The auditory sensitivity is increased in tinnitus ears

Disparities between objectively measured hearing loss and subjectively perceived aided hearing loss: A scoping review

Objectives

This scoping review aims to summarize and synthesize research findings on the disparities between audiometrically diagnosed and aided hearing loss versus the individual's own experience of hearing loss.

Methods

A systematic search strategy was employed across multiple databases to identify studies published between 1990 and October 2023 focusing on the experiences of hearing problems among individuals with aided hearing loss. The selected studies underwent screening based on predetermined inclusion and exclusion criteria. These criteria revolved around including papers featuring a population of adult (+18) individuals with audiometrically measured hearing loss who had undergone technological rehabilitation. Data charting was employed to provide an overview of the studies and was additionally utilized to identify key themes. Narrative analysis was used to identify subthemes within the data set.

Results

A total of 11 articles met the inclusion criteria. The analysis identified five themes: "disability experience and discrepancy between measured and self-perceived hearing loss"; "listening effort"; "mental burden/psychological consequences"; "factors that alleviate the consequences of HL"; and "sociodemographic factors."

Conclusions

The scoping review shows that, despite the proliferation of technological options, there is a pressing need for a more concentrated effort to identify and scrutinize the supplementary facets of hearing loss that remain inadequately addressed by current hearing technology. This includes subjective experiences associated with hearing loss that may not be effectively treated solely with hearing aids.

Oval and round window reinforcement surgery leads to improvements in sound tolerance and quality of life for hyperacusis patients

PURPOSE

Hyperacusis is an audiological disorder in which patients become persistently sensitive and intolerant to everyday environmental sounds. For those patients that fail conservative options, a minimally invasive surgical procedure has been developed.

MATERIALS & METHODS

Retrospective case series of 73 adult patients with hyperacusis who underwent oval and round window reinforcement surgery between 1/2017-6/2023. Small pieces of temporalis fascia were used to reinforce the round and oval windows. Patients were separated into two groups based on their preoperative speech Loudness Discomfort Level (LDL). Patients with a preoperative speech LDL ≤ 70 dB were placed in the "low LDL group" whereas patients with a preoperative speech LDL >70 dB were placed in the "high LDL group." Preoperative and one-week postoperative audiogram and speech LDLs were compared. Quality of life was assessed using the Glasgow Benefit Inventory (GBI) survey.

RESULTS

73 patients met inclusion criteria - 21 patients in the low LDL group and 52 in the high LDL group. Patients in the high LDL group significantly improved their LDLs by an average of 3.5 dB (P < 0.0001). 42 patients (80.8 %) in the high LDL group had improvement and would recommend the surgery for hyperacusis. Patients in the low LDL group significantly improved their LDL by an average of 12.9 dB (P = 0.032). Ten patients (47.6 %) from the low LDL group experienced improvement and would recommend hyperacusis surgery.

CONCLUSION

Many patients with hyperacusis who undergo oval and round window reinforcement can receive significant improvement in sound tolerance and quality of life. Patients with a pre-op speech LDL > 70 dB have the greatest potential for improvement with surgery (80.8 %), probably because their hyperacusis was less severe. In the high LDL group(>70dB) the improvement in 1-10 scale went from 8.6 pre-op to 2.4 post op. In the low LDL group(<70dB) went from 9.2 pre-op to 6.8 post-op. These findings were consistent with the GBI results.

Noise sensitivity or hyperacusis? Comparing the Weinstein and Khalfa questionnaires in a community and a clinical samples

Noise sensitivity and hyperacusis are decreased sound tolerance conditions that are not well delineated or defined. This paper presents the correlations and distributions of the Noise Sensitivity Scale (NSS) and the Hyperacusis Questionnaire (HQ) scores in two distinct large samples. In Study 1, a community-based sample of young healthy adults (n = 103) exhibited a strong correlation (r = 0.74) between the two questionnaires. The mean NSS and HQ scores were 54.4 ± 16.9 and 12.5 ± 7.5, respectively. NSS scores displayed a normal distribution, whereas HQ scores showed a slight positive skew. In Study 2, a clinical sample of Veterans with or without clinical comorbidities (n = 95) showed a moderate correlation (r = 0.58) between the two questionnaires. The mean scores were 66.6 ± 15.6 and 15.3 ± 7.3 on the NSS and HQ, respectively. Both questionnaires' scores followed a normal distribution. In both samples, participants who self-identified as having decreased sound tolerance scored higher on both questionnaires. These findings provide reference data from two diverse sample groups. The moderate to strong correlations observed in both studies suggest a significant overlap between noise sensitivity and hyperacusis. The results underscore that NSS and HQ should not be used interchangeably, as they aim to measure distinct constructs, however to what extent they actually do remains to be determined. Further investigation should distinguish between these conditions through a comprehensive psychometric analysis of the questionnaires and a thorough exploration of psychoacoustic, neurological, and physiological differences that set them apart.

Differential cortical activation patterns: pioneering sub-classification of tinnitus with and without hyperacusis by combining audiometry, gamma oscillations, and hemodynamics

The ongoing controversies about the neural basis of tinnitus, whether linked with central neural gain or not, may hamper efforts to develop therapies. We asked to what extent measurable audiometric characteristics of tinnitus without (T) or with co-occurrence of hyperacusis (TH) are distinguishable on the level of cortical responses. To accomplish this, electroencephalography (EEG) and concurrent functional near-infrared spectroscopy (fNIRS) were measured while patients performed an attentionally demanding auditory discrimination task using stimuli within the individual tinnitus frequency (fTin) and a reference frequency (fRef). Resting-state-fMRI-based functional connectivity (rs-fMRI-bfc) in ascending auditory nuclei (AAN), the primary auditory cortex (AC-I), and four other regions relevant for directing attention or regulating distress in temporal, parietal, and prefrontal cortex was compiled and compared to EEG and concurrent fNIRS activity in the same brain areas. We observed no group differences in pure-tone audiometry (PTA) between 10 and 16 kHz. However, the PTA threshold around the tinnitus pitch was positively correlated with the self-rated tinnitus loudness and also correlated with distress in T-groups, while TH experienced their tinnitus loudness at minimal loudness levels already with maximal suffering scores. The T-group exhibited prolonged auditory brain stem (ABR) wave I latency and reduced ABR wave V amplitudes (indicating reduced neural synchrony in the brainstem), which were associated with lower rs-fMRI-bfc between AAN and the AC-I, as observed in previous studies. In T-subjects, these features were linked with elevated spontaneous and reduced evoked gamma oscillations and with reduced deoxygenated hemoglobin (deoxy-Hb) concentrations in response to stimulation with lower frequencies in temporal cortex (Brodmann area (BA) 41, 42, 22), implying less synchronous auditory responses during active auditory discrimination of reference frequencies. In contrast, in the TH-group gamma oscillations and hemodynamic responses in temporoparietal regions were reversed during active discrimination of tinnitus frequencies. Our findings suggest that T and TH differ in auditory discrimination and memory-dependent directed attention during active discrimination at either tinnitus or reference frequencies, offering a test paradigm that may allow for more precise sub-classification of tinnitus and future improved treatment approaches.

Hyperacusis: Focus on Gender Differences: A Systematic Review

BACKGROUND

While gender differences of several diseases have been already described in the literature, studies in the area of hyperacusis are still scant. Despite the fact that hyperacusis is a condition that severely affects the patient's quality of life, it is not well investigated; a comprehensive understanding of its features, eventually including gender differences, could be a valuable asset in developing clinical intervention strategies.

AIM

To evaluate gender differences among subjects affected by hyperacusis.

METHODS

A literature search was conducted focused on adult patients presenting hyperacusis, using the MedLine bibliographic database. Relevant peer-reviewed studies, published in the last 20 years, were sought. A total of 259 papers have been identified, but only 4 met the inclusion criteria. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.

RESULTS

The four selected papers included data from 604 patients; of these, 282 subjects resulted as affected by hyperacusis (125 females and 157 males). Questionnaires for analyzing factors affecting the attentional, social and emotional variance of hyperacusis (such as VAS, THI, TSCH, MASH) were administered to all included subjects. The data suggest that there are no hyperacusis gender-specific differences in the assessed population samples.

CONCLUSIONS

The literature data suggest that males and females exhibit a similar level of hyperacusis. However, in light of the subjective nature of this condition, the eventual set up of further tests to assess hyperacusis features could be very helpful in the near future.

Improving Audiology Student Training by Clinical Simulation of Tinnitus: A Glimpse of the Lived Experience of Tinnitus

PURPOSE

Student audiology training in tinnitus evaluation and management is heterogeneous and has been found to be insufficient. We designed a new clinical simulation laboratory for training students on psychoacoustic measurements of tinnitus: one student plays the role of the tinnitus patient, wearing a device producing a sound like tinnitus on one ear, while another student plays the role of the audiologist, evaluating their condition. The objective of the study was to test this new clinical simulation laboratory of tinnitus from the perspective of the students.

