401
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Mahboubi H, Lin HW, Bhattacharyya N. Prevalence, Characteristics, and Treatment Patterns of Hearing Difficulty in the United States. JAMA Otolaryngol Head Neck Surg 2017; 144:65-70. [PMID: 29167904 DOI: 10.1001/jamaoto.2017.2223] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance Hearing loss is one of the most prevalent chronic conditions in the United States and has been associated with negative physical, social, cognitive, economic, and emotional consequences. Despite the high prevalence of hearing loss, substantial gaps in the utilization of amplification options, including hearing aids and cochlear implants (CI), have been identified. Objective To investigate the contemporary prevalence, characteristics, and patterns of specialty referral, evaluation, and treatment of hearing difficulty among adults in the United States. Design, Setting, and Participants A cross-sectional analysis of responses from a nationwide clustered representative sample of adults who participated in the 2014 National Health Interview Survey and responded to the hearing module questions was carried out. Main Outcomes and Measures Data regarding demographics as well as self-reported hearing status, functional hearing, laterality, onset, and primary cause of the hearing loss were collected. In addition, specific data regarding hearing-related clinician visits, hearing tests, referrals to hearing specialist, and utilization of hearing aids and CIs were analyzed. Results Among 239.6 million adults, 40.3 million (16.8%) indicated their hearing was less than "excellent/good," ranging from "a little trouble hearing" to "deaf." The mean (SD) age of participants was 47 (0.2) years with 48.2% being men and 51.8% women. Approximately 48.8 million (20.6%) had visited a physician for hearing problems in the preceding 5 years. Of these, 32.6% were referred to an otolaryngologist and 27.3% were referred to an audiologist. Functional hearing was reported as the ability to hear "whispering" or "normal voice" (225.4 million; 95.5%), to "only hear shouting" (8.0 million; 3.4%), and "not appreciating shouting" (2.8 million; 1.1%). Among the last group, 5.3% were recommended to have a CI, of which 22.1% had received one. Of the adults who indicated their hearing from "a little trouble hearing" to being "deaf," 12.9 million (32.2%) had never seen a clinician for hearing problems and 11.1 million (28.0%) had never had their hearing tested. Conclusions and Relevance There are considerable gaps between self-reported hearing loss and patients receiving medical evaluation and recommended treatments for hearing loss. Improved awareness regarding referrals to otolaryngologists and audiologists as well as auditory rehabilitative options among clinicians may improve hearing loss care.
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Affiliation(s)
- Hossein Mahboubi
- Division of Neurotology and Skull Base Surgery, Department of Otolaryngology-Head and Neck Surgery, University of California, Irvine
| | - Harrison W Lin
- Division of Neurotology and Skull Base Surgery, Department of Otolaryngology-Head and Neck Surgery, University of California, Irvine
| | - Neil Bhattacharyya
- Department of Otology & Laryngology, Harvard Medical School, Boston, Massachusetts
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402
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Allen PD, Luebke AE. Reflex Modification Audiometry Reveals Dual Roles for Olivocochlear Neurotransmission. Front Cell Neurosci 2017; 11:361. [PMID: 29213229 PMCID: PMC5702649 DOI: 10.3389/fncel.2017.00361] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Accepted: 11/03/2017] [Indexed: 11/23/2022] Open
Abstract
Approximately 15% of American adults report some degree of difficulty hearing in a noisy environment or have auditory filtering difficulties. There are objective clinical tests of auditory filtering, yet few tests exist for mouse models that do not rely on extensive training. We have used reflex modification audiometry (RMA) and developed exclusion criteria for the mouse model. This RMA based test makes use of the acoustic startle response (ASR) and the ability of prepulses to inhibit the ASR [i.e., prepulse inhibition (PPI)] to assess the mouse's ability to detect prepulse signals presented in quiet or embedded in masking noise. We have studied PPI behavior across four inbred mouse strains with normal cochlear function and developed pre-testing exclusion criteria and test/retest reliability measures. Moreover, because both the medial (MOC) and the lateral (LOC) olivocochlear efferent feedback systems have been proposed to improve auditory behavior performance, especially in noisy backgrounds, we have examined PPI abilities in mice (with their littermate controls) either lacking the MOC receptor subunit α9 nicotinic acetylcholine receptor [α9 nAChR (–/–)] or expressing an overactive receptor [Ld'T mutation in α9 nAChR KI], or lacking an LOC efferent neuropeptide, alpha calcitonin gene-related peptide [αCGRP (–/–)] only in the CNS. Because CGRP receptor formation has been shown to mature from juvenile to adult ages, we also studied if this maturation would be reflected in PPI behavioral responses in juvenile and adult (+/+) controls and in adult αCGRP (–/–) animals. We show that 50% PPI response thresholds (sound level with 50% correct responses) in quiet are decreased in the (–/–) α9 nAChR animals, and 50% PPI responses are increased for mice with an overactive receptor (α9 nAChR KI) and are increased in adult mice lacking αCGRP (–/–). However, in background noise, only mice lacking αCGRP exhibited increased 50% PPI response thresholds, as there were no significant differences between α9 nAChR adult mouse lines and their littermate controls. These findings suggest that MOC and LOC olivocochlear neurotransmission work in tandem to improve behavioral responses to sound. These experiments further pave the way for rapid behavioral hearing assessments in other mouse models.
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Affiliation(s)
- Paul D Allen
- Department of Otolaryngology, University of Rochester Medical Center, Rochester, NY, United States
| | - Anne E Luebke
- Department of Neuroscience and the Ernst J. Del Monte Institute for Neuroscience, University of Rochester Medical Center, Rochester, NY, United States.,Department of Biomedical Engineering, University of Rochester, Rochester, NY, United States
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403
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Bakhos D, Aussedat C, Legris E, Aoustin JM, Nevoux J. [Adult deafness: Towards new paradigm]. Presse Med 2017; 46:1033-1042. [PMID: 29107467 DOI: 10.1016/j.lpm.2017.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 09/13/2017] [Accepted: 09/14/2017] [Indexed: 11/24/2022] Open
Abstract
Screening and early treatment of deafness regardless of age is essential. Deafness leads to social isolation, depression, and decreased cognitive function. The diagnosis requires an otoscopy and a confirmation of the type and degree of deafness by audiometry. Sudden deafness and meningitis are neuro-sensorial emergencies. Deafness may be the mode of disclosure of an autoimmune disease or part of the evolutionary profile. Hearing complaints with a normal classical audiogram may be the manifestation of a so-called "hidden" hearing loss and must be explored more carefully.
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Affiliation(s)
- David Bakhos
- CHU de Tours, service ORL et chirurgie cervicofaciale, 37000 Tours, France; Université François-Rabelais de Tours, faculté de médecine, Inserm UMR-S930, 37000 Tours, France.
| | - Charles Aussedat
- CHU de Tours, service ORL et chirurgie cervicofaciale, 37000 Tours, France
| | - Elsa Legris
- CHU de Tours, service ORL et chirurgie cervicofaciale, 37000 Tours, France
| | - Jean-Marie Aoustin
- CHU de Tours, service ORL et chirurgie cervicofaciale, 37000 Tours, France
| | - Jérôme Nevoux
- AP-HP, hôpital Bicêtre, service d'ORL et de chirurgie cervicofaciale, 94270 Le Kremlin-Bicêtre, France; Université Paris-Saclay, faculté de médecine, 94275 Le Kremlin-Bicêtre, France; Inserm U1185, 94275 Le Kremlin-Bicêtre, France
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404
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Noise History and Auditory Function in Young Adults With and Without Type 1 Diabetes Mellitus. Ear Hear 2017; 38:724-735. [DOI: 10.1097/aud.0000000000000457] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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405
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Gao K, Ding D, Sun H, Roth J, Salvi R. Kanamycin Damages Early Postnatal, but Not Adult Spiral Ganglion Neurons. Neurotox Res 2017; 32:603-613. [PMID: 28656549 PMCID: PMC5711550 DOI: 10.1007/s12640-017-9773-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/31/2017] [Accepted: 06/13/2017] [Indexed: 01/13/2023]
Abstract
Although aminoglycoside antibiotics such as kanamycin are widely used clinically to treat life-threatening bacterial infections, ototoxicity remains a significant dose-limiting side effect. The prevailing view is that the hair cells are the primary ototoxic target of aminoglycosides and that spiral ganglion neurons begin to degenerate weeks or months after the hair cells have died due to lack of neurotrophic support. To test the early developmental aspects of this issue, we compared kanamycin-induced hair cell and spiral ganglion pathology in rat postnatal day 3 cochlear organotypic cultures with adult whole cochlear explants. In both adult and postnatal day 3 cultures, hair cell damage began at the base of the cochleae and progressed toward the apex in a dose-dependent manner. In postnatal day 3 cultures, spiral ganglion neurons were rapidly destroyed by kanamycin prior to hair cell loss. In contrast, adult spiral ganglion neurons were resistant to kanamycin damage even at the highest concentration, consistent with in vivo models of delayed SGN degeneration. In postnatal day 3 cultures, kanamycin preferentially damaged type I spiral ganglion neurons, whereas type II neurons were resistant. Spiral ganglion degeneration of postnatal day 3 neurons was associated with upregulation of the superoxide radical and caspase-3-mediated cell death. These results show for the first time that kanamycin is toxic to postnatal day 3 spiral ganglion neurons, but not adult neurons.
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Affiliation(s)
- Kelei Gao
- Department of Otolaryngology Head and Neck Surgery, Xiang Ya Hospital, Central South University, Changsha, Hunan, 410013, China
| | - Dalian Ding
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY, 14214, USA
| | - Hong Sun
- Department of Otolaryngology Head and Neck Surgery, Xiang Ya Hospital, Central South University, Changsha, Hunan, 410013, China
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY, 14214, USA
| | - Jerome Roth
- Department of Audiology and Speech-Language Pathology, Asia University, Taichung, Taiwan
| | - Richard Salvi
- Department of Otolaryngology Head and Neck Surgery, Xiang Ya Hospital, Central South University, Changsha, Hunan, 410013, China.
- Department of Audiology and Speech-Language Pathology, Asia University, Taichung, Taiwan.
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406
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Fulbright AN, Le Prell CG, Griffiths SK, Lobarinas E. Effects of Recreational Noise on Threshold and Suprathreshold Measures of Auditory Function. Semin Hear 2017; 38:298-318. [PMID: 29026263 PMCID: PMC5634805 DOI: 10.1055/s-0037-1606325] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Noise exposure that causes a temporary threshold shift but no permanent threshold shift can cause degeneration of synaptic ribbons and afferent nerve fibers, with a corresponding reduction in wave I amplitude of the auditory brainstem response (ABR) in animals. This form of underlying damage, hypothesized to also occur in humans, has been termed synaptopathy , and it has been hypothesized that there will be a hidden hearing loss consisting of functional deficits at suprathreshold stimulus levels. This study assessed whether recreational noise exposure history was associated with smaller ABR wave I amplitude and poorer performance on suprathreshold auditory test measures. Noise exposure histories were collected from 26 men and 34 women with hearing thresholds ≤ 25 dB hearing loss (HL; 250 Hz to 8 kHz), and a variety of functional suprathreshold hearing tests were performed. Wave I amplitudes of click-evoked ABR were obtained at 70, 80, 90, and 99 dB (nHL) and tone-burst evoked ABR were obtained at 90 dB nHL. Speech recognition performance was measured in quiet and in competing noise, using the Words in Noise test, and the NU-6 word list in broadband noise (BBN). In addition, temporal summation to tonal stimuli was assessed in quiet and in competing BBN. To control for the effects of subclinical conventional hearing loss, distortion product otoacoustic emission amplitude, an indirect measure of outer hair cell integrity, was measured. There was no statistically significant relationship between noise exposure history scores and ABR wave I amplitude in either men or women for any of the ABR conditions. ABR wave I amplitude and noise exposure history were not reliably correlated with suprathreshold functional hearing tests. Taken together, this study found no evidence of noise-induced decreases in ABR wave I amplitude or signal processing in noise in a cohort of subjects with a history of recreational noise exposure.
