Postoperative complications in cochlear implant surgery and their possible risk factors.

OBJECTIVE: This is a retrospective analysis of the major and minor complications of cochlear implants, as well as the Risk Factors (RF) involved. METHODS: We analyzed the medical records of patients submitted to cochlear implants at public University from 2006 to July 2019, and list here the major and minor complications found, and their risk factors. RESULTS: There were 193 ears, 100 (51.3%) from females and 93 (48.2%) from males, with a mean age of 23.63 years. In 54 of them (28%), there were alterations seen in the Temporal Bone CT scan, and 44 (22.8%) in the brain MRI. There were 158 (81.9%) insertions performed; 127 (65.8%) of them through the round window. There were 78 complications: 19 (9.8%) major and 56 (29%) minor complications. Among the major complications, there were 3 (1.6%) Surgical Site infections (SS); 5 (2.6%) hematomas/seromas; 5 (2.6%) electrode extrusion; 5 (2.6%) device faults; 1 (0.5%) wrong path. Among the minor complications, there were 6 (3.1%) Acute Otitis Media (AOM); 9 (4.7%) SS infections; 4 (2.1%) facial paresis; 17 (8.8%) vertigos; 9 (4.7%) with tinnitus. The most important RF was age. Patients younger than 2.5 years had more major complications: SS infection (p = 0.018) and electrode extrusion (p = 0.017). There was a higher rate of vertigo in adults (p = 0.003), and it was more often associated with comorbidities (p = 0.008). The insertion route, the presence of changes in CT and MRI and the CI brand used did not impact the number of complications. CONCLUSION: Among the minor complications, those involving the vestibular system were the most common, especially in adults with comorbidities. Regarding major complications, there was an emphasis on SS infections, hematomas, seromas, electrode extrusion, especially in children under two years of age. There were implanted device faults (2.6%), with none of the brands evaluated standing out.

Cochlear implantation in an animal model documents cochlear damage at the tip of the implant.

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.

Use of scanning electron microscopy in the cochlea of guinea pigs.

INTRODUCTION: The use of electron microscopy in the study of the inner ear has allowed us to observe minute details of the hair cells, especially in ototoxicity studies; however, the preparation of this material is a difficult and delicate task. In an attempt to simplify the handling of these materials, two agents, toluidine blue and ethylenediamine tetra-acetic acid were tested, in addition to the elimination of osmium tetroxide during the preparation of albino guinea pig cochleae. We also tested the applicability of these methodologies in an ototoxicity protocol. OBJECTIVE: To verify the quality of the images obtained with and without the use of ethylenediamine tetra-acetic acid, toluidine blue and osmium tetroxide in the preparation of cochleae of albino guinea pigs for the scanning electron microscopy. METHODS: Three groups of cochleae were used. In Group 1, 10 cochleae were prepared with the usual methodology, dissecting the optical capsule without decalcification and using osmium tetroxide as a post-fixative agent. In Group 2, we prepared 10 cochleae decalcified with ethylenediamine tetra-acetic acid, injecting toluidine blue in the endolymphatic space to facilitate the identification of the organ of Corti. In Group 3, we used 4 cochleae of guinea pigs that received 3 doses of cisplatin (7.5mg/kg, D1-D5-D6), two prepared according to the methodology used in Group 1 and two with that used in Group 2. Scanning electron microscopy images were obtained from the organ of Corti region of the basal turn of each cochlea. RESULTS: The organ of Corti was more easily identified with the use of toluidine blue. The dissection of the cochlea was more accurate in the decalcified cochleae. The quality of the images and the preservation of the organ of Corti obtained with the two methodologies were similar. CONCLUSION: The proposed modifications resulted in images of similar quality as those observed using the traditional methodology.

Study of distortion-product otoacoustic emissions during hypothermia in humans.

