scholarly journals Towards a differential diagnosis of cochlear synaptopathy and outer-hair-cell deficits in mixed sensorineural hearing loss pathologies

2019 ◽  
Author(s):  
Viacheslav Vasilkov ◽  
Sarah Verhulst
Keyword(s):  
Hearing Loss ◽  
Differential Diagnosis ◽  
Hair Cell ◽  
Sensorineural Hearing Loss ◽  
Noise Exposure ◽  
Outer Hair Cell ◽  
Cell Damage ◽  
Sensorineural Hearing ◽  
Inner Hair Cell ◽  
Hearing Thresholds

AbstractDamage to the auditory periphery is more widespread than predicted by the gold-standard clinical audiogram. Noise exposure, ototoxicity and aging can destroy cochlear inner-hair-cell afferent synapses and result in a degraded subcortical representation of sound while leaving hearing thresholds unaffected. Damaged afferent synapses, i.e. cochlear synaptopathy, can be quantified using histology, but a differential diagnosis in living humans is difficult: histology cannot be applied and existing auditory evoked potential (AEP) metrics for synaptopathy become insensitive when other sensorineural hearing impairments co-exist (e.g., outer-hair-cell damage associated with elevated hearing thresholds). To develop a non-invasive diagnostic method which quantifies synaptopathy in humans and animals with normal or elevated hearing thresholds, we employ a computational model approach in combination with human AEP and psychoacoustics. We propose the use of a sensorineural hearing loss (SNHL) map which comprises two relative AEP-based metrics to quantify the respective degrees of synaptopathy and OHC damage and evaluate to which degree our predictions of AEP alterations can explain individual data-points in recorded SNHL maps from male and female listeners with normal or elevated audiometric thresholds. We conclude that SNHL maps can offer a more precise diagnostic tool than existing AEP methods for individual assessment of the synaptopathy and OHC-damage aspect of sensorineural hearing loss.Significance StatementHearing loss ranks fourth in global causes for disability and risk factors include noise exposure, ototoxicity and aging. The most vulnerable parts of the cochlea are the inner-hair-cell afferent synapses and their damage (cochlear synaptopathy) results in a degraded subcortical representation of sound. While synaptopathy can be estimated reliably using histology, it cannot be quantified this way in living humans. Secondly, other co-existing sensorineural hearing deficits (e.g., outer-hair-cell damage) can complicate a differential diagnosis. To quantify synaptopathy in humans and animals with normal or elevated hearing thresholds, we adopt a theoretical and interdisciplinary approach. Sensitive diagnostic metrics for synaptopathy are crucial to assess its prevalence in humans, study its impact on sound perception and yield effective hearing restoration strategies.

scholarly journals Enhancing the sensitivity of the envelope-following response for cochlear synaptopathy screening in humans: the role of stimulus envelope

2020 ◽  
Author(s):  
Viacheslav Vasilkov ◽  
Markus Garrett ◽  
Manfred Mauermann ◽  
Sarah Verhulst
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Sensorineural Hearing Loss ◽  
Auditory Nerve ◽  
Outer Hair Cell ◽  
Cell Damage ◽  
Modulation Depth ◽  
Auditory Evoked Potential ◽  
Sensorineural Hearing ◽  
Age Related