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407
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Paul BT, Waheed S, Bruce IC, Roberts LE. Subcortical amplitude modulation encoding deficits suggest evidence of cochlear synaptopathy in normal-hearing 18-19 year olds with higher lifetime noise exposure. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 142:EL434. [PMID: 29195459 DOI: 10.1121/1.5009603] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Noise exposure and aging can damage cochlear synapses required for suprathreshold listening, even when cochlear structures needed for hearing at threshold remain unaffected. To control for effects of aging, behavioral amplitude modulation (AM) detection and subcortical envelope following responses (EFRs) to AM tones in 25 age-restricted (18-19 years) participants with normal thresholds, but different self-reported noise exposure histories were studied. Participants with more noise exposure had smaller EFRs and tended to have poorer AM detection than less-exposed individuals. Simulations of the EFR using a well-established cochlear model were consistent with more synaptopathy in participants reporting greater noise exposure.
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MESH Headings
- Acoustic Stimulation
- Adolescent
- Age Factors
- Audiometry, Pure-Tone
- Auditory Cortex/physiopathology
- Auditory Perception
- Auditory Threshold
- Cochlea/physiopathology
- Computer Simulation
- Electroencephalography
- Evoked Potentials, Auditory
- Female
- Hearing
- Hearing Loss, Noise-Induced/diagnosis
- Hearing Loss, Noise-Induced/etiology
- Hearing Loss, Noise-Induced/physiopathology
- Hearing Loss, Noise-Induced/psychology
- Hearing Loss, Sensorineural/diagnosis
- Hearing Loss, Sensorineural/etiology
- Hearing Loss, Sensorineural/physiopathology
- Hearing Loss, Sensorineural/psychology
- Humans
- Male
- Models, Neurological
- Noise/adverse effects
- Psychoacoustics
- Risk Factors
- Synapses/ultrastructure
- Young Adult
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Affiliation(s)
- Brandon T Paul
- School of Speech Therapy and Audiology, University of Montreal, Montreal, Quebec H3T 1J4, Canada
| | - Sajal Waheed
- Department of Psychology, Neuroscience, & Behaviour, McMaster University, Hamilton, Ontario L8S 4 K1, Canada
| | - Ian C Bruce
- Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario L8S 4 K1, Canada , , ,
| | - Larry E Roberts
- Department of Psychology, Neuroscience, & Behaviour, McMaster University, Hamilton, Ontario L8S 4 K1, Canada
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408
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Normal tissue complication probability modeling of radiation-induced sensorineural hearing loss after head-and-neck radiation therapy. Int J Radiat Biol 2017; 93:1327-1333. [DOI: 10.1080/09553002.2017.1385872] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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409
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Shinn-Cunningham B. Cortical and Sensory Causes of Individual Differences in Selective Attention Ability Among Listeners With Normal Hearing Thresholds. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2017; 60:2976-2988. [PMID: 29049598 PMCID: PMC5945067 DOI: 10.1044/2017_jslhr-h-17-0080] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/23/2017] [Accepted: 07/05/2017] [Indexed: 05/28/2023]
Abstract
PURPOSE This review provides clinicians with an overview of recent findings relevant to understanding why listeners with normal hearing thresholds (NHTs) sometimes suffer from communication difficulties in noisy settings. METHOD The results from neuroscience and psychoacoustics are reviewed. RESULTS In noisy settings, listeners focus their attention by engaging cortical brain networks to suppress unimportant sounds; they then can analyze and understand an important sound, such as speech, amidst competing sounds. Differences in the efficacy of top-down control of attention can affect communication abilities. In addition, subclinical deficits in sensory fidelity can disrupt the ability to perceptually segregate sound sources, interfering with selective attention, even in listeners with NHTs. Studies of variability in control of attention and in sensory coding fidelity may help to isolate and identify some of the causes of communication disorders in individuals presenting at the clinic with "normal hearing." CONCLUSIONS How well an individual with NHTs can understand speech amidst competing sounds depends not only on the sound being audible but also on the integrity of cortical control networks and the fidelity of the representation of suprathreshold sound. Understanding the root cause of difficulties experienced by listeners with NHTs ultimately can lead to new, targeted interventions that address specific deficits affecting communication in noise. PRESENTATION VIDEO http://cred.pubs.asha.org/article.aspx?articleid=2601617.
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Affiliation(s)
- Barbara Shinn-Cunningham
- Center for Research in Sensory Communication and Emerging Neural Technology, Boston University, MA
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410
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Jiang M, Karasawa T, Steyger PS. Aminoglycoside-Induced Cochleotoxicity: A Review. Front Cell Neurosci 2017; 11:308. [PMID: 29062271 PMCID: PMC5640705 DOI: 10.3389/fncel.2017.00308] [Citation(s) in RCA: 171] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 09/15/2017] [Indexed: 12/20/2022] Open
Abstract
Aminoglycoside antibiotics are used as prophylaxis, or urgent treatment, for many life-threatening bacterial infections, including tuberculosis, sepsis, respiratory infections in cystic fibrosis, complex urinary tract infections and endocarditis. Although aminoglycosides are clinically-essential antibiotics, the mechanisms underlying their selective toxicity to the kidney and inner ear continue to be unraveled despite more than 70 years of investigation. The following mechanisms each contribute to aminoglycoside-induced toxicity after systemic administration: (1) drug trafficking across endothelial and epithelial barrier layers; (2) sensory cell uptake of these drugs; and (3) disruption of intracellular physiological pathways. Specific factors can increase the risk of drug-induced toxicity, including sustained exposure to higher levels of ambient sound, and selected therapeutic agents such as loop diuretics and glycopeptides. Serious bacterial infections (requiring life-saving aminoglycoside treatment) induce systemic inflammatory responses that also potentiate the degree of ototoxicity and permanent hearing loss. We discuss prospective clinical strategies to protect auditory and vestibular function from aminoglycoside ototoxicity, including reduced cochlear or sensory cell uptake of aminoglycosides, and otoprotection by ameliorating intracellular cytotoxicity.
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Affiliation(s)
- Meiyan Jiang
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR, United States
| | - Takatoshi Karasawa
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR, United States
| | - Peter S Steyger
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR, United States.,National Center for Rehabilitative Auditory Research, Portland VA Medical Center (VHA), Portland, OR, United States
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411
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Tan WJT, Song L, Graham M, Schettino A, Navaratnam D, Yarbrough WG, Santos-Sacchi J, Ivanova AV. Novel Role of the Mitochondrial Protein Fus1 in Protection from Premature Hearing Loss via Regulation of Oxidative Stress and Nutrient and Energy Sensing Pathways in the Inner Ear. Antioxid Redox Signal 2017; 27:489-509. [PMID: 28135838 PMCID: PMC5564041 DOI: 10.1089/ars.2016.6851] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
AIMS Acquired hearing loss is a worldwide epidemic that affects all ages. It is multifactorial in etiology with poorly characterized molecular mechanisms. Mitochondria are critical components in hearing. Here, we aimed to identify the mechanisms of mitochondria-dependent hearing loss using Fus1 KO mice, our novel model of mitochondrial dysfunction/oxidative stress. RESULTS Using auditory brainstem responses (ABRs), we characterized the Fus1 KO mouse as a novel, clinically relevant model of age-related hearing loss (ARHL) of metabolic etiology. We demonstrated early decline of the endocochlear potential (EP) that may occur due to severe mitochondrial and vascular pathologies in the Fus1 KO cochlear stria vascularis. We showed that pathological alterations in antioxidant (AO) and nutrient and energy sensing pathways (mTOR and PTEN/AKT) occur in cochleae of young Fus1 KO mice before major hearing loss. Importantly, short-term AO treatment corrected pathological molecular changes, while longer AO treatment restored EP, improved ABR parameters, restored mitochondrial structure, and delayed the development of hearing loss in the aging mouse. INNOVATION Currently, no molecular mechanisms linked to metabolic ARHL have been identified. We established pathological and molecular mechanisms that link the disease to mitochondrial dysfunction and oxidative stress. CONCLUSION Since chronic mitochondrial dysfunction is common in many patients, it could lead to developing hearing loss that can be alleviated/rescued by AO treatment. Our study creates a framework for clinical trials and introduces the Fus1 KO model as a powerful platform for developing novel therapeutic strategies to prevent/delay hearing loss associated with mitochondrial dysfunction. Antioxid. Redox Signal. 27, 489-509.
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Affiliation(s)
- Winston J T Tan
- 1 Department of Surgery, Section of Otolaryngology, Yale University School of Medicine , New Haven, Connecticut
| | - Lei Song
- 2 Department of Otolaryngology-Head and Neck Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai, China .,3 Ear Institute, Shanghai Jiao Tong University School of Medicine , Shanghai, China .,4 Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases , Shanghai, China
| | - Morven Graham
- 5 CCMI EM Core Facility, Yale University School of Medicine , New Haven, Connecticut
| | | | - Dhasakumar Navaratnam
- 7 Department of Neurology, Yale University School of Medicine , New Haven, Connecticut.,8 Department of Neuroscience, Yale University School of Medicine , New Haven, Connecticut
| | - Wendell G Yarbrough
- 1 Department of Surgery, Section of Otolaryngology, Yale University School of Medicine , New Haven, Connecticut.,9 Department of Pathology, Yale University School of Medicine , New Haven, Connecticut
| | - Joseph Santos-Sacchi
- 1 Department of Surgery, Section of Otolaryngology, Yale University School of Medicine , New Haven, Connecticut.,8 Department of Neuroscience, Yale University School of Medicine , New Haven, Connecticut.,10 Department of Cellular and Molecular Physiology, Yale University School of Medicine , New Haven, Connecticut
| | - Alla V Ivanova
- 1 Department of Surgery, Section of Otolaryngology, Yale University School of Medicine , New Haven, Connecticut
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412
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Bhatt I. Increased medial olivocochlear reflex strength in normal-hearing, noise-exposed humans. PLoS One 2017; 12:e0184036. [PMID: 28886123 PMCID: PMC5590870 DOI: 10.1371/journal.pone.0184036] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 08/16/2017] [Indexed: 11/23/2022] Open
Abstract
Research suggests that college-aged adults are vulnerable to tinnitus and hearing loss due to exposure to traumatic levels of noise on a regular basis. Recent human studies have associated exposure to high noise exposure background (NEB, i.e., routine noise exposure) with the reduced cochlear output and impaired speech processing ability in subjects with clinically normal hearing sensitivity. While the relationship between NEB and the functions of the auditory afferent neurons are studied in the literature, little is known about the effects of NEB on functioning of the auditory efferent system. The objective of the present study was to investigate the relationship between medial olivocochlear reflex (MOCR) strength and NEB in subjects with clinically normal hearing sensitivity. It was hypothesized that subjects with high NEB would exhibit reduced afferent input to the MOCR circuit which would subsequently lead to reduced strength of the MOCR. In normal-hearing listeners, the study examined (1) the association between NEB and baseline click-evoked otoacoustic emissions (CEOAEs) and (2) the association between NEB and MOCR strength. The MOCR was measured using CEOAEs evoked by 60 dB pSPL linear clicks in a contralateral acoustic stimulation (CAS)-off and CAS-on (a broadband noise at 60 dB SPL) condition. Participants with at least 6 dB signal-to-noise ratio (SNR) in the CAS-off and CAS-on conditions were included for analysis. A normalized CEOAE inhibition index was calculated to express MOCR strength in a percentage value. NEB was estimated using a validated questionnaire. The results showed that NEB was not associated with the baseline CEOAE amplitude (r = -0.112, p = 0.586). Contrary to the hypothesis, MOCR strength was positively correlated with NEB (r = 0.557, p = 0.003). NEB remained a significant predictor of MOCR strength (β = 2.98, t(19) = 3.474, p = 0.003) after the unstandardized coefficient was adjusted to control for effects of smoking, sound level tolerance (SLT) and tinnitus. These data provide evidence that MOCR strength is associated with NEB. The functional significance of increased MOCR strength is discussed.