AIM: To evaluate the function of cochlear outer hair-cells under the influence of extra-corporeal circulation and moderate hypothermia during cardiac surgery. STUDY DESIGN: Prospective clinical study. METHODS: Distortion-product otoacoustic emissions (DPOAE) were registered before surgery, immediately after general anesthesia induction, during extra-corporeal circulation with moderate hypothermia and after the surgical procedure. RESULTS: Comparison of response-amplitudes before and after surgery and before and after general anesthesia initiation did not demonstrate statistical difference. Comparison of amplitudes before and after extra-corporeal circulation with moderate hypothermia demonstrated a statistically significant decrease in responses amplitudes during hypothermia. CONCLUSIONS: The amplitudes of DPOAE decreased during moderate hypothermia induced during extra-corporeal circulation.

Anatomical study of a temporal bone from a non-human primate (Callithrix sp).

UNLABELLED: The search for experimental (animal) models is essential to the development of clinical studies. AIM: To demonstrate, by means of micro dissection techniques, the anatomical structures of temporal bones from the primate Callithrix sp. STUDY DESIGN: Experimental. METHODS: Dissection of temporal bone structures of Callithrix sp and photographic documentation. RESULTS: We identified the main constituents of the temporal bone (external, medium and inner ear and facial nerve). CONCLUSION: The non-human primate Callithrix sp. is an adequate experimental model for the studies of temporal bone structures given its close anatomical similarities to that found in humans.

Influence of cyclic AMP on facial nerve regeneration in rats.

UNLABELLED: Promoting facial nerve regeneration is a significant challenge. AIM: To evaluate the possible neurotrophic influence of cyclic AMP on facial nerve regeneration of Wistar rats. METHOD: The right facial nerve of thirty-two animals were completely transected and immediately sutured, followed by exposure or not to topical cyclic AMP. Behavioral and histometric analyses were done at 14 and 28 days. RESULTS: Statistical differences (p<0.05) were found in the behavioral and histometric analyses on the 14th day, suggesting an early regenerative response of the facial nerve to cAMP exposure. CONCLUSION: This study demonstrates a possible neurotrophic effect of cAMP on facial nerve regeneration in rats.

Sigmoid sinus thrombosis associated to chronic otitis media.

UNLABELLED: Otogenous lateral sinus thrombosis (OLST) is a rare disease and presents a controversial treatment. AIM: Clinical aspects and treatment were reported based on our experience. METHODS: Retrospective study. Six cases of OLST were treated in our institution in the last ten years. Clinical and imaging data were analyzed. RESULTS: All six patients had the lateral sinus thrombosis detected during image evaluation for other symptoms related to chronic otitis media (COM) complications. Fever, headache and facial paralysis were the main clinical manifestation related to mastoiditis, meningitis and cerebellar abscess. We could not identify, in any case, specific features of lateral sinus thrombosis. In all cases a mastoidectomy was associated with large spectrum antibiotics maintained for 3 months. In three cases anticoagulation therapy was introduced and in three cases anticoagulation was not indicated. All cases presented a good clinical evolution, without sequelae. CONCLUSIONS: OLST is almost always associated with other complications of COM. It is diagnosed almost by accident during the investigative image study. We believe such disease is underestimated. In our experience, OLST presents a benign course, and mastoidectomy with antibiotics is the treatment of choice.

Cochlear implantation in an animal model documents cochlear damage at the tip of the implant / Implante coclear em um modelo animal documenta o dano coclear na extremidade do implante

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.

Behavioral and histologic experimental model of facial nerve regeneration in rats.

UNLABELLED: To setup an experimental model is the first step to study neural regeneration. AIM: Setting up an experimental model on facial nerve regeneration. MATERIAL AND METHODS: Wistar rats with complete sectioning and suturing of the extratemporal facial nerve trunk; with a behavioral and histological analysis for 9 weeks. STUDY DESIGN: Experimental prospective study. RESULTS: Progressive clinical and histological recovery of the animals. CONCLUSION: Our method is acceptable to study facial nerve regeneration in rats.

Transcanal endoscopic myringoplasty: a case series in a university center.

