The aVOR App Increases Medical Students’ Competence in Treating Benign Paroxysmal Positional Vertigo (BPPV)

Hypothesis: Implementation of the “aVOR app” into teaching courses at medical school enhances students’ satisfaction with the course and increases their competence in treating benign paroxysmal positional vertigo (BPPV). Background: BPPV is often underdiagnosed and left untreated. One problem in teaching the management of BPPV to health care professionals is the lack of simulation-based training tools. The aVOR app (aVOR = angular vestibulo-ocular reflex) works as a bionic labyrinth that simulates the activation of the semicircular canals by rotational acceleration and the resulting vestibular evoked eye movements. Methods: In this prospective, randomized, controlled study, medical students at a university hospital were randomly assigned to two kinds of small instructional groups. Students of the control group (n = 67) practiced diagnostic and therapeutic maneuvers for BPPV on each other, while the participants of the study group (n = 46) used the aVOR app as a virtual patient in addition. At the end of the term, students were asked to arrange the steps of the canalith repositioning procedure in the correct order in a written test. Results: Quality of the teaching media was rated significantly better in the aVOR group (two-sided Mann–Whitney test: P 

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Visual Performance and Perception as a Target of Saccadic Strategies in Patients With Unilateral Vestibular Loss

Objectives: To evaluate the ability of saccadic strategies developed during vestibular compensation to reduce the effect of an impaired vestibulo-ocular reflex (VOR) on a retinal smear and image motion sensation. Design: Twenty patients with unilateral vestibular loss were examined with a video head impulse test before and after vestibular rehabilitation (VR) with the use of gaze stabilization and refixation saccades training. Head and eye velocity functions were processed to infer the retinal eccentricity, and through its correlation with visual acuity (VA), several measurements are proposed to evaluate the influence of VR on saccades behavior and visual performance. To isolate the effect of saccades on the findings and avoid bias because of gain differences, only patients whose VOR gain values remained unchanged after VR were included. Results: Improved contribution of covert saccades and reduction of overt saccades latency were measured after VR. We found significant differences when assessing both the interval less than 70% VA (50.25 ms), which is considered the limit of a moderate low vision, and less than 50% VA (39.515 ms), which is the limit for severe low vision. Time to recover a VA of 75% (near normal) was reduced in all the patients (median: 56.472 ms). Conclusion: Despite the absence of VOR gain improvement, patients with unilateral vestibular loss are able to develop saccadic strategies that allow the shortening of the interval of retinal smear and image motion. The proposed measurements might be of use to evaluate VR outcomes and visually induced impairment. ACKNOWLEDGMENTS: All authors contributed to this work, discussed the results and implications, and commented on the article at all stages. G. T. performed explorations, designed and performed measurements, analyzed data, and wrote the article; J. R. designed the RV protocol, performed explorations, and reviewed the article; A. B. performed explorations and reviewed the article; E. M. performed explorations and reviewed the article; N. P. participated in the study design, performed explorations, and reviewed the article. The authors have no conflicts of interest to disclose. Address for correspondence: Gabriel Trinidad-Ruiz, Neurotology Unit, Department of Otorhinolaryngology, University hospital of Badajoz, Spain. E-mail: gtrinidad@gmail.com Received November 17, 2017; accepted February 1, 2018. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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Development of a Novel Bone Conduction Verification Tool Using a Surface Microphone: Validation With Percutaneous Bone Conduction Users