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Affiliation(s)
- Ishan Bhatt
- Department of Communication Sciences & Disorders, Northern Arizona University, Flagstaff, AZ, United States of America
- * E-mail:
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413
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Abstract
HYPOTHESIS The compound action potential (CAP) is a purely neural component of the cochlea's response to sound, and may provide information regarding the existing neural substrate in cochlear implant (CI) subjects that can help account for variance in speech perception outcomes. BACKGROUND Measurement of the "total response" (TR), or sum of the magnitudes of spectral components in the ongoing responses to tone bursts across frequencies, has been shown to account for 40 to 50% of variance in speech perception outcomes. The ongoing response is composed of both hair cell and neural components. This correlation may be improved with the addition of the CAP. METHODS Intraoperative round window electrocochleography (ECochG) was performed in adult and pediatric CI subjects (n = 238). Stimuli were tones of different frequencies (250 Hz-4 kHz) at 90 dB nHL. The CAP was assessed in two ways, as an amplitude and with a scaling factor derived from a function fitted to the response. The results were correlated with consonant-nucleus-consonant (CNC) word scores at 6 months post-implantation (n = 51). RESULTS Only about half of the subjects had a measurable CAP at any frequency. The CNC word scores correlated weakly with both amplitude (r = 0.20, p < 0.001) and scaling factor (r = 0.25, p < 0.01). In contrast, the TR alone accounted for 43% of the variance, and addition of either CAP measurement in multiple regression did not account for additional variance. CONCLUSIONS The underlying pathology in CI patients causes the CAP to be often absent and highly variable when present. The TR is a better predictor of speech perception outcomes than the CAP.
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414
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Investigating the role of temporal lobe activation in speech perception accuracy with normal hearing adults: An event-related fNIRS study. Neuropsychologia 2017; 106:31-41. [PMID: 28888891 DOI: 10.1016/j.neuropsychologia.2017.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 08/29/2017] [Accepted: 09/04/2017] [Indexed: 12/14/2022]
Abstract
Functional near infrared spectroscopy (fNIRS) is a safe, non-invasive, relatively quiet imaging technique that is tolerant of movement artifact making it uniquely ideal for the assessment of hearing mechanisms. Previous research demonstrates the capacity for fNIRS to detect cortical changes to varying speech intelligibility, revealing a positive relationship between cortical activation amplitude and speech perception score. In the present study, we use an event-related design to investigate the hemodynamic response in the temporal lobe across different listening conditions. We presented participants with a speech recognition task using sentences in quiet, sentences in noise, and vocoded sentences. Hemodynamic responses were examined across conditions and then compared when speech perception was accurate compared to when speech perception was inaccurate in the context of noisy speech. Repeated measures, two-way ANOVAs revealed that the speech in noise condition (-2.8dB signal-to-noise ratio/SNR) demonstrated significantly greater activation than the easier listening conditions on multiple channels bilaterally. Further analyses comparing correct recognition trials to incorrect recognition trials (during the presentation phase of the trial) revealed that activation was significantly greater during correct trials. Lastly, during the repetition phase of the trial, where participants correctly repeated the sentence, the hemodynamic response demonstrated significantly higher deoxyhemoglobin than oxyhemoglobin, indicating a difference between the effects of perception and production on the cortical response. Using fNIRS, the present study adds meaningful evidence to the body of knowledge that describes the brain/behavior relationship related to speech perception.
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415
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Grinn SK, Wiseman KB, Baker JA, Le Prell CG. Hidden Hearing Loss? No Effect of Common Recreational Noise Exposure on Cochlear Nerve Response Amplitude in Humans. Front Neurosci 2017; 11:465. [PMID: 28919848 PMCID: PMC5585187 DOI: 10.3389/fnins.2017.00465] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 08/07/2017] [Indexed: 11/22/2022] Open
Abstract
This study tested hypothesized relationships between noise exposure and auditory deficits. Both retrospective assessment of potential associations between noise exposure history and performance on an audiologic test battery and prospective assessment of potential changes in performance after new recreational noise exposure were completed. Methods: 32 participants (13M, 19F) with normal hearing (25-dB HL or better, 0.25–8 kHz) were asked to participate in 3 pre- and post-exposure sessions including: otoscopy, tympanometry, distortion product otoacoustic emissions (DPOAEs) (f2 frequencies 1–8 kHz), pure-tone audiometry (0.25–8 kHz), Words-in-Noise (WIN) test, and electrocochleography (eCochG) measurements at 70, 80, and 90-dB nHL (click and 2–4 kHz tone-bursts). The first session was used to collect baseline data, the second session was collected the day after a loud recreational event, and the third session was collected 1-week later. Of the 32 participants, 26 completed all 3 sessions. Results: The retrospective analysis did not reveal statistically significant relationships between noise exposure history and any auditory deficits. The day after new exposure, there was a statistically significant correlation between noise “dose” and WIN performance overall, and within the 4-dB signal-to-babble ratio. In contrast, there were no statistically significant correlations between noise dose and changes in threshold, DPOAE amplitude, or AP amplitude the day after new noise exposure. Additional analyses revealed a statistically significant relationship between TTS and DPOAE amplitude at 6 kHz, with temporarily decreased DPOAE amplitude observed with increasing TTS. Conclusions: There was no evidence of auditory deficits as a function of previous noise exposure history, and no permanent changes in audiometric, electrophysiologic, or functional measures after new recreational noise exposure. There were very few participants with TTS the day after exposure - a test time selected to be consistent with previous animal studies. The largest observed TTS was approximately 20-dB. The observed pattern of small TTS suggests little risk of synaptopathy from common recreational noise exposure, and that we should not expect to observe changes in evoked potentials for this reason. No such changes were observed in this study. These data do not support suggestions that common, recreational noise exposure is likely to result in “hidden hearing loss”.
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Affiliation(s)
- Sarah K Grinn
- School of Behavioral and Brain Sciences, University of Texas at DallasDallas, TX, United States.,College of Public Health and Health Professions, University of FloridaGainesville, FL, United States
| | - Kathryn B Wiseman
- School of Behavioral and Brain Sciences, University of Texas at DallasDallas, TX, United States
| | - Jason A Baker
- School of Behavioral and Brain Sciences, University of Texas at DallasDallas, TX, United States
| | - Colleen G Le Prell
- School of Behavioral and Brain Sciences, University of Texas at DallasDallas, TX, United States
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416
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Eggermont JJ. Effects of long-term non-traumatic noise exposure on the adult central auditory system. Hearing problems without hearing loss. Hear Res 2017; 352:12-22. [DOI: 10.1016/j.heares.2016.10.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 10/18/2016] [Accepted: 10/21/2016] [Indexed: 11/27/2022]
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417
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Valero MD, Burton JA, Hauser SN, Hackett TA, Ramachandran R, Liberman MC. Noise-induced cochlear synaptopathy in rhesus monkeys (Macaca mulatta). Hear Res 2017; 353:213-223. [PMID: 28712672 PMCID: PMC5632522 DOI: 10.1016/j.heares.2017.07.003] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 06/02/2017] [Accepted: 07/06/2017] [Indexed: 12/21/2022]
Abstract
Cochlear synaptopathy can result from various insults, including acoustic trauma, aging, ototoxicity, or chronic conductive hearing loss. For example, moderate noise exposure in mice can destroy up to ∼50% of synapses between auditory nerve fibers (ANFs) and inner hair cells (IHCs) without affecting outer hair cells (OHCs) or thresholds, because the synaptopathy occurs first in high-threshold ANFs. However, the fiber loss likely impairs temporal processing and hearing-in-noise, a classic complaint of those with sensorineural hearing loss. Non-human primates appear to be less vulnerable to noise-induced hair-cell loss than rodents, but their susceptibility to synaptopathy has not been studied. Because establishing a non-human primate model may be important in the development of diagnostics and therapeutics, we examined cochlear innervation and the damaging effects of acoustic overexposure in young adult rhesus macaques. Anesthetized animals were exposed bilaterally to narrow-band noise centered at 2 kHz at various sound-pressure levels for 4 h. Cochlear function was assayed for up to 8 weeks following exposure via auditory brainstem responses (ABRs) and otoacoustic emissions (OAEs). A moderate loss of synaptic connections (mean of 12-27% in the basal half of the cochlea) followed temporary threshold shifts (TTS), despite minimal hair-cell loss. A dramatic loss of synapses (mean of 50-75% in the basal half of the cochlea) was seen on IHCs surviving noise exposures that produced permanent threshold shifts (PTS) and widespread hair-cell loss. Higher noise levels were required to produce PTS in macaques compared to rodents, suggesting that primates are less vulnerable to hair-cell loss. However, the phenomenon of noise-induced cochlear synaptopathy in primates is similar to that seen in rodents.
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Affiliation(s)
- M D Valero
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA; Department of Otolaryngology, Harvard Medical School, Boston, MA 02115, USA.
| | - J A Burton
- Vanderbilt University Medical Center, Dept. of Hearing and Speech Sciences, Nashville, TN 37232, USA
| | - S N Hauser
- Vanderbilt University Medical Center, Dept. of Hearing and Speech Sciences, Nashville, TN 37232, USA
| | - T A Hackett
- Vanderbilt University Medical Center, Dept. of Hearing and Speech Sciences, Nashville, TN 37232, USA
| | - R Ramachandran
- Vanderbilt University Medical Center, Dept. of Hearing and Speech Sciences, Nashville, TN 37232, USA
| | - M C Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA; Department of Otolaryngology, Harvard Medical School, Boston, MA 02115, USA
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418
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Abstract
Noise levels are truly continuous in relatively few occupations, with some degree of intermittency the most common condition. The sound levels of intermittent noise are often referred to as non-Gaussian in that they are not normally distributed in the time domain. In some conditions, intermittent noise affects the ear differently from continuous noise, and it is this assumption that underlies the selection of the 5-dB exchange rate (ER). The scientific and professional communities have debated this assumption over recent decades. This monograph explores the effect of non-Gaussian noise on the auditory system. It begins by summarizing an earlier report by the same author concentrating on the subject of the ER. The conclusions of the earlier report supported the more conservative 3-dB ER with possible adjustments to the permissible exposure limit for certain working conditions. The current document has expanded on the earlier report in light of the relevant research accomplished in the intervening decades. Although some of the animal research has supported the mitigating effect of intermittency, a closer look at many of these studies reveals certain weaknesses, along with the fact that these noise exposures were not usually representative of the conditions under which people actually work. The more recent animal research on complex noise shows that intermittencies do not protect the cochlea and that many of the previous assumptions about the ameliorative effect of intermittencies are no longer valid, lending further support to the 3-dB ER. The neurologic effects of noise on hearing have gained increasing attention in recent years because of improvements in microscopy and immunostaining techniques. Animal experiments showing damage to auditory synapses from noise exposures previously considered harmless may signify the need for a more conservative approach to the assessment of noise-induced hearing loss and consequently the practice of hearing conservation programs.
