Study of cochlear microphonic potentials in auditory neuropathy / Estudo do microfonismo coclear na neuropatia auditiva

Abstract Introduction: Auditory Neuropathy/Dyssynchrony is a disorder characterized by the presence of Otoacoustic Emissions and Cochlear Microphonic Potentials, an absence or severe alteration of Brainstem Evoked Auditory Potential, auditory thresholds incompatible with speech thresholds and altered acoustic reflexes. The study of the Cochlear Microphonic Potential appears to be the most important tool for an accurate diagnosis of this pathology. Objective: Determine the characteristics of the Cochlear Microphonic in Auditory Neuropathy/Dyssynchrony using an integrative review. Methods: Bibliographic survey of Pubmed and Bireme platforms and MedLine, LILACS and SciELO data banks, with standardized searches up to July 2014, using keywords. Criteria were established for the selection and assessment of the scientific studies surveyed, considering the following aspects: author, year/place, degree of recommendation/level of scientific evidence, objective, sample, age range, mean age, tests, results and conclusion. Results: Of the 1959 articles found, 1914 were excluded for the title, 20 for the abstract, 9 for the text of the article, 2 for being repeated and 14 were selected for the study. Conclusion: The presence of the Cochlear Microphonic is a determining finding in the differential diagnosis of Auditory Neuropathy/Dyssynchrony. The protocol for the determination of Cochlear Microphonic must include the use of insert earphones, reverse polarity and blocking the stimulus tube to eliminate electrical artifact interference. The amplitude of the Cochlear Microphonic in Auditory Neuropathy/Dyssynchrony shows no significant difference from that of normal individuals. The duration of the Cochlear Microphonic is longer in individuals with Auditory Neuropathy/Dyssynchrony.

Resumo Introdução: A Neuropatia/Dessincronia Auditiva é uma doença caracterizada pela presença das Emissões Otoacústicas e do Microfonismo Coclear, com ausência ou grave alteração do Potencial Evocado Auditivo de Tronco Encefálico, limiares auditivos incompatíveis com limiares vocais e reflexos acústicos alterados. O estudo do Microfonismo Coclear parece ser a ferramenta mais importante para um diagnóstico preciso desta patologia. Objetivo: Verificar por meio de uma revisão integrativa as características do Microfonismo Coclear na Neuropatia/Dessincronia Auditiva. Método: Levantamento bibliográfico nas plataformas Pubmed e Bireme e nas bases de dados MedLine, LILACS e SciELO, com buscas padronizadas até julho de 2014, utilizando-se palavraschave. Para a seleção e avaliação dos estudos científicos levantados, foram estabelecidos critérios, contemplando os aspectos: autor, ano/local, grau de recomendação/nível de evidência científica, objetivo, amostra, faixa etária, média de idade em anos, testes, resultados e conclusão. Resultados: Dos 1959 artigos encontrados, 1914 foram excluídos pelo título, 20 pelo resumo, nove pela leitura do artigo, dois eram repetidos e 14 foram selecionados para o estudo. Conclusão: A presença do Microfonismo Coclear é um achado determinante no diagnóstico diferencial da Neuropatia/Dessincronia auditiva. O protocolo de registro do Microfonismo Coclear deve contar com o uso de fones de inserção, a inversão da polaridade e o bloqueio do tubo do estímulo para impedir a interferência de artefato elétrico. A amplitude do Microfonismo Coclear na Neuropatia/Dessincronia auditiva não apresenta diferença significante entre a amplitude do Microfonismo Coclear em ouvintes normais. A duração do Microfonismo Coclear é maior em indivíduos com Neuropatia/Dessincronia auditiva.

Role of Cochlear Microphonic in Newborn Hearing Test / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Cochlear microphonic (CM) is an electrical potential generated by outer hair cells in response to acoustic stimulation. The aim of this study is to evaluate the significance of CM in neonatal hearing loss. SUBJECTS AND METHOD: From April 2013 to April 2014, 64 neonates hospitalized in neonatal intensive care unit were enrolled. Subjects underwent transient evoked otoacoustic emission (TEOAE), auditory brain stem response (ABR) and CM. We analyzed the results of hearing tests and the correlation between CM and the other test modalities. RESULTS: Ninety two ears showed normal ABR waves whereas the other 36 ears had abnormal ABR. There were two neonates who were suspected of auditory neuropathy because of the presence of TEOAE and CM. Among 14 ears who showed abnormal OAE results, 12 ears (86%) were identified as having CM. The amplitudes of CMs were correlated with the reproducibility of TEOAE (p<0.005). Between the ears with positive TEOAE and others with negative TEOAE, the amplitudes of CMs were significantly different (p<0.005). CONCLUSION: Many ears were identified with the presence of CM without TEOAE response because of the the vulnerability of OAE from middle ear status and environment. We suppose that CM might provide information on outer hair cell function to complement the OAE in neonatal hearing test.

