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https://www.readbyqxmd.com/read/28087419/cochlear-synaptopathy-in-acquired-sensorineural-hearing-loss-manifestations-and-mechanisms
#1
REVIEW
M Charles Liberman, Sharon G Kujawa
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...
January 10, 2017: Hearing Research
https://www.readbyqxmd.com/read/28087418/degeneration-of-auditory-nerve-fibers-in-guinea-pigs-with-severe-sensorineural-hearing-loss
#2
Steven Kroon, Dyan Ramekers, Emma M Smeets, Ferry G J Hendriksen, Sjaak F L Klis, Huib Versnel
Damage to and loss of the organ of Corti leads to secondary degeneration of the spiral ganglion cell (SGC) somata of the auditory nerve. Extensively examined in animal models, this degeneration process of SGC somata following deafening is well known. However, degeneration of auditory nerve axons, which conduct auditory information towards the brainstem, and its relation to SGC soma degeneration are largely unknown. The consequences of degeneration of the axons are relevant for cochlear implantation, which is applied to a deafened system but depends on the condition of the auditory nerve...
January 10, 2017: Hearing Research
https://www.readbyqxmd.com/read/28087093/audiologic-and-radiologic-findings-in-cochlear-hypoplasia
#3
Betul Cicek Cinar, Merve Ozbal Batuk, Emel Tahir, Gonca Sennaroglu, Levent Sennaroglu
OBJECTIVE: The aim of the current study is to evaluate audiologic and radiologic findings of cochlear hypoplasia which is a subgroup of inner ear malformations. METHODS: This study was a prospective clinical study and based on voluntary participation from cases with cochlear hypoplasia diagnosis. The study was conducted at Hacettepe University, Department of Otolaryngology, Head and Neck Surgery and Department of Audiology. Subjects were selected from an inner ear malformations database...
January 10, 2017: Auris, Nasus, Larynx
https://www.readbyqxmd.com/read/28079677/cadaveric-testing-of-robot-assisted-access-to-the-internal-auditory-canal-for-vestibular-schwannoma-removal
#4
Neal P Dillon, Ramya Balachandran, Michael A Siebold, Robert J Webster, George B Wanna, Robert F Labadie
HYPOTHESIS: An image-guided robotic system can safely perform the bulk removal of bone during the translabyrinthine approach to vestibular schwannoma (VS). BACKGROUND: The translabyrinthine approach to VS removal involves extensive manual milling in the temporal bone to gain access to the internal auditory canal (IAC) for tumor resection. This bone removal is time consuming and challenging due to the presence of vital anatomy (e.g., facial nerve) embedded within the temporal bone...
January 10, 2017: Otology & Neurotology
https://www.readbyqxmd.com/read/28077712/changes-in-properties-of-auditory-nerve-synapses-following-conductive-hearing-loss
#5
Xiaowen Zhuang, Wei Sun, Matthew A Xu-Friedman
: Auditory activity plays an important role in the development of the auditory system. Decreased activity can result from conductive hearing loss (CHL) associated with otitis media, which may lead to long-term perceptual deficits. The effects of CHL have been mainly studied at later stages of the auditory pathway, but early stages remain less examined. However, changes in early stages could be important because they would affect how information about sounds is conveyed to higher-order areas for further processing and localization...
January 11, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28063006/therapeutic-value-of-nerve-growth-factor-in-promoting-neural-stem-cell-survival-and-differentiation-and-protecting-against-neuronal-hearing-loss
#6
Zhao Han, Cong-Pin Wang, Ning Cong, Yu-Yan Gu, Rui Ma, Fang-Lu Chi
Nerve growth factor (NGF) is a neurotrophic factor that modulates survival and differentiation of neural stem cells (NSCs). We investigated the function of NGF in promoting growth and neuronal differentiation of NSCs isolated from mouse cochlear tissue, as well as its protective properties against gentamicin (GMC) ototoxicity. NSCs were isolated from the cochlea of mice and cultured in vitro. Effect of NGF on survival, neurosphere formation, and differentiation of the NSCs, as well as neurite outgrowth and neural excitability in the subsequent in vitro neuronal network, was examined...
January 7, 2017: Molecular and Cellular Biochemistry
https://www.readbyqxmd.com/read/28060175/cochlear-nerve-deficiency-and-brain-abnormalities-in-pediatric-patients
#7
Thierry Morlet, Markian Pazuniak, Robert C O'Reilly, Vinay Kandula, Arabinda K Choudhary
HYPOTHESIS: To investigate the intracranial abnormalities present in children with cochlear nerve deficiency (CND), including abnormalities of other cranial nerves, and to describe their auditory abilities. BACKGROUND: The prevalence of CND has increased with the development of high resolution magnetic resonance imaging (MRI). There are varying degrees of CND from true aplasia to hypoplasia. The etiology of CND remains unclear and it may be associated with intracranial abnormalities in some instances...