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419
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Wise AK, Pujol R, Landry TG, Fallon JB, Shepherd RK. Structural and Ultrastructural Changes to Type I Spiral Ganglion Neurons and Schwann Cells in the Deafened Guinea Pig Cochlea. J Assoc Res Otolaryngol 2017; 18:751-769. [PMID: 28717876 DOI: 10.1007/s10162-017-0631-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 06/21/2017] [Indexed: 01/03/2023] Open
Abstract
Sensorineural hearing loss is commonly caused by damage to cochlear sensory hair cells. Coinciding with hair cell degeneration, the peripheral fibres of type I spiral ganglion neurons (SGNs) that normally form synaptic connections with the inner hair cell gradually degenerate. We examined the time course of these degenerative changes in type I SGNs and their satellite Schwann cells at the ultrastructural level in guinea pigs at 2, 6, and 12 weeks following aminoglycoside-induced hearing loss. Degeneration of the peripheral fibres occurred prior to the degeneration of the type I SGN soma and was characterised by shrinkage of the fibre followed by retraction of the axoplasm, often leaving a normal myelin lumen devoid of axoplasmic content. A statistically significant reduction in the cross-sectional area of peripheral fibres was evident as early as 2 weeks following deafening (p < 0.001, ANOVA). This was followed by a decrease in type I SGN density within Rosenthal's canal that was statistically significant 6 weeks following deafening (p < 0.001, ANOVA). At any time point examined, few type I SGN soma were observed undergoing degeneration, implying that once initiated, soma degeneration was rapid. While there was a significant reduction in soma area as well as changes to the morphology of the soma, the ultrastructure of surviving type I SGN soma appeared relatively normal over the 12-week period following deafening. Satellite Schwann cells exhibited greater survival traits than their type I SGN; however, on loss of neural contact, they reverted to a non-myelinating phenotype, exhibiting an astrocyte-like morphology with the formation of processes that appeared to be searching for new neural targets. In 6- and 12-week deafened cochlea, we observed cellular interaction between Schwann cell processes and residual SGNs that distorted the morphology of the SGN soma. Understanding the response of SGNs, Schwann cells, and the complex relationship between them following aminoglycoside deafening is important if we are to develop effective therapeutic techniques designed to rescue SGNs.
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Affiliation(s)
- Andrew K Wise
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria, 3002, Australia.
- Department of Medical Bionics, University of Melbourne, Melbourne, Australia.
- Department of Otolaryngology, University of Melbourne, Melbourne, Australia.
| | - Remy Pujol
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria, 3002, Australia
- INSERM Unit 1051, INM, Montpellier, France
| | - Thomas G Landry
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria, 3002, Australia
| | - James B Fallon
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria, 3002, Australia
- Department of Medical Bionics, University of Melbourne, Melbourne, Australia
- Department of Otolaryngology, University of Melbourne, Melbourne, Australia
| | - Robert K Shepherd
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria, 3002, Australia
- Department of Medical Bionics, University of Melbourne, Melbourne, Australia
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420
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Hackelberg S, Tuck SJ, He L, Rastogi A, White C, Liu L, Prieskorn DM, Miller RJ, Chan C, Loomis BR, Corey JM, Miller JM, Duncan RK. Nanofibrous scaffolds for the guidance of stem cell-derived neurons for auditory nerve regeneration. PLoS One 2017; 12:e0180427. [PMID: 28672008 PMCID: PMC5495534 DOI: 10.1371/journal.pone.0180427] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 06/15/2017] [Indexed: 01/13/2023] Open
Abstract
Impairment of spiral ganglion neurons (SGNs) of the auditory nerve is a major cause for hearing loss occurring independently or in addition to sensory hair cell damage. Unfortunately, mammalian SGNs lack the potential for autonomous regeneration. Stem cell based therapy is a promising approach for auditory nerve regeneration, but proper integration of exogenous cells into the auditory circuit remains a fundamental challenge. Here, we present novel nanofibrous scaffolds designed to guide the integration of human stem cell-derived neurons in the internal auditory meatus (IAM), the foramen allowing passage of the spiral ganglion to the auditory brainstem. Human embryonic stem cells (hESC) were differentiated into neural precursor cells (NPCs) and seeded onto aligned nanofiber mats. The NPCs terminally differentiated into glutamatergic neurons with high efficiency, and neurite projections aligned with nanofibers in vitro. Scaffolds were assembled by seeding GFP-labeled NPCs on nanofibers integrated in a polymer sheath. Biocompatibility and functionality of the NPC-seeded scaffolds were evaluated in vivo in deafened guinea pigs (Cavia porcellus). To this end, we established an ouabain-based deafening procedure that depleted an average 72% of SGNs from apex to base of the cochleae and caused profound hearing loss. Further, we developed a surgical procedure to implant seeded scaffolds directly into the guinea pig IAM. No evidence of an inflammatory response was observed, but post-surgery tissue repair appeared to be facilitated by infiltrating Schwann cells. While NPC survival was found to be poor, both subjects implanted with NPC-seeded and cell-free control scaffolds showed partial recovery of electrically-evoked auditory brainstem thresholds. Thus, while future studies must address cell survival, nanofibrous scaffolds pose a promising strategy for auditory nerve regeneration.
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Affiliation(s)
- Sandra Hackelberg
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - Samuel J. Tuck
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Long He
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
- Departments of Otorhinolaryngology, Guangzhou First Peoples' Hospital and First Affiliated Hospital, School of Medicine, Jinan University, Guangdong, China
| | - Arjun Rastogi
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
| | - Christina White
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Liqian Liu
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - Diane M. Prieskorn
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - Ryan J. Miller
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Che Chan
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Benjamin R. Loomis
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - Joseph M. Corey
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States of America
| | - Josef M. Miller
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - R. Keith Duncan
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
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421
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Abstract
OBJECTIVE To critically review and evaluate the proposed mechanisms and documented results of the therapeutics currently in active clinical drug trials for the treatment of sensorineural hearing loss. DATA SOURCES US National Institutes of Health (NIH) Clinical Trials registry, MEDLINE/PubMed. STUDY SELECTION & DATA EXTRACTION A review of the NIH Clinical Trials registry identified candidate hearing loss therapies, and supporting publications were acquired from MEDLINE/PubMed. Proof-of-concept, therapeutic mechanisms, and clinical outcomes were critically appraised. DATA SYNTHESIS Twenty-two active clinical drug trials registered in the United States were identified, and six potentially therapeutic molecules were reviewed. Of the six molecules reviewed, four comprised mechanisms pertaining to mitigating oxidative stress pathways that presumably lead to inner ear cell death. One remaining therapy sought to manipulate the cell death cascade, and the last remaining therapy was a novel cell replacement therapy approach to introduce a transcription factor that promotes hair cell regeneration. CONCLUSION A common theme in recent clinical trials registered in the United States appears to be the targeting of cell death pathways and influence of oxidant stressors on cochlear sensory neuroepithelium. In addition, a virus-delivered cell replacement therapy would be the first of its kind should it prove safe and efficacious. Significant challenges for bringing these bench-to-bedside therapies to market remain. It is never assured that results in non-human animal models translate to effective therapies in the setting of human biology. Moreover, as additional processes are described in association with hearing loss, such as an immune response and loss of synaptic contacts, additional pathways for targeting become available.
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Affiliation(s)
- Matthew G. Crowson
- Division of Head & Neck Surgery & Communication Sciences, Department of Surgery, Duke University Medical Center, Durham, NC USA
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head & Neck Surgery, Anatomy and Neurobiology and Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD USA
| | - Debara Tucci
- Division of Head & Neck Surgery & Communication Sciences, Department of Surgery, Duke University Medical Center, Durham, NC USA
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422
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Lauer AM. Minimal Effects of Age and Exposure to a Noisy Environment on Hearing in Alpha9 Nicotinic Receptor Knockout Mice. Front Neurosci 2017. [PMID: 28626386 PMCID: PMC5454393 DOI: 10.3389/fnins.2017.00304] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Studies have suggested a role of weakened medial olivocochlear (OC) efferent feedback in accelerated hearing loss and increased susceptibility to noise. The present study investigated the progression of hearing loss with age and exposure to a noisy environment in medial OC-deficient mice. Alpha9 nicotinic acetylcholine receptor knockout (α9KO) and wild types were screened for hearing loss using auditory brainstem responses. α9KO mice housed in a quiet environment did not show increased hearing loss compared to wild types in young adulthood and middle age. Challenging the medial OC system by housing in a noisy environment did not increase hearing loss in α9KO mice compared to wild types. ABR wave 1 amplitudes also did not show differences between α9KO mice and wild types. These data suggest that deficient medial OC feedback does not result in early onset of hearing loss.
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Affiliation(s)
- Amanda M Lauer
- Department of Otolaryngology-HNS, Center for Hearing and Balance, Johns Hopkins University School of MedicineBaltimore, MD, United States
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423
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Liberman MC, Kujawa SG. Cochlear synaptopathy in acquired sensorineural hearing loss: Manifestations and mechanisms. Hear Res 2017; 349:138-147. [PMID: 28087419 PMCID: PMC5438769 DOI: 10.1016/j.heares.2017.01.003] [Citation(s) in RCA: 430] [Impact Index Per Article: 61.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 12/19/2016] [Accepted: 01/05/2017] [Indexed: 12/20/2022]
Abstract
Common causes of hearing loss in humans - exposure to loud noise or ototoxic drugs and aging - often damage sensory hair cells, reflected as elevated thresholds on the clinical audiogram. Recent studies in animal models suggest, however, that well before this overt hearing loss can be seen, a more insidious, but likely more common, process is taking place that permanently interrupts synaptic communication between sensory inner hair cells and subsets of cochlear nerve fibers. The silencing of affected neurons alters auditory information processing, whether accompanied by threshold elevations or not, and is a likely contributor to a variety of perceptual abnormalities, including speech-in-noise difficulties, tinnitus and hyperacusis. Work described here will review structural and functional manifestations of this cochlear synaptopathy and will consider possible mechanisms underlying its appearance and progression in ears with and without traditional 'hearing loss' arising from several common causes in humans.
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MESH Headings
- Animals
- Auditory Perception
- Auditory Threshold
- Cochlear Nerve/metabolism
- Cochlear Nerve/pathology
- Cochlear Nerve/physiopathology
- Glutamic Acid/metabolism
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/pathology
- Hearing
- Hearing Loss, Noise-Induced/metabolism
- Hearing Loss, Noise-Induced/pathology
- Hearing Loss, Noise-Induced/physiopathology
- Hearing Loss, Noise-Induced/psychology
- Hearing Loss, Sensorineural/metabolism
- Hearing Loss, Sensorineural/pathology
- Hearing Loss, Sensorineural/physiopathology
- Hearing Loss, Sensorineural/psychology
- Humans
- Nerve Degeneration
- Noise/adverse effects
- Risk Factors
- Synapses/metabolism
- Synapses/pathology
- Synaptic Transmission
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Affiliation(s)
- M Charles Liberman
- Department of Otology and Laryngology, Harvard Medical School, Boston MA, USA; Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston MA, USA
| | - Sharon G Kujawa
- Department of Otology and Laryngology, Harvard Medical School, Boston MA, USA; Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston MA, USA.
