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CoDAS 2023To identify the pathophysiological definitions adopted by studies investigating "cochlear synaptopathy" (CS) and "hidden hearing loss" (HHL). (Review)
Review
PURPOSE
To identify the pathophysiological definitions adopted by studies investigating "cochlear synaptopathy" (CS) and "hidden hearing loss" (HHL).
RESEARCH STRATEGIES
The combination of keywords "Auditory Synaptopathy" or "Neuronal Synaptopathy" or "Hidden Hearing Loss" with "etiology" or "causality" or "diagnosis" was used in the databases EMBASE, Pubmed (MEDLINE), CINAHL (EBSCO), and Web of Science.
SELECTION CRITERIA
Studies that investigated CS or HHL in humans using behavioral and/or electrophysiological procedures were included.
DATA ANALYSIS
Data analysis and extraction were performed with regard to terminology, definitions, and population.
RESULTS
49 articles were included. Of these, 61.2% used the CS terminology, 34.7% used both terms, and 4.1% used HHL. The most-studied conditions were exposure to noise and tinnitus.
CONCLUSION
CS terminology was used in most studies, referring to the pathophysiological process of deafferentiation between the cochlear nerve fibers and inner hair cells.
Topics: Humans; Hearing Loss, Noise-Induced; Auditory Threshold; Evoked Potentials, Auditory, Brain Stem; Cochlea; Noise; Deafness
PubMed: 37991055
DOI: 10.1590/2317-1782/20232023032pt -
Otology & Neurotology : Official... Jun 2024The degree of intracochlear trauma and force associated with manual electrode insertion may negatively impact cochlear implant (CI) outcomes and preservation of residual...
The degree of intracochlear trauma and force associated with manual electrode insertion may negatively impact cochlear implant (CI) outcomes and preservation of residual acoustic hearing. Robotics-assisted CI insertion systems have recently been developed to overcome human kinematic constraints associated with manual surgical techniques to allow lower force and slower electrode insertions, with the goal of improving performance and hearing preservation outcomes. The iotaSOFT (iotaMotion Inc., USA) is an FDA approved robotics-assisted CI insertion tool compatible with modern lateral-wall electrode designs. Pre-clinical studies suggest lower force and less traumatic CI insertions are possible with this system compared to manual insertion techniques. The slower insertion speeds of this system allow more precise control of electrode insertion in response to simultaneous electrocochleography feedback. We demonstrate application of this system with concurrent electrocochleography for hearing preservation cochlear implantation and highlight relevant surgical technique (see Video, Supplemental Digital Content 1, which demonstrates robotics-assisted CI insertion).
Topics: Humans; Cochlear Implantation; Cochlear Implants; Robotic Surgical Procedures; Male
PubMed: 38728567
DOI: 10.1097/MAO.0000000000004187 -
Pediatrics Nov 2023Noise exposure is a major cause of hearing loss in adults. Yet, noise affects people of all ages, and noise-induced hearing loss is also a problem for young people.... (Review)
Review
Noise exposure is a major cause of hearing loss in adults. Yet, noise affects people of all ages, and noise-induced hearing loss is also a problem for young people. Sensorineural hearing loss caused by noise and other toxic exposures is usually irreversible. Environmental noise, such as traffic noise, can affect learning, physiologic parameters, and quality of life. Children and adolescents have unique vulnerabilities to noise. Children may be exposed beginning in NICUs and well-baby nurseries, at home, at school, in their neighborhoods, and in recreational settings. Personal listening devices are increasingly used, even by small children. Infants and young children cannot remove themselves from noisy situations and must rely on adults to do so, children may not recognize hazardous noise exposures, and teenagers generally do not understand the consequences of high exposure to music from personal listening devices or attending concerts and dances. Environmental noise exposure has disproportionate effects on underserved communities. In this report and the accompanying policy statement, common sources of noise and effects on hearing at different life stages are reviewed. Noise-abatement interventions in various settings are discussed. Because noise exposure often starts in infancy and its effects result mainly from cumulative exposure to loud noise over long periods of time, more attention is needed to its presence in everyday activities starting early in life. Listening to music and attending dances, concerts, and celebratory and other events are sources of joy, pleasure, and relaxation for many people. These situations, however, often result in potentially harmful noise exposures. Pediatricians can potentially lessen exposures, including promotion of safer listening, by raising awareness in parents, children, and teenagers. Noise exposure is underrecognized as a serious public health issue in the United States, with exposure limits enforceable only in workplaces and not for the general public, including children and adolescents. Greater awareness of noise hazards is needed at a societal level.