Objectives: To determine if a newly-designed, forehead-mounted surface microphone would yield equivalent estimates of audibility when compared to audibility measured with a skull simulator for adult bone conduction users. Design: Data was analyzed using a within subjects, repeated measures design. There were two different sensors (skull simulator and surface microphone) measuring the same hearing aid programmed to the same settings for all subjects. We were looking for equivalent results. Patients: Twenty-one adult percutaneous bone conduction users (12 females and 9 males) were recruited for this study. Mean age was 54.32 years with a standard deviation of 14.51 years. Nineteen of the subjects had conductive/mixed hearing loss and two had single-sided deafness. Methods: To define audibility, we needed to establish two things: (1) in situ–level thresholds at each audiometric frequency in force (skull simulator) and in sound pressure level (SPL; surface microphone). Next, we measured the responses of the preprogrammed test device in force on the skull simulator and in SPL on the surface mic in response to pink noise at three input levels: 55, 65, and 75 dB SPL. The skull simulator responses were converted to real head force responses by means of an individual real head to coupler difference transform. Subtracting the real head force level thresholds from the real head force output of the test aid yielded the audibility for each audiometric frequency for the skull simulator. Subtracting the SPL thresholds from the surface microphone from the SPL output of the test aid yielded the audibility for each audiometric frequency for the surface microphone. The surface microphone was removed and retested to establish the test–retest reliability of the tool. Results: We ran a 2 (sensor) × 3 (input level) × 10 (frequency) mixed analysis of variance to determine if there were any significant main effects and interactions. There was a significant three-way interaction, so we proceeded to explore our planned comparisons. There were 90 planned comparisons of interest, three at each frequency (3 × 10) for the three input levels (30 × 3). Therefore, to minimize a type 1 error associated with multiple comparisons, we adjusted alpha using the Holm–Bonferroni method. There were five comparisons that yielded significant differences between the skull simulator and surface microphone (test and retest) in the estimation of audibility. However, the mean difference in these effects was small at 3.3 dB. Both sensors yielded equivalent results for the majority of comparisons. Conclusions: Models of bone conduction devices that have intact skin cannot be measured with the skull simulator. This study is the first to present and evaluate a new tool for bone conduction verification. The surface microphone is capable of yielding equivalent audibility measurements as the skull simulator for percutaneous bone conduction users at multiple input levels. This device holds potential for measuring other bone conduction devices (Sentio, BoneBridge, Attract, Soft headband devices) that do not have a percutaneous implant. ACKNOWLEDGMENTS: Portions of this work were paid for from a grant to W. Hodgetts from the Oticon Foundation. P. M. works for Oticon Medical. The other authors have no competing interests to declare. Received August 22, 2017; accepted January 26, 2018. Address for correspondence: William Hodgetts, Department of Communication Sciences and Disorders, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada. E-mail: bill.hodgetts@ualberta.ca Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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Visual Performance and Perception as a Target of Saccadic Strategies in Patients With Unilateral Vestibular Loss

Objectives: To evaluate the ability of saccadic strategies developed during vestibular compensation to reduce the effect of an impaired vestibulo-ocular reflex (VOR) on a retinal smear and image motion sensation. Design: Twenty patients with unilateral vestibular loss were examined with a video head impulse test before and after vestibular rehabilitation (VR) with the use of gaze stabilization and refixation saccades training. Head and eye velocity functions were processed to infer the retinal eccentricity, and through its correlation with visual acuity (VA), several measurements are proposed to evaluate the influence of VR on saccades behavior and visual performance. To isolate the effect of saccades on the findings and avoid bias because of gain differences, only patients whose VOR gain values remained unchanged after VR were included. Results: Improved contribution of covert saccades and reduction of overt saccades latency were measured after VR. We found significant differences when assessing both the interval less than 70% VA (50.25 ms), which is considered the limit of a moderate low vision, and less than 50% VA (39.515 ms), which is the limit for severe low vision. Time to recover a VA of 75% (near normal) was reduced in all the patients (median: 56.472 ms). Conclusion: Despite the absence of VOR gain improvement, patients with unilateral vestibular loss are able to develop saccadic strategies that allow the shortening of the interval of retinal smear and image motion. The proposed measurements might be of use to evaluate VR outcomes and visually induced impairment. ACKNOWLEDGMENTS: All authors contributed to this work, discussed the results and implications, and commented on the article at all stages. G. T. performed explorations, designed and performed measurements, analyzed data, and wrote the article; J. R. designed the RV protocol, performed explorations, and reviewed the article; A. B. performed explorations and reviewed the article; E. M. performed explorations and reviewed the article; N. P. participated in the study design, performed explorations, and reviewed the article. The authors have no conflicts of interest to disclose. Address for correspondence: Gabriel Trinidad-Ruiz, Neurotology Unit, Department of Otorhinolaryngology, University hospital of Badajoz, Spain. E-mail: gtrinidad@gmail.com Received November 17, 2017; accepted February 1, 2018. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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Development of a Novel Bone Conduction Verification Tool Using a Surface Microphone: Validation With Percutaneous Bone Conduction Users

