about the frequency and length of the presentations. Based on their answers, each worker was categorized as having no tinnitus or any tinnitus, with an additional group of workers with any tinnitus subcategorized as having constant tinnitus. Exposure assessment was conducted using an automated expert assessment method. Exposures included daily noise (L Aeq,8h ), hand-arm vibration (A(8)), impulse noise, smoking status, styrene, trichloroethylene, toluene, n-hexane, p-xylene, ethylbenzene, lead, and carbon monoxide. Univariate and multivariate logistic regression models were used to examine the associations between workplace exposures and tinnitus.

RESULTS

Workers with an estimated noise exposure above the workplace limit (L Aeq,8h > 85 dBA) had 1.73 (95% confidence interval [CI]: 1.42 to 2.11) increased odds of any tinnitus and 2.15 (95% CI: 1.60 to 2.89) odds of constant tinnitus. The odds of workers having any tinnitus increased with increasing noise exposure levels in a dose-response relationship that strengthened when considering only those with constant tinnitus. In the fully adjusted model, statistically significant associations were seen for lead exposure with both any and constant tinnitus, toluene exposure with constant tinnitus, and carbon monoxide exposure with any tinnitus.

CONCLUSIONS

These results suggest that, in addition to workplace noise, occupational exposures to lead, toluene, and carbon monoxide are associated with tinnitus.

Correlation of Tinnitus Severity Index and Tinnitus Handicap Inventory with Hematological Parameters in Patients with Subjective Tinnitus

Introduction  Tinnitus etiopathogenesis is still unclear and treatment options are controversial despite current advances in medicine. Objectives  To analyze the correlation between patients' symptom scores, systemic inflammation, and trombosis biomarkers. Methods  In this prospective study, we evaluated the degree of complaints of subjective tinnitus patients with the tinnitus severity index (TSI) and tinnitus handicap inventory (THI), and correlated these symptom scores with hematological parameters such as the neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), mean thrombocyte volume (MPV), and platelet distribution width (PDW). Results  A total of 44 patients with subjective tinnitus, 25 (56.8%) men and 19 (43.2%) women, were included in this study. The mean age of the patients was 42.3 ± 14.8 years. When the correlation between TSI and NLR, PLR, PDW, and MPV values of the patients were analyzed, no statistically significant correlation was found between TSI, NLR, and PLR ( p  > 0.05). However, there was a statistically weak positive correlation between TSI, MPV, and PDW.( p  < 0.05). When the correlation between THI and NLR, PLR, PDW, and MPV values of the patients were analyzed, no statistically significant correlation was found between THI, NLR, and PLR ( p  > 0.05). There was a statistically weak positive correlation between THI, MPV, and PDW ( p  < 0.05). Conclusion  We were unable to detect any relationship between systemic inflammation markers (NLR and PLR) and symptom scores, but a weakly positive correlation was observed between thrombosis markers (MPV and PDW) and symptom scores, and as the subclinical thrombosis markers elevated, so did the symptom scores.

A symptom network model of misophonia: From heightened sensory sensitivity to clinical comorbidity

OBJECTIVES

Misophonia-an unusually strong intolerance of certain sounds-can cause significant distress and disruption to those who have it but is an enigma in terms of our scientific understanding. A key challenge for explaining misophonia is that, as with other disorders, it is likely to emerge from an interaction of traits that also occur in the general population (e.g., sensory sensitivity and anxiety) and that are transdiagnostic in nature (i.e., shared with other disorders).

METHODS

In this preregistered study with a large sample of participants (N = 1430), we performed a cluster analysis (based on responses to questions relating to misophonia) and identified two misophonia subgroups differing in severity, as well as a third group without misophonia. A subset of this sample (N = 419) then completed a battery of measures designed to assess sensory sensitivity and clinical comorbidities.

RESULTS

Clinical symptoms were limited to the most severe group of misophonics (including autistic traits, migraine with visual aura, anxiety sensitivity, obsessive-compulsive traits). Both the moderate and severe groups showed elevated attention-to-detail and hypersensitivity (across multiple senses). A novel symptom network model of the data shows the presence of a central hub linking misophonia to sensory sensitivity which, in turn, connects to other symptoms in the network (relating to autism, anxiety, etc.).

CONCLUSION

The core features of misophonia are sensory-attentional in nature with severity linked strongly to comorbidities.

Barriers to Adoption of Digital Therapeutics (DTx) into Audiology Clinical Practice: Acknowledging the Challenges, Adapting to the Future

The continuous advancements in technologies supporting digital health and digital therapeutics (DTx) bring new possibilities to the field of audiology. This study considers a new DTx for tinnitus called Tinnibot and the willingness of a group of Australian university audiology students to consider this new DTx in their future careers as practicing audiologists. A single-group case-series design (pretest/posttest) was used to examine the opinions of 10 university audiology students before and after participating in a 2-hour information workshop on the topics of tinnitus, DTx, cognitive behavioral therapy, and a new digital therapy tool for tinnitus called Tinnibot. Student knowledge levels of the main topic areas increased from poor (before the workshop) to moderate to high after the workshop, with 40% of participants reporting they would very likely use digital therapies for future patients. A common barrier to improving this rating was the need for direct hands-on training on the DTx before the students would be confident to recommend the DTx to patients. Incorporating direct training on DTx into university audiology programs would allow greater uptake of DTx by students as they begin their careers as practicing audiologists.