January 4, 2017: Otology & Neurotology
https://www.readbyqxmd.com/read/28056182/noise-stress-induces-an-epidermal-growth-factor-receptor-xeroderma-pigmentosum-a-response-in-the-auditory-nerve
#8
O'neil W Guthrie
In response to toxic stressors, cancer cells defend themselves by mobilizing one or more epidermal growth factor receptor (EGFR) cascades that employ xeroderma pigmentosum-A (XPA) to repair damaged genes. Recent experiments discovered that neurons within the auditory nerve exhibit basal levels of EGFR+XPA co-expression. This finding implied that auditory neurons in particular or neurons in general have the capacity to mobilize an EGFR+XPA defense. Therefore, the current study tested the hypothesis that noise stress would alter the expression pattern of EGFR/XPA within the auditory nerve...
December 1, 2016: Journal of Histochemistry and Cytochemistry: Official Journal of the Histochemistry Society
https://www.readbyqxmd.com/read/28054149/a-model-of-electrically-stimulated-auditory-nerve-fiber-responses-with-peripheral-and-central-sites-of-spike-generation
#9
Suyash Narendra Joshi, Torsten Dau, Bastian Epp
A computational model of cat auditory nerve fiber (ANF) responses to electrical stimulation is presented. The model assumes that (1) there exist at least two sites of spike generation along the ANF and (2) both an anodic (positive) and a cathodic (negative) charge in isolation can evoke a spike. A single ANF is modeled as a network of two exponential integrate-and-fire point-neuron models, referred to as peripheral and central axons of the ANF. The peripheral axon is excited by the cathodic charge, inhibited by the anodic charge, and exhibits longer spike latencies than the central axon; the central axon is excited by the anodic charge, inhibited by the cathodic charge, and exhibits shorter spike latencies than the peripheral axon...
January 4, 2017: Journal of the Association for Research in Otolaryngology: JARO
https://www.readbyqxmd.com/read/28050647/deleting-the-hcn1-subunit-of-hyperpolarization-activated-ion-channels-in-mice-impairs-acoustic-startle-reflexes-gap-detection-and-spatial-localization
#10
James R Ison, Paul D Allen, Donata Oertel
It has been proposed that the high temporal and spatial acuities of human listeners and animals tested in the hearing laboratory depend in part on the short time constants of auditory neurons that are able to preserve or sharpen the information conveyed in the timing of firing of auditory nerve fibers. We tested this hypothesis in a series of in vivo experiments, based on previous in vitro experiments showing that neuronal time constants are raised in brainstem slices when HCN1 channels are blocked or in slices obtained from Hcn1 (-/-) null mutant mice...
January 3, 2017: Journal of the Association for Research in Otolaryngology: JARO
https://www.readbyqxmd.com/read/28039919/hearing-impairment-in-a-female-infant-with-interstitial-deletion-of-2q24-1q24-3
#11
Hiroaki Ono, Kenji Kurosawa, Nobuaki Wakamatsu, Shin Masuda
Patients with interstitial deletions in 2q24.1q24.3 are rarely reported. These patients manifest a variety of clinical features in addition to intellectual disability, depending on the size and location of the deletion. We report a female patient with interstitial deletion of 5.5 Mb in 2q24.1q24.3, who showed intrauterine growth retardation, hypotonia, global developmental delay, microcephaly, and characteristic facial appearance. In addition, she had hearing impairment, with no auditory brainstem response...
December 30, 2016: Congenital Anomalies
https://www.readbyqxmd.com/read/28024827/evaluation-of-peripheral-auditory-pathways-and-brainstem-in-obstructive-sleep-apnea
#12
Erika Matsumura, Carla Gentile Matas, Fernanda Cristina Leite Magliaro, Raquel Meirelles Pedreño, Geraldo Lorenzi-Filho, Seisse Gabriela Gandolfi Sanches, Renata Mota Mamede Carvallo
INTRODUCTION: Obstructive sleep apnea causes changes in normal sleep architecture, fragmenting it chronically with intermittent hypoxia, leading to serious health consequences in the long term. It is believed that the occurrence of respiratory events during sleep, such as apnea and hypopnea, can impair the transmission of nerve impulses along the auditory pathway that are highly dependent on the supply of oxygen. However, this association is not well established in the literature. OBJECTIVE: To compare the evaluation of peripheral auditory pathway and brainstem among individuals with and without obstructive sleep apnea...
November 25, 2016: Brazilian Journal of Otorhinolaryngology
https://www.readbyqxmd.com/read/28024462/predicting-the-perceptual-consequences-of-hidden-hearing-loss
#13
Andrew J Oxenham
Recent physiological studies in several rodent species have revealed that permanent damage can occur to the auditory system after exposure to a noise that produces only a temporary shift in absolute thresholds. The damage has been found to occur in the synapses between the cochlea's inner hair cells and the auditory nerve, effectively severing part of the connection between the ear and the brain. This synaptopathy has been termed hidden hearing loss because its effects are not thought to be revealed in standard clinical, behavioral, or physiological measures of absolute threshold...
