Electrococleografía en implante coclear / Electrocochleography in cochlear implant

La electrococleografía es una técnica electrofisiológica desarrollada en modelos animales hace más de 90 años. En la actualidad se utiliza en la práctica clínica en audiolo-gía y otoneurología, ya que permite evaluar la función coclear, a través del registro del potencial microfónico coclear, y la funcionalidad del nervio auditivo por medio del registro del potencial de acción compuesto. Debido al avance de la tecnología de los implantes cocleares, actualmente existe la posibilidad de realizar mediciones clínicas a tiempo real con electrococleografía intraoperatoria, por lo que se puede monitorizar la función auditiva residual durante la inserción de los electrodos del implante coclear. En este artículo se presenta una revisión narrativa del uso y aplicación clínica de la electrococleografía en la evaluación de pacientes con implante coclear para predecir el desempeño auditivo y la percepción del habla. La literatura muestra que la electroco-cleografía es una técnica que se encuentra, plenamente, vigente para evaluar la función auditiva en pacientes usuarios de implantes cocleares. Si bien las respuestas cocleares han demostrado ser un buen predictor de los umbrales perceptuales auditivos y del habla en silencio en adultos, aún es una técnica que requiere más desarrollo para ser una herramienta clínica que permita predecir el habla en ruido y la función auditiva en niños y adultos mayores.

Electrocochleography is an electrophysiological technique developed in animal models more than 90 years ago. It is currently used in clinical practice in audiology and otoneurology, since it allows the evaluation of cochlear function, through the recording of the cochlear microphonic potentials, and the functionality of the auditory nerve by means of compound action potential recordings. Due to the advancement of cochlear implant technology, there is currently the possibility of real-time clinical measurements with intraoperative electrocochleography, so that residual hearing function can be monitored during the insertion of the cochlear implant electrodes. This article presents a narrative review of the use and clinical application of electrocochleography in the evaluation of patients with cochlear implants to predict auditory performance and speech perception. The literature shows that electrocochleography is a technique that is fully in force to assess hearing function in patients who use cochlear implants. Although cochlear responses have been shown to be a good predictor of auditory perceptual thresholds and speech in quiet in adults, it is still a technique that requires further development to become a clinical tool for predicting speech in noise and auditory function in children and older adults.

Evaluation of vestibular evoked myogenic potentials (VEMP) and electrocochleography for the diagnosis of Ménière's disease / Avaliação dos potenciais evocados miogênicos vestibulares (VEMP) e eletrococleografia no diagnóstico da doença de Ménière

Abstract Introduction: Ménière's disease (MD) is an inner ear disorder characterized by episodic vertigo, tinnitus, ear fullness, and fluctuating hearing. Its diagnosis can be especially difficult in cases where vestibular symptoms are present in isolation (vestibular MD). The definitive diagnosis is made histologically and can only be performed post-mortem, after analysis of the temporal bone. Endolymphatic hydrops is a histopathological finding of the disease and occurs more often in the cochlea and saccule, followed by the utricle and semicircular canals. Vestibular evoked myogenic potentials (VEMP) emerged as the method of assessment of vestibular function in 1994. Until then, there was no unique way of assessing saccular function and the inferior vestibular nerve. Given that the saccule is responsible for most cases of severe hydrops, VEMP appears as a new tool to assist in the diagnosis of MD. Objective: To evaluate the sensitivity and specificity of VEMP and electrocochleography (EcochG) in the diagnosis of definite MD compared with clinical diagnosis. Methods: The study includes 12 patients (24 ears) diagnosed with definite MD defined according to the clinical criteria proposed by the American Academy of Otolaryngology - Head and Neck Surgery (AAO-HNS) in 1995, as well as 12 healthy volunteers allocated to the control group (24 ears). A clinical diagnosis by the AAO-HNS criteria was considered as the gold standard. All patients underwent an otoneurological examination, including pure tone and speech audiometry, VEMP, and extratympanic EcochG. The sensitivity and specificity to detect the presence or absence of disease were calculated, as well as their 95% confidence intervals. The reliability of VEMP and EcochG in both ears was assessed using the kappa index. Results: In both tests and in both ears, the ability to diagnose healthy cases was high, with specificity ranging from 84.6% to 100%. Moreover, the ability of the tests to diagnose the disease varied from low to moderate sensitivity, with values ranging from 37.5% to 63.6%. The agreement of both tests in the right ear, measured by the kappa coefficient, was equal to 0.54 (95% CI: 0.20-0.89), indicating a moderate agreement. In the left ear, that agreement was equal to 0.07 (95% CI: −0.33 to 0.46), indicating a weak correlation between the tests. The sensitivity of the VEMP for the right ear was 63.6% and for the left ear, 62.5%. The sensitivity of EcochG for the right ear was 63.6% and 37.5% for the left ear. Conclusion: The specificity of both tests was high, and the sensitivity of VEMP was higher than that of EcochG.