Herbal medicines in the treatment of tinnitus: An updated review

Tinnitus is perception of sound in the absence of an apparent external acoustic stimulus. The condition is prevalent in adults, especially the elderly (≥65 years), and may be associated with cognitive function decline and significantly impacts on the quality of life, heralding difficulties in managing this challenging disorder. Interventions for tinnitus have been varied. However, drugs have not yet been approved for the treatment of tinnitus and there is no pharmacotherapy recommended by existing guidelines. Still, herbal medicines are used for the treatment of tinnitus in many countries, especially Gingko (G.) biloba. In the current updated literature review, we evaluated the efficacy of herbal medicines in the treatment of tinnitus by reviewing the evidence of relevant randomized controlled trials. The authors also highlight some of the issues in clinical trials of herbal medicines given that currently available evidence on herbal medicines for tinnitus is overall of insufficient quality and the conclusions from existing trials are conflicting. Nevertheless, there is a clear and urgent need for safe and effective pharmacotherapy of tinnitus.

Characteristics of tinnitus and factors influencing its severity

Background and Objectives

There is a wealth of information regarding the treatment methods for tinnitus; however, the treatment available is unsatisfactory because of the following reasons: first, tinnitus has various etiologies and second, it has distinct heterogeneity among different individuals. Numerous studies have focused on understanding the causes of tinnitus severity, but the conclusions have been inconsistent. The purpose of the present study was to define factors that differentially influence subjectively perceived tinnitus severity.

Methods

Clinical data of patients with chronic tinnitus who visited our outpatient clinic from April 2020 to April 2021 were collected. Tinnitus Handicap Inventory (THI) and Tinnitus Evaluation Questionnaire (TEQ) were used to evaluate tinnitus severity among patients, and the independent factors influencing the severity of tinnitus were investigated by performing univariate and multivariate stepwise regression analyses.

Results

Eleven variables were associated with THI and TEQ scores, of which nine were identical. Multiple regression analyses results revealed that five variables had a significantly unique predictive effect on tinnitus severity based on THI and the TEQ scores. Three factors including Self-Rating Scale of Sleep (SRSS), change in loudness, and Self-Rating Anxiety Scale (SAS) were identical.

Conclusion

Sleep status, anxiety level, and change in loudness in patients with chronic tinnitus were significantly correlated with severity of tinnitus. Follow-up studies should investigate the causal relationship between these factors and tinnitus severity.

Tinnitus and the triple network model: a perspective

Tinnitus is defined as the conscious awareness of a sound without an identifiable external sound source, and tinnitus disorder as tinnitus with associated suffering. Chronic tinnitus has been anatomically and phenomenologically separated into three pathways: a lateral “sound” pathway, a medial “suffering” pathway, and a descending noise-canceling pathway. Here, the triple network model is proposed as a unifying framework common to neuropsychiatric disorders. It proposes that abnormal interactions among three cardinal networks—the self-representational default mode network, the behavioral relevance-encoding salience network and the goal-oriented central executive network—underlie brain disorders. Tinnitus commonly leads to negative cognitive, emotional, and autonomic responses, phenomenologically expressed as tinnitus-related suffering, processed by the medial pathway. This anatomically overlaps with the salience network, encoding the behavioral relevance of the sound stimulus. Chronic tinnitus can also become associated with the self-representing default mode network and becomes an intrinsic part of the self-percept. This is likely an energy-saving evolutionary adaptation, by detaching tinnitus from sympathetic energy-consuming activity. Eventually, this can lead to functional disability by interfering with the central executive network. In conclusion, these three pathways can be extended to a triple network model explaining all tinnitus-associated comorbidities. This model paves the way for the development of individualized treatment modalities.

Different bimodal neuromodulation settings reduce tinnitus symptoms in a large randomized trial