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424
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Noise-induced cochlear synaptopathy: Past findings and future studies. Hear Res 2017; 349:148-154. [DOI: 10.1016/j.heares.2016.12.008] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/08/2016] [Accepted: 12/08/2016] [Indexed: 01/12/2023]
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425
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Audiologic characteristics in a sample of recently-separated military Veterans: The Noise Outcomes in Servicemembers Epidemiology Study (NOISE Study). Hear Res 2017; 349:21-30. [DOI: 10.1016/j.heares.2016.11.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/03/2016] [Accepted: 11/21/2016] [Indexed: 11/23/2022]
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426
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Semeraro HD, Rowan D, van Besouw RM, Allsopp AA. Development and evaluation of the British English coordinate response measure speech-in-noise test as an occupational hearing assessment tool. Int J Audiol 2017; 56:749-758. [PMID: 28537138 DOI: 10.1080/14992027.2017.1317370] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVE The studies described in this article outline the design and development of a British English version of the coordinate response measure (CRM) speech-in-noise (SiN) test. Our interest in the CRM is as a SiN test with high face validity for occupational auditory fitness for duty (AFFD) assessment. DESIGN Study 1 used the method of constant stimuli to measure and adjust the psychometric functions of each target word, producing a speech corpus with equal intelligibility. After ensuring all the target words had similar intelligibility, for Studies 2 and 3, the CRM was presented in an adaptive procedure in stationary speech-spectrum noise to measure speech reception thresholds and evaluate the test-retest reliability of the CRM SiN test. STUDY SAMPLE Studies 1 (n = 20) and 2 (n = 30) were completed by normal-hearing civilians. Study 3 (n = 22) was completed by hearing impaired military personnel. RESULTS The results display good test-retest reliability (95% confidence interval (CI) < 2.1 dB) and concurrent validity when compared to the triple-digit test (r ≤ 0.65), and the CRM is sensitive to hearing impairment. CONCLUSION The British English CRM using stationary speech-spectrum noise is a "ready to use" SiN test, suitable for investigation as an AFFD assessment tool for military personnel.
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Affiliation(s)
- Hannah D Semeraro
- a Institute of Sound and Vibration Research, University of Southampton , Southampton , UK and
| | - Daniel Rowan
- a Institute of Sound and Vibration Research, University of Southampton , Southampton , UK and
| | - Rachel M van Besouw
- a Institute of Sound and Vibration Research, University of Southampton , Southampton , UK and
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427
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Nguyen MF, Bonnefoy M, Adrait A, Gueugnon M, Petitot C, Collet L, Roux A, Perrot X. Efficacy of Hearing Aids on the Cognitive Status of Patients with Alzheimer’s Disease and Hearing Loss: A Multicenter Controlled Randomized Trial. J Alzheimers Dis 2017; 58:123-137. [DOI: 10.3233/jad-160793] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Marie-France Nguyen
- Geriatric Medicine Unit, Lyon Sud Hospital, Hospices Civils de Lyon, Pierre Bénite, France
| | - Marc Bonnefoy
- Geriatric Medicine Unit, Lyon Sud Hospital, Hospices Civils de Lyon, Pierre Bénite, France
- University Claude Bernard Lyon 1, Faculty of Medicine Lyon Sud, Pierre Bénite, France
| | - Arnaud Adrait
- Geriatric Medicine Unit, Lyon Sud Hospital, Hospices Civils de Lyon, Pierre Bénite, France
| | - Marine Gueugnon
- Clinical Research Unit, Pole IMER, Hospices Civils de Lyon, Lyon, France
| | - Charles Petitot
- Geriatric Medicine Unit, Lyon Sud Hospital, Hospices Civils de Lyon, Pierre Bénite, France
| | - Lionel Collet
- Department of Audiology, Edouard Herriot Hospital, Hospices Civils de Lyon, Lyon, France
| | - Adeline Roux
- Clinical Research Unit, Pole IMER, Hospices Civils de Lyon, Lyon, France
| | - Xavier Perrot
- University Claude Bernard Lyon 1, Faculty of Medicine Lyon Sud, Pierre Bénite, France
- Department of Audiology, Edouard Herriot Hospital, Hospices Civils de Lyon, Lyon, France
- Institute of Sciences and Techniques for Rehabilitation (ISTR), Lyon 1 University, University of Lyon, Lyon, France
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428
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Basinou V, Park JS, Cederroth CR, Canlon B. Circadian regulation of auditory function. Hear Res 2017; 347:47-55. [PMID: 27665709 PMCID: PMC5364078 DOI: 10.1016/j.heares.2016.08.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 08/25/2016] [Indexed: 12/11/2022]
Abstract
The circadian system integrates environmental cues to regulate physiological functions in a temporal fashion. The suprachiasmatic nucleus, located in the hypothalamus, is the master clock that synchronizes central and peripheral organ clocks to orchestrate physiological functions. Recently, molecular clock machinery has been identified in the cochlea unravelling the potential involvement in the circadian regulation of auditory functions. Here, we present background information on the circadian system and review the recent findings that introduce circadian rhythms to the auditory field. Understanding the mechanisms by which circadian rhythms regulate auditory function will provide fundamental knowledge on the signalling networks that control vulnerability and resilience to auditory insults.
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Affiliation(s)
- Vasiliki Basinou
- Department of Physiology and Pharmacology, Laboratory of Experimental Audiology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Jung-Sub Park
- Department of Physiology and Pharmacology, Laboratory of Experimental Audiology, Karolinska Institutet, 171 77 Stockholm, Sweden; Department of Otolaryngology, Ajou University School of Medicine, 164, Worldcup-ro, Yeongtong-gu, Suwon, 16499, South Korea
| | - Christopher R Cederroth
- Department of Physiology and Pharmacology, Laboratory of Experimental Audiology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Barbara Canlon
- Department of Physiology and Pharmacology, Laboratory of Experimental Audiology, Karolinska Institutet, 171 77 Stockholm, Sweden.
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429
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Fuentes-Santamaría V, Alvarado JC, Melgar-Rojas P, Gabaldón-Ull MC, Miller JM, Juiz JM. The Role of Glia in the Peripheral and Central Auditory System Following Noise Overexposure: Contribution of TNF-α and IL-1β to the Pathogenesis of Hearing Loss. Front Neuroanat 2017; 11:9. [PMID: 28280462 PMCID: PMC5322242 DOI: 10.3389/fnana.2017.00009] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 02/09/2017] [Indexed: 12/12/2022] Open
Abstract
Repeated noise exposure induces inflammation and cellular adaptations in the peripheral and central auditory system resulting in pathophysiology of hearing loss. In this study, we analyzed the mechanisms by which noise-induced inflammatory-related events in the cochlea activate glial-mediated cellular responses in the cochlear nucleus (CN), the first relay station of the auditory pathway. The auditory function, glial activation, modifications in gene expression and protein levels of inflammatory mediators and ultrastructural changes in glial-neuronal interactions were assessed in rats exposed to broadband noise (0.5-32 kHz, 118 dB SPL) for 4 h/day during 4 consecutive days to induce long-lasting hearing damage. Noise-exposed rats developed a permanent threshold shift which was associated with hair cell loss and reactive glia. Noise-induced microglial activation peaked in the cochlea between 1 and 10D post-lesion; their activation in the CN was more prolonged reaching maximum levels at 30D post-exposure. RT-PCR analyses of inflammatory-related genes expression in the cochlea demonstrated significant increases in the mRNA expression levels of pro- and anti-inflammatory cytokines, inducible nitric oxide synthase, intercellular adhesion molecule and tissue inhibitor of metalloproteinase-1 at 1 and 10D post-exposure. In noise-exposed cochleae, interleukin-1β (IL-1β), and tumor necrosis factor α (TNF-α) were upregulated by reactive microglia, fibrocytes, and neurons at all time points examined. In the CN, however, neurons were the sole source of these cytokines. These observations suggest that noise exposure causes peripheral and central inflammatory reactions in which TNF-α and IL-1β are implicated in regulating the initiation and progression of noise-induced hearing loss.
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Affiliation(s)
- Verónica Fuentes-Santamaría
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - Juan Carlos Alvarado
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - Pedro Melgar-Rojas
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - María C Gabaldón-Ull
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - Josef M Miller
- Center for Hearing and Communication Research and Department of Clinical Neuroscience, Karolinska InstitutetStockholm, Sweden; Kresge Hearing Research Institute, University of MichiganAnn Arbor, MI, USA
| | - José M Juiz
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
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430
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Langguth B, Landgrebe M, Schlee W, Schecklmann M, Vielsmeier V, Steffens T, Staudinger S, Frick H, Frick U. Different Patterns of Hearing Loss among Tinnitus Patients: A Latent Class Analysis of a Large Sample. Front Neurol 2017; 8:46. [PMID: 28265258 PMCID: PMC5316929 DOI: 10.3389/fneur.2017.00046] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 01/31/2017] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND The heterogeneity of tinnitus is a major challenge for tinnitus research. Even if a complex interaction of many factors is involved in the etiology of tinnitus, hearing loss (HL) has been identified as the most relevant etiologic factor. Here, we used a data-driven approach to identify patterns of hearing function in a large sample of tinnitus patients presenting in a tinnitus clinic. METHODS Data from 2,838 patients presenting at the Tinnitus Center of the University Regensburg between 2007 and 2014 have been analyzed. Standard audiometric data were frequency-wise categorized in four categories [a: normal hearing (0-20 dB HL); b: moderate HL (25-50 dB HL; representing outer hair cell loss); c: severe HL (>50 dB HL; representing outer and inner hair cell loss); d: no data available] and entered in a latent class analysis, a statistical method to find subtypes of cases in multivariate categorical data. To validate the clinical relevance of the identified latent classes, they were compared with respect to clinical and demographic characteristics of their members. RESULTS The classification algorithm identified eight distinct latent classes with an excellent separation. Patient classes differed with respect to demographic (e.g., age, gender) and clinical characteristics (e.g., tinnitus location, tinnitus severity, gradual, or abrupt onset, etc.). DISCUSSION Our results demonstrate that data-driven categorization of hearing function seems to be a promising approach for profiling tinnitus patients, as it revealed distinct subtypes that reflect prototypic forms of HL and that differ in several relevant clinical characteristics.