Resumo Introdução: A doença de Ménière (DM) é uma doença da orelha interna caracterizada por vertigem episódica, zumbido, plenitude aural e audição flutuante. Seu diagnóstico pode ser especialmente difícil nos casos em que os sintomas vestibulares estão presentes isoladamente (DM vestibular). O diagnóstico de certeza é histológico e somente pode ser feito no post mortem, após análise do osso temporal. A hidropisia endolinfática é um achado histopatológico da doença e ocorre mais frequentemente na cóclea e sáculo, seguidos pelo utrículo e canais semicirculares. Os potenciais evocados miogênicos vestibulares (VEMP) surgiram como método de avaliação da função vestibular em 1994. Até então não havia uma maneira exclusiva de avaliação da função sacular e do nervo vestibular inferior e como o sáculo era responsável por grande parte dos casos de hidropisia severa, o VEMP apareceu como uma nova ferramenta para auxiliar no diagnóstico da DM. Objetivo: Avaliar a sensibilidade e especificidade do VEMP e da eletrococleografia (ECochG) no diagnóstico da DM em comparação com o diagnóstico clínico. Método: Foram selecionados 12 pacientes (24 orelhas) com diagnóstico de DM definida de acordo com os critérios clínicos propostos pela American Academy of Otolaryngology-Head and Neck Surgery 1995 (AAO-HNS) e 12 voluntários saudáveis alocados no grupo controle (24 orelhas). Considerou-se o diagnóstico clínico pela AAO-HNS como padrão ouro. Todos os pacientes foram submetidos a exame otoneurológico, incluindo audiometria tonal e vocal, VEMP e eletrococleografia extratimpânica. A sensibilidade e especificidade para detectar a presença ou ausência de doença foram calculadas e os respectivos intervalos de confiança de 95% obtidos. A confiabilidade dos testes de diagnóstico VEMP e eletrococleografia em ambas as orelhas foi avaliada pelo índice kappa. Resultados: Em ambos os testes e em ambas as orelhas, a capacidade para diagnosticar os casos saudáveis é alta, a especificidade varia de 84,6%-100%. Além disso, a capacidade dos testes para o diagnóstico da doença varia de baixa a moderada sensibilidade, com valores de 37,5%-63,6%. A concordância dos dois testes na orelha direita, medida pelo coeficiente de kappa, foi igual a 0,54; 95% IC (0,20-0,89) indicaram uma concordância moderada. Para a orelha esquerda essa concordância foi igual a 0,07 com 95% IC (-0,33-0,46), o que indicou uma concordância fraca entre os testes. A sensibilidade do VEMP para a orelha direita foi de 63,6% e para a orelha esquerda, de 62,5%. A sensibilidade da ECochG para a orelha direita foi de 63,6% e 37,5% para a orelha esquerda. Conclusão: A especificidade de ambos os testes foi alta e a sensibilidade do VEMP foi maior do que a da eletrococleografia.

Is Electrocochleography Still Helpful in Early Diagnosis of Meniere Disease?