METHOD

This study reports the findings from twenty-one audiology students (20 female and 1 male, mean age = 29, SD = 7.7) who participated in this laboratory for a mandatory audiology class at the Laval University of Quebec. Three students had hearing loss (one mild, two moderate). All students played the role of both the clinician and the patient, alternately. They also had to fill out a questionnaire about their overall experience of the laboratory.

RESULTS

The qualitative analysis revealed three main themes: "Benefits of the laboratory on future practice", "Barriers and facilitators of the psychoacoustic assessment", and "Awareness of living with tinnitus". The participants reported that this experience would have a positive impact on their ability to manage tinnitus patients in their future career.

CONCLUSION

This fast, cheap, and effective clinical simulation method could be used by audiology and other healthcare educators to strengthen students' skills and confidence in tinnitus evaluation and management. The protocol is made available to all interested parties.

Acoustic deprivation modulates central gain in human auditory brainstem and cortex

Beyond reduced audibility, there is convincing evidence that the auditory system adapts according to the principles of homeostatic plasticity in response to a hearing loss. Such compensatory changes include modulation of central auditory gain mechanisms. Earplugging is a common experimental method that has been used to introduce a temporary, reversible hearing loss that induces changes consistent with central gain modulation. In the present study, young, normal-hearing adult participants wore a unilateral earplug for two weeks, during which we measured changes in the acoustic reflex threshold (ART), loudness perception, and cortically-evoked (40 Hz) auditory steady-state response (ASSR) to assess potential modulation in central gain with reduced peripheral input. The ART decreased on average by 8 to 10 dB during the treatment period, with modest increases in loudness perception after one week but not after two weeks of earplug use. Significant changes in both the magnitude and hemispheric laterality of source-localized cortical ASSR measures revealed asymmetrical changes in stimulus-driven cortical activity over time. The ART results following unilateral earplugging are consistent with the literature and suggest that homeostatic plasticity is evident in the brainstem. The novel findings from the cortical ASSR in the present study indicates that reduced peripheral input induces adaptive homeostatic plasticity reflected as both an increase in central gain in the auditory brainstem and reduced cortical activity ipsilateral to the deprived ear. Both the ART and the novel use of the 40-Hz ASSR provide sensitive measures of central gain modulation in the brainstem and cortex of young, normal hearing listeners, and thus may be useful in future studies with other clinical populations.

Combined evaluation of audiology examination and self-reported symptoms in patients with hyperacusis

To investigate the application of combined audiological examination and a self-reported symptoms survey in the evaluation of hyperacusis. Patients who visited the outpatient department of Otolaryngology Head and Neck Surgery and Otological medicine, Affiliated Hospital of Southwest Medical University, from January 2019 to March 2021 were divided into a hyperacusis group and a normal control group. We measured the loudness discomfort level (LDL) and hearing threshold (HT) of the subjects and investigated their self-reported symptoms. We compared the demographic characteristics, loudness discomfort level, and hearing threshold of the two groups and analyzed the self-reported symptoms and audiological characteristics of hyperacusis. We considered 87 subjects, comprising 40 patients with hyperacusis and 47 healthy individuals. Among the hyperacusis patients, bilateral disease was predominant. Among them, 33 were females, 23 had hearing loss, and 20 had tinnitus. Patients are mainly in the 21-60 age group. Patients with hyperacusis had low discomfort thresholds at all frequencies except 500 Hz (P ≤ 0.05, mean LDL decreased by 6.14-1.37 dB HL for all frequencies). The incidences of feeling upset, pain, and anxiety or fear were 95%, 65%, and 82.5%, respectively, in patients with hyperacusis. The severity of symptoms varies between patients with hyperacusis and healthy individuals. A combination of LDL measurements and self-reported symptom surveys allows for an accurate and comprehensive assessment of hyperacusis.Trial registration: This study was retrospectively registered (TRN: ChiCTR2100047391) on June 13, 2021.

Towards a psychological framework on time perception in patients with chronic tinnitus

Although disabling tinnitus is a chronic auditory phantom sensation, current knowledge on time perception (i.e., subjective time) in sufferers is limited and unsystematic. This theoretical analysis provides a first approach to this topic, highlighting the heterogeneity of time perception in humans as shown in various research areas. This heterogeneity is inherently related to goal attainment. Our immediate perception of time is restricted to present moment and recent past, whereas our sense of time is mostly future-oriented and represented as our past in a mental time line. The heterogeneity of time translates into a tension between anticipated changes one wants to see happen and full commitment that is required to goal attainment. Tinnitus sufferers are intensely aware of this tension in their self-perception. Their most compelling desire is that they no longer perceive tinnitus, but they get closer to this goal only by avoiding to put all their thoughts into it. Our analysis provides new perspectives on acceptance of tinnitus in relation to this time paradox. Building on the Tolerance model and the role of self-awareness in time perception, we contend that the main way for patients to gain long-term self-confidence is to engage in the present moment. Attention to this attitude is obscured in chronic sufferers by worries and ruminations associated with the ongoing presence of tinnitus. We provide arguments that time perception is a social perception, emphasizing the role of rewarding interactions in helping sufferers to overcome the feeling of being prevented from living in the moment. In the course of improvement towards acceptance, different changes in time perception are hypothesized that promote individuals' disengagement from unattainable goal (i.e., tinnitus suppression). A framework for future research is proposed, which distinguishes individuals' behaviors and associated emotions in relation to the time paradox.

Developmental spontaneous activity promotes formation of sensory domains, frequency tuning and proper gain in central auditory circuits

Neurons that process sensory information exhibit bursts of electrical activity during development, providing early training to circuits that will later encode similar features of the external world. In the mammalian auditory system, this intrinsically generated activity emerges from the cochlea prior to hearing onset, but its role in maturation of auditory circuitry remains poorly understood. We show that selective suppression of cochlear supporting cell spontaneous activity disrupts patterned burst firing of central auditory neurons without affecting cell survival or acoustic thresholds. However, neurons in the inferior colliculus of these mice exhibit enhanced acoustic sensitivity and broader frequency tuning, resulting in wider isofrequency laminae. Despite this enhanced neural responsiveness, total tone-responsive regions in the auditory cortex are substantially smaller. Thus, disruption of pre-hearing cochlear activity causes profound changes in neural encoding of sound, with important implications for restoration of hearing in individuals who experience reduced activity during this critical developmental period.

Neural signatures of auditory hypersensitivity following acoustic trauma

Neurons in sensory cortex exhibit a remarkable capacity to maintain stable firing rates despite large fluctuations in afferent activity levels. However, sudden peripheral deafferentation in adulthood can trigger an excessive, non-homeostatic cortical compensatory response that may underlie perceptual disorders including sensory hypersensitivity, phantom limb pain, and tinnitus. Here, we show that mice with noise-induced damage of the high-frequency cochlear base were behaviorally hypersensitive to spared mid-frequency tones and to direct optogenetic stimulation of auditory thalamocortical neurons. Chronic two-photon calcium imaging from ACtx pyramidal neurons (PyrNs) revealed an initial stage of spatially diffuse hyperactivity, hyper-correlation, and auditory hyperresponsivity that consolidated around deafferented map regions three or more days after acoustic trauma. Deafferented PyrN ensembles also displayed hypersensitive decoding of spared mid-frequency tones that mirrored behavioral hypersensitivity, suggesting that non-homeostatic regulation of cortical sound intensity coding following sensorineural loss may be an underlying source of auditory hypersensitivity. Excess cortical response gain after acoustic trauma was expressed heterogeneously among individual PyrNs, yet 40% of this variability could be accounted for by each cell's baseline response properties prior to acoustic trauma. PyrNs with initially high spontaneous activity and gradual monotonic intensity growth functions were more likely to exhibit non-homeostatic excess gain after acoustic trauma. This suggests that while cortical gain changes are triggered by reduced bottom-up afferent input, their subsequent stabilization is also shaped by their local circuit milieu, where indicators of reduced inhibition can presage pathological hyperactivity following sensorineural hearing loss.

Silk Fibroin-Based Biomaterials for Tissue Engineering Applications

Tissue engineering (TE) involves the combination of cells with scaffolding materials and appropriate growth factors in order to regenerate or replace damaged and degenerated tissues and organs. The scaffold materials serve as templates for tissue formation and play a vital role in TE. Among scaffold materials, silk fibroin (SF), a naturally occurring protein, has attracted great attention in TE applications due to its excellent mechanical properties, biodegradability, biocompatibility, and bio-absorbability. SF is usually dissolved in an aqueous solution and can be easily reconstituted into different forms, including films, mats, hydrogels, and sponges, through various fabrication techniques, including spin coating, electrospinning, freeze drying, and supercritical CO₂-assisted drying. Furthermore, to facilitate the fabrication of more complex SF-based scaffolds, high-precision techniques such as micro-patterning and bio-printing have been explored in recent years. These processes contribute to the diversity of surface area, mean pore size, porosity, and mechanical properties of different silk fibroin scaffolds and can be used in various TE applications to provide appropriate morphological and mechanical properties. This review introduces the physicochemical and mechanical properties of SF and looks into a range of SF-based scaffolds that have recently been developed. The typical applications of SF-based scaffolds for TE of bone, cartilage, teeth and mandible tissue, cartilage, skeletal muscle, and vascular tissue are highlighted and discussed followed by a discussion of issues to be addressed in future studies.

Review: Neural Mechanisms of Tinnitus and Hyperacusis in Acute Drug-Induced Ototoxicity

Purpose Tinnitus and hyperacusis are debilitating conditions often associated with age-, noise-, and drug-induced hearing loss. Because of their subjective nature, the neural mechanisms that give rise to tinnitus and hyperacusis are poorly understood. Over the past few decades, considerable progress has been made in deciphering the biological bases for these disorders using animal models. Method Important advances in understanding the biological bases of tinnitus and hyperacusis have come from studies in which tinnitus and hyperacusis are consistently induced with a high dose of salicylate, the active ingredient in aspirin. Results Salicylate induced a transient hearing loss characterized by a reduction in otoacoustic emissions, a moderate cochlear threshold shift, and a large reduction in the neural output of the cochlea. As the weak cochlear neural signals were relayed up the auditory pathway, they were progressively amplified so that the suprathreshold neural responses in the auditory cortex were much larger than normal. Excessive central gain (neural amplification), presumably resulting from diminished inhibition, is believed to contribute to hyperacusis and tinnitus. Salicylate also increased corticosterone stress hormone levels. Functional imaging studies indicated that salicylate increased spontaneous activity and enhanced functional connectivity between structures in the central auditory pathway and regions of the brain associated with arousal (reticular formation), emotion (amygdala), memory/spatial navigation (hippocampus), motor planning (cerebellum), and motor control (caudate/putamen). Conclusion These results suggest that tinnitus and hyperacusis arise from aberrant neural signaling in a complex neural network that includes both auditory and nonauditory structures.

Prevalence of Hyperacusis in the General and Special Populations: A Scoping Review

Objectives: To study the prevalence of hyperacusis in the general population and the special population, and to determine the effect of population differences on hyperacusis.

Methods: The two authors followed a scoping review methodology and screened nearly 30 years of English literature in Pubmed, Web of Science, OVID, and EBSCO. Then, the extracted results of each study were discussed in groups and subgroups.

Results: The authors selected 42 pieces of scientific literature that met the requirements, studying a total of 34,796 subjects, including the general population (28,425 subjects), the special occupation population (2,746 subjects), and the patients with concomitant diseases (5,093 subjects). The prevalence was 0.2–17.2% in the general population, 3.8–67% in the special occupation population, and 4.7–95% in the patients with special diseases. It was found that in the general population, the high prevalence occurs in adolescents and older adults. The prevalence of hyperacusis in women is significantly higher than in men. In people with hearing disorders, the prevalence of hyperacusis is significantly higher than in people with normal hearing. Various diseases (such as Williams syndrome, tinnitus, and autism), as well as various occupations (musicians, music students, teachers, and others), have been found to be high risk factors for hyperacusis.

Conclusion: The high prevalence of hyperacusis and the large differences between reported prevalence in different studies deserves our great attention. Additionally, in order to increase the comparability of the studies, a standardized set of criteria are needed to study the prevalence of hyperacusis.

Large-scale collaboration in ENIGMA-EEG: A perspective on the meta-analytic approach to link neurological and psychiatric liability genes to electrophysiological brain activity

BACKGROUND AND PURPOSE

The ENIGMA-EEG working group was established to enable large-scale international collaborations among cohorts that investigate the genetics of brain function measured with electroencephalography (EEG). In this perspective, we will discuss why analyzing the genetics of functional brain activity may be crucial for understanding how neurological and psychiatric liability genes affect the brain.

METHODS

We summarize how we have performed our currently largest genome-wide association study of oscillatory brain activity in EEG recordings by meta-analyzing the results across five participating cohorts, resulting in the first genome-wide significant hits for oscillatory brain function located in/near genes that were previously associated with psychiatric disorders. We describe how we have tackled methodological issues surrounding genetic meta-analysis of EEG features. We discuss the importance of harmonizing EEG signal processing, cleaning, and feature extraction. Finally, we explain our selection of EEG features currently being investigated, including the temporal dynamics of oscillations and the connectivity network based on synchronization of oscillations.

RESULTS

We present data that show how to perform systematic quality control and evaluate how choices in reference electrode and montage affect individual differences in EEG parameters.

CONCLUSION

The long list of potential challenges to our large-scale meta-analytic approach requires extensive effort and organization between participating cohorts; however, our perspective shows that these challenges are surmountable. Our perspective argues that elucidating the genetic of EEG oscillatory activity is a worthwhile effort in order to elucidate the pathway from gene to disease liability.

Prevalence of Hyperacusis and Its Relation to Health: The Busselton Healthy Ageing Study

Importance

The prevalence of hyperacusis and its relationship with mental and general health is unknown in a nonclinical sample. Therefore, we aimed to determine the prevalence of hyperacusis and its relation with hearing, general and mental health in a population‐based study.

Study Design

Prospective population‐based study.

Material and Methods

This study uses data from the Busselton Healthy Ageing Study (BHAS). A sample of 5,107 eligible inhabitants aged 45 to 70 years completed a detailed questionnaire and a clinical assessment. A positive answer to “Do you consider yourself sensitive or intolerant to everyday sounds” was used to indicate hyperacusis. Logistic regression was used to examine the association between hearing, mental and general health factors, and hyperacusis.

Results

Of 5,107 participants, 775 (15.2%) reported hyperacusis. The majority of participants with hyperacusis reported an occasional effect on daily life (72.0%). Being female, older in age, having a lower income, physical or mental health difficulties, more severe hearing loss, and tinnitus were all associated with the presence of hyperacusis. Individuals who experience hearing impairment, poorer general or mental health have a higher possibility of hyperacusis having an effect on their daily life.

Conclusions

In this community population‐based cohort study, we found a prevalence of hyperacusis of 15.2%. Individuals with hearing loss, mental health problems, and lower physical health have a higher possibility of experiencing effects on their daily life associated with their hyperacusis. Unravelling the relationship between hyperacusis hearing, general and mental health can be of major importance for a better understanding of the condition and its consequences.

Level of Evidence

2 Laryngoscope, 131:E2887–E2896, 2021

Simulated transient hearing loss improves auditory sensitivity

Recently, it was proposed that a processing principle called adaptive stochastic resonance plays a major role in the auditory system, and serves to maintain optimal sensitivity even to highly variable sound pressure levels. As a side effect, in case of reduced auditory input, such as permanent hearing loss or frequency specific deprivation, this mechanism may eventually lead to the perception of phantom sounds like tinnitus or the Zwicker tone illusion. Using computational modeling, the biological plausibility of this processing principle was already demonstrated. Here, we provide experimental results that further support the stochastic resonance model of auditory perception. In particular, Mongolian gerbils were exposed to moderate intensity, non-damaging long-term notched noise, which mimics hearing loss for frequencies within the notch. Remarkably, the animals developed significantly increased sensitivity, i.e. improved hearing thresholds, for the frequency centered within the notch, but not for frequencies outside the notch. In addition, most animals treated with the new paradigm showed identical behavioral signs of phantom sound perception (tinnitus) as animals with acoustic trauma induced tinnitus. In contrast, animals treated with broadband noise as a control condition did not show any significant threshold change, nor behavioral signs of phantom sound perception.

A Phenotypic Comparison of Loudness and Pain Hyperacusis: Symptoms, Comorbidity, and Associated Features in a Multinational Patient Registry

Purpose Hyperacusis is a complex and poorly understood auditory disorder characterized by decreased tolerance to sound at levels that would not trouble most individuals. Recently, it has been suggested that individuals who experience otalgia in response to everyday sounds (termed pain hyperacusis) may differ clinically from those whose primary symptom is the perception of everyday sounds as excessively loud (termed loudness hyperacusis). Despite this theoretical distinction, there have been no empirical studies directly comparing these two populations of hyperacusis patients. Method Using data from a multinational patient registry (the Coordination of Rare Diseases at Sanford Registry), we examined self-reported demographics, symptoms, comorbidity, and response to treatment in a sample of 243 adults with hyperacusis, 152 of whom were classified as having pain hyperacusis based on reported symptoms. Bayesian statistical tests were used to investigate both the presence and absence of group differences between patients with loudness and pain hyperacusis. Results Individuals with pain hyperacusis presented with a more severe clinical phenotype, reporting a higher frequency of temporary symptom exacerbations (i.e., "setbacks"), less perceived symptom improvement over time, more severe comorbid headache disorders, and reduced benefit from sound therapy. However, the two hypothesized hyperacusis subtypes exhibited more similarities than differences, with the majority of symptoms and comorbidities being equally prevalent across groups. Multiple comorbidities were commonly observed, including tinnitus, primary headache disorders, psychiatric disorders, and functional somatic syndromes. Intolerance of sensory stimuli in other modalities was also frequently reported. Conclusion Although this study provides little evidence that loudness and pain hyperacusis are pathophysiologically distinct conditions, our findings indicate that a pain-predominant phenotype may be a meaningful prognostic marker in patients with hyperacusis.

Hearing loss and brain plasticity: the hyperactivity phenomenon

Many aging adults experience some form of hearing problems that may arise from auditory peripheral damage. However, it has been increasingly acknowledged that hearing loss is not only a dysfunction of the auditory periphery but also results from changes within the entire auditory system, from periphery to cortex. Damage to the auditory periphery is associated with an increase in neural activity at various stages throughout the auditory pathway. Here, we review neurophysiological evidence of hyperactivity, auditory perceptual difficulties that may result from hyperactivity, and outline open conceptual and methodological questions related to the study of hyperactivity. We suggest that hyperactivity alters all aspects of hearing-including spectral, temporal, spatial hearing-and, in turn, impairs speech comprehension when background sound is present. By focusing on the perceptual consequences of hyperactivity and the potential challenges of investigating hyperactivity in humans, we hope to bring animal and human electrophysiologists closer together to better understand hearing problems in older adulthood.

Tinnitus and Neuropsychological Dysfunction in the Elderly: A Systematic Review on Possible Links

INTRODUCTION

Tinnitus is a common and disabling symptom often associated with hearing loss. While clinical practice frequently shows that a certain degree of psychological discomfort often characterizes tinnitus suffers, it has been recently suggested in adults as a determining factor for cognitive decline affecting attention and memory domains. The aim of our systematic review was to provide evidence for a link between tinnitus, psychological distress, and cognitive dysfunction in older patients and to focus on putative mechanisms of this relationship.

METHODS

We performed a systematic review, finally including 192 articles that were screened. This resulted in 12 manuscripts of which the full texts were included in a qualitative analysis.

RESULTS

The association between tinnitus and psychological distress, mainly depression, has been demonstrated in older patients, although only few studies addressed the aged population. Limited studies on cognitive dysfunction in aged patients affected by chronic tinnitus are hardly comparable, as they use different methods to validate cognitive impairment. Actual evidence does not allow us with certainty to establish if tinnitus matters as an independent risk factor for cognitive impairment or evolution to dementia.

CONCLUSION

Tinnitus, which is usually associated with age-related hearing loss, might negatively affect emotional wellbeing and cognitive capacities in older people, but further studies are required to improve the evidence.

A contribution to the debate on tinnitus definition

Tinnitus is generally defined as an auditory perception in the absence of environmental sound stimulation. However, this definition is quite incomplete as it omits an essential aspect, the patient's point of view. This point of view constitutes, first and foremost, a global and unified lived experience, which is not only sensory (localization, loudness, pitch and tone), but also cognitive (thoughts, attentiveness, behaviors) and emotional (discomfort, suffering). This experience can be lived in a very unpleasant way and consequently have a very negative impact on quality of life. This article proposes and justifies a new definition for tinnitus elaborated by a group of French clinicians and researchers, which is more in line with its phenomenology. It also provides a minimum knowledge base, including possibilities for clinical care, hoping to eradicate all misinformation, misconceptions and inappropriate attitudes or practices toward this condition. Here is the short version of our definition: Tinnitus is an auditory sensation without an external sound stimulation or meaning, which can be lived as an unpleasant experience, possibly impacting quality of life.

What's the buzz? The neuroscience and the treatment of tinnitus

Tinnitus is a pervasive public health issue that affects ∼15% of the United States population. Similar estimates have also been shown on a global scale, with similar prevalence found in Europe, Asia, and Africa. The severity of tinnitus is heterogeneous, ranging from mildly bothersome to extremely disruptive. In the United States, ∼10-20% of individuals who experience tinnitus report symptoms that severely reduce their quality of life. Due to the huge personal and societal burden, in the last 20 yr a concerted effort on basic and clinical research has significantly advanced our understanding and treatment of this disorder. Yet, neither full understanding, nor cure exists. We know that tinnitus is the persistent involuntary phantom percept of internally generated nonverbal indistinct noises and tones, which in most cases is initiated by acquired hearing loss and maintained only when this loss is coupled with distinct neuronal changes in auditory and extra-auditory brain networks. Yet, the exact mechanisms and patterns of neural activity that are necessary and sufficient for the perceptual generation and maintenance of tinnitus remain incompletely understood. Combinations of animal model and human research will be essential in filling these gaps. Nevertheless, the existing progress in investigating the neurophysiological mechanisms has improved current treatment and highlighted novel targets for drug development and clinical trials. The aim of this review is to thoroughly discuss the current state of human and animal tinnitus research, outline current challenges, and highlight new and exciting research opportunities.

Co-occurrence of Hyperacusis Accelerates With Tinnitus Burden Over Time and Requires Medical Care

Although tinnitus represents a major global burden, no causal therapy has yet been established. Ongoing controversies about the neuronal pathophysiology of tinnitus hamper efforts in developing advanced therapies. Hypothesizing that the unnoticed co-occurrence of hyperacusis and differences in the duration of tinnitus may possibly differentially influence the neural correlate of tinnitus, we analyzed 33 tinnitus patients without (T-group) and 20 tinnitus patients with hyperacusis (TH-group). We found crucial differences between the T-group and the TH-group in the increase of annoyance, complaints, tinnitus loudness, and central neural gain as a function of tinnitus duration. Hearing thresholds did not differ between T-group and TH-group. In the TH-group, the tinnitus complaints (total tinnitus score) were significantly greater from early on and the tinnitus intensity distinctly increased over time from ca. 12 to 17 dB when tinnitus persisted more than 5 years, while annoyance responses to normal sound remained nearly constant. In contrast, in the T-group tinnitus complaints remained constant, although the tinnitus intensity declined over time from ca. 27 down to 15 dB beyond 5 years of tinnitus persistence. This was explained through a gradually increased annoyance to normal sound over time, shown by a hyperacusis questionnaire. Parallel a shift from a mainly unilateral (only 17% bilateral) to a completely bilateral (100%) tinnitus percept occurred in the T-group, while bilateral tinnitus dominated in the TH-group from the start (75%). Over time in the T-group, ABR wave V amplitudes (and V/I ratios) remained reduced and delayed. By contrast, in the TH-group especially the ABR wave III and V (and III/I ratio) continued to be enhanced and shortened in response to high-level sound stimuli. Interestingly, in line with signs of an increased co-occurrence of hyperacusis in the T-group over time, ABR wave III also slightly increased in the T-group. The findings disclose an undiagnosed co-occurrence of hyperacusis in tinnitus patients as a main cause of distress and the cause of complaints about tinnitus over time. To achieve urgently needed and personalized therapies, possibly using the objective tools offered here, a systematic sub-classification of tinnitus and the co-occurrence of hyperacusis is recommended.

The stochastic resonance model of auditory perception: A unified explanation of tinnitus development, Zwicker tone illusion, and residual inhibition

Stochastic resonance (SR) has been proposed to play a major role in auditory perception, and to maintain optimal information transmission from the cochlea to the auditory system. By this, the auditory system could adapt to changes of the auditory input at second or even sub-second timescales. In case of reduced auditory input, somatosensory projections to the dorsal cochlear nucleus would be disinhibited in order to improve hearing thresholds by means of SR. As a side effect, the increased somatosensory input corresponding to the observed tinnitus-associated neuronal hyperactivity is then perceived as tinnitus. In addition, the model can also explain transient phantom tone perceptions occurring after ear plugging, or the Zwicker tone illusion. Vice versa, the model predicts that via stimulation with acoustic noise, SR would not be needed to optimize information transmission, and hence somatosensory noise would be tuned down, resulting in a transient vanishing of tinnitus, an effect referred to as residual inhibition.

Modulation of hyperacusis and tinnitus loudness in tinnitus patients with and without hearing loss following 3 weeks of acoustic stimulation: A proof-of-concept study

Tinnitus and hyperacusis are two debilitating conditions that are highly comorbid. It has been postulated that they may originate from similar pathophysiological mechanisms such as an increase in central gain. Interestingly, sound stimulation has been shown to reduce central gain and is currently used for the treatment of both conditions. This study investigates the effect of sound stimulation on both tinnitus and hyperacusis in the same patients. Two distinct series of tinnitus participants were tested: one with normal or near-normal hearing (n=16) and one with hearing loss (n=14). A broadband noise shaped to cover most of the tinnitus frequency spectrum was delivered through hearing aids using the noise generator feature (no amplification) and verified through real-ear measurements. Participants received sound stimulation for 3 weeks and were tested before (at baseline), then after 1 week and at the end of the 3 weeks of sound stimulation. There was also a 1-month follow-up after the end of the stimulation protocol. The measurements included self-reported measures of tinnitus and hyperacusis (VAS), validated questionnaires (THI, HQ) and psychoacoustic measurements (tinnitus battery and loudness functions). On both self-assessment (VAS of sound tolerance and tinnitus loudness) and psychoacoustic measures (loudness function and tinnitus loudness in dB), about 50% of tinnitus participants had a synchronous (either a decrease or an increase) modulation of hyperacusis and tinnitus loudness after 1 week and 3 weeks of acoustic stimulation and up to about 70% of participants at 1-M follow-up. The decrease of hyperacusis and tinnitus loudness was more prevalent in normal-hearing participants. There was a significant increase in tinnitus loudness during and following the stimulation in the group with hearing loss. Hyperacusis improvement as assessed by loudness function was significantly correlated with the intensity level of the acoustic stimulation (dB level of the noise produced by the noise generator) in tinnitus participants with normal/near-normal hearing thresholds. Our study partly supports the central gain hypothesis by showing synchronous modulation of hyperacusis and tinnitus loudness. It also shows beneficial effects of acoustic stimulation in some tinnitus individuals, in particular those with normal or near-normal hearing, while highlighting the importance of a careful fitting of sound generators to prevent increase. Since the amplification feature was not turned on in our study, future work should determine whether amplification alone, or in addition to acoustic stimulation (sound generators), would benefit to those with hearing loss.

A review of decreased sound tolerance in autism: Definitions, phenomenology, and potential mechanisms

Atypical behavioral responses to environmental sounds are common in autistic children and adults, with 50-70 % of this population exhibiting decreased sound tolerance (DST) at some point in their lives. This symptom is a source of significant distress and impairment across the lifespan, contributing to anxiety, challenging behaviors, reduced community participation, and school/workplace difficulties. However, relatively little is known about its phenomenology or neurocognitive underpinnings. The present article synthesizes a large body of literature on the phenomenology and pathophysiology of DST-related conditions to generate a comprehensive theoretical account of DST in autism. Notably, we argue against conceptualizing DST as a unified construct, suggesting that it be separated into three phenomenologically distinct conditions: hyperacusis (the perception of everyday sounds as excessively loud or painful), misophonia (an acquired aversive reaction to specific sounds), and phonophobia (a specific phobia of sound), each responsible for a portion of observed DST behaviors. We further elaborate our framework by proposing preliminary neurocognitive models of hyperacusis, misophonia, and phonophobia that incorporate neurophysiologic findings from studies of autism.

Electrophysiological assessment and pharmacological treatment of blast-induced tinnitus

Tinnitus, the phantom perception of sound, often occurs as a clinical sequela of auditory traumas. In an effort to develop an objective test and therapeutic approach for tinnitus, the present study was performed in blast-exposed rats and focused on measurements of auditory brainstem responses (ABRs), prepulse inhibition of the acoustic startle response, and presynaptic ribbon densities on cochlear inner hair cells (IHCs). Although the exact mechanism is unknown, the “central gain theory” posits that tinnitus is a perceptual indicator of abnormal increases in the gain (or neural amplification) of the central auditory system to compensate for peripheral loss of sensory input from the cochlea. Our data from vehicle-treated rats supports this rationale; namely, blast-induced cochlear synaptopathy correlated with imbalanced elevations in the ratio of centrally-derived ABR wave V amplitudes to peripherally-derived wave I amplitudes, resulting in behavioral evidence of tinnitus. Logistic regression modeling demonstrated that the ABR wave V/I amplitude ratio served as a reliable metric for objectively identifying tinnitus. Furthermore, histopathological examinations in blast-exposed rats revealed tinnitus-related changes in the expression patterns of key plasticity factors in the central auditory pathway, including chronic loss of Arc/Arg3.1 mobilization. Using a formulation of N-acetylcysteine (NAC) and disodium 2,4-disulfophenyl-N-tert-butylnitrone (HPN-07) as a therapeutic for addressing blast-induced neurodegeneration, we measured a significant treatment effect on preservation or restoration of IHC ribbon synapses, normalization of ABR wave V/I amplitude ratios, and reduced behavioral evidence of tinnitus in blast-exposed rats, all of which accorded with mitigated histopathological evidence of tinnitus-related neuropathy and maladaptive neuroplasticity.

A Delphi survey to determine a definition and description of hyperacusis by clinician consensus

OBJECTIVE

There is currently no singularly accepted definition of hyperacusis. The aim of this study was to determine a definition and description of hyperacusis by clinician consensus.

DESIGN

A three-round Delphi survey involving hearing healthcare professionals built towards clinical consensus on a definition of hyperacusis. Round 1 involved three open-ended questions about hyperacusis. Seventy-nine statements were generated on descriptions, impact, sounds, and potential features of hyperacusis. Agreement on the relevance of each statement to defining or describing hyperacusis was then measured in Rounds 2 and 3. General consensus was defined a priori as ≥70% agreement, or ≥90 for clinical decision making.

STUDY SAMPLE

Forty-five hearing healthcare professionals were recruited to take part in this study. Forty-one completed Round 1, 36 completed Round 2, and 33 completed Round 3.

RESULTS

Consensus was reached on 42/79 statements. From these a consensus definition includes "A reduced tolerance to sound(s) that are perceived as normal to the majority of the population or were perceived as normal to the person before their onset of hyperacusis". A consensus description of hyperacusis was also determined.

CONCLUSIONS

This consensus definition of hyperacusis will help to determine the scope of clinical practice guidelines and influence needed research on hyperacusis.

A psychoacoustic test for diagnosing hyperacusis based on ratings of natural sounds

Hyperacusis is defined as an increased sensitivity to sounds, i.e. sounds presented at moderate levels can produce discomfort or even pain. Existing diagnostic methods, like the Hyperacusis Questionnaire (HQ) and Loudness Discomfort Levels (LDLs), have been challenged because of their variability and lack of agreement on appropriate cut-off values. We propose a novel approach by using psychoacoustic ratings of natural sounds as an assessment tool for hyperacusis. Subjects (n = 81) were presented with natural and artificial (tone pips, noises) sounds (n = 69) in a controlled environment at four sound levels (60, 70, 80 and 90 dB SPL). The task was to rate them on a pleasant to unpleasant visual analog scale. The inherent challenge of this study was to create a new diagnostic tool when no gold standard of hyperacusis diagnosis exists. We labeled our subjects as hyperacusic (n = 26) when they were diagnosed as such by at least two of three methods (HQ, LDLs and self-report). There was a significant difference between controls (n = 23) and hyperacusics in the median global rating of pleasant sounds. Median global ratings of unpleasant sounds and artificial sounds did not differ significantly. Then we selected the subset of sounds that could best discriminate the controls from the hyperacusics, the Core Discriminant Sounds (CDS), and we used them to develop a new metric: The CDS score. A normalized global score and a score for each sound level can be computed with respect to a control population without hyperacusis. A receiver operating characteristic analysis showed that the accuracy of our method in distinguishing subjects with and without complaints of hyperacusis (86%, 95% Confidence Interval (CI): 76-93%) is comparable to that of existing methods such as the LDL (77%, CI: 67-86%) and the HQ (80%, CI: 69-88%). We believe that the CDS score is more relevant to subject's complaints than LDLs and that it could be applied in a clinical environment in a fast and effective way, while minimizing discomfort and biases.

Hyperexcitability of the Nucleus Accumbens Is Involved in Noise-Induced Hyperacusis

Reduced tolerance to sound stimuli (hyperacusis) is commonly seen in tinnitus patients. Dysfunction of limbic systems, such as the nucleus accumbens (NAc), may be involved in emotional reactions to the sound stimuli in tinnitus patients. To study the functional changes in the NAc in hyperacusis, we have examined the neural activity changes of the NAc using c-Fos staining in an animal model of hyperacusis. The c-Fos staining was also examined in the medial geniculate nucleus (MGN), a central auditory pathway which has neural projections to the NAc. Postnatal rats (14 days) were exposed to loud noise (115 dB SPL, 4 hours for two consecutive days) to induce hyperacusis (n = 4). Rats without noise exposure were used as the controls (n = 4). After P35, rats in both groups were put in a behavioral training for sound detection. After they were trained to detect sound stimuli, their reaction time to noise bursts centered at 2 kHz (40-110 dB SPL) was measured. Rats in the noise group showed a significantly shorter reaction time than those in the control group to the noise bursts at high intensities, suggesting the noise exposure induced hyperacusis behavior. The c-Fos expressions in the NAc and the MGNs of the noise group were significantly higher than those of the control group. Our results suggested that early-age noise exposure caused hyperactivity in the NAc and the MGNs which may induce the loudness increase in these rats.

Maximum Expected Information Approach for Improving Efficiency of Categorical Loudness Scaling

Categorical loudness scaling (CLS) measures provide useful information about an individual's loudness perception across the dynamic range of hearing. A probability model of CLS categories has previously been described as a multi-category psychometric function (MCPF). In the study, a representative "catalog" of potential listener MCPFs was used in conjunction with maximum-likelihood estimation to derive CLS functions for participants with normal hearing and with hearing loss. The approach of estimating MCPFs for each listener has the potential to improve the accuracy of the CLS measurements, particularly when a relatively low number of data points are available. The present study extends the MCPF approach by using Bayesian inference to select stimulus parameters that are predicted to yield maximum expected information (MEI) during data collection. The accuracy and reliability of the MCPF-MEI approach were compared to the standardized CLS measurement procedure (ISO 16832:2006, 2006). A non-adaptive, fixed-level, paradigm served as a "gold-standard" for this comparison. The test time required to obtain measurements in the standard procedure is a major barrier to its clinical uptake. Test time was reduced from approximately 15 min to approximately 3 min with the MEI-adaptive procedure. Results indicated that the test-retest reliability and accuracy of the MCPF-MEI adaptive procedures were similar to the standardized CLS procedure. Computer simulations suggest that the reliability and accuracy of the MEI procedure were limited by intrinsic uncertainty of the listeners represented in the MCPF catalog. In other words, the MCPF provided insufficient predictive power to significantly improve adaptive-tracking efficiency under practical conditions. Concurrent optimization of both the MCPF catalog and the MEI-adaptive procedure have the potential to produce better results. Regardless of the adaptive-tracking method used in the CLS procedure, the MCPF catalog remains clinically useful for enabling maximum-likelihood determination of loudness categories.

Tinnitus and hyperacusis: Central noise, gain and variance

Tinnitus is a phantom auditory sensation in the absence of external sounds, while hyperacusis is an atypical sensitivity to external sounds that leads them to be perceived as abnormally loud or even painful. Both conditions may reflect the brain's over-compensation for reduced input from the ear. The present work differentiates between two compensation models: The additive central noise compensates for hearing loss and is likely to generate tinnitus, whereas the multiplicative central gain compensates for hidden hearing loss and is likely to generate hyperacusis. Importantly, both models predict increased variance in central representations of sounds, especially a nonlinear increase in variance by the central gain. The increased central variance limits the amount of central compensation and reduces temporal synchrony, which can explain the insufficient central gain reported in the literature. Future studies need to collect trial-by-trial firing variance data so that the present variance-based model can be falsified.

Within-Subject Comparisons of the Auditory Brainstem Response and Uncomfortable Loudness Levels in Ears With and Without Tinnitus in Unilateral Tinnitus Subjects With Normal Audiograms

OBJECTIVE

To evaluate whether cochlear synaptopathy is a common pathophysiologic cause of tinnitus in individuals with normal audiograms.

STUDY DESIGN

Prospective study.

SETTING

Tertiary referral center.

METHODS

We enrolled 27 subjects with unilateral tinnitus and normal symmetric hearing thresholds, and 27 age- and sex-matched control subjects with normal symmetric hearing thresholds. We measured 1) the amplitudes of waves I and V with 90 dB nHL click stimuli in quiet conditions; 2) the latency shift of wave V with 80 dB nHL click stimuli in background noise, varying from 40 dB HL to 70 dB HL; and 3) uncomfortable loudness levels (UCLs) at 500 Hz and 3000 Hz pure tones.

RESULTS

There were no significant differences in the wave V/I amplitude ratio or the latency shift in wave V with increasing noise levels among the tinnitus ears (TEs), nontinnitus ears (NTEs), and control ears. There were no significant differences in UCLs at 500 Hz or 3000 Hz between TEs and NTEs, but the UCLs were lower in TEs (mean 111.3 dB or 104.1 dB) and NTEs (mean 109.4 dB or 100.6 dB) than in control ears (mean 117.9 dB or 114.1 dB, p < 0.017). No subject met our criteria for cochlear synaptopathy or increased central gain in terms of all three parameters.

CONCLUSION

Based on these results for UCL, increased central gain is a major mechanism of tinnitus in humans with normal audiograms. However, this compensatory mechanism for reduced auditory input may originate from other pathophysiologic factors rather than from cochlear synaptopathy.

A Novel Mouse Model of Aminoglycoside-Induced Hyperacusis and Tinnitus

Aminoglycosides (AG) such as amikacin are commonly used in cystic fibrosis patients with opportunistic pulmonary infections including multi-drug resistant mycobacterium tuberculous and non-tuberculous mycobacterium. Unfortunately, this class of drugs is known to cause peripheral damage to the cochlea leading to hearing loss that can fluctuate and become permanent over time or multiple exposures. However, whether amikacin can lead to central auditory dysfunction like hyperacusis (increased sensitivity to sound) or tinnitus (perception of sound in the absence of acoustic stimulation) is not well-described in the literature. Thus, an animal model needs to be developed that documents these side effects in order to develop therapeutic solutions to reduce AG-induced auditory dysfunction. Here we present pioneer work in mice which demonstrates that amikacin can lead to fluctuating behavioral evidence of hyperacusis and tinnitus as assessed by the acoustic startle reflex. Additionally, electrophysiological assessments of hearing via auditory brainstem response demonstrate increased central activity in the auditory brainstem. These data together suggest that peripheral AG-induced dysfunction can lead to central hyperactivity and possible behavioral manifestations of hyperacusis and tinnitus. Importantly, we demonstrate that ebselen, a novel investigational drug that acts as both an antioxidant and anti-inflammatory, can mitigate AG-induced hyperacusis.

An Empowerment Model for Individuals with Chronic Tinnitus

OBJECTIVE

This qualitative study sought to construct a model of empowerment for clinical implementation, based on the first-hand experience of a sample of individuals with chronic tinnitus.

DESIGN

The study was conducted in accordance with the inductive approach to data in classic grounded theory (GT). GT aims to build a model of behavior that accounts for the main concern of individuals and how they strive to resolve it. Twenty-one participants with chronic tinnitus (10 females, 11 males, age 31-85, mean: 57.6 years, mean duration of tinnitus: 12 years) were recruited through the patient association France Acouphènes and ENT consultations. Open-ended, tape-recorded interviews addressed the variation in the intrusiveness of tinnitus in daily life. A constant comparison analysis was undertaken to identify a core category and to distinguish stages in behavioral changes toward the tolerance of tinnitus.

RESULTS

Participants' main concern was to limit the intrusiveness of tinnitus day in, day out. They continuously had to handle tinnitus-induced frustration, which was found to be the core category of the analysis accounting for how all the participants tried to deal with the condition. The more they managed to handle their frustration, the better they coped with the condition. Three behavior patterns were identified as facilitating the ongoing management of tinnitus-induced frustration: (1) searching for perspective upon tinnitus; (2) maintaining order in perception despite its interference; and (3) alleviating conflict arising from social interactions. A model of empowerment is presented that is based on four stages toward tolerance of tinnitus. They are dominated by lack of perspective upon tinnitus (circuit 1), preservation of energy through attempts to control its intrusiveness (circuit 2), attempts to detach oneself from the interference of tinnitus through constant activities (circuit 3), and self-induced relief through the fulfillment of meaningful goals (circuit 4).

CONCLUSION

Tolerance of tinnitus requires finding balance between limiting one's social participation and spontaneity in carrying out meaningful activities. Tolerance can be enhanced by the preservation of one's energy and the mediating role of enjoyment through the fulfillment of gratifying goals. In patient counseling, it is essential to address the individual's desire for direct relief from tinnitus through its elimination. Individuals should be made aware that such a desire will likely be thwarted, resulting in the worsening of intrusiveness. Improvement in tolerance is accompanied by the attenuation of niggling self-awareness, a change that is typical of full commitment with valued goals and that helps in alleviating the interference of tinnitus. By understanding the role of frustration, individuals may develop a sense of responsibility in dealing with disabling tinnitus.

Fluctuations in Subjective Tinnitus Ratings Over Time: Implications for Clinical Research

OBJECTIVE

Patients with chronic, subjective tinnitus are often administered a battery of audiometric tests to characterize their tinnitus percept. Even a comprehensive battery, if applied just once, cannot capture fluctuations in tinnitus strength or quality over time. Moreover, subjects experience a learning curve when reporting the detailed characteristics of their tinnitus percept, such that a single assessment will reflect a lack of familiarity with test requirements. We addressed these challenges by programming an automated software platform for at-home tinnitus characterization over a 2-week period.

STUDY DESIGN

Prospective case series.

SETTING

Tertiary referral center, patients' homes.

INTERVENTIONS

Following an initial clinic visit, 25 subjects with chronic subjective tinnitus returned home with a tablet computer and calibrated headphones to complete questionnaires, hearing tests, and tinnitus psychoacoustic testing. We repeatedly characterized loudness discomfort levels and tinnitus matching over a 2-week period.

MAIN OUTCOME MEASURES

Primary outcomes included intrasubject variability in loudness discomfort levels, tinnitus intensity, and tinnitus acoustic matching over the course of testing.

RESULTS

Within-subject variability for all outcome measures could be reduced by approximately 25 to 50% by excluding initial measurements and by focusing only on tinnitus matching attempts where subjects report high confidence in the accuracy of their ratings.

CONCLUSIONS

Tinnitus self-report is inherently variable but can converge on reliable values with extended testing. Repeated, self-directed tinnitus assessments may have implications for identifying malingerers. Further, these findings suggest that extending the baseline phase of tinnitus characterizations will increase the statistical power for future studies focused on tinnitus interventions.

Hyperacusis and stapes surgery: An observation in fifty patients after stapedotomy

Objective

To assess hyperacusis after stapedotomy and its possible influencing factors.

Study design

Prospective, interventional, and longitudinal study.

Setting

A tertiary referral center.

Patients

Fifty consecutive patients (35 females, mean age = 46.8 years).

Intervention

All patients underwent stapedotomy. The validated Portuguese version of the “Hyperacusis Questionnaire” (HQ) was administered before and two weeks and one month after surgery.

Results

No hyperacusis was reported by any patient before surgery. At two weeks after surgery, all patients experienced hyperacusis, with a mean HQ at 16.88 ± 6.54 (range 4–25). One month after surgery, hyperacusis had already resolved in most patients. Gender, preoperative presentation or surgeon had no influence on HQ scores (p > 0.05). Patients with previous contralateral stapedotomy showed lower HQ scores (p = 0.001). Audiological parameters improvement measured at one month after surgery (PTA, SRT and contralateral SRT) were associated with HQ higher scores.

Conclusion

This study confirms that hyperacusis is a common complaint after stapedotomy that usually resolves in one month after surgery. The HQ highest scores were registered among patients with the highest audiological gain after surgery. This suggests that hyperacusis may be a positive prognostic factor for audiological success after stapedotomy.

Single-Session of Combined tDCS-TMS May Increase Therapeutic Effects in Subjects With Tinnitus

To treat motor and psychiatric disorders, transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS) are used in clinics worldwide. We combined these two types of neuromodulation technique to increase the effective response of a single session of neuromodulation in subjective tinnitus. Eighty tinnitus subjects were split into four different treatment groups: tDCS, tDCS with sham TMS, tDCS-TMS, and TMS group. Subjects were given 1.5 mA tDCS on the bi-frontal area and TMS stimulated the contralateral single side of the temporo-parietal cortex with 200 pulses at 1 Hz stimulation. Comparing pre-treatment questionnaire scores to post-treatment questionnaire scores, all four groups showed statistically significant improvements. Although there was no significant difference among group comparison, the largest mean difference was shown in the combined group, especially for tinnitus intensity and tinnitus-related distress. Responders in the combined group were the highest for VAS intensity, with a maximum of 80% of twenty subjects. To summarize, dual-neuromodulation responders could consist of responders of frontal tDCS and temporal TMS. In addition, abnormal activity in the frontal or temporal area of the responders is presumed to be modulated by treatment and will be suggested as the target areas in future studies.

Evaluation of Differential Sensitivity for Frequency, Intensity, and Duration around the Tinnitus Frequency in Adults with Tonal Tinnitus

OBJECTIVES

The perceptual characteristics of tinnitus are usually assessed by a matching procedure, where loudness and pitch of an external sound are matched to those of the tinnitus percept. The duration discrimination test (DDT), differential limen for intensity (DLI) and differential limen for frequency (DLF) are relatively simple psychoacoustic methods of measuring differential sensitivity.

MATERIALS AND METHODS

15 participants with normal or minimal hearing loss with tinnitus in the age range of 18 to 40 years were enrolled in the present study. Pure tone audiometry (PTA), immittance audiometry and otoacoustic emissions were done to diagnose the degree of hearing loss. Duration discrimination test (DDT), differential limen for intensity (DLI) and differential limen for frequency (DLF) was administered on all the participants using MATLAB software (MLP toolbox) at the matched tinnitus frequency, half an octave below - above the frequency.

RESULTS

The results show that there was a significant increase in DDT, DLI and DLF thresholds at the tinnitus frequency compared to half an octave above and below the matched frequency. The result suggests that differential sensitivity abilities regarding frequency, intensity, and duration are affected at the tinnitus frequency in individuals with tinnitus.

CONCLUSION

The results of the study suggest that the differential sensitivity ability is affected in individuals with tinnitus especially at the frequency of tinnitus.

Minimally invasive surgery for the treatment of hyperacusis: New technique and long term results

OBJECTIVE

A minimally invasive surgery developed by the senior author has previously been reported to significantly improve sound tolerance after surgery. This report compares the new versus original surgical technique used and long-term results of all patients who have undergone minimally invasive surgery for hyperacusis.

STUDY DESIGN

A prospective, IRB approved clinical research trial at a single institution with surgery performed by the author (HS).

SETTING

All patients were evaluated and treated at a tertiary level otologic referral center.

SUBJECTS AND METHODS

47 subjects were enrolled from 2014 through 2019, 40 met inclusion criteria including adequate follow-up in the analysis. All subjects underwent oval and round window reinforcement. 20 subjects underwent surgery before 2017 with the original technique of round window reinforcement. 20 subjects underwent new technique with additional oval window and stapes reinforcement.

RESULTS

80% of subjects who underwent the new surgical technique had improvement in hyperacusis symptoms after surgery compared to 60% of subjects who underwent the original technique. Long term follow-up showed sustained results with both techniques with a mean follow-up of 2 years after surgery.

CONCLUSIONS

The most recent, newer technique employed appears to have an 80% success rate in improving sound tolerance with small changes to hearing. The improvement in hyperacusis symptoms after surgery is significant and now found to be sustainable with a mean follow-up of 2 years after initial surgery. Psychological measures of anxiety and depression also were found to be significantly improved after surgery in the newer technique group.

Psychiatric Distress as a Common Risk Factor for Tinnitus and Joint Pain: A National Population-Based Survey

OBJECTIVES

This study aimed to investigate the relationship between tinnitus and joint pain from representative samples of Koreans.

METHODS

The demographics and the responses to a questionnaire about tinnitus and joint pain severity and mental health status of adults aged ≥50 years in the 2010-2012 Korean National Health and Nutrition Examination Survey were analyzed.

RESULTS

Among 9,032 individuals, 26.7% reported experiencing tinnitus within the past year. Participants with tinnitus were more frequently older, hearing loss, and had lower education levels, income, and body weight. Participants with regular exercise and sleep had a lower tinnitus prevalence. The incidences of stress, depressed mood, and suicidal ideation were significantly higher in the tinnitus group and participants with joint pain. The rates of participants with tinnitus according to the number of joint pain sites (zero, one, two, and three) was 22.1%, 31.4%, 33.3%, and 44.2%, and those of participants with severely annoying tinnitus according to the number of joint pain sites (zero, one, two, and three) were 3.3%, 6.8%, 7.9%, and 10.7%, respectively.

CONCLUSION

Tinnitus prevalence and severity were significantly related to joint pain, and both conditions were related to psychiatric distress. Thus, the authors suggest that psychiatric distress as a common risk factor for tinnitus and joint pain should be considered when deciding treatment strategies and in guiding public health policy.

Auditory Brainstem Changes in Timing may Underlie Hyperacusis in a Salicylate-induced Acute Rat Model

Hyperacusis, an exaggerated, sometimes painful perception of loudness even for soft sounds, is a poorly understood distressing condition. While the involvement of modified gain of central auditory neurons and the influence of nonauditory brain regions are well-documented, the issue of where in the auditory system these abnormalities arise remains open, particularly when hyperacusis comes without sensorineural hearing loss. Here we used acute intraperitoneal administration of sodium salicylate (150 mg/kg) in rats, enough to produce > 10-dB decrease in acoustic startle threshold with mild hearing loss at low frequencies (<10 kHz). Anesthesia, necessary for middle-ear-reflex (MEMR) threshold measurements, abolished the olivocochlear efferent reflex but not the MEMR acting on frequencies < 10 kHz, and its mean threshold increased from 55 dB SPL in controls to 80 dB SPL in salicylate-treated animals 60-90 minutes after injection, with an about 3-dB increase in acoustic energy reaching the cochlea. The mean latencies of auditory brainstem-evoked responses (ABR) conspicuously decreased after salicylate, by 0.25 millisecond at 6 kHz at every level, a frequency-dependent effect absent above 12 kHz. A generic model of loudness based upon cross-frequency coincidence detection predicts that with such timing changes, a transient sound may seem as loud at <40 dB SPL as it does in controls at >60 dB SPL. Candidate circuits able to act at the same time on the startle reflex, the MEMR and ABRs may be serotoninergic, as salicylate is known to increase brain serotonin and 5-HT neurons participate in MEMR and ABR circuits.

Neural plasticity and its initiating conditions in tinnitus

BACKGROUND AND OBJECTIVE

Deafferentation caused by cochlear pathology (which can be hidden from the audiogram) activates forms of neural plasticity in auditory pathways, generating tinnitus and its associated conditions including hyperacusis. This article discusses tinnitus mechanisms and suggests how these mechanisms may relate to those involved in normal auditory information processing.

MATERIALS AND METHODS

Research findings from animal models of tinnitus and from electromagnetic imaging of tinnitus patients are reviewed which pertain to the role of deafferentation and neural plasticity in tinnitus and hyperacusis.

RESULTS

Auditory neurons compensate for deafferentation by increasing their input/output functions (gain) at multiple levels of the auditory system. Forms of homeostatic plasticity are believed to be responsible for this neural change, which increases the spontaneous and driven activity of neurons in central auditory structures in animals expressing behavioral evidence of tinnitus. Another tinnitus correlate, increased neural synchrony among the affected neurons, is forged by spike-timing-dependent neural plasticity in auditory pathways. Slow oscillations generated by bursting thalamic neurons verified in tinnitus animals appear to modulate neural plasticity in the cortex, integrating tinnitus neural activity with information in brain regions supporting memory, emotion, and consciousness which exhibit increased metabolic activity in tinnitus patients.

DISCUSSION AND CONCLUSION

The latter process may be induced by transient auditory events in normal processing but it persists in tinnitus, driven by phantom signals from the auditory pathway. Several tinnitus therapies attempt to suppress tinnitus through plasticity, but repeated sessions will likely be needed to prevent tinnitus activity from returning owing to deafferentation as its initiating condition.

The sound-sensitive tinnitus index: Psychometric properties of a scale to assess the impact of tinnitus exacerbated by sound

CONTEXT

Although studies of tinnitus exacerbated by sound exposure have indicated increased treatment challenges and intensified mental health and quality of life concerns, there is a lack of valid screening measures to differentiate or assess diagnostic factors and areas of impact unique to this specific symptom manifestation.

AIMS

The purpose of this study was to design a self-rated measurement tool that can accurately assess the subjective impact of tinnitus negatively modulated by external sound.

SETTINGS AND DESIGN

Based on review of established models of tinnitus and hyperacusis measurement and a two-part pilot study, the 20-item Sound-Sensitive Tinnitus Index (SSTI) was developed and administered in online survey format to 277 individuals worldwide.

METHODS AND MATERIAL

Cronbach's alpha was used to estimate reliability properties, and dimensional factor analysis was performed. To establish validity, statistical correlations of the SSTI were estimated with valid measures of related constructs including tinnitus, hyperacusis, depression, anxiety, and quality of life.

RESULTS

Statistical analysis yielded high levels of internal consistency reliability, and convergent validity was demonstrated through significant correlations with all established measures of related constructs. Initial factor analysis indicated two components split between overall functional impact and coping factors, while rotated factor analyses revealed four distinct scale dimensions, labeled: functional challenges, relational and communication challenges, coping factors, and prevention and hearing protection.

CONCLUSIONS

As a valid and reliable measure, the SSTI fills an important gap as a clinical and research tool that can differentiate and assess severity and treatment progress in manifestations of combined tinnitus and auditory sensitivity symptoms.

Dynamic Changes of Functional Neuronal Activities Between the Auditory Pathway and Limbic Systems Contribute to Noise-Induced Tinnitus with a Normal Audiogram

Tinnitus is thought to be triggered by aberrant neural activity in the central auditory pathway and is often accompanied by comorbidities of emotional distress and anxiety, which imply maladaptive functional connectivity to limbic structures, such as the amygdala and hippocampus. Tinnitus patients with normal audiograms can also have accompanying anxiety and depression, clinically. To test the role of functional connectivity between the central auditory pathway and limbic structures in patients with tinnitus with normal audiograms, we developed a murine noise-induced tinnitus model with a temporary threshold shift (TTS). Tinnitus mice exhibited reduced auditory brainstem response wave I amplitude, and an enhanced wave IV amplitude and wave IV/I amplitude ratio, as compared with control and non-tinnitus mice. Resting-state functional magnetic resonance imaging (fMRI) was used to identify abnormal connectivity of the amygdala and hippocampus and to determine the relationship with tinnitus characteristics. We found increased fMRI responses with amplitude of low-frequency fluctuation (ALFF) in the auditory cortex and decreased ALFF in the amygdala and hippocampus at day 1, but decreased ALFF in the auditory cortex and increased ALFF in the amygdala at day 28 post-noise exposure in tinnitus mice. Decreased functional connectivity between auditory brain regions and limbic structures was demonstrated at day 28 in tinnitus mice. Therefore, aberrant neural activities in tinnitus mice with TTS involved not only the central auditory pathway, but also limbic structures, and there was maladaptive functional connectivity between the central auditory pathway and limbic structures, such as the amygdala and hippocampus.

Towards a Mechanistic-Driven Precision Medicine Approach for Tinnitus

In this position review, we propose to establish a path for replacing the empirical classification of tinnitus with a taxonomy from precision medicine. The goal of a classification system is to understand the inherent heterogeneity of individuals experiencing and suffering from tinnitus and to identify what differentiates potential subgroups. Identification of different patient subgroups with distinct audiological, psychophysical, and neurophysiological characteristics will facilitate the management of patients with tinnitus as well as the design and execution of drug development and clinical trials, which, for the most part, have not yielded conclusive results. An alternative outcome of a precision medicine approach in tinnitus would be that additional mechanistic phenotyping might not lead to the identification of distinct drivers in each individual, but instead, it might reveal that each individual may display a quantitative blend of causal factors. Therefore, a precision medicine approach towards identifying these causal factors might not lead to subtyping these patients but may instead highlight causal pathways that can be manipulated for therapeutic gain. These two outcomes are not mutually exclusive, and no matter what the final outcome is, a mechanistic-driven precision medicine approach is a win-win approach for advancing tinnitus research and treatment. Although there are several controversies and inconsistencies in the tinnitus field, which will not be discussed here, we will give a few examples, as to how the field can move forward by exploring the major neurophysiological tinnitus models, mostly by taking advantage of the common features supported by all of the models. Our position stems from the central concept that, as a field, we can and must do more to bring studies of mechanisms into the realm of neuroscience.

A New Method for Assessing Masking and Residual Inhibition of Tinnitus

Tinnitus masking and residual inhibition (RI) are two well-known psychoacoustic measures of tinnitus. While it has long been suggested that they may provide diagnostic and prognostic information, these measures are still rarely performed in clinics, as they are too time consuming. Given this issue, the main goal of the present study was to validate a new method for assessing these measures. An acoustic sequence made of pulsed stimuli, which included a fixed stimulus duration and interstimulus interval, was applied to 68 tinnitus patients at two testing sites. First, the minimum masking level (MML) was measured by raising the stimulus intensity until the tinnitus was unheard during the stimulus presentation. Second, the level of the stimulus was further increased until the tinnitus was suppressed during the silence interval between the acoustic pulses. This level was called the minimum residual inhibition level (MRIL). The sequential measurement of MML and MRIL from the same stimulus condition offers several advantages such as time efficiency and the ability to compare results between the MRIL and MML. Our study confirms that, from this new approach, MML and MRIL can be easily and quickly obtained from a wide variety of patients displaying either normal hearing or different hearing loss configurations. Indeed, MML was obtained in all patients except one (98.5%), and some level of MRIL was found on 59 patients (86.7%). More so, this approach allows the categorization of tinnitus patients into different subgroups based on the properties of their MRIL.