INTRODUCTION: Transcanal myringoplasty has the advantages of demanding lower operative time and minimal external incisions. It can be performed using the microscopic or endoscopic approach. In the last decade, the use of endoscopes in ear surgery has increased significantly. This technique may allow "around the corner" visualization of small recesses, through narrow spaces, without the aid of canalplasty in unfavorable ear canals. OBJECTIVE: To describe a case series of transcanal endoscopic myringoplasty performed in a university service. The characteristics, advantages, and disadvantages of this technique are also discussed. METHODS: A case series study, based on the chart review of patients submitted to transcanal endoscopic myringoplasty in the period from January of 2012 to October of 2014. RESULTS: Data from 22 patients were analyzed. Tympanic perforation closure three months after surgery was observed in 86.4% of all patients. There was statistically significant improvement in pure tone average thresholds after surgery (p<0.001). CONCLUSION: Transcanal endoscopic myringoplasty is a feasible, safe, and effective procedure; it can be an alternative to microscopic surgery.

Clinical, etiological and progression factors of hearing in sudden deafness.

UNLABELLED: Out of the many forms of therapy for sudden deafness, some require hospitalization and present significant risks. AIM: This prospective study analyzes etiology and evolution in cases of sudden deafness (SD) where outpatient oral treatment was used. STUDY DESIGN: Clinical with transversal cohort. MATERIAL AND METHOD: Forty cases of sudden hearing loss were followed for at least one year. All were submitted to initial clinical evaluation, auditory tests, routine blood analysis, and magnetic resonance imaging. All received initial treatment with pentoxifylline and prednisone. RESULTS: 45% (n=18) presented normal auditory thresholds, 40% (n=16) showed some improvement in hearing, 15% (n=6) maintained initial hearing level. Nine cases (22.5%) presented clinical conditions possibly implicated in hearing loss (viral infection, immunomediated hearing loss, vascular disorders, and so on); three (7.5%) had cerebellopontine tumors. Evolution of hearing in these 12 cases with presumed etiology presented no differences from hearing in the 28 cases without any known etiological factor. Clinical treatment within the first seven days was the only statistically significantly different condition in patients who improved hearing. CONCLUSIONS: An objective search for etiological bases should be conducted in any case of acute sensorineural hearing loss. The presence of cerebellopontine tumors in 7.5% of cases of SD, among other treated causes, justifies a thorough clinical investigation in these patients. Overall good evolution of hearing was observed in 67.5% of cases of SD, regardless of its etiology. Therapy within the first seven days of SD was significantly related to better outcomes in hearing.

Use of scanning electron microscopy in the cochlea of guinea pigs / Microscopia eletrônica de varredura em cócleas de cobaias

Abstract Introduction: The use of electron microscopy in the study of the inner ear has allowed us to observe minute details of the hair cells, especially in ototoxicity studies; however, the preparation of this material is a difficult and delicate task. In an attempt to simplify the handling of these materials, two agents, toluidine blue and ethylenediamine tetra-acetic acid were tested, in addition to the elimination of osmium tetroxide during the preparation of albino guinea pig cochleae. We also tested the applicability of these methodologies in an ototoxicity protocol. Objective: To verify the quality of the images obtained with and without the use of ethylenediamine tetra-acetic acid, toluidine blue and osmium tetroxide in the preparation of cochleae of albino guinea pigs for the scanning electron microscopy. Methods: Three groups of cochleae were used. In Group 1, 10 cochleae were prepared with the usual methodology, dissecting the optical capsule without decalcification and using osmium tetroxide as a post-fixative agent. In Group 2, we prepared 10 cochleae decalcified with ethylenediamine tetra-acetic acid, injecting toluidine blue in the endolymphatic space to facilitate the identification of the organ of Corti. In Group 3, we used 4 cochleae of guinea pigs that received 3 doses of cisplatin (7.5 mg/kg, D1-D5-D6), two prepared according to the methodology used in Group 1 and two with that used in Group 2. Scanning electron microscopy images were obtained from the organ of Corti region of the basal turn of each cochlea. Results: The organ of Corti was more easily identified with the use of toluidine blue. The dissection of the cochlea was more accurate in the decalcified cochleae. The quality of the images and the preservation of the organ of Corti obtained with the two methodologies were similar. Conclusion: The proposed modifications resulted in images of similar quality as those observed using the traditional methodology.