Comparison of differental intracochlear pressures between round window stimulation and ear canal stimulation / 生物医学工程学杂志

Stimulation of the round window (RW) for coupling an implantable hearing system to the cochlea has gained increasing clinical importance. To compare the vibration transfer to the cochlear fluids and partition in response to normal acoustic stimulation and to mechanical stimulation of the RW, we carried out an acoustic-structure coupled finite element analysis using a recently developed finite element (FE) model in our laboratory, which consisted of external ear canal, middle ear and cochlea. Intracochlear pressures were derived during normal forward sound stimulation as well as reverse RW stimulation. A model was utilized to calculate the force required of an actuator at the RW to produce a differential intracochlear pressure that is equivalent to a stimulus produced in normal ear by a given external ear-canal pressure. The current results provided further information to support the optimization of the actuators and adapt existing prostheses for RW stimulation in order to insure sufficient acoustic output.

Estudio electrofisiológico y electroacústico de un desorden del espectro de neuropatía auditiva: reporte de un caso en recién nacido de alto riesgo / Electrophysiology and electroacoustic study of spectrum disorder of auditory neuropathy: report of a case in high-risk newborn

El desorden del espectro de neuropatía auditiva (DENA) describe una condición en la cual se observa o se ha observado emisiones otoacústicas (EOA) junto con potenciales evocados auditivos de tronco (PEAT) anormales o ausentes. Su identificación se basa en la presencia de potencial microfónico coclear (PMIC) junto con un PEAT anormal o ausente y EOA presentes o antecedentes de su presencia. Los umbrales tonales pueden encontrarse entre los rangos de normalidad hasta pérdidas auditivas profundas. El reconocimiento del habla generalmente se encuentra afectado particularmente en presencia de ruido de fondo, sin embargo en algunos individuos se mantiene conservado (sin ruido). Se presenta caso clínico de un recién nacido de sexo femenino de pretérmino de 29 semanas y 810 grs (GIII), apgar 7/8, presenta displasia broncopulmonar, sospecha de infección connatal tratada, hiperbilirrubinemia (max 11 mg/dl) tratada con fototerapia. Es derivada al Servicio de Otorrinolaringología para su evaluación auditiva. La evaluación auditiva realizada corresponde a potenciales evocados auditivos de tronco (PEAT), impedanciometria, audiometría de campo de respuesta reflejas y emisiones oto-acústicas. Los resultados obtenidos concuerdan con lo descrito en la literatura para un DENA.

Auditory neuropathy spectrum disorder (ANSD) describes a condition in which it is possible to find otoacoustic emissions (OAE) in presence of abnormal or absent auditory brainstem evoked potentials (ABR). The pure tone thresholds may show a spectrum from normal to profound hearing loss. Speech recognition is often affected in presence of background noise, but in some individuals remains intact. We report a case of a pre term newborn (female) of 29 weeks and 810 grams, Apgar 7/8, bronchopulmonary dysplasia, suspected connatal infection, and hyperbilirubinemia (max 11 mg / dl). She was referred to Hospital Padre Hurtado for hearing assessment. The hearing test performed were an ABR, tympanometry & acoustic reflex, visual reinforcement audiometry and otoacoustic emissions. The results are consistent with those described in the literature for ANSD.