Objectives: To determine if a newly-designed, forehead-mounted surface microphone would yield equivalent estimates of audibility when compared to audibility measured with a skull simulator for adult bone conduction users. Design: Data was analyzed using a within subjects, repeated measures design. There were two different sensors (skull simulator and surface microphone) measuring the same hearing aid programmed to the same settings for all subjects. We were looking for equivalent results. Patients: Twenty-one adult percutaneous bone conduction users (12 females and 9 males) were recruited for this study. Mean age was 54.32 years with a standard deviation of 14.51 years. Nineteen of the subjects had conductive/mixed hearing loss and two had single-sided deafness. Methods: To define audibility, we needed to establish two things: (1) in situ–level thresholds at each audiometric frequency in force (skull simulator) and in sound pressure level (SPL; surface microphone). Next, we measured the responses of the preprogrammed test device in force on the skull simulator and in SPL on the surface mic in response to pink noise at three input levels: 55, 65, and 75 dB SPL. The skull simulator responses were converted to real head force responses by means of an individual real head to coupler difference transform. Subtracting the real head force level thresholds from the real head force output of the test aid yielded the audibility for each audiometric frequency for the skull simulator. Subtracting the SPL thresholds from the surface microphone from the SPL output of the test aid yielded the audibility for each audiometric frequency for the surface microphone. The surface microphone was removed and retested to establish the test–retest reliability of the tool. Results: We ran a 2 (sensor) × 3 (input level) × 10 (frequency) mixed analysis of variance to determine if there were any significant main effects and interactions. There was a significant three-way interaction, so we proceeded to explore our planned comparisons. There were 90 planned comparisons of interest, three at each frequency (3 × 10) for the three input levels (30 × 3). Therefore, to minimize a type 1 error associated with multiple comparisons, we adjusted alpha using the Holm–Bonferroni method. There were five comparisons that yielded significant differences between the skull simulator and surface microphone (test and retest) in the estimation of audibility. However, the mean difference in these effects was small at 3.3 dB. Both sensors yielded equivalent results for the majority of comparisons. Conclusions: Models of bone conduction devices that have intact skin cannot be measured with the skull simulator. This study is the first to present and evaluate a new tool for bone conduction verification. The surface microphone is capable of yielding equivalent audibility measurements as the skull simulator for percutaneous bone conduction users at multiple input levels. This device holds potential for measuring other bone conduction devices (Sentio, BoneBridge, Attract, Soft headband devices) that do not have a percutaneous implant. ACKNOWLEDGMENTS: Portions of this work were paid for from a grant to W. Hodgetts from the Oticon Foundation. P. M. works for Oticon Medical. The other authors have no competing interests to declare. Received August 22, 2017; accepted January 26, 2018. Address for correspondence: William Hodgetts, Department of Communication Sciences and Disorders, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada. E-mail: bill.hodgetts@ualberta.ca Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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Visual Performance and Perception as a Target of Saccadic Strategies in Patients With Unilateral Vestibular Loss

Objectives: To evaluate the ability of saccadic strategies developed during vestibular compensation to reduce the effect of an impaired vestibulo-ocular reflex (VOR) on a retinal smear and image motion sensation. Design: Twenty patients with unilateral vestibular loss were examined with a video head impulse test before and after vestibular rehabilitation (VR) with the use of gaze stabilization and refixation saccades training. Head and eye velocity functions were processed to infer the retinal eccentricity, and through its correlation with visual acuity (VA), several measurements are proposed to evaluate the influence of VR on saccades behavior and visual performance. To isolate the effect of saccades on the findings and avoid bias because of gain differences, only patients whose VOR gain values remained unchanged after VR were included. Results: Improved contribution of covert saccades and reduction of overt saccades latency were measured after VR. We found significant differences when assessing both the interval less than 70% VA (50.25 ms), which is considered the limit of a moderate low vision, and less than 50% VA (39.515 ms), which is the limit for severe low vision. Time to recover a VA of 75% (near normal) was reduced in all the patients (median: 56.472 ms). Conclusion: Despite the absence of VOR gain improvement, patients with unilateral vestibular loss are able to develop saccadic strategies that allow the shortening of the interval of retinal smear and image motion. The proposed measurements might be of use to evaluate VR outcomes and visually induced impairment. ACKNOWLEDGMENTS: All authors contributed to this work, discussed the results and implications, and commented on the article at all stages. G. T. performed explorations, designed and performed measurements, analyzed data, and wrote the article; J. R. designed the RV protocol, performed explorations, and reviewed the article; A. B. performed explorations and reviewed the article; E. M. performed explorations and reviewed the article; N. P. participated in the study design, performed explorations, and reviewed the article. The authors have no conflicts of interest to disclose. Address for correspondence: Gabriel Trinidad-Ruiz, Neurotology Unit, Department of Otorhinolaryngology, University hospital of Badajoz, Spain. E-mail: gtrinidad@gmail.com Received November 17, 2017; accepted February 1, 2018. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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Development of a Novel Bone Conduction Verification Tool Using a Surface Microphone: Validation With Percutaneous Bone Conduction Users

Objectives: To determine if a newly-designed, forehead-mounted surface microphone would yield equivalent estimates of audibility when compared to audibility measured with a skull simulator for adult bone conduction users. Design: Data was analyzed using a within subjects, repeated measures design. There were two different sensors (skull simulator and surface microphone) measuring the same hearing aid programmed to the same settings for all subjects. We were looking for equivalent results. Patients: Twenty-one adult percutaneous bone conduction users (12 females and 9 males) were recruited for this study. Mean age was 54.32 years with a standard deviation of 14.51 years. Nineteen of the subjects had conductive/mixed hearing loss and two had single-sided deafness. Methods: To define audibility, we needed to establish two things: (1) in situ–level thresholds at each audiometric frequency in force (skull simulator) and in sound pressure level (SPL; surface microphone). Next, we measured the responses of the preprogrammed test device in force on the skull simulator and in SPL on the surface mic in response to pink noise at three input levels: 55, 65, and 75 dB SPL. The skull simulator responses were converted to real head force responses by means of an individual real head to coupler difference transform. Subtracting the real head force level thresholds from the real head force output of the test aid yielded the audibility for each audiometric frequency for the skull simulator. Subtracting the SPL thresholds from the surface microphone from the SPL output of the test aid yielded the audibility for each audiometric frequency for the surface microphone. The surface microphone was removed and retested to establish the test–retest reliability of the tool. Results: We ran a 2 (sensor) × 3 (input level) × 10 (frequency) mixed analysis of variance to determine if there were any significant main effects and interactions. There was a significant three-way interaction, so we proceeded to explore our planned comparisons. There were 90 planned comparisons of interest, three at each frequency (3 × 10) for the three input levels (30 × 3). Therefore, to minimize a type 1 error associated with multiple comparisons, we adjusted alpha using the Holm–Bonferroni method. There were five comparisons that yielded significant differences between the skull simulator and surface microphone (test and retest) in the estimation of audibility. However, the mean difference in these effects was small at 3.3 dB. Both sensors yielded equivalent results for the majority of comparisons. Conclusions: Models of bone conduction devices that have intact skin cannot be measured with the skull simulator. This study is the first to present and evaluate a new tool for bone conduction verification. The surface microphone is capable of yielding equivalent audibility measurements as the skull simulator for percutaneous bone conduction users at multiple input levels. This device holds potential for measuring other bone conduction devices (Sentio, BoneBridge, Attract, Soft headband devices) that do not have a percutaneous implant. ACKNOWLEDGMENTS: Portions of this work were paid for from a grant to W. Hodgetts from the Oticon Foundation. P. M. works for Oticon Medical. The other authors have no competing interests to declare. Received August 22, 2017; accepted January 26, 2018. Address for correspondence: William Hodgetts, Department of Communication Sciences and Disorders, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada. E-mail: bill.hodgetts@ualberta.ca Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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A Gain-of-Function Mutation in the α9 Nicotinic Acetylcholine Receptor Alters Medial Olivocochlear Efferent Short Term Synaptic Plasticity.

A Gain-of-Function Mutation in the α9 Nicotinic Acetylcholine Receptor Alters Medial Olivocochlear Efferent Short Term Synaptic Plasticity.

J Neurosci. 2018 Mar 23;:

Authors: Wedemeyer C, Vattino LG, Moglie MJ, Ballestero J, Maison SF, Di Guilmi MN, Taranda J, Liberman MC, Fuchs PA, Katz E, Elgoyhen AB