January 2016: Trends in Hearing
https://www.readbyqxmd.com/read/28011083/impaired-auditory-processing-and-altered-structure-of-the-endbulb-of-held-synapse-in-mice-lacking-the-glua3-subunit-of-ampa-receptors
#14
Sofía García-Hernández, Manabu Abe, Kenji Sakimura, María E Rubio
AMPA glutamate receptor complexes with fast kinetics conferred by subunits like GluA3 and GluA4 are essential for temporal precision of synaptic transmission. The specific role of GluA3 in auditory processing and experience related changes in the auditory brainstem remain unknown. We investigated the role of the GluA3 in auditory processing by using wild type (WT) and GluA3 knockout (GluA3-KO) mice. We recorded auditory brainstem responses (ABR) to assess auditory function and used electron microscopy to evaluate the ultrastructure of the auditory nerve synapse on bushy cells (AN-BC synapse)...
February 2017: Hearing Research
https://www.readbyqxmd.com/read/28007525/the-mammalian-cretaceous-cochlear-revolution
#15
REVIEW
Geoffrey A Manley
The hearing organs of amniote vertebrates show large differences in their size and structure between the species' groups. In spite of this, their performance in terms of hearing sensitivity and the frequency selectivity of auditory-nerve units shows unexpectedly small differences. The only substantial difference is that therian, defined as live-bearing, mammalian groups are able to hear ultrasonic frequencies (above 15-20 kHz), whereas in contrast monotreme (egg laying) mammals and all non-mammalian amniotes cannot...
December 19, 2016: Hearing Research
https://www.readbyqxmd.com/read/28003148/evidence-of-hidden-hearing-loss-following-noise-exposures-that-produce-robust-tts-and-abr-wave-i-amplitude-reductions
#16
Edward Lobarinas, Christopher Spankovich, Colleen G Le Prell
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...
December 19, 2016: Hearing Research
https://www.readbyqxmd.com/read/27997448/the-retroauricular-approach-to-the-facial-nerve-trunk
#17
Jordan W Swanson, Jason W Yu, Jesse A Taylor, Stephen Kovach, Suhail Kanchwala, Laurent Lantieri
BACKGROUND: Exposure of the common trunk of the facial nerve has traditionally been approached based on principles of parotidectomy, which is associated with high rates of facial nerve palsy and landmarks that may be unreliable. On the basis of experience gained with vascularized composite allotransplantation of the face, the authors propose a retroauricular approach that may be more time-effective and safe. METHODS: In the proposed retroauricular facial nerve approach, an incision is made posterior to the ear in the retroauricular sulcus, and dissection proceeds anteriorly to the mastoid fascia to the base of the conchal bowl...
December 16, 2016: Journal of Craniofacial Surgery
https://www.readbyqxmd.com/read/27992391/auditory-brainstem-response-altered-in-humans-with-noise-exposure-despite-normal-outer-hair-cell-function
#18
Naomi F Bramhall, Dawn Konrad-Martin, Garnett P McMillan, Susan E Griest
OBJECTIVES: Recent animal studies demonstrated that cochlear synaptopathy, a partial loss of inner hair cell-auditory nerve fiber synapses, can occur in response to noise exposure without any permanent auditory threshold shift. In animal models, this synaptopathy is associated with a reduction in the amplitude of wave I of the auditory brainstem response (ABR). The goal of this study was to determine whether higher lifetime noise exposure histories in young people with clinically normal pure-tone thresholds are associated with lower ABR wave I amplitudes...
January 2017: Ear and Hearing
https://www.readbyqxmd.com/read/27965072/rare-lesions-of-the-internal-auditory-canal
#19
Kentaro Watanabe, Mary In-Ping Huang Cobb, Ali R Zomorodi, Calhoun D Cunningham, Yoichi Nonaka, Shunsuke Satoh, Allan H Friedman, Takanori Fukushima
BACKGROUND: Approximately 95% of tumors occurring within the internal auditory canal (IAC) are vestibular schwannomas (VSs). Many undergo stereotactic radiation without definitive tissue diagnosis. Rare IAC tumors are not all radiosensitive and are poorly described. METHODS: Between 1992 and 2015, 289 consecutive patients with IAC lesions operated on were retrospectively reviewed. RESULTS: Fifteen patients (5.2%) (16 operations) had unusual histological findings, including non-vestibular schwannomas (two facial schwannomas, two cochlear schwannomas, two intermedius schwannomas), three meningiomas, three cavernous hemangiomas, a mucosa associated lymphoid tissue (MALT) lymphoma, an arachnoid cyst, and a lipochoristoma...
December 10, 2016: World Neurosurgery
https://www.readbyqxmd.com/read/27964937/tinnitus-with-a-normal-audiogram-relation-to-noise-exposure-but-no-evidence-for-cochlear-synaptopathy
#20
Hannah Guest, Kevin J Munro, Garreth Prendergast, Simon Howe, Christopher J Plack
In rodents, exposure to high-level noise can destroy synapses between inner hair cells and auditory nerve fibers, without causing hair cell loss or permanent threshold elevation. Such "cochlear synaptopathy" is associated with amplitude reductions in wave I of the auditory brainstem response (ABR) at moderate-to-high sound levels. Similar ABR results have been reported in humans with tinnitus and normal audiometric thresholds, leading to the suggestion that tinnitus in these cases might be a consequence of synaptopathy...
December 11, 2016: Hearing Research
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