Study for cochlear microphonic potential test in patients with profound sensorineural hearing loss / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To report intraoperative round window cochlear microphonic potential test (CM) in patients with profound sensorineural deafness.@*METHOD@#Intraoperative round window CM test were performed on 40 cases with profound sensorineural deafness during cochlear implantation surgery under general anesthesia in the standard operating room. CM were compared with their reliable preoperation distortion product otoacoustic emission (DPOAE).@*RESULT@#The CM were found in 40 patients. The rate at 0.5, 1.0, 2.0, 4.0. kHz was respectively 90%, 97.5%, 100%, 92.5%. The preoperation DPOAE were found in some frequency in 9 cases. The rate at 0.5, 1.0, 2.0, 4.0 kHz was respectively was 2.5%, 2.5%, 17.5%, 2.5%.@*CONCLUSION@#The elicited rate of CM was obviously higher than the one of DPOAE in the same patient with profound sensorineural deafness. The intraoperative round window CM may objectively and accurately estimate the part of cochlear function in patients with profound sensorineural deafness.

Eletrococleografia extratimpânica na neuropatia/dessincronia auditiva: [revisão] / Extratympanic electrocochleography in the diagnosis of auditory neuropathy/auditory dyssynchrony: [review]

O potencial evocado auditivo de tronco encefálico (PEATE) vem sendo amplamente utilizado como método para avaliação da função coclear em indivíduos com diagnóstico de neuropatia/dessincronia auditiva (NA/DA). Na ausência das emissões otoacústicas, muitos casos de NA/DA foram diagnosticados pela presença do microfonismo coclear (MC) identificado no PEATE. OBJETIVO: Demonstrar a aplicabilidade clínica da eletrococleografia extratimpânica (Ecog-ET) no diagnóstico diferencial da NA/DA quando comparada ao PEATE. MATERIAL E MÉTODO: Uma criança com 4 anos de idade, com diagnóstico de NA/DA atendida no Centro de Pesquisas Audiológicas realizou a Ecog-ET com tone burst de 2000Hz nas polaridades de rarefação e condensação. RESULTADOS: Ilustrou-se o registro da Ecog-ET. Com a utilização de protocolo apropriado, o MC pode ser evidenciado e confirmado na Ecog, com qualidade de registro superior ao obtido no PEATE. CONCLUSÃO: A Ecog-ET permitiu uma análise mais detalhada do MC quando comparada ao PEATE tendo, portanto aplicabilidade clínica na investigação da função coclear na NA/DA.

The brainstem auditory evoked potential (BAEP) is being extensively used as a method for the evaluation of cochlear function in individuals with diagnosis of auditory neuropathy/auditory dyssynchrony (AN/AD). In the absence of otoacoustic emissions, many cases of AN/AD have been diagnosed by the presence of CM identified in the BAEP. AIM: to demonstrate the clinical applicability of extratympanic electrocochleography (ET-Ecochg) in the differential diagnosis of AN/AD compared to the BAEP. METHOD: a 4-year-old child with a diagnosis of AN/AD seen at the Audiological Research Center was submitted to ET-Ecochg with a 2000 Hz tone burst in rarefaction and condensation polarities. RESULTS: the ET-Ecochg exam was illustrated. Using an appropriate protocol, it was possible to demonstrate CM and to confirm it in the Ecochg, with a recording quality superior to that obtained in the BAEP. CONCLUSION: ET-Ecochg permitted a more detailed analysis of CM compared to the BAEP, thus showing clinical applicability for the investigation of cochlear function in AN/AD.

Auditory neuropathy in deaf school students / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To investigate incidents and clinical features of auditory neuropathy in Nanjing deaf school students.@*METHOD@#Three hundred and fifty-eight deaf students in the school accepted the first examination including otoscopic examination, tympanometry and transiently evoked otoacoustic emissions (TEOAE) screening. Detailed audiological and vestibular evaluations including pure-tone audiometry, immittance audiometry and acoustic reflex measures, transiently evoked otoacoustic emissions (TEOAE), distortion product otoacoustic emissions (DPOAE), auditory brain stem response (ABR), electronystagmography (ENG) and vestibular evoked myogenic potential (VEMP) were given to whom had positive TEOAE screening.@*RESULT@#Three hundred and twenty-three students entered the program of screening for auditory neuropathy. One student had positive TEOAE in single ear while the other two had positive TEOAE in both ears. In the screening stage,there were strong evidences in these three students with auditory neuropathy in the detailed audiological procedures.@*CONCLUSION@#Auditory neuropathy, which can also be found in deaf schools, is not as rare as we thought before. Early identification and intervention may help those children to avoid entering the deaf school and to return to normal society.

Regulation of nitric oxide-cyclic guanosine monophosphate pathway on cochlear sensitivity / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the effect of nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway on cochlear sensitivity. Methods Ten groups of guinea pigs were treated with the following solutions by whole cochlear perfusion for 2 hours: (1) Artificial perilymph; (2) L-arginine; 93) Ca(2+)-ATPase inhibitor; (4) Ca(2+)-ATPase inhibitor + L-arginine; (5) Ca(2+)-ATPase inhibitor + cGMP; (6) Ca 2+ ATPase inhibitor + L-arginine + Non-selective NOS inhibitor; (7) eNOS inhibitor; (8) eNOS inhibitor + Ca(2+)-ATPase inhibitor; (9) eNOS inhibitor + Ca(2+)-ATPase inhibitor + L-arginine; (10) eNOS inhibitor + Ca(2+)-ATPase inhibitor + L-arginine + nNOS inhibitor. The compound action potential (CAP) and cochlea microphonics (CM) were measured to assess the changes of cochlear sensitivity. After the perfusion, the cochleae were harvested and prepared for transmission electron microscopy.</p><p><b>RESULTS</b>The average threshold shift of CAP after perfusion Ca(2+)-ATPase inhibitor was 28.5 dB, and it was improved in group 4 with 9 dB by L-arginine, similar with group 5. The threshold shift of CAP in group 8 was 42.5 dB, and it decreased in group 9 by L-arginine, on this foundation nNOS inhibitor was added, increased threshold shift of CAP was 6.5 dB, similar with group 8. The results indicated that L-arginine could rivalry the role of Ca(2+)-ATPase inhibitor through the path of NO-cGMP. Transmission electron microscopy showed that Ca(2+)-ATPase inhibitor + L-arginine combined administration resulted in less vacuolization in out hair cell than that treated with Ca(2+)-ATPase inhibitor only.</p><p><b>CONCLUSIONS</b>The NO-cGMP pathway could regulate cochlear sensitivity; L-arginine may improve the function of Corti's organ via nNOS, and they indicate an important role of supporting cells in the modulation of cochlear function.</p>

A eletrococleografia na neuropatia/dessincronia auditiva / The electrococleography in the auditory neuropathy/auditory dysynchrony

Este estudo avaliou a função coclear e neural em indivíduos com neuropatia/dessincronia auditiva. Vinte e seis orelhas foram analisadas: grupo controle (n=10) e grupo estudo (n=16). Os grupos apresentaram resultados semelhantes em relação à amplitude do microfonismo coclear. No grupo estudo, o microfonismo coclear teve início atrasado, mas sem diferença estatisticamente significante. Houve diferenças estatísticas em relação aos parâmetros de término e duração do microfonismo coclear...

This study evaluated the cochlear and neural functions in individuals with auditory neuropathy/dyssynchrony.. Twenty-six ears were analyzed: the control group (n=10) and the study group (n=16). The groups present similar results in relation to the amplitude of the cochlear microphonic. In the study group, the cochlear microphonic had a late beginning but with no statistical significance. There were statistical differences in relation to the ending and duration parameters of the cochlear microphonic...

Análise das emissões otoacústicas - produto de distorção - após a aplicação de toxina botulínica A (botox®) sobre a janela redonda de chinchilas / Analysis of otoacustic emissions - distortion product - after the use of botulinum toxin A (botox®) on the round window of chinchillas

Através das emissões otoacústicas pré e pós operatória foi avaliada a inativação da contração das células ciliadas externas pela ação da toxina botulínica A. No grupo de estudo aplicou-se uma unidade de toxina botulínica sobre a janela redonda de oito chinchilas. O grupo controle usou soro fisiológico. As emissões otoacústicas estiveram ausentes nos exames pós operatórios de todas as orelhas do grupo de estudo e estiveram presentes em todos os exames pós-operatórios do grupo controle. Esses resultados sugerem que a toxina botulínica pode ser uma eficiente ferramenta para o estudo das vias eferentes cocleares, pois a cirurgia é de fácil realização e não requer a intervenção intracerebral.The action of botulinum toxin A inactivating the contraction of the outer hair cells was evaluated by pre and postoperative otoacoustic emissions exams. In the study group, one unit of toxin was applied onto the round window of eight chinchillas. The control group was submitted to saline solution. Otoacoustic emissions were absent in all postoperative exams of the study group, in contrast to the control group. Those results suggest that botulinum toxin can be an efficient tool for the study of efferent auditory pathways. The surgery can be easily done without an intracranial intervention...