BACKGROUND AND OBJECTIVES: Despite the extensive research for the Meniere's disease (MD), it's pathophysiology still remains uncertain and questionable among scientists. Clinical symptoms and audiometric tests form the basis for the diagnosis. Nevertheless the differential diagnosis can be extremely challenging, due to subjective and not specific results. Incorrect diagnosis is most likely and for this reason there is a great demand for objective and reliable tests. SUBJECTS AND METHODS: The presence of endolymphatic hydrops is necessary condition but non enough for the diagnosis. In this study we analyze retrospectively the summating potentials (SP)/action protentials (AP) ratio from peritympanic electrocochleography in 34 patients,divided in two groups (13 patients classified as defined MD and 21 patients classified as probable MD). The purpose was to identify the utility of the exam so to be able to achieve an early defined diagnosis. Furthermore our intention was to obtain an objective test, besides the clinical criteria currently in use for the diagnosis and the classification of the MD. RESULTS: The analysis of the SP/AP results shows high predictability for the MD (positive in six out of seven cases with a sensitivity greater than 80%). CONCLUSIONS: Our study demonstrates a satisfactory sensibility percentage in recurrent defined MD presentation (>80%). Early identification of MD can lead to an early treatment and control of the progression of the disease. Furthermore it could be a valuable instrument for the follow up and evaluation of the patients classified as probable MD in accordance with the criteria of the American Academy of Otolaryngology-Head and Neck Surgery (1995).

Analysis of Electrocochleography: According to the Position of Summating Potential Peak / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The aim of this study was to analyze the summating potential (SP)/action potential (AP) ratio of electrocochleography (ECoG) recorded from the position of SP peak. We compared the SP/AP ratios of negative polarity and positive polarity graphs from the same ECoG of each patient by assuming different the position of SP peak. In addition, we attempted to evaluate the utility of two different manners of recording the ECoG graph in the diagnosis of Meniere's disease. SUBJECTS AND METHOD: Retrospectively, we analyzed the results of ECoG in 67 patients with unilateral definite Meniere's disease. ECoG was analyzed in two different manners. From the AP peak, the SP peak was determined close when positioned in the negative polarity; on the other hand, SP peak was considered distant when positioned in the positive polarity. The SP/AP ratio was interpreted with reference to the base line value. The ratio of two different ECoG values from each patient of Meniere's disease was calculated. RESULTS: In the abnormal side, the negative polarity ECoG showed significantly greater value of SP/AP ratio (mean: 0.334±0.10) than the positive polarity ECoG (mean: 0.283±0.09) (p<0.001). In the normal side, the negative polarity ECoG, showed significantly greater value of SP/AP ratio (mean: 0.250±0.09) than the positive polarity ECoG (mean: 0.204±0.06), as well as in the abnormal cases (p<0.001). CONCLUSION: The standard SP/AP ratio for the diagnosis of Meniere's disease can be variable according to the manner of determining the SP peak.

Ruido eléctrico de la ventana redonda / Round window electrical noise

Desde hace décadas se sabe que al colocar un electrodo cerca de la ventana redonda de la cóclea es posible registrar potenciales cocleares en respuesta a estímulos sonoros, tales como el potencial microfónico coclear o el potencial de acción compuesto del nervio auditivo. Sin embargo, hace algunos años, se ha descrito que al posicionar un electrodo en el nicho de la ventana redonda en animales de experimentación y en ausencia de estimulación acústica, se obtiene actividad eléctrica aparentemente aleatoria y no desencadenada por estímulo. Esta actividad eléctrica se ha denominado ruido eléctrico de ventana redonda (RWN, por su sigla en inglés Round Window Noise) y representaría la descarga espontánea de fibras del nervio auditivo. La técnica para su registro es similar a la utilizada en la electrococleografía para obtener potenciales cocleares en humanos. Esta señal se distingue del ruido eléctrico no biológico por tener un peak en su poder espectral centrado en torno a los 900 Hz. La amplitud de esta banda de frecuencia se correlaciona con la sensibilidad auditiva en la región basal de la cóclea, entre los 12 a 30 kHz en cobayos y gatos. El RWN se ha estudiado a través de estimulación acústica y bloqueo farmacológico, logrando caracterizar sus propiedades electrofisiológicas para desarrollar modelos de estudio con aplicación clínica.