More than 10% of the population suffers from tinnitus, which is a phantom auditory condition that is coded within the brain. A new neuromodulation approach to treat tinnitus has emerged that combines sound with electrical stimulation of somatosensory pathways, supported by multiple animal studies demonstrating that bimodal stimulation can elicit extensive neural plasticity within the auditory brain. More recently, in a large-scale clinical trial, bimodal neuromodulation combining sound and tongue stimulation drove significant reductions in tinnitus symptom severity during the first 6 weeks of treatment, followed by diminishing improvements during the second 6 weeks of treatment. The primary objective of the large-scale randomized and double-blinded study presented in this paper was to determine if background wideband noise as used in the previous clinical trial was necessary for bimodal treatment efficacy. An additional objective was to determine if adjusting the parameter settings after 6 weeks of treatment could overcome treatment habituation effects observed in the previous study. The primary endpoint at 6-weeks involved within-arm and between-arm comparisons for two treatment arms with different bimodal neuromodulation settings based on two widely used and validated outcome instruments, Tinnitus Handicap Inventory and Tinnitus Functional Index. Both treatment arms exhibited a statistically significant reduction in tinnitus symptoms during the first 6-weeks, which was further reduced significantly during the second 6-weeks by changing the parameter settings (Cohen’s d effect size for full treatment period per arm and outcome measure ranged from − 0.7 to − 1.4). There were no significant differences between arms, in which tongue stimulation combined with only pure tones and without background wideband noise was sufficient to reduce tinnitus symptoms. These therapeutic effects were sustained up to 12 months after the treatment ended. The study included two additional exploratory arms, including one arm that presented only sound stimuli during the first 6 weeks of treatment and bimodal stimulation in the second 6 weeks of treatment. This arm revealed the criticality of combining tongue stimulation with sound for treatment efficacy. Overall, there were no treatment-related serious adverse events and a high compliance rate (83.8%) with 70.3% of participants indicating benefit. The discovery that adjusting stimulation parameters overcomes previously observed treatment habituation can be used to drive greater therapeutic effects and opens up new opportunities for optimizing stimuli and enhancing clinical outcomes for tinnitus patients with bimodal neuromodulation.

Integrating Distribution-Based and Anchor-Based Techniques to Identify Minimal Important Change for the Tinnitus Functional Index (TFI) Questionnaire

The Tinnitus Functional Index (TFI) was developed to be responsive to small treatment-related changes in the impact of tinnitus. Yet, no studies have integrated anchor-based and distribution-based techniques to produce a single Minimal Important Change (MIC) score. Here, we evaluated the responsiveness and interpretability of the TFI, determining for the first time a robust MIC score in a UK clinical population. Two-hundred and fifty-five patients with tinnitus participated in this prospective longitudinal validation study. Distribution-based estimates (Standard Error of Measurement, Smallest Detectable Change and Effect size) and anchor-based estimates of important change (minimal clinically important difference and Receiver Operator Curve optimal value) were calculated and then integrated using a visual anchor-based MIC distribution plot. A reduction in score of −14 was determined as the MIC estimate that exceeds the measurement error, most of the variability and reliably identifies patients demonstrating true improvement. It is therefore recommended that a reduction of 14 points should be used as a minimum change required when calculating statistical power and sample size in tinnitus intervention studies and assessing patients in clinical practice.

Shedding Light on SARS-CoV-2, COVID-19, COVID-19 Vaccination, and Auditory Symptoms: Causality or Spurious Conjunction?

There are reports of associations between SARS-CoV2, COVID-19, COVID-19 vaccines, and auditory symptoms (hearing difficulty, tinnitus). However, most studies have relied on self-report and lack baseline and/or non-COVID control groups. This makes it problematic to differentiate if symptoms are associated with SARS-CoV2, COVID-19, the vaccine, psychosocial factors or recall bias. In this study, we differentiate these by comparing hearing and tinnitus survey data collected pre- and during the pandemic. The survey conducted during the pandemic asked about the onset and change in three types of symptom. Type One—known association (loss of smell, memory/concentration issues, persistent fatigue), Type Two—indeterminate association (auditory symptoms), and Type Three—no established association with COVID-19 (toothache). We hypothesized that if auditory symptoms are directly associated with COVID-19, their onset and change would be similar to Type One symptoms, but if indirectly associated (reflecting psychosocial factors and/or recall bias) would be more similar to Type Three symptoms. Of the 6,881 individuals who responded, 6% reported confirmed COVID-19 (positive test), 11% probably had COVID-19, and 83% reported no COVID-19. Those with confirmed or probable COVID-19 more commonly reported new and/or worsened auditory symptoms than those not reporting COVID-19. However, this does not imply causality because: (1) new auditory symptoms coincided with COVID-19 illness among just 1/3 of those with confirmed or probable COVID-19, and another 1/3 said their symptoms started before the pandemic—despite reporting no symptoms in the pre-pandemic survey. (2) >60% of individuals who had COVID-19 said it had affected their Type 3 symptoms, despite a lack of evidence linking the two. (3) Those with confirmed COVID-19 reported more Type 1 symptoms, but reporting of Type 2 and Type 3 symptoms did not differ between those with confirmed COVID-19 and those without COVID-19, while those who probably had COVID-19 most commonly reported these symptom types. Despite more reports of auditory symptoms in confirmed or probable COVID-19, there is inconsistent reporting, recall bias, and possible nocebo effects. Studies that include appropriate control groups and use audiometric measures in addition to self-report to investigate change in auditory symptoms relative to pre-COVID-19 are urgently needed.