AbstractAuditory de-afferentation, a permanent reduction in the number of innerhair-cells and auditory-nerve synapses due to cochlear damage or synaptopathy, can reliably be quantified using temporal bone histology and immunostaining. However, there is an urgent need for non-invasive markers of synaptopathy to study its perceptual consequences in live humans and to develop effective therapeutic interventions. While animal studies have identified candidate auditory-evoked-potential (AEP) markers for synaptopathy, their interpretation in humans has suffered from translational issues related to neural generator differences, unknown hearing-damage histopathologies or lack of measurement sensitivity. To render AEP-based markers of synaptopathy more sensitive and differential to the synaptopathy aspect of sensorineural hearing loss, we followed a combined computational and experimental approach. Starting from the known characteristics of auditory-nerve physiology, we optimized the stimulus envelope to stimulate the available auditory-nerve population optimally and synchronously to generate strong envelope-following-responses (EFRs). We further used model simulations to explore which stimuli evoked a response that was sensitive to synaptopathy, while being maximally insensitive to possible co-existing outer-hair-cell pathologies. We compared the model-predicted trends to AEPs recorded in younger and older listeners (N=44, 24f) who had normal or impaired audiograms with suspected age-related synaptopathy in the older cohort. We conclude that optimal stimulation paradigms for EFR-based quantification of synaptopathy should have sharply rising envelope shapes, a minimal plateau duration of 1.7-2.1 ms for a 120-Hz modulation rate, and inter-peak intervals which contain near-zero amplitudes. From our recordings, the optimal EFR-evoking stimulus had a rectangular envelope shape with a 25% duty cycle and a 95% modulation depth. Older listeners with normal or impaired audiometric thresholds showed significantly reduced EFRs, which were consistent with how (age-induced) synaptopathy affected these responses in the model.Significance StatementCochlear synaptopathy was in 2009 identified as a new form of sensorineural hearing loss (SNHL) that also affects primates and humans. However, clinical practice does not routinely screen for synaptopathy, and hence its consequences for degraded sound and speech perception remain unclear. Cochlear synaptopathy may thus remain undiagnosed and untreated in the aging population who often report self-reported hearing difficulties. To enable an EEG-based differential diagnosis of synaptopathy in humans, it is crucial to develop a recording method that evokes a robust response and emphasizes inter-individual differences. These differences should reflect the synaptopathy aspect of SNHL, while being insensitive to other aspects of SNHL (e.g. outer-hair-cell damage). This study uniquely combines computational modeling with experiments in normal and hearing-impaired listeners to design an EFR stimulation and recording paradigm that can be used for the diagnosis of synaptopathy in humans.

scholarly journals How Drill-Generated Acoustic Trauma effects Hearing Functions in an Ear Surgery?

2012 ◽  
Vol 3 (3) ◽  
pp. 127-132 ◽  
Author(s):  
Mustafa Paksoy ◽  
Arif Sanli ◽  
Umit Hardal ◽  
Sermin Kibar ◽  
Gokhan Altin ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Sensorineural Hearing Loss ◽  
Noise Exposure ◽  
Bone Conduction ◽  
Acoustic Trauma ◽  
Sensorineural Hearing ◽  
Radical Mastoidectomy ◽  
Ear Surgery ◽  
Hearing Thresholds ◽  
Mastoid Surgery

ABSTRACT Objective In otology, a wide variety of devices are used that have significant noise output, both operated ear and the patient. We aimed to determine hearing damages due to drill-generated acoustic trauma in ear surgery. We want to find how degree drill-generated acoustic trauma is responsible from sensorineural hearing loss in ear surgery. Materials and methods We designed a retrospective study about 100 patients who underwent radical or modiphied radical mastoidectomy and tympanoplasty. The audiometric testing was done both pre and postoperatively to detect any significant hearing loss in the immediate postoperative period. The data were analyzed using the Wilcoxon sign and Mann-Whitney U tests. This study proposes that hearing loss is caused by drill noise conducted to the operated ear by vibrations of temporal bone. Results A sensorineural hearing loss soon after mastoid surgery is seen due to the noise generated by the drill. Mean pure-tone thresholds obtained was significantly more in mastoidectomy applied patients when compared to tympanoplasty . Mean bone conduction (BC) hearing levels impaired 6,6 dB in 1 kHz, 5.5 dB in 0.5 kHz, 5 dB in 4.kHz and 3.1 dB in 2 kHz in mastoidectomy groups but improved 5.5 dB in 0.5 kHz, 2.2 dB in 1 kHz, 2.7 dB in 2 kHz in tympanoplasty groups. Statistically significant differences were observed at the 0.5-1 and 4 kHz frequencies pre and postoperative in the hearing thresholds of BC changing in mastoidectomy group, however, the averages of ranks of all pre and postoperative measurement of hearing levels show differences between mastoidectomy and tympanoplasty groups was significant in statistically at independent groups (p < 0.05). Conclusion We conclude that drill-generated noise during mastoid surgery has been incriminated as a cause of sensorineural hearing loss. Drilling during mastoid surgery may result in temporary or permanent noise-induced hearing loss. Possible noise disturbance to the inner ear can only be avoided by minimizing the duration of harmful noise exposure and carefull using burr to near the cochlear structures. How to cite this article Paksoy M, Sanli A, Hardal U, Kibar S, Altin G, Erdogan BA, Bekmez ZE. How Drill-Generated Acoustic Trauma effects Hearing Functions in an Ear Surgery? Int J Head and Neck Surg 2012;3(3):127-132.