For decades, it has been known that placing an electrode near the round window niche allows the recording of cochlear potentials in response to auditory stimuli, such as the cochlear microphonic potential and the compound action potential of the auditory nerve. However, some years ago, it was discovered, that by positioning an electrode in the round window niche of experimental animals, and in the absence of acoustic stimulation, apparently random electrical activity is obtained. This electrical activity is called round window electrical noise (RWN) and represents the spontaneous discharge of auditory nerve fibers. The recording technique is similar to that used in electrocochleography in humans. This bioelectrical signal is distinguished from that of non-biological electrical noise, as it has a power spectral peak centered around 900 Hz. The magnitude of this frequency peak is correlated with hearing sensitivity in the basal region of the cochlea, between 12 to 30 kHz in guinea pigs and cats. The RWN has been characterized using sound stimulation or pharmacologic suppression, and its electrophysiological properties could be used to develop models of auditory nerve function with possible clinical application.

The Correlation Analysis of Endolymphatic Hydrops Degree in Vestibule and the Symptoms and Audiovestibular Functions in Patients with Meniere’s Disease / 听力学及言语疾病杂志

Objective To evaluate the correlation between the endolymphatic hydrops in vestibule and symp‐toms ,audiovestibular functions in patients with Meniere's disease .Methods Twenty -four hours after bilateral intra-tympanic 8 times diluted gadolinium administration , three - dimensional fluid - attenuated inversion recovery MRI ,using a three-Tesla unit ,was performed in 34 patients .The extent of endolymphatic hydrops in the MRI images was assessed and compared the hydrops with age ,duration ,stage of the disease ,frequency of attacks ,pure tone audiometry ,caloric test ,electrocochleography and vestibular evoked myogenic potentials .Results Thirty -four patients showed different levels of enhancement of perilymth in the inner ears .In these patients ,obvious signs of endolymphatic hydrops were visualized ,including 8 slight hydrops ,11 mild hydrops and 15 significant hydrops . In all 34 patients ,the results of PTA were 9 dB HL to 90 dB HL ,with average of 43 .56 dB HL and there were 21 abnormal and 13 normal patients in caloric test with a diagnostic rate 61 .76% ;17 normal ,7 abnormal and 10 not elicited patients in VEMP with a diagnostic rate 50% ;22 abnormal and 12 normal patients in electrocochleography with a diagnostic rate 64 .71% .There were almost no complications in all 34 patients after bilateral intra-tympanic injec‐tion except short vertigo among 5 of them .A statistically significant correlation was found between degrees of en‐dolymphatic hydrops in vestibule and age ,stage of the disease and VEMP (P 0 .05) and the correlation coefficient were 0 .494 ,0 .568 ,0 .590 , 0 .495 ,respectively .Conclusion The degree of endolymphatic hydrops in Ménière's disease has significant correlation with age ,VEMP ,stage of the disease and pure tone audiometry .No significant correlation was found between hy‐drops and duration ,frequency of attacks ,functional level scale ,caloric test and electrocochleography .

Clinical Usefulness of Vestibular Evoked Myogenic Potential in Unilateral Meniere's Disease / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Because the saccule, next to the cochlea, is the second most frequent site of hydrops formation, we evaluated whether vestibular evoked myogenic potential (VEMP) responses can reflect the diagnosis and the stage of Meniere's disease. SUBJECTS AND METHOD: Retrospectively, we analyzed the results of VEMP in 40 patients (11 men and 29 women) with unilateral definite Meniere's disease. All subjects underwent VEMP testing using ipsilateral 500 Hz-tone burst sound with 90 dBnHL (rise/fall time=2 msec, plateau time=3 msec). RESULTS: VEMP was present in 92.5% of Meniere's affected ear (37/40). The latency of p13 of affected ears in patients with Meniere's disease was significantly prolonged than that of normal ