A review of the effects of unilateral hearing loss on spatial hearing

Publication date: Available online 11 August 2018

Source: Hearing Research

Author(s): Daniel P. Kumpik, Andrew J. King

Abstract

The capacity of the auditory system to extract spatial information relies principally on the detection and interpretation of binaural cues, i.e., differences in the time of arrival or level of the sound between the two ears. In this review, we consider the effects of unilateral or asymmetric hearing loss on spatial hearing, with a focus on the adaptive changes in the brain that may help to compensate for an imbalance in input between the ears. Unilateral hearing loss during development weakens the brain's representation of the deprived ear, which may outlast the restoration of function in that ear and therefore impair performance on tasks such as sound localization and spatial release from masking that rely on binaural processing. However, loss of hearing in one ear also triggers a reweighting of the cues used for sound localization, resulting in increased dependence on the spectral cues provided by the other ear for localization in azimuth, as well as adjustments in binaural sensitivity that help to offset the imbalance in inputs between the two ears. These adaptive strategies enable the developing auditory system to compensate to a large degree for asymmetric hearing loss, thereby maintaining accurate sound localization. They can also be leveraged by training following hearing loss in adulthood. Although further research is needed to determine whether this plasticity can generalize to more realistic listening conditions and to other tasks, such as spatial unmasking, the capacity of the auditory system to undergo these adaptive changes has important implications for rehabilitation strategies in the hearing impaired.

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A review of the effects of unilateral hearing loss on spatial hearing

Publication date: Available online 11 August 2018

Source: Hearing Research

Author(s): Daniel P. Kumpik, Andrew J. King

Abstract

The capacity of the auditory system to extract spatial information relies principally on the detection and interpretation of binaural cues, i.e., differences in the time of arrival or level of the sound between the two ears. In this review, we consider the effects of unilateral or asymmetric hearing loss on spatial hearing, with a focus on the adaptive changes in the brain that may help to compensate for an imbalance in input between the ears. Unilateral hearing loss during development weakens the brain's representation of the deprived ear, which may outlast the restoration of function in that ear and therefore impair performance on tasks such as sound localization and spatial release from masking that rely on binaural processing. However, loss of hearing in one ear also triggers a reweighting of the cues used for sound localization, resulting in increased dependence on the spectral cues provided by the other ear for localization in azimuth, as well as adjustments in binaural sensitivity that help to offset the imbalance in inputs between the two ears. These adaptive strategies enable the developing auditory system to compensate to a large degree for asymmetric hearing loss, thereby maintaining accurate sound localization. They can also be leveraged by training following hearing loss in adulthood. Although further research is needed to determine whether this plasticity can generalize to more realistic listening conditions and to other tasks, such as spatial unmasking, the capacity of the auditory system to undergo these adaptive changes has important implications for rehabilitation strategies in the hearing impaired.

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Body balance function of cochlear implant patients with and without sound conditions.

Body balance function of cochlear implant patients with and without sound conditions.

Clin Neurophysiol. 2018 Aug 02;129(10):2112-2117

Authors: Oikawa K, Kobayashi Y, Hiraumi H, Yonemoto K, Sato H

Abstract
OBJECTIVE: The relation between well-controlled auditory stimulation through cochlear implant (CI) and the body balance has been sparsely investigated. The purpose of this study was to evaluate the body balance function of CI patients with- and without-sound in anechoic sound-shielded room.
METHODS: We recorded 8 experienced CI recipients and 8 young normal-hearing volunteers. All subjects were assessed using posturography under 4 conditions: (1) eyes open with-sound, (2) eyes closed with-sound, (3) eyes open without-sound, and (4) eyes closed without-sound.
RESULTS: The total path length and the total area were significantly larger in the eyes closed condition than in the eyes open condition. In normal hearing subjects, the average displacement of center of pressure (COP) in the mediolateral direction under with-sound condition was not different from that under without-sound condition. In CI recipients, the COP significantly displaced to the CI side after the deprivation of visual cues in without-sound condition. This shift was eliminated in with-sound condition (significant interaction among sound condition, eye condition, and between-group factor).
CONCLUSION: In CI subjects, sound stimulation improves the abnormal displacement of COP in the mediolateral direction.
SIGNIFICANCE: A posturographic study under an anechoic condition proved that sound stimulation improves body balance function in CI subjects.