Resumo Introdução: O emprego da microscopia eletrônica no estudo da orelha interna permitiu observar detalhes minuciosos das células ciliadas especialmente em estudos de ototoxicidade. Entretanto, o preparo desse material é trabalhoso e delicado. Para simplificar a manipulação desses materiais, testou-se o uso de dois agentes, azul de toluidina e ácido etilenodiamino tetra-acético, além da retirada do tetróxido de ósmio na preparação de cócleas de cobaias albinas. Testamos também a aplicabilidade dessas metodologias em um protocolo de ototoxicidade. Objetivo: Verificar a qualidade das imagens obtidas com e sem o uso de ácido etilenodiamino tetra-acético, azul de toluidina e tetróxido de ósmio na preparação de cócleas de cobaias albinas para a microscopia eletrônica de varredura. Método: Foram utilizados três grupos de cócleas. No Grupo 1 preparou-se 10 cócleas com a metodologia usual, dissecando a cápsula ótica sem descalcificac¸ão e utilizando tetróxido de ósmio como pós-fixador. No Grupo 2 preparamos 10 cócleas descalcificadas com ácido etilenodiamino tetra-acético, injetando azul de toluidina no espac¸o endolinfático para facilitar a identificação do órgão de Corti. No Grupo 3 utilizamos 4 cócleas de cobaias que receberam 3 doses de cisplatina (7,5 mg/kg, D1-D5-D6), duas preparadas com a metodologia do Grupo 1 e duas com a do Grupo 2. Foram obtidas imagens da microscopia eletrônica de varredura da região do órgão de Corti do giro basal de cada cóclea. Resultados: O órgão de Corti foi mais facilmente identificado com o azul de touidina. A dissecção da cóclea foi mais precisa nas cócleas descalcificadas A qualidade das imagens e a preservac¸ão do órgão de Corti obtidas com as duas metodologias foi similar. Conclusão: As modificações propostas resultaram em imagens de qualidade similar as observadas com o uso da metodologia tradicional.

Autopercepção do benefício auditivo e o reconhecimento de fala em usuários de implante coclear / Auditory benefit self-assessment and speech recognition in cochlear implant users

RESUMO Objetivo Correlacionar o desempenho de usuários de implante coclear unilateral em testes de reconhecimento de fala, no silêncio e no ruído, com as respostas ao questionário de autoavaliação Hearing Implant Sound Quality Index (HISQUI19) e correlacionar o desempenho em testes de reconhecimento de fala com o tempo de uso do dispositivo e a orelha implantada. Métodos Participaram 27 usuários de implante coclear unilateral com deficiência auditiva pós-lingual, que faziam uso do dispositivo há, pelo menos, um ano e apresentavam limiar tonal em campo livre menor que 40 dBA. Todos os participantes foram submetidos à audiometria tonal em campo livre, responderam ao questionário HISQUI19 e realizaram testes de reconhecimento de fala no silêncio e no ruído. Resultados As respostas ao questionário foram comparadas com os testes de reconhecimento de fala no silêncio e no ruído e não houve diferença estatisticamente significativa. Na comparação em relação ao tempo de uso do implante coclear, só houve diferença estatisticamente significativa para o teste de reconhecimento de fala no silêncio. Não houve correlação significativa entre o reconhecimento de fala e a orelha implantada. Conclusão independentemente do tempo de uso do dispositivo e/ou do desempenho nos testes de reconhecimento de fala, muitos participantes classificaram a qualidade sonora do implante coclear como moderada. A aplicação de testes que possibilitem mensurar a satisfação e o benefício dos usuários deve fazer parte da rotina clínica dos centros de implante.