Topics: Adolescent; Adult; Child; Child, Preschool; Humans; Infant; Deafness; Hearing; Hearing Loss, Noise-Induced; Music; Noise; Quality of Life
PubMed: 37864408
DOI: 10.1542/peds.2023-063753 -
Nature Communications Jan 2024Tinnitus is a heritable, highly prevalent auditory disorder treated by multiple medical specialties. Previous GWAS indicated high genetic correlations between tinnitus... (Meta-Analysis)
Meta-Analysis
Tinnitus is a heritable, highly prevalent auditory disorder treated by multiple medical specialties. Previous GWAS indicated high genetic correlations between tinnitus and hearing loss, with little indication of differentiating signals. We present a GWAS meta-analysis, triple previous sample sizes, and expand to non-European ancestries. GWAS in 596,905 Million Veteran Program subjects identified 39 tinnitus loci, and identified genes related to neuronal synapses and cochlear structural support. Applying state-of-the-art analytic tools, we confirm a large number of shared variants, but also a distinct genetic architecture of tinnitus, with higher polygenicity and large proportion of variants not shared with hearing difficulty. Tissue-expression analysis for tinnitus infers broad enrichment across most brain tissues, in contrast to hearing difficulty. Finally, tinnitus is not only correlated with hearing loss, but also with a spectrum of psychiatric disorders, providing potential new avenues for treatment. This study establishes tinnitus as a distinct disorder separate from hearing difficulties.
Topics: Humans; Tinnitus; Cochlea; Deafness; Hearing Loss, Noise-Induced
PubMed: 38242899
DOI: 10.1038/s41467-024-44842-x -
International Journal of Molecular... Nov 2023Tinnitus is the perception of noise in the absence of acoustic stimulation (phantom noise). In most patients suffering from chronic peripheral tinnitus, an alteration of... (Review)
Review
Tinnitus is the perception of noise in the absence of acoustic stimulation (phantom noise). In most patients suffering from chronic peripheral tinnitus, an alteration of outer hair cells (OHC) starting from the stereocilia (SC) occurs. This is common following ototoxic drugs, sound-induced ototoxicity, and acoustic degeneration. In all these conditions, altered coupling between the tectorial membrane (TM) and OHC SC is described. The present review analyzes the complex interactions involving OHC and TM. These need to be clarified to understand which mechanisms may underlie the onset of tinnitus and why the neuropathology of chronic degenerative tinnitus is similar, independent of early triggers. In fact, the fine neuropathology of tinnitus features altered mechanisms of mechanic-electrical transduction (MET) at the level of OHC SC. The appropriate coupling between OHC SC and TM strongly depends on autophagy. The involvement of autophagy may encompass degenerative and genetic tinnitus, as well as ototoxic drugs and acoustic trauma. Defective autophagy explains mitochondrial alterations and altered protein handling within OHC and TM. This is relevant for developing novel treatments that stimulate autophagy without carrying the burden of severe side effects. Specific phytochemicals, such as curcumin and berberin, acting as autophagy activators, may mitigate the neuropathology of tinnitus.
Topics: Humans; Tinnitus; Hair Cells, Auditory, Outer; Stereocilia; Sound; Acoustic Stimulation
PubMed: 38068993
DOI: 10.3390/ijms242316664 -
Seminars in Hearing Nov 2023Noise-induced hearing loss (NIHL) continues to be a pervasive problem for the nation's workforce, particularly the nation's mining personnel. As one of the leading... (Review)
Review
Noise-induced hearing loss (NIHL) continues to be a pervasive problem for the nation's workforce, particularly the nation's mining personnel. As one of the leading health and safety organizations in the world, the National Institute for Occupational Health and Safety (NIOSH) in Pittsburgh maintains a Hearing Loss Prevention Program (HLPP) to conduct research to reduce NIHL loss among the nation's miners. This document provides a brief overview of this HLPP, describing some of the research techniques involved in the development of engineering noise controls, methods for the development of administrative noise controls, and some of the products available to the public to protect the nation's workers hearing.