PMID: 30096566 [PubMed - as supplied by publisher]

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Restoration of Balance and Unilateral Hearing Using Alternating and Filtering Auditory Training in Shunt-Treated Hydrocephalus Following Subarachnoid Hemorrhage: A Case Report.

Restoration of Balance and Unilateral Hearing Using Alternating and Filtering Auditory Training in Shunt-Treated Hydrocephalus Following Subarachnoid Hemorrhage: A Case Report.

Am J Case Rep. 2018 Aug 10;19:935-940

Authors: Milantoni N, Di Bella N, Chahbazian K

Abstract
BACKGROUND Although rehabilitation for balance disorders is commonly undertaken following a stroke, hearing dysfunction is rarely investigated, even though hearing loss affects the ability to maintain balance. This report presents a case of restoration of balance and unilateral hearing using an alternating and filtering auditory training (AFAT) protocol in a patient with subarachnoid hemorrhage (SAH) and shunt-treated hydrocephalus. CASE REPORT A 54-year-old woman with a five-month history of SAH due to a ruptured aneurysm in the anterior communicating artery and hydrocephalus treated with a shunt was admitted to our unit for neurorehabilitation. The patient had a history of anorexia. Her initial neurological examination on admission for rehabilitation therapy showed postural instability, hemi-hyposthenia, proprioceptive left-sided ataxia, a confusional state including temporospatial disorientation, memory disorder and hearing loss. Two weeks after the start of her neurorehabilitation program the AFAT program was commenced. Pure tone audiometry (PTA) showed lower left hearing thresholds, extending from a hearing level (HL) of between 5-25 decibel (dB) or more when compared with the right ear. With a rapid and improved regain of unilateral hearing loss, balance, cognitive, and motor function also improved. CONCLUSIONS This case report supports that patients who undergo rehabilitation following stroke, SAH, and hydrocephalus might benefit from a rehabilitation program that includes hearing assessment and early improvement of hearing loss, leading to a shorter rehabilitation time.

PMID: 30093608 [PubMed - in process]

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The Use of Aspirin to Reduce the Risk of Thrombotic Events in Patients With End-Stage Renal Disease: Protocol for a Randomized Controlled Trial.

The Use of Aspirin to Reduce the Risk of Thrombotic Events in Patients With End-Stage Renal Disease: Protocol for a Randomized Controlled Trial.

JMIR Res Protoc. 2018 Aug 09;7(8):e10516

Authors: Lemos Cerqueira T, Fartolino Guerrero A, Pérez Fermin CK, Wang R, Balbino EE, Breeze JL, Gonzalez Mego P, Argentina Silva D, Omer WE, Vandevelde NM