Active Hair Bundle Movements and the Cochlear Amplifier

2003 ◽  
Vol 14 (06) ◽  
pp. 325-338 ◽  
Author(s):  
Anthony Ricci
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Sensorineural Hearing Loss ◽  
Outer Hair Cell ◽  
Sensorineural Hearing ◽  
Hair Bundle ◽  
Cochlear Amplifier ◽  
Active Process ◽  
Slow Adaptation ◽  
Active Processes

The “active process” is a term used to describe amplification and filtering processes that are essential for obtaining the exquisite sensitivity of hearing organs. Understanding the components of the active process is important both for our understanding of the normal physiology of hearing and because perturbations of the cochlear amplifier may lead to such maladies as threshold shifts (both temporary and permanent), tinnitus, sensorineural hearing loss and presbicusis. To date the cochlear amplifier has largely been attributed to outer hair cell electro motility; however, recent evidence suggests, that active properties of the hair bundle may also be important. Most likely both somatic motility and active hair bundle movements contribute to establishing the cochlear active process. This paper reviews recent evidence regarding known active processes in the hair bundle gating compliance, and fast and slow adaptation.

Hearing Loss Associated with Xylene Exposure in a Laboratory Worker

2012 ◽  
Vol 23 (10) ◽  
pp. 824-830 ◽  
Author(s):  
Adrian Fuente ◽  
Bradley McPherson ◽  
Linda J. Hood
Keyword(s):  
Hearing Loss ◽  
Sensorineural Hearing Loss ◽  
Otoacoustic Emissions ◽  
Outer Hair Cell ◽  
Cell Damage ◽  
Auditory Brainstem ◽  
Sensorineural Hearing ◽  
Auditory Brainstem Responses ◽  
Initial Assessment ◽  
Laboratory Worker

Background: Xylene is an organic solvent, widely used in histology laboratories and other occupational settings. Research in animals has demonstrated that xylene induces outer hair cell damage. Evidence regarding the effects of xylene in humans is only available from studies investigating workers exposed to mixtures of solvents containing xylene. These data indicate that mixtures of solvents containing xylene may induce hearing loss and central auditory dysfunction. Purpose: To comprehensively evaluate the peripheral and central auditory system of a histology laboratory worker exposed to xylene, who had presented with bilateral mild sensorineural hearing loss at an initial assessment. Research Design: A case report of a male histology laboratory worker who has been exposed to xylene for over 20 yr. Results: A diagnosis of bilateral mild sensorineural hearing loss of cochlear origin was made on the basis of otological, neuroimaging, and audiological examinations. Results indicating the absence of transient-evoked otoacoustic emissions, and auditory brainstem responses as expected for a mild cochlear hearing loss, were obtained. Conclusions: The observed bilateral mild sensorineural hearing loss was considered to have been induced by xylene exposure, due to the absence of any other etiological factors related to the onset of hearing loss. The results found in this patient are in agreement with animal data indicating xylene-induced ototoxicity. Xylene-exposed individuals should be audiologically monitored on a regular basis.

Outer hair cell receptor current and sensorineural hearing loss

1989 ◽  
Vol 42 (1) ◽  
pp. 47-72 ◽  
Author(s):  
R.B. Patuzzi ◽  
G.K. Yates ◽  
B.M. Johnstone
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Sensorineural Hearing Loss ◽  
Outer Hair Cell ◽  
Cell Receptor ◽  
Sensorineural Hearing

scholarly journals Is Sensorineural Hearing Loss Related to Chronic Rhinosinusitis Caused by Outer Hair Cell Injury?