PubMed: 37818149
DOI: 10.1055/s-0043-1769500 -
Trends in Hearing 2024Cochlear synaptopathy, a form of cochlear deafferentation, has been demonstrated in a number of animal species, including non-human primates. Both age and noise exposure... (Review)
Review
Cochlear synaptopathy, a form of cochlear deafferentation, has been demonstrated in a number of animal species, including non-human primates. Both age and noise exposure contribute to synaptopathy in animal models, indicating that it may be a common type of auditory dysfunction in humans. Temporal bone and auditory physiological data suggest that age and occupational/military noise exposure also lead to synaptopathy in humans. The predicted perceptual consequences of synaptopathy include tinnitus, hyperacusis, and difficulty with speech-in-noise perception. However, confirming the perceptual impacts of this form of cochlear deafferentation presents a particular challenge because synaptopathy can only be confirmed through post-mortem temporal bone analysis and auditory perception is difficult to evaluate in animals. Animal data suggest that deafferentation leads to increased central gain, signs of tinnitus and abnormal loudness perception, and deficits in temporal processing and signal-in-noise detection. If equivalent changes occur in humans following deafferentation, this would be expected to increase the likelihood of developing tinnitus, hyperacusis, and difficulty with speech-in-noise perception. Physiological data from humans is consistent with the hypothesis that deafferentation is associated with increased central gain and a greater likelihood of tinnitus perception, while human data on the relationship between deafferentation and hyperacusis is extremely limited. Many human studies have investigated the relationship between physiological correlates of deafferentation and difficulty with speech-in-noise perception, with mixed findings. A non-linear relationship between deafferentation and speech perception may have contributed to the mixed results. When differences in sample characteristics and study measurements are considered, the findings may be more consistent.
Topics: Humans; Cochlea; Tinnitus; Animals; Speech Perception; Hyperacusis; Noise; Auditory Perception; Synapses; Hearing Loss, Noise-Induced; Loudness Perception
PubMed: 38738337
DOI: 10.1177/23312165241239541 -
Hearing Research Mar 2024Chronic tinnitus is a debilitating condition with very few management options. Acoustic trauma that causes tinnitus has been shown to induce neuronal hyperactivity in...
Chronic tinnitus is a debilitating condition with very few management options. Acoustic trauma that causes tinnitus has been shown to induce neuronal hyperactivity in multiple brain areas in the auditory pathway, including the inferior colliculus. This neuronal hyperactivity could be attributed to an imbalance between excitatory and inhibitory neurotransmission. However, it is not clear how the levels of neurotransmitters, especially neurotransmitters in the extracellular space, change over time following acoustic trauma and the development of tinnitus. In the present study, a range of amino acids were measured in the inferior colliculus of rats during acoustic trauma as well as at 1 week and 5 months post-trauma using in vivo microdialysis and high-performance liquid chromatography. Amino acid levels in response to sound stimulation were also measured at 1 week and 5 months post-trauma. It was found that unilateral exposure to a 16 kHz pure tone at 115 dB SPL for 1 h caused immediate hearing loss in all the animals and chronic tinnitus in 58 % of the animals. Comparing to the sham condition, extracellular levels of GABA were significantly increased at both the acute and 1 week time points after acoustic trauma. However, there was no significant difference in any of the amino acid levels measured between sham, tinnitus positive and tinnitus negative animals at 5 months post-trauma. There was also no clear pattern in the relationship between neurochemical changes and sound frequency/acoustic trauma/tinnitus status, which might be due to the relatively poorer temporal resolution of the microdialysis compared to electrophysiological responses.
Topics: Rats; Animals; Hearing Loss, Noise-Induced; Tinnitus; Acoustic Stimulation; Amino Acids; Inferior Colliculi; Neurotransmitter Agents
PubMed: 38219615
DOI: 10.1016/j.heares.2024.108948