Abstract
BACKGROUND: End-stage renal disease (ESRD) is the last stage of chronic kidney disease, mainly caused by type 2 diabetes mellitus and characterized by an increased mortality risk related to cardiovascular disease. Low-dose aspirin (acetylsalicylic acid or ASA) seems to effectively prevent cardiovascular events in patients with ESRD. However, the number of interventional studies in this population remains limited and the mechanisms of aspirin-related bleeding remain poorly understood. Aspirin's efficacy and safety may be modified by the presence of type 2 diabetes mellitus or platelet hyperreactivity.
OBJECTIVE: The overall objective of this protocol is to (1) evaluate aspirin's safety and efficacy in reducing the risk of thrombotic events in patients with ESRD on hemodialysis and (2) examine whether aspirin's efficacy is modified by the presence of type 2 diabetes mellitus or platelet hyperreactivity. Specifically, the primary objective is to compare the 12-month rate of any thrombotic event (cardiac death, nonfatal myocardial infarction, nonfatal stroke, arteriovenous fistula thrombosis) and Thrombolysis in Myocardial Infarction (TIMI) major bleeding in patients treated with aspirin compared to those on placebo. Secondary objectives are to test for effect modification of treatment by the presence of type 2 diabetes mellitus or platelet hyperreactivity and compare the rate of TIMI minor bleeding between treatment groups.
METHODS: We developed a protocol for a phase 2 randomized, single-center, placebo-controlled, triple-blind, superiority clinical trial to assess the prophylactic efficacy and safety of aspirin in patients with ESRD and on hemodialysis. It follows the ethical principles of the Declaration of Helsinki of the World Medical Association. A total of 342 participants would be enrolled over 12 months at a large dialysis center. Patients will be randomized in a 1:1 ratio and stratified by presence of type 2 diabetes mellitus and platelet hyperreactivity to receive either oral aspirin (100 mg/d) or placebo for a treatment period of 12 months. An intention-to-treat statistical analysis will be performed.
RESULTS: The randomized clinical trial will be performed after approval by the ethical committee of the participating center and registration at ClinicalTrials.gov.
CONCLUSIONS: We provide a protocol for a randomized controlled trial to evaluate the safety and efficacy of treatment with aspirin to reduce the risk of thrombotic events. In addition, such a study would further our understanding of the mechanism of aspirin-related bleeding and help identify subgroups of best-responders and patients with a higher risk of adverse events.
REGISTERED REPORT IDENTIFIER: RR1-10.2196/10516.

PMID: 30093367 [PubMed]

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Body balance function of cochlear implant patients with and without sound conditions.

Body balance function of cochlear implant patients with and without sound conditions.

Clin Neurophysiol. 2018 Aug 02;129(10):2112-2117

Authors: Oikawa K, Kobayashi Y, Hiraumi H, Yonemoto K, Sato H

Abstract
OBJECTIVE: The relation between well-controlled auditory stimulation through cochlear implant (CI) and the body balance has been sparsely investigated. The purpose of this study was to evaluate the body balance function of CI patients with- and without-sound in anechoic sound-shielded room.
METHODS: We recorded 8 experienced CI recipients and 8 young normal-hearing volunteers. All subjects were assessed using posturography under 4 conditions: (1) eyes open with-sound, (2) eyes closed with-sound, (3) eyes open without-sound, and (4) eyes closed without-sound.
RESULTS: The total path length and the total area were significantly larger in the eyes closed condition than in the eyes open condition. In normal hearing subjects, the average displacement of center of pressure (COP) in the mediolateral direction under with-sound condition was not different from that under without-sound condition. In CI recipients, the COP significantly displaced to the CI side after the deprivation of visual cues in without-sound condition. This shift was eliminated in with-sound condition (significant interaction among sound condition, eye condition, and between-group factor).
CONCLUSION: In CI subjects, sound stimulation improves the abnormal displacement of COP in the mediolateral direction.
SIGNIFICANCE: A posturographic study under an anechoic condition proved that sound stimulation improves body balance function in CI subjects.

PMID: 30096566 [PubMed - as supplied by publisher]

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Restoration of Balance and Unilateral Hearing Using Alternating and Filtering Auditory Training in Shunt-Treated Hydrocephalus Following Subarachnoid Hemorrhage: A Case Report.

Restoration of Balance and Unilateral Hearing Using Alternating and Filtering Auditory Training in Shunt-Treated Hydrocephalus Following Subarachnoid Hemorrhage: A Case Report.