ABSTRACT Purpose To correlate the performance of unilateral cochlear implant users in speech recognition tests, in quiet and noise, with the answers to the Hearing Implant Sound Quality Index (HISQUI19) self-assessment questionnaire; also, to correlate the performance in speech recognition tests with the time of CI use and the implanted ear. Methods A total of 27 unilateral CI users with postlingual hearing loss, who had been using the device for at least one year and had free-field pure-tone threshold lower than 40 dBA, participated in the study. All the participants were submitted to free-field pure-tone audiometry, answered the HISQUI19 questionnaire, and took speech recognition tests in quiet and noise. Results The answers to the questionnaire were compared with the speech recognition tests in quiet and noise; there was no statistically significant difference. When comparing with the time of CI use, there was a statistically significant difference only for the speech recognition test in quiet. There was no significant correlation between speech recognition and the implanted ear. Conclusion Regardless of the time of CI use and/or performance in the speech recognition tests, many participants classified the sound quality of their cochlear implant as moderate. Administering tests to measure the users' level of satisfaction and benefit should integrate the clinical routine in implantation centers.

Expression of aquaporin 2 following facial nerve crush in rats.

CONCLUSION: We demonstrated an early increase in aquaporin 2 (AQP2) expression in a motor nerve (extratemporal facial nerve, FN) following acute peripheral compression (crush), concomitant to effective development of motor dysfunction (facial palsy). The early increase in AQP2 expression that occurred concomitantly with the appearance of a deficit in a peripheral motor nerve suggests that this protein is involved in the physiological events associated with post-injury edema, similar to the already demonstrated behavior of AQP4 in the central nervous system (CNS). OBJECTIVE: The aim of this study was to assess the expression of AQP2 in the FN of rats up to 7 days after crush. METHODS: The extratemporal trunk of the right FN of rats was subjected to mechanical crush, and the expression of AQP2 in the affected (right) and non-affected (left) FN was measured by means of western blotting at days 1, 3, and 7 after injury. Behavioral analysis of the development of facial palsy was also performed over the same time period. RESULTS: Increased expression of AQP2 was shown in the affected FN compared with its corresponding control at day 1 after compression, simultaneously with the appearance of facial palsy.

Carotid-artery cochlear dehiscence

Changes in course of the internal carotid artery (ICA) are uncommon, and dehiscence of the carotid canal with cochlea may occur. A 48-year-old female individual with pulsatile tinnitus. No other otologic symptoms observed. Otolaryngologic examination and audiometric test with normal results. Computed tomography (CT) scan of the mastoid bones showed dehiscence of cochlea with ICA on the right side. An option for monitored observation was made after analysis of the risks and undefined results of surgery. Patient maintained clinical and audiometric profile. Carotid-artery cochlear dehiscence is a condition that must be known, remembered and investigated, because it may mimic other otologic pathologies. Knowledge about it prevents serious complications that can be difficult to reverse.

Micro-endoscopic ear anatomy of guinea pig applied to experimental surgery.

PURPOSE: To describe topographic and endoscopic anatomy of guinea pig ear for development of surgical approaches in experimental studies. METHODS: Experimental study. Eight adult guinea pigs (Cavia porcellus) were used in this study. Four animals were described through endoscopic view and four animals were used to describe topographic anatomy. RESULTS: The main structures of middle ear were well identified through endoscopy view: oval and round window, ossicles and vascular structures. Temporal bone position, landmarks and its relations to skull are perceived with topographic description. CONCLUSION: Topographic anatomic description allowed exposition of temporal bone relations for external surgical approaches. Alternatively, grooves and middle ear structures were identified and may be used to transcanal accesses.

Nitric oxide levels in cochlear fluids of guinea pig.

PURPOSE: To describe a technique to obtain guinea pigs cochlear fluids and measure nitric oxide (NO) concentration. METHODS: Six guinea pigs were used and sacrificed. The cochlear fluids collected for measurement of NO, performed by chemiluminescence (NOA 280). RESULTS: Through the chemiluminescence was possible to analyze the concentration of NO in cochlear fluids obtained. Average levels of nitric oxide from guinea pigs was 12.55 µM. CONCLUSION: It is possible to obtain nitric oxide cochlear fluids, with this technique and nitric oxide concentration measure by chemiluminescence, a quantitative and more precise method.