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1.
Braz. j. otorhinolaryngol. (Impr.) ; Braz. j. otorhinolaryngol. (Impr.);88(4): 546-555, July-Aug. 2022. graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1394148

RESUMO

Abstract Introduction: Electrocochleography has recently emerged as a diagnostic tool in cochlear implant surgery, purposing hearing preservation and optimal electrode positioning. Objective: In this experimental study, extra-cochlear potentials were obtained during cochlear implant surgery in guinea pigs. The aim was to determine electrophysiological changes indicating cochlear trauma after cochleostomy and after electrode implantation in different insertion depths. Methods: Normal-hearing guinea pigs (n = 14) were implanted uni- or bilaterally with a multichannel electrode. The extra-cochlear cochlear nerve action potentials were obtained in response to acoustic stimuli at specific frequencies before and after cochleostomy, and after introduction of the electrode bundle. After the electrophysiological experiments, the guinea pigs were euthanized and microtomography was performed, in order to determine the position of the electrode and to calculate of the depth of insertion. Based on the changes of amplitude and thresholds in relation to the stimulus frequency, the electrophysiological data and the position obtained by the microtomography reconstruction were compared. Results: Cochleostomy promoted a small electrophysiological impact, while electrode insertion caused changes in the amplitude of extra-cochlear electrophysiological potentials over a wide range of frequencies, especially in the deepest insertions. There was, however, preservation of the electrical response to low frequency stimuli in most cases, indicating a limited auditory impact in the intraoperative evaluation. The mean insertion depth of the apical electrodes was 5339.56 μm (±306.45 - 6 inserted contacts) and 4447.75 μm (±290.23 - 5 inserted contacts). Conclusions: The main electrophysiological changes observed during surgical procedures occurred during implantation of the electrode, especially the deepest insertions, whereas the cochleostomy disturbed the potentials to a lesser extent. While hearing loss was often observed apical to the cochlear implant, it was possible to preserve low frequencies after insertion. © 2020 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).


Resumo Introdução: A eletrococleografia surgiu recentemente como uma ferramenta diagnóstica na cirurgia de implante coclear, objetiva a preservação da audição e o posicionamento ideal dos eletrodos. Objetivo: Determinar as alterações eletrofisiológicas indicativas de trauma coclear após a cocleostomia e após o implante do eletrodo em diferentes profundidades de inserção. Método: Neste estudo experimental, potenciais extracocleares foram obtidos durante a cirurgia de implante coclear em cobaias. Cobaias com audição normal (n = 14) foram implantadas uni- ou bilateralmente com eletrodo multicanal. Os potenciais de ação do nervo coclear extracoclear foram obtidos em resposta a estímulos acústicos em frequências específicas antes e após a cocleostomia e após a introdução do feixe de eletrodos. Após os experimentos eletrofisiológicos, as cobaias foram submetidas à eutanásia e a microtomografia foi feita para determinar a posição do eletrodo e calcular a profundidade de inserção. Com base nas mudanças de amplitude e limiares em relação à frequência do estímulo, os dados eletrofisiológicos e a posição obtida na reconstrução microtomográfica foram comparados. Resultados: A cocleostomia promoveu um pequeno impacto eletrofisiológico, enquanto a inserção do eletrodo causou alterações na amplitude dos potenciais eletrofisiológicos extra-cocleares em uma ampla faixa de frequências, especialmente nas inserções mais profundas. Houve, entretanto, preservação da resposta elétrica aos estímulos de baixa frequência na maioria dos casos, indicou um impacto auditivo limitado na avaliação intraoperatória. A profundidade média de inserção dos eletrodos apicais foi 5339,56 μm (± 306,45 - 6 contatos inseridos) e 4447,75 μm (± 290,23 - 5 contatos inseridos). Conclusão: As principais alterações eletrofisiológicas observadas durante os procedimentos cirúrgicos ocorreram durante o implante do eletrodo, especialmente nas inserções mais profundas, enquanto a cocleostomia alterou os potenciais em menor grau. Embora a perda auditiva seja frequentemente observada em posição apical ao implante coclear, foi possível preservar as baixas frequências após a inserção.

2.
Braz J Otorhinolaryngol ; 88(4): 546-555, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-33039317

RESUMO

INTRODUCTION: Electrocochleography has recently emerged as a diagnostic tool in cochlear implant surgery, purposing hearing preservation and optimal electrode positioning. OBJECTIVE: In this experimental study, extra-cochlear potentials were obtained during cochlear implant surgery in guinea pigs. The aim was to determine electrophysiological changes indicating cochlear trauma after cochleostomy and after electrode implantation in different insertion depths. METHODS: Normal-hearing guinea pigs (n = 14) were implanted uni- or bilaterally with a multichannel electrode. The extra-cochlear cochlear nerve action potentials were obtained in response to acoustic stimuli at specific frequencies before and after cochleostomy, and after introduction of the electrode bundle. After the electrophysiological experiments, the guinea pigs were euthanized and microtomography was performed, in order to determine the position of the electrode and to calculate of the depth of insertion. Based on the changes of amplitude and thresholds in relation to the stimulus frequency, the electrophysiological data and the position obtained by the microtomography reconstruction were compared. RESULTS: Cochleostomy promoted a small electrophysiological impact, while electrode insertion caused changes in the amplitude of extra-cochlear electrophysiological potentials over a wide range of frequencies, especially in the deepest insertions. There was, however, preservation of the electrical response to low frequency stimuli in most cases, indicating a limited auditory impact in the intraoperative evaluation. The mean insertion depth of the apical electrodes was 5339.56 µm (±306.45 - 6 inserted contacts) and 4447.75 µm (±290.23 - 5 inserted contacts). CONCLUSIONS: The main electrophysiological changes observed during surgical procedures occurred during implantation of the electrode, especially the deepest insertions, whereas the cochleostomy disturbed the potentials to a lesser extent. While hearing loss was often observed apical to the cochlear implant, it was possible to preserve low frequencies after insertion.


Assuntos
Implante Coclear , Implantes Cocleares , Animais , Cóclea/cirurgia , Implante Coclear/efeitos adversos , Implante Coclear/métodos , Implantes Cocleares/efeitos adversos , Modelos Animais de Doenças , Cobaias , Audição
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