2019 ◽  
Vol 25 ◽  
pp. 627-636 ◽  
Author(s):  
Xi Lin ◽  
Xin Shan ◽  
Shaolian Lin ◽  
Bo Shu ◽  
Yingge Wang ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Sensorineural Hearing Loss ◽  
Chronic Rhinosinusitis ◽  
Cell Injury ◽  
Outer Hair Cell ◽  
Sensorineural Hearing

MicroRNAs in Noise-Induced Hearing Loss and their Regulation by Oxidative Stress and Inflammation

2020 ◽  
Vol 21 (12) ◽  
pp. 1216-1224
Author(s):  
Fatemeh Forouzanfar ◽  
Samira Asgharzade
Keyword(s):  
Oxidative Stress ◽  
Hearing Loss ◽  
Hair Cell ◽  
Noise Exposure ◽  
Cell Damage ◽  
Sensory Cells ◽  
Noise Induced Hearing Loss ◽  
Irreversible Damage ◽  
Open Access Journals

Noise exposure (NE) has been recognized as one of the causes of sensorineural hearing loss (SNHL), which can bring about irreversible damage to sensory hair cells in the cochlea, through the launch of oxidative stress pathways and inflammation. Accordingly, determining the molecular mechanism involved in regulating hair cell apoptosis via NE is essential to prevent hair cell damage. However, the role of microRNAs (miRNAs) in the degeneration of sensory cells of the cochlea during NE has not been so far uncovered. Thus, the main purpose of this study was to demonstrate the regulatory role of miRNAs in the oxidative stress pathway and inflammation induced by NE. In this respect, articles related to noise-induced hearing loss (NIHL), oxidative stress, inflammation, and miRNA from various databases of Directory of Open Access Journals (DOAJ), Google Scholar, PubMed; Library, Information Science & Technology Abstracts (LISTA), and Web of Science were searched and retrieved. The findings revealed that several studies had suggested that up-regulation of miR-1229-5p, miR-451a, 185-5p, 186 and down-regulation of miRNA-96/182/183 and miR-30b were involved in oxidative stress and inflammation which could be used as biomarkers for NIHL. There was also a close relationship between NIHL and miRNAs, but further research is required to prove a causal association between miRNA alterations and NE, and also to determine miRNAs as biomarkers indicating responses to NE.

scholarly journals Prevention of acquired sensorineural hearing loss in mice by in vivo Htra2 gene editing

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xi Gu ◽  
Daqi Wang ◽  
Zhijiao Xu ◽  
Jinghan Wang ◽  
Luo Guo ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Protective Effect ◽  
Hair Cell ◽  
Sensorineural Hearing Loss ◽  
Auditory Brainstem Response ◽  
Gene Editing ◽  
Auditory Brainstem ◽  
Sensorineural Hearing ◽  
Brainstem Response

Abstract Background Aging, noise, infection, and ototoxic drugs are the major causes of human acquired sensorineural hearing loss, but treatment options are limited. CRISPR/Cas9 technology has tremendous potential to become a new therapeutic modality for acquired non-inherited sensorineural hearing loss. Here, we develop CRISPR/Cas9 strategies to prevent aminoglycoside-induced deafness, a common type of acquired non-inherited sensorineural hearing loss, via disrupting the Htra2 gene in the inner ear which is involved in apoptosis but has not been investigated in cochlear hair cell protection. Results The results indicate that adeno-associated virus (AAV)-mediated delivery of CRISPR/SpCas9 system ameliorates neomycin-induced apoptosis, promotes hair cell survival, and significantly improves hearing function in neomycin-treated mice. The protective effect of the AAV–CRISPR/Cas9 system in vivo is sustained up to 8 weeks after neomycin exposure. For more efficient delivery of the whole CRISPR/Cas9 system, we also explore the AAV–CRISPR/SaCas9 system to prevent neomycin-induced deafness. The in vivo editing efficiency of the SaCas9 system is 1.73% on average. We observed significant improvement in auditory brainstem response thresholds in the injected ears compared with the non-injected ears. At 4 weeks after neomycin exposure, the protective effect of the AAV–CRISPR/SaCas9 system is still obvious, with the improvement in auditory brainstem response threshold up to 50 dB at 8 kHz. Conclusions These findings demonstrate the safe and effective prevention of aminoglycoside-induced deafness via Htra2 gene editing and support further development of the CRISPR/Cas9 technology in the treatment of non-inherited hearing loss as well as other non-inherited diseases.