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Affiliation(s)
- Berthold Langguth
- Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany; Interdisciplinary Tinnitus Center of the University of Regensburg, Regensburg, Germany
| | - Michael Landgrebe
- Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany; kbo Lech-Mangfall-Klinik Agatharied, Hausham, Germany
| | - Winfried Schlee
- Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany; Interdisciplinary Tinnitus Center of the University of Regensburg, Regensburg, Germany
| | - Martin Schecklmann
- Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany; Interdisciplinary Tinnitus Center of the University of Regensburg, Regensburg, Germany
| | - Veronika Vielsmeier
- Interdisciplinary Tinnitus Center of the University of Regensburg, Regensburg, Germany; Department of Otorhinolaryngology, University of Regensburg, Regensburg, Germany
| | - Thomas Steffens
- Interdisciplinary Tinnitus Center of the University of Regensburg, Regensburg, Germany; Department of Otorhinolaryngology, University of Regensburg, Regensburg, Germany
| | - Susanne Staudinger
- Interdisciplinary Tinnitus Center of the University of Regensburg , Regensburg , Germany
| | - Hannah Frick
- Department of Statistical Science, University College London , London , UK
| | - Ulrich Frick
- Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany; HSD University of Applied Sciences, Cologne, Germany
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431
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Wan G, Corfas G. Transient auditory nerve demyelination as a new mechanism for hidden hearing loss. Nat Commun 2017; 8:14487. [PMID: 28211470 PMCID: PMC5321746 DOI: 10.1038/ncomms14487] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 01/04/2017] [Indexed: 12/31/2022] Open
Abstract
Hidden hearing loss (HHL) is a recently described auditory neuropathy believed to contribute to speech discrimination and intelligibility deficits in people with normal audiological tests. Animals and humans with HHL have normal auditory thresholds but defective cochlear neurotransmission, that is, reduced suprathreshold amplitude of the sound-evoked auditory nerve compound action potential. Currently, the only cellular mechanism known for HHL is loss of inner hair cell synapses (synaptopathy). Here we report that transient loss of cochlear Schwann cells results in permanent auditory deficits characteristic of HHL. This auditory neuropathy is not associated with synaptic loss, but rather with disruption of the first heminodes at the auditory nerve peripheral terminal. Thus, this study identifies a new mechanism for HHL, highlights the long-term consequences of transient Schwann cell loss on hearing and might provide insights into the causes of the auditory deficits reported in patients that recover from acute demyelinating diseases such as Guillain–Barré syndrome. Hidden hearing loss (HHL) is an auditory neuropathy that impairs one's ability to hear, particularly in a noisy environment. Here the authors show that in mice, transient loss of cochlear Schwann cells results in permanent disruption of the cochlear heminodal structure, leading to auditory deficits characteristic of HHL.
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Affiliation(s)
- Guoqiang Wan
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109, USA.,MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, Jiangsu Province, China
| | - Gabriel Corfas
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109, USA
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432
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The Coupling between Ca 2+ Channels and the Exocytotic Ca 2+ Sensor at Hair Cell Ribbon Synapses Varies Tonotopically along the Mature Cochlea. J Neurosci 2017; 37:2471-2484. [PMID: 28154149 PMCID: PMC5354352 DOI: 10.1523/jneurosci.2867-16.2017] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 01/06/2017] [Accepted: 01/10/2017] [Indexed: 11/24/2022] Open
Abstract
The cochlea processes auditory signals over a wide range of frequencies and intensities. However, the transfer characteristics at hair cell ribbon synapses are still poorly understood at different frequency locations along the cochlea. Using recordings from mature gerbils, we report here a surprisingly strong block of exocytosis by the slow Ca2+ buffer EGTA (10 mM) in basal hair cells tuned to high frequencies (∼30 kHz). In addition, using recordings from gerbil, mouse, and bullfrog auditory organs, we find that the spatial coupling between Ca2+ influx and exocytosis changes from nanodomain in low-frequency tuned hair cells (∼<2 kHz) to progressively more microdomain in high-frequency cells (∼>2 kHz). Hair cell synapses have thus developed remarkable frequency-dependent tuning of exocytosis: accurate low-latency encoding of onset and offset of sound intensity in the cochlea's base and submillisecond encoding of membrane receptor potential fluctuations in the apex for precise phase-locking to sound signals. We also found that synaptic vesicle pool recovery from depletion was sensitive to high concentrations of EGTA, suggesting that intracellular Ca2+ buffers play an important role in vesicle recruitment in both low- and high-frequency hair cells. In conclusion, our results indicate that microdomain coupling is important for exocytosis in high-frequency hair cells, suggesting a novel hypothesis for why these cells are more susceptible to sound-induced damage than low-frequency cells; high-frequency inner hair cells must have a low Ca2+ buffer capacity to sustain exocytosis, thus making them more prone to Ca2+-induced cytotoxicity. SIGNIFICANCE STATEMENT In the inner ear, sensory hair cells signal reception of sound. They do this by converting the sound-induced movement of their hair bundles present at the top of these cells, into an electrical current. This current depolarizes the hair cell and triggers the calcium-induced release of the neurotransmitter glutamate that activates the postsynaptic auditory fibers. The speed and precision of this process enables the brain to perceive the vital components of sound, such as frequency and intensity. We show that the coupling strength between calcium channels and the exocytosis calcium sensor at inner hair cell synapses changes along the mammalian cochlea such that the timing and/or intensity of sound is encoded with high precision.
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433
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Salvi R, Sun W, Ding D, Chen GD, Lobarinas E, Wang J, Radziwon K, Auerbach BD. Inner Hair Cell Loss Disrupts Hearing and Cochlear Function Leading to Sensory Deprivation and Enhanced Central Auditory Gain. Front Neurosci 2017; 10:621. [PMID: 28149271 PMCID: PMC5241314 DOI: 10.3389/fnins.2016.00621] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 12/30/2016] [Indexed: 11/13/2022] Open
Abstract
There are three times as many outer hair cells (OHC) as inner hair cells (IHC), yet IHC transmit virtually all acoustic information to the brain as they synapse with 90–95% of type I auditory nerve fibers. Here we review a comprehensive series of experiments aimed at determining how loss of the IHC/type I system affects hearing by selectively destroying these cells in chinchillas using the ototoxic anti-cancer agent carboplatin. Eliminating IHC/type I neurons has no effect on distortion product otoacoustic emission or the cochlear microphonic potential generated by OHC; however, it greatly reduces the summating potential produced by IHC and the compound action potential (CAP) generated by type I neurons. Remarkably, responses from remaining auditory nerve fibers maintain sharp tuning and low thresholds despite innervating regions of the cochlea with ~80% IHC loss. Moreover, chinchillas with large IHC lesions have surprisingly normal thresholds in quiet until IHC losses exceeded 80%, suggesting that only a few IHC are needed to detect sounds in quiet. However, behavioral thresholds in broadband noise are elevated significantly and tone-in-narrow band noise masking patterns exhibit greater remote masking. These results suggest the auditory system is able to compensate for considerable loss of IHC/type I neurons in quiet but not in difficult listening conditions. How does the auditory brain deal with the drastic loss of cochlear input? Recordings from the inferior colliculus found a relatively small decline in sound-evoked activity despite a large decrease in CAP amplitude after IHC lesion. Paradoxically, sound-evoked responses are generally larger than normal in the auditory cortex, indicative of increased central gain. This gain enhancement in the auditory cortex is associated with decreased GABA-mediated inhibition. These results suggest that when the neural output of the cochlea is reduced, the central auditory system compensates by turning up its gain so that weak signals once again become comfortably loud. While this gain enhancement is able to restore normal hearing under quiet conditions, it may not adequately compensate for peripheral dysfunction in more complex sound environments. In addition, excessive gain increases may convert recruitment into the debilitating condition known as hyperacusis.
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Affiliation(s)
- Richard Salvi
- Center for Hearing and Deafness, University at Buffalo Buffalo, NY, USA
| | - Wei Sun
- Center for Hearing and Deafness, University at Buffalo Buffalo, NY, USA
| | - Dalian Ding
- Center for Hearing and Deafness, University at Buffalo Buffalo, NY, USA
| | - Guang-Di Chen
- Center for Hearing and Deafness, University at Buffalo Buffalo, NY, USA
| | | | - Jian Wang
- School of Human Communication Disorders, Dalhousie University Halifax, NS, Canada
| | - Kelly Radziwon
- Center for Hearing and Deafness, University at Buffalo Buffalo, NY, USA
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434
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Grose JH, Buss E, Hall JW. Loud Music Exposure and Cochlear Synaptopathy in Young Adults: Isolated Auditory Brainstem Response Effects but No Perceptual Consequences. Trends Hear 2017; 21:2331216517737417. [PMID: 29105620 PMCID: PMC5676494 DOI: 10.1177/2331216517737417] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 09/21/2017] [Indexed: 01/20/2023] Open
Abstract
The purpose of this study was to test the hypothesis that listeners with frequent exposure to loud music exhibit deficits in suprathreshold auditory performance consistent with cochlear synaptopathy. Young adults with normal audiograms were recruited who either did ( n = 31) or did not ( n = 30) have a history of frequent attendance at loud music venues where the typical sound levels could be expected to result in temporary threshold shifts. A test battery was administered that comprised three sets of procedures: (a) electrophysiological tests including distortion product otoacoustic emissions, auditory brainstem responses, envelope following responses, and the acoustic change complex evoked by an interaural phase inversion; (b) psychoacoustic tests including temporal modulation detection, spectral modulation detection, and sensitivity to interaural phase; and (c) speech tests including filtered phoneme recognition and speech-in-noise recognition. The results demonstrated that a history of loud music exposure can lead to a profile of peripheral auditory function that is consistent with an interpretation of cochlear synaptopathy in humans, namely, modestly abnormal auditory brainstem response Wave I/Wave V ratios in the presence of normal distortion product otoacoustic emissions and normal audiometric thresholds. However, there were no other electrophysiological, psychophysical, or speech perception effects. The absence of any behavioral effects in suprathreshold sound processing indicated that, even if cochlear synaptopathy is a valid pathophysiological condition in humans, its perceptual sequelae are either too diffuse or too inconsequential to permit a simple differential diagnosis of hidden hearing loss.
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Affiliation(s)
- John H. Grose
- Department of Otolaryngology—Head and Neck Surgery, University of North Carolina at Chapel Hill, NC, USA
| | - Emily Buss
- Department of Otolaryngology—Head and Neck Surgery, University of North Carolina at Chapel Hill, NC, USA
| | - Joseph W. Hall
- Department of Otolaryngology—Head and Neck Surgery, University of North Carolina at Chapel Hill, NC, USA
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435
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Vlajkovic SM, Ambepitiya K, Barclay M, Boison D, Housley GD, Thorne PR. Adenosine receptors regulate susceptibility to noise-induced neural injury in the mouse cochlea and hearing loss. Hear Res 2016; 345:43-51. [PMID: 28034618 DOI: 10.1016/j.heares.2016.12.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 11/15/2016] [Accepted: 12/20/2016] [Indexed: 12/20/2022]
Abstract
Our previous studies have shown that the stimulation of A1 adenosine receptors in the inner ear can mitigate the loss of sensory hair cells and hearing loss caused by exposure to traumatic noise. Here, we focus on the role of adenosine receptors (AR) in the development of noise-induced neural injury in the cochlea using A1AR and A2AAR null mice (A1AR-/- and A2AAR-/-). Wildtype (WT) and AR deficient mice were exposed to octave band noise (8-16 kHz, 100 dB SPL) for 2 h to induce cochlear injury and hearing loss. Auditory thresholds and input/output functions were assessed using auditory brainstem responses (ABR) before and two weeks post-exposure. The loss of outer hair cells (OHC), afferent synapses and spiral ganglion neurons (SGN) were assessed by quantitative histology. A1AR-/- mice (6-8 weeks old) displayed a high frequency hearing loss (ABR threshold shift and reduced ABR wave I and II amplitudes). This hearing loss was further aggravated by acute noise exposure and exceeded the hearing loss in the WT and A2AAR-/- mice. All mice experienced the loss of OHC, synaptic ribbons and SGN after noise exposure, but the loss of SGN was significantly higher in A1AR-/- mice than in the A2AAR-/- and WT genotypes. The A2AAR-/- demonstrated better preservation of OHC and afferent synapses and the minimal loss of SGN after noise exposure. The findings suggest that the loss of A1AR expression results in an increased susceptibility to cochlear neural injury and hearing loss, whilst absence of A2AAR increases cochlear resistance to acoustic trauma.
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Affiliation(s)
- Srdjan M Vlajkovic
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand; Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand.
| | - Kaushi Ambepitiya
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand; Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand
| | - Meagan Barclay
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand; Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand
| | - Detlev Boison
- RS Dow Neurobiology Laboratories, Legacy Research, Portland, OR, 97232, USA
| | - Gary D Housley
- Department of Physiology and Translational Neuroscience Facility, School of Medical Sciences, UNSW Australia, Sydney, NSW, 2052, Australia
| | - Peter R Thorne
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand; Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland, New Zealand
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436
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Abstract
OBJECTIVE Hearing loss is the most common sensory deficit and congenital anomaly, yet the decision-making processes involved in disclosing hearing loss have been little studied. To address this issue, we have explored the phrases that adults with hearing loss use to disclose their hearing loss. DESIGN Since self-disclosure research has not focused on hearing loss-specific issues, we created a 15-question survey about verbally disclosing hearing loss. English speaking adults (>18 years old) with hearing loss of any etiology were recruited from otology clinics in a major referral hospital. Three hundred and thirty-seven participants completed the survey instrument. Participants' phrase(s) used to tell people they have hearing loss were compared across objective characteristics (age; sex; type, degree, and laterality of hearing loss; word recognition scores) and self-reported characteristics (degree of hearing loss; age of onset and years lived with hearing loss; use of technology; hearing handicap score). RESULTS Participants' responses revealed three strategies to address hearing loss: Multipurpose disclosure (phrases that disclose hearing loss and provide information to facilitate communication), Basic disclosure (phrases that disclose hearing loss through the term, a label, or details about the condition), or nondisclosure (phrases that do not disclose hearing loss). Variables were compared between patients who used and who did not use each disclosure strategy using χ or Wilcoxon rank sum tests. Multipurpose disclosers were mostly female (p = 0.002); had experienced reactions of help, support, and accommodation after disclosing (p = 0.008); and had experienced reactions of being overly helpful after disclosing (p=0.039). Basic disclosers were predominantly male (p = 0.004); reported feeling somewhat more comfortable disclosing their hearing loss over time (p = 0.009); had not experienced reactions of being treated unfairly or discriminated against (p = 0.021); and were diagnosed with mixed hearing loss (p = 0.004). Nondisclosers tended not to disclose in a group setting (p = 0.002) and were diagnosed with bilateral hearing loss (p = 0.005). In addition, all of the variables were examined to build logistic regression models to predict the use of each disclosure strategy. CONCLUSIONS Our results reveal three simple strategies for verbally addressing hearing loss that can be used in a variety of contexts. We recommend educating people with hearing loss about these strategies-this could improve the experience of disclosing hearing loss, and could educate society at large about how to interact with those who have a hearing loss.
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437
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Lobarinas E, Spankovich C, Le Prell CG. Evidence of "hidden hearing loss" following noise exposures that produce robust TTS and ABR wave-I amplitude reductions. Hear Res 2016; 349:155-163. [PMID: 28003148 DOI: 10.1016/j.heares.2016.12.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/21/2016] [Accepted: 12/12/2016] [Indexed: 11/30/2022]
Abstract
In animals, noise exposures that produce robust temporary threshold shifts (TTS) can produce immediate damage to afferent synapses and long-term degeneration of low spontaneous rate auditory nerve fibers. This synaptopathic damage has been shown to correlate with reduced auditory brainstem response (ABR) wave-I amplitudes at suprathreshold levels. The perceptual consequences of this "synaptopathy" remain unknown but have been suggested to include compromised hearing performance in competing background noise. Here, we used a modified startle inhibition paradigm to evaluate whether noise exposures that produce robust TTS and ABR wave-I reduction but not permanent threshold shift (PTS) reduced hearing-in-noise performance. Animals exposed to 109 dB SPL octave band noise showed TTS >30 dB 24-h post noise and modest but persistent ABR wave-I reduction 2 weeks post noise despite full recovery of ABR thresholds. Hearing-in-noise performance was negatively affected by the noise exposure. However, the effect was observed only at the poorest signal to noise ratio and was frequency specific. Although TTS >30 dB 24-h post noise was a predictor of functional deficits, there was no relationship between the degree of ABR wave-I reduction and degree of functional impairment.
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Affiliation(s)
- Edward Lobarinas
- The University of Texas at Dallas, School of Behavioral and Brain Sciences, USA.
| | - Christopher Spankovich
- University of Mississippi Medical Center, Department of Otolaryngology and Communicative Sciences, USA
| | - Colleen G Le Prell
- The University of Texas at Dallas, School of Behavioral and Brain Sciences, USA
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438
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Sha SH, Schacht J. Emerging therapeutic interventions against noise-induced hearing loss. Expert Opin Investig Drugs 2016; 26:85-96. [PMID: 27918210 DOI: 10.1080/13543784.2017.1269171] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Noise-induced hearing loss (NIHL) due to industrial, military, and recreational noise exposure is a major, but also potentially preventable cause of acquired hearing loss. For the United States it is estimated that 26 million people (15% of the population) between the ages of 20 and 69 have a high-frequency NIHL at a detriment to the quality of life of the affected individuals and great economic cost to society. Areas covered: This review outlines the pathology and pathophysiology of hearing loss as seen in humans and animal models. Results from molecular studies are presented that have provided the basis for therapeutic strategies successfully applied to animals. Several compounds emerging from these studies (mostly antioxidants) are now being tested in field trials. Expert opinion: Although no clinically applicable intervention has been approved yet, recent trials are encouraging. In order to maximize protective therapies, future work needs to apply stringent criteria for noise exposure and outcome parameters. Attention needs to be paid not only to permanent NIHL due to death of sensory cells but also to temporary effects that may show delayed consequences. Existing results combined with the search for efficacious new therapies should establish a viable treatment within a decade.
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Affiliation(s)
- Su-Hua Sha
- a Department of Pathology and Laboratory Medicine , Medical University of South Carolina , Charleston , SC , USA
| | - Jochen Schacht
- b Kresge Hearing Research Institute , University of Michigan , Ann Arbor , MI , USA
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439
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Bezdjian A, Kraaijenga VJC, Ramekers D, Versnel H, Thomeer HGXM, Klis SFL, Grolman W. Towards Clinical Application of Neurotrophic Factors to the Auditory Nerve; Assessment of Safety and Efficacy by a Systematic Review of Neurotrophic Treatments in Humans. Int J Mol Sci 2016; 17:ijms17121981. [PMID: 27898033 PMCID: PMC5187781 DOI: 10.3390/ijms17121981] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/11/2016] [Accepted: 11/21/2016] [Indexed: 01/31/2023] Open
Abstract
Animal studies have evidenced protection of the auditory nerve by exogenous neurotrophic factors. In order to assess clinical applicability of neurotrophic treatment of the auditory nerve, the safety and efficacy of neurotrophic therapies in various human disorders were systematically reviewed. Outcomes of our literature search included disorder, neurotrophic factor, administration route, therapeutic outcome, and adverse event. From 2103 articles retrieved, 20 randomized controlled trials including 3974 patients were selected. Amyotrophic lateral sclerosis (53%) was the most frequently reported indication for neurotrophic therapy followed by diabetic polyneuropathy (28%). Ciliary neurotrophic factor (50%), nerve growth factor (24%) and insulin-like growth factor (21%) were most often used. Injection site reaction was a frequently occurring adverse event (61%) followed by asthenia (24%) and gastrointestinal disturbances (20%). Eighteen out of 20 trials deemed neurotrophic therapy to be safe, and six out of 17 studies concluded the neurotrophic therapy to be effective. Positive outcomes were generally small or contradicted by other studies. Most non-neurodegenerative diseases treated by targeted deliveries of neurotrophic factors were considered safe and effective. Hence, since local delivery to the cochlea is feasible, translation from animal studies to human trials in treating auditory nerve degeneration seems promising.
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Affiliation(s)
- Aren Bezdjian
- Department of Otorhinolaryngology and Head & Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands.
| | - Véronique J C Kraaijenga
- Department of Otorhinolaryngology and Head & Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands.
| | - Dyan Ramekers
- Department of Otorhinolaryngology and Head & Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands.
| | - Huib Versnel
- Department of Otorhinolaryngology and Head & Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands.
| | - Hans G X M Thomeer
- Department of Otorhinolaryngology and Head & Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands.
| | - Sjaak F L Klis
- Department of Otorhinolaryngology and Head & Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands.
| | - Wilko Grolman
- Department of Otorhinolaryngology and Head & Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands.
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440
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Dobie RA, Humes LE. Commentary on the regulatory implications of noise-induced cochlear neuropathy. Int J Audiol 2016; 56:74-78. [DOI: 10.1080/14992027.2016.1255359] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Robert A. Dobie
- Department of Otolaryngology, Head and Neck Surgery, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA and
| | - Larry E. Humes
- Department of Speech and Hearing Sciences, Indiana University, Bloomington, IN, USA
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441
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Guthrie OW. Noise Induced DNA Damage Within the Auditory Nerve. Anat Rec (Hoboken) 2016; 300:520-526. [DOI: 10.1002/ar.23494] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 06/21/2016] [Accepted: 07/09/2016] [Indexed: 11/06/2022]
Affiliation(s)
- O'neil W. Guthrie
- Cell and Molecular Pathology Laboratory, Department of Communication Sciences and Disorders; Northern Arizona University; Flagstaff Arizona
- Research Service-151 Loma Linda Veterans Affairs Medical Center; Loma Linda California
- Department of Otolaryngology and Head & Neck Surgery, School of Medicine; Loma Linda University Medical Center; Loma Linda California
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442
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Schlittenlacher J, Moore BCJ. Discrimination of amplitude-modulation depth by subjects with normal and impaired hearing. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:3487. [PMID: 27908066 DOI: 10.1121/1.4966117] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The loudness recruitment associated with cochlear hearing loss increases the perceived amount of amplitude modulation (AM), called "fluctuation strength." For normal-hearing (NH) subjects, fluctuation strength "saturates" when the AM depth is high. If such saturation occurs for hearing-impaired (HI) subjects, they may show poorer AM depth discrimination than NH subjects when the reference AM depth is high. To test this hypothesis, AM depth discrimination of a 4-kHz sinusoidal carrier, modulated at a rate of 4 or 16 Hz, was measured in a two-alternative forced-choice task for reference modulation depths, mref, of 0.5, 0.6, and 0.7. AM detection was assessed using mref = 0. Ten older HI subjects, and five young and five older NH subjects were tested. Psychometric functions were measured using five target modulation depths for each mref. For AM depth discrimination, the HI subjects performed more poorly than the NH subjects, both at 30 dB sensation level (SL) and 75 dB sound pressure level (SPL). However, for AM detection, the HI subjects performed better than the NH subjects at 30 dB SL; there was no significant difference between the HI and NH groups at 75 dB SPL. The results for the NH subjects were not affected by age.
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Affiliation(s)
- Josef Schlittenlacher
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, England
| | - Brian C J Moore
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, England
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443
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444
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Longenecker RJ, Galazyuk AV. Variable Effects of Acoustic Trauma on Behavioral and Neural Correlates of Tinnitus In Individual Animals. Front Behav Neurosci 2016; 10:207. [PMID: 27826232 PMCID: PMC5078752 DOI: 10.3389/fnbeh.2016.00207] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/10/2016] [Indexed: 12/20/2022] Open
Abstract
The etiology of tinnitus is known to be diverse in the human population. An appropriate animal model of tinnitus should incorporate this pathological diversity. Previous studies evaluating the effect of acoustic over exposure (AOE) have found that animals typically display increased spontaneous firing rates and bursting activity of auditory neurons, which often has been linked to behavioral evidence of tinnitus. However, only a subset of studies directly associated these neural correlates to individual animals. Furthermore, the vast majority of tinnitus studies were conducted on anesthetized animals. The goal of this study was to test for a possible relationship between tinnitus, hearing loss, hyperactivity and bursting activity in the auditory system of individual unanesthetized animals following AOE. Sixteen mice were unilaterally exposed to 116 dB SPL narrowband noise (centered at 12.5 kHz) for 1 h under ketamine/xylazine anesthesia. Gap-induced prepulse inhibition of the acoustic startle reflex (GPIAS) was used to assess behavioral evidence of tinnitus whereas hearing performance was evaluated by measurements of auditory brainstem response (ABR) thresholds and prepulse inhibition PPI audiometry. Following behavioral assessments, single neuron firing activity was recorded from the inferior colliculus (IC) of four awake animals and compared to recordings from four unexposed controls. We found that AOE increased spontaneous activity in all mice tested, independently of tinnitus behavior or severity of threshold shifts. Bursting activity did not increase in two animals identified as tinnitus positive (T+), but did so in a tinnitus negative (T−) animal with severe hearing loss (SHL). Hyperactivity does not appear to be a reliable biomarker of tinnitus. Our data suggest that multidisciplinary assessments on individual animals following AOE could offer a powerful experimental tool to investigate mechanisms of tinnitus.
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Affiliation(s)
- Ryan J Longenecker
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University Rootstown, OH, USA
| | - Alexander V Galazyuk
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University Rootstown, OH, USA
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445
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Le Prell CG, Clavier OH. Effects of noise on speech recognition: Challenges for communication by service members. Hear Res 2016; 349:76-89. [PMID: 27743882 DOI: 10.1016/j.heares.2016.10.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/05/2016] [Accepted: 10/11/2016] [Indexed: 12/20/2022]
Abstract
Speech communication often takes place in noisy environments; this is an urgent issue for military personnel who must communicate in high-noise environments. The effects of noise on speech recognition vary significantly according to the sources of noise, the number and types of talkers, and the listener's hearing ability. In this review, speech communication is first described as it relates to current standards of hearing assessment for military and civilian populations. The next section categorizes types of noise (also called maskers) according to their temporal characteristics (steady or fluctuating) and perceptive effects (energetic or informational masking). Next, speech recognition difficulties experienced by listeners with hearing loss and by older listeners are summarized, and questions on the possible causes of speech-in-noise difficulty are discussed, including recent suggestions of "hidden hearing loss". The final section describes tests used by military and civilian researchers, audiologists, and hearing technicians to assess performance of an individual in recognizing speech in background noise, as well as metrics that predict performance based on a listener and background noise profile. This article provides readers with an overview of the challenges associated with speech communication in noisy backgrounds, as well as its assessment and potential impact on functional performance, and provides guidance for important new research directions relevant not only to military personnel, but also to employees who work in high noise environments.
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Affiliation(s)
- Colleen G Le Prell
- The University of Texas at Dallas, School of Behavioral and Brain Sciences, USA.
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446
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Abstract
Diagnosing and treating hearing impairment is challenging because people with similar degrees of sensorineural hearing loss (SNHL) often have different speech-recognition abilities. The speech-based envelope power spectrum model (sEPSM) has demonstrated that the signal-to-noise ratio (SNRENV) from a modulation filter bank provides a robust speech-intelligibility measure across a wider range of degraded conditions than many long-standing models. In the sEPSM, noise (N) is assumed to: (a) reduce S + N envelope power by filling in dips within clean speech (S) and (b) introduce an envelope noise floor from intrinsic fluctuations in the noise itself. While the promise of SNRENV has been demonstrated for normal-hearing listeners, it has not been thoroughly extended to hearing-impaired listeners because of limited physiological knowledge of how SNHL affects speech-in-noise envelope coding relative to noise alone. Here, envelope coding to speech-in-noise stimuli was quantified from auditory-nerve model spike trains using shuffled correlograms, which were analyzed in the modulation-frequency domain to compute modulation-band estimates of neural SNRENV. Preliminary spike-train analyses show strong similarities to the sEPSM, demonstrating feasibility of neural SNRENV computations. Results suggest that individual differences can occur based on differential degrees of outer- and inner-hair-cell dysfunction in listeners currently diagnosed into the single audiological SNHL category. The predicted acoustic-SNR dependence in individual differences suggests that the SNR-dependent rate of susceptibility could be an important metric in diagnosing individual differences. Future measurements of the neural SNRENV in animal studies with various forms of SNHL will provide valuable insight for understanding individual differences in speech-in-noise intelligibility.
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Affiliation(s)
- Varsha H. Rallapalli
- Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, IN, USA
| | - Michael G. Heinz
- Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, IN, USA
- Weldon School of Biomedical Engineering, Purdue University, IN, USA
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447
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High mobility group box 1 (HMGB1): dual functions in the cochlear auditory neurons in response to stress? Histochem Cell Biol 2016; 147:307-316. [PMID: 27704212 DOI: 10.1007/s00418-016-1506-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2016] [Indexed: 12/19/2022]
Abstract
High mobility group box 1 (HMGB1) is a DNA-binding protein that facilitates gene transcription and may act extracellularly as a late mediator of inflammation. The roles of HMGB1 in the pathogenesis of the spiral ganglion neurons (SGNs) of the cochlea are currently unknown. In the present study, we tested the hypothesis that early phenotypical changes in the SGNs of the amikacin-poisoned rat cochlea are mediated by HMGB1. Our results showed that a marked downregulation of HMGB1 had occurred by completion of amikacin treatment, coinciding with acute damage at the dendrite extremities of the SGNs. A few days later, during the recovery of the SGN dendrites, the protein was re-expressed and transiently accumulated within the nuclei of the SGNs. The phosphorylated form of the transcription factor c-Jun (p-c-Jun) was concomitantly detected in the nuclei of the SGNs where it often co-localized with HMGB1, while the anti-apoptotic protein BCL2 was over-expressed in the cytoplasm. In animals co-treated with amikacin and the histone deacetylase inhibitor trichostatin A, both HMGB1 and p-c-Jun were exclusively found within the cytoplasm. The initial disappearance of HMGB1 from the affected SGNs may be due to its release into the external medium, where it may have a cytokine-like function. Once re-expressed and translocated into the nucleus, HMGB1 may facilitate the transcriptional activity of p-c-Jun, which in turn may promote repair mechanisms. Our study therefore suggests that HMGB1 can positively influence the survival of SGNs following ototoxic exposure via both its extracellular and intranuclear functions.
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448
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Xie R. Transmission of auditory sensory information decreases in rate and temporal precision at the endbulb of Held synapse during age-related hearing loss. J Neurophysiol 2016; 116:2695-2705. [PMID: 27683884 DOI: 10.1152/jn.00472.2016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/22/2016] [Indexed: 12/16/2022] Open
Abstract
Age-related hearing loss (ARHL) is largely attributed to structural changes and functional declines in the peripheral auditory system, which include synaptopathy at the inner hair cell/spiral ganglion cell (SGC) connection and the loss of SGCs. However, functional changes at the central terminals of SGCs, namely the auditory nerve synapses in the cochlear nucleus, are not yet fully understood during ARHL. With the use of young (1-3 mo) and old (25-30 mo) CBA/CaJ mice, this study evaluated the intrinsic properties of the bushy neurons postsynaptic to the endbulb of Held synapses, and the firing properties of these neurons to direct current injections as well as to synaptic inputs from the auditory nerve. Results showed that bushy neurons in old mice are more excitable and are able to fire spikes at similar rate and timing to direct current injections as those in young mice. In response to synaptic inputs, however, bushy neurons from old mice fired spikes with significantly decreased rate and reduced temporal precision to stimulus trains at 100 and 400 Hz, with the drop in firing probability more profound at 400 Hz. It suggests that transmission of auditory information at the endbulb is declined in both rate and timing during aging, which signifies the loss of sensory inputs to the central auditory system under ARHL. The study proposes that, in addition to damages at the peripheral terminals of SGCs as well as the loss of SGCs, functional decline at the central terminals of surviving SGCs is also an essential component of ARHL.
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Affiliation(s)
- Ruili Xie
- Department of Neurosciences, University of Toledo, Toledo, Ohio
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449
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Cochlear Synaptopathy and Noise-Induced Hidden Hearing Loss. Neural Plast 2016; 2016:6143164. [PMID: 27738526 PMCID: PMC5050381 DOI: 10.1155/2016/6143164] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 08/09/2016] [Accepted: 08/21/2016] [Indexed: 11/18/2022] Open
Abstract
Recent studies on animal models have shown that noise exposure that does not lead to permanent threshold shift (PTS) can cause considerable damage around the synapses between inner hair cells (IHCs) and type-I afferent auditory nerve fibers (ANFs). Disruption of these synapses not only disables the innervated ANFs but also results in the slow degeneration of spiral ganglion neurons if the synapses are not reestablished. Such a loss of ANFs should result in signal coding deficits, which are exacerbated by the bias of the damage toward synapses connecting low-spontaneous-rate (SR) ANFs, which are known to be vital for signal coding in noisy background. As there is no PTS, these functional deficits cannot be detected using routine audiological evaluations and may be unknown to subjects who have them. Such functional deficits in hearing without changes in sensitivity are generally called “noise-induced hidden hearing loss (NIHHL).” Here, we provide a brief review to address several critical issues related to NIHHL: (1) the mechanism of noise induced synaptic damage, (2) reversibility of the synaptic damage, (3) the functional deficits as the nature of NIHHL in animal studies, (4) evidence of NIHHL in human subjects, and (5) peripheral and central contribution of NIHHL.
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450
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Micro-optical coherence tomography of the mammalian cochlea. Sci Rep 2016; 6:33288. [PMID: 27633610 PMCID: PMC5025881 DOI: 10.1038/srep33288] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/23/2016] [Indexed: 12/27/2022] Open
Abstract
The mammalian cochlea has historically resisted attempts at high-resolution, non-invasive imaging due to its small size, complex three-dimensional structure, and embedded location within the temporal bone. As a result, little is known about the relationship between an individual’s cochlear pathology and hearing function, and otologists must rely on physiological testing and imaging methods that offer limited resolution to obtain information about the inner ear prior to performing surgery. Micro-optical coherence tomography (μOCT) is a non-invasive, low-coherence interferometric imaging technique capable of resolving cellular-level anatomic structures. To determine whether μOCT is capable of resolving mammalian intracochlear anatomy, fixed guinea pig inner ears were imaged as whole temporal bones with cochlea in situ. Anatomical structures such as the tunnel of Corti, space of Nuel, modiolus, scalae, and cell groupings were visualized, in addition to individual cell types such as neuronal fibers, hair cells, and supporting cells. Visualization of these structures, via volumetrically-reconstructed image stacks and endoscopic perspective videos, represents an improvement over previous efforts using conventional OCT. These are the first μOCT images of mammalian cochlear anatomy, and they demonstrate μOCT’s potential utility as an imaging tool in otology research.
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