Abstract
Gain control of the auditory system operates at multiple levels. Cholinergic medial olivocochlear (MOC) fibers originate in the brainstem and make synaptic contacts at the base of the outer hair cells (OHCs), the final targets of several feedback loops from the periphery and higher processing centers. Efferent activation inhibits OHC active amplification within the mammalian cochlea, through the activation of a calcium permeable α9α10 ionotropic cholinergic nicotinic receptor (nAChR), functionally coupled to calcium activated SK2 potassium channels. Correct operation of this feedback requires careful matching of acoustic input with the strength of cochlear inhibition (Galambos, 1956, Wiederhold and Kiang, 1970, Gifford and Guinan, 1987), which is driven by the rate of MOC activity and short term facilitation at the MOC-OHC synapse (Ballestero et al., 2011, Katz and Elgoyhen, 2014). The present work shows (in mice of either sex) that a mutation in the α9α10 nAChR with increased duration of channel gating (Taranda et al., 2009) greatly elongates hair cell evoked inhibitory postsynaptic currents and Ca2+ signals. Interestingly, MOC-OHC synapses of L9'T mice presented reduced quantum content and increased presynaptic facilitation. These phenotypic changes lead to enhanced and sustained synaptic responses and OHC hyperpolarization upon high frequency stimulation of MOC terminals. At the cochlear physiology level these changes were matched by a longer time course of efferent MOC suppression. This indicates that the properties of the MOC-OHC synapse directly determine the efficacy of the MOC feedback to the cochlea being a main player in the "gain control" of the auditory periphery.SIGNIFICANCE STATEMENTPlasticity can involve reciprocal signaling across chemical synapses. An opportunity to study this phenomenon occurs in the mammalian cochlea whose sensitivity is regulated by efferent olivocochlear neurons. These release acetylcholine to inhibit sensory hair cells. A point mutation in the hair cell's acetylcholine receptor that leads to increased gating of the receptor greatly elongates inhibitory postsynaptic currents. Interestingly, efferent terminals from mutant mice present a reduced resting release probability. However, upon high frequency stimulation transmitter release facilitates strongly to produce stronger and far longer-lasting inhibition of cochlear function. Thus, central neuronal feedback on cochlear hair cells provides an opportunity to define plasticity mechanisms in cholinergic synapses other than the highly studied neuromuscular junction.

PMID: 29572431 [PubMed - as supplied by publisher]

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A Gain-of-Function Mutation in the α9 Nicotinic Acetylcholine Receptor Alters Medial Olivocochlear Efferent Short Term Synaptic Plasticity.

A Gain-of-Function Mutation in the α9 Nicotinic Acetylcholine Receptor Alters Medial Olivocochlear Efferent Short Term Synaptic Plasticity.

J Neurosci. 2018 Mar 23;:

Authors: Wedemeyer C, Vattino LG, Moglie MJ, Ballestero J, Maison SF, Di Guilmi MN, Taranda J, Liberman MC, Fuchs PA, Katz E, Elgoyhen AB

Abstract
Gain control of the auditory system operates at multiple levels. Cholinergic medial olivocochlear (MOC) fibers originate in the brainstem and make synaptic contacts at the base of the outer hair cells (OHCs), the final targets of several feedback loops from the periphery and higher processing centers. Efferent activation inhibits OHC active amplification within the mammalian cochlea, through the activation of a calcium permeable α9α10 ionotropic cholinergic nicotinic receptor (nAChR), functionally coupled to calcium activated SK2 potassium channels. Correct operation of this feedback requires careful matching of acoustic input with the strength of cochlear inhibition (Galambos, 1956, Wiederhold and Kiang, 1970, Gifford and Guinan, 1987), which is driven by the rate of MOC activity and short term facilitation at the MOC-OHC synapse (Ballestero et al., 2011, Katz and Elgoyhen, 2014). The present work shows (in mice of either sex) that a mutation in the α9α10 nAChR with increased duration of channel gating (Taranda et al., 2009) greatly elongates hair cell evoked inhibitory postsynaptic currents and Ca2+ signals. Interestingly, MOC-OHC synapses of L9'T mice presented reduced quantum content and increased presynaptic facilitation. These phenotypic changes lead to enhanced and sustained synaptic responses and OHC hyperpolarization upon high frequency stimulation of MOC terminals. At the cochlear physiology level these changes were matched by a longer time course of efferent MOC suppression. This indicates that the properties of the MOC-OHC synapse directly determine the efficacy of the MOC feedback to the cochlea being a main player in the "gain control" of the auditory periphery.SIGNIFICANCE STATEMENTPlasticity can involve reciprocal signaling across chemical synapses. An opportunity to study this phenomenon occurs in the mammalian cochlea whose sensitivity is regulated by efferent olivocochlear neurons. These release acetylcholine to inhibit sensory hair cells. A point mutation in the hair cell's acetylcholine receptor that leads to increased gating of the receptor greatly elongates inhibitory postsynaptic currents. Interestingly, efferent terminals from mutant mice present a reduced resting release probability. However, upon high frequency stimulation transmitter release facilitates strongly to produce stronger and far longer-lasting inhibition of cochlear function. Thus, central neuronal feedback on cochlear hair cells provides an opportunity to define plasticity mechanisms in cholinergic synapses other than the highly studied neuromuscular junction.

PMID: 29572431 [PubMed - as supplied by publisher]

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