Amplitudes das emissöes otoacústicas transientes e por distorçäo, em jovens e idosos / Amplitude of Transient and distortion product otoacoustic emissions, in young and elderly people

Introduçäo: As emissöes otoacústicas refletem, preferencialmente, o status funcional da cóclea. Como a passagem da informaçäo sonora, tanto em sua direçäo aferente quanto na eferente, depende também das condiçöes da orelha média, säo vários os fatores que podem regular o registro final das emissöes otoacústicas. Objetivos: Este estudo teve o objetivo de verificar o comportamento das respostas cocleares captadas através de EOAT e de EOAPD em adultos jovens e em idosos com funçäo normal de orelha média, observando-se a amplitude das respostas nas duas condiçöes. Resultados: Foram analisados os resultados obtidos em 40 orelhas de 20 adultos jovens entre 20 e 25 anos de idade, e de 30 orelhas de 15 idosos entre 60 e 75 anos de idade, ambos os grupos sem queixa auditiva e com nível de audiçäo dentro dos limites da normalidade. Conclusäo: Comparando-se as emissöes otoacústicas transientes (EOATs) com as emissöes otoacústicas por produto de distorçäo (EOAPD), as primeiras sofreram maiores impedimentos em sua captaçäo, tanto em adultos jovens quanto em idosos

Exploración de la función coclear en niños mediante emisiones otoacústicas / Examination of cochlear function in children with otoacoustic emissions

Introducción. Este estudio fue realizado con el fin de conocer la prevalencia de las emisiones otoacústicas espontáneas y provocadas por sonidos transitorios en la población pediátrica de alto riesgo. Material y métodos. Se examinaron 44 niños con edad promedio de 3.7 años, en quienes se comprobó que tenían audición normal y que estaban libres de infecciones y disfunciones del oído medio. Resultados. Se encontró una prevalencia de 56.8 por ciento de emisiones otoacústicas espontáneas y un 73.8 por ciento de emisiones otoacústicas provocadas. Estos resultados son comparables con los encontrados por otros autores en poblaciones similares. Conclusiones. Este método diagnóstico, además de ser un procedimiento rápido comparado con los potenciales provocados auditivos de tallo cerebral y la electrococleografía, nos informa sobre la función coclear con el fin de obtener una detección temprana de alteraciones auditivas, aún las que no son permanentes, como sucede en los cambios temporales que resultan de la ototoxicidad. Además separa las lesiones colcleares de las neurológicas, o madurativas, de la vía auditiva por ser una señal preneural

Emisiones otoacústicas en productos de distorsión cocleares en chinchillas / Otoacoustic emissions of cochlear distortion products in chinchillas

Al estimular el oído con dos tonos puros simultáneos (primarios), se obtienen respuestas cocleares no sólo a los tonos primarios sino también a productos de distorsión (PDs) con frecuencia que son combinaciones de las frecuencias de los estímulos. Estos PDs han sido estudiados en experimentos psicofísicos, en registros de fibras aisladas del nervio coclear y mas recientemente en emisiones otoacústicas medidas en el meato externo. Hemos montado la técnica de medición de PDs en emisiones otoacústicas en la chinchilla usando una sonda acústica construida en nuestro laboratorio. Se presentaron simultáneamente dos tonos primarios en el conducto auditivo externo por medio de fonos miniatura ubicados en la sonda. Esta presión se amplificó, se muestreó y se analizó para obtener sus componentes espectorales. Resultados obtenidos en 8 chinchillas muestran que, para tonos primarios (Ÿ1 y Ÿ2) con frecuencias entre 2 kHz y 8 kHz, se registran PDs a frecuencias tanto menores (p.ej., 2Ÿ1-Ÿ2), como mayores (p.ej., 2Ÿ2-Ÿ1), que las de los tonos primarios. Los PDs a 2Ÿ1-Ÿ2 alcanzan niveles de hasta 24 dB bajo el nivel de los tonos primarios, mientras que los de frecuencia 2Ÿ2-Ÿ1 son de menor intensidad. Se discuten algunas aplicaciones clínicas de las emisiones de PDs en humanos