scholarly journals Acoustic reflex measurements and the loudness function in sensorineural hearing loss

1980 ◽  
Vol 27 (1) ◽  
Author(s):  
Sheila Uliel
Keyword(s):  
Hearing Loss ◽  
Differential Diagnosis ◽  
Sensorineural Hearing Loss ◽  
Acoustic Impedance ◽  
Pure Tone ◽  
Sensorineural Hearing ◽  
Acoustic Reflex ◽  
Reflex Responses ◽  
Loudness Function ◽  
The Individual

The suprathreshold acoustic reflex responses of forty two ears affected by sensorineural hearing loss of cochlear origin and fifty-eight ears demonstrating normal hearing, were recorded by means of an electro-acoustic impedance meter and attached X-Y recorder. The recordings were done in ascending and descending fashion,  at successively increasing and decreasing 5dB intensity levels from 90-120-90 dB HL respectively, for the individual pure-tone frequencies of 500, 1 000, 2 000 and 4 000 Hz. The contralateral mode of measurement was employed. Analysis of  these recordings indicated that the acoustic reflex  responses could be differentiated into five  characteristic patterns of  growth, which could be depicted upon a continuum of peaked, peaked-rounded, rounded, rounded-flat,  and flat  shapes. The peaked and peaked-rounded patterns were found  to predominate at all four pure-tone frequencies  in the normal ears, while the rounded-fiat  and flat  patterns were found  to predominate only at the higher pure-tone frequencies of 2 000 and 4 000 Hz in the ears affected  by sensorineural hearing loss. This latter relationship was also able to be applied to two disorders of  the loudness functio— loudness recruitment and hyperacusis. It was concluded that the flattened  acoustic reflex  patterns at the higher pure-tone frequencies  constituted a potential diagnostic cue related to the differential  diagnosis of sensorineural hearing loss, and to disorders of  the loudness function.

scholarly journals Noise-induced and age-related hearing loss:  new perspectives and potential therapies

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 927 ◽  
Author(s):  
M Charles Liberman
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Sensorineural Hearing Loss ◽  
Hair Cells ◽  
Auditory Nerve ◽  
Cell Loss ◽  
Sensorineural Hearing ◽  
Hair Cell Loss ◽  
Age Related ◽  
Age Related Hearing Loss

The classic view of sensorineural hearing loss has been that the primary damage targets are hair cells and that auditory nerve loss is typically secondary to hair cell degeneration. Recent work has challenged that view. In noise-induced hearing loss, exposures causing only reversible threshold shifts (and no hair cell loss) nevertheless cause permanent loss of >50% of the synaptic connections between hair cells and the auditory nerve. Similarly, in age-related hearing loss, degeneration of cochlear synapses precedes both hair cell loss and threshold elevation. This primary neural degeneration has remained a “hidden hearing loss” for two reasons: 1) the neuronal cell bodies survive for years despite loss of synaptic connection with hair cells, and 2) the degeneration is selective for auditory nerve fibers with high thresholds. Although not required for threshold detection when quiet, these high-threshold fibers are critical for hearing in noisy environments. Research suggests that primary neural degeneration is an important contributor to the perceptual handicap in sensorineural hearing loss, and it may be key to the generation of tinnitus and other associated perceptual anomalies. In cases where the hair cells survive, neurotrophin therapies can elicit neurite outgrowth from surviving auditory neurons and re-establishment of their peripheral synapses; thus, treatments may be on the horizon.

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