Am J Case Rep. 2018 Aug 10;19:935-940

Authors: Milantoni N, Di Bella N, Chahbazian K

Abstract
BACKGROUND Although rehabilitation for balance disorders is commonly undertaken following a stroke, hearing dysfunction is rarely investigated, even though hearing loss affects the ability to maintain balance. This report presents a case of restoration of balance and unilateral hearing using an alternating and filtering auditory training (AFAT) protocol in a patient with subarachnoid hemorrhage (SAH) and shunt-treated hydrocephalus. CASE REPORT A 54-year-old woman with a five-month history of SAH due to a ruptured aneurysm in the anterior communicating artery and hydrocephalus treated with a shunt was admitted to our unit for neurorehabilitation. The patient had a history of anorexia. Her initial neurological examination on admission for rehabilitation therapy showed postural instability, hemi-hyposthenia, proprioceptive left-sided ataxia, a confusional state including temporospatial disorientation, memory disorder and hearing loss. Two weeks after the start of her neurorehabilitation program the AFAT program was commenced. Pure tone audiometry (PTA) showed lower left hearing thresholds, extending from a hearing level (HL) of between 5-25 decibel (dB) or more when compared with the right ear. With a rapid and improved regain of unilateral hearing loss, balance, cognitive, and motor function also improved. CONCLUSIONS This case report supports that patients who undergo rehabilitation following stroke, SAH, and hydrocephalus might benefit from a rehabilitation program that includes hearing assessment and early improvement of hearing loss, leading to a shorter rehabilitation time.

PMID: 30093608 [PubMed - in process]

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The Use of Aspirin to Reduce the Risk of Thrombotic Events in Patients With End-Stage Renal Disease: Protocol for a Randomized Controlled Trial.

The Use of Aspirin to Reduce the Risk of Thrombotic Events in Patients With End-Stage Renal Disease: Protocol for a Randomized Controlled Trial.

JMIR Res Protoc. 2018 Aug 09;7(8):e10516

Authors: Lemos Cerqueira T, Fartolino Guerrero A, Pérez Fermin CK, Wang R, Balbino EE, Breeze JL, Gonzalez Mego P, Argentina Silva D, Omer WE, Vandevelde NM

Abstract
BACKGROUND: End-stage renal disease (ESRD) is the last stage of chronic kidney disease, mainly caused by type 2 diabetes mellitus and characterized by an increased mortality risk related to cardiovascular disease. Low-dose aspirin (acetylsalicylic acid or ASA) seems to effectively prevent cardiovascular events in patients with ESRD. However, the number of interventional studies in this population remains limited and the mechanisms of aspirin-related bleeding remain poorly understood. Aspirin's efficacy and safety may be modified by the presence of type 2 diabetes mellitus or platelet hyperreactivity.
OBJECTIVE: The overall objective of this protocol is to (1) evaluate aspirin's safety and efficacy in reducing the risk of thrombotic events in patients with ESRD on hemodialysis and (2) examine whether aspirin's efficacy is modified by the presence of type 2 diabetes mellitus or platelet hyperreactivity. Specifically, the primary objective is to compare the 12-month rate of any thrombotic event (cardiac death, nonfatal myocardial infarction, nonfatal stroke, arteriovenous fistula thrombosis) and Thrombolysis in Myocardial Infarction (TIMI) major bleeding in patients treated with aspirin compared to those on placebo. Secondary objectives are to test for effect modification of treatment by the presence of type 2 diabetes mellitus or platelet hyperreactivity and compare the rate of TIMI minor bleeding between treatment groups.
METHODS: We developed a protocol for a phase 2 randomized, single-center, placebo-controlled, triple-blind, superiority clinical trial to assess the prophylactic efficacy and safety of aspirin in patients with ESRD and on hemodialysis. It follows the ethical principles of the Declaration of Helsinki of the World Medical Association. A total of 342 participants would be enrolled over 12 months at a large dialysis center. Patients will be randomized in a 1:1 ratio and stratified by presence of type 2 diabetes mellitus and platelet hyperreactivity to receive either oral aspirin (100 mg/d) or placebo for a treatment period of 12 months. An intention-to-treat statistical analysis will be performed.
RESULTS: The randomized clinical trial will be performed after approval by the ethical committee of the participating center and registration at ClinicalTrials.gov.
CONCLUSIONS: We provide a protocol for a randomized controlled trial to evaluate the safety and efficacy of treatment with aspirin to reduce the risk of thrombotic events. In addition, such a study would further our understanding of the mechanism of aspirin-related bleeding and help identify subgroups of best-responders and patients with a higher risk of adverse events.
REGISTERED REPORT IDENTIFIER: RR1-10.2196/10516.

PMID: 30093367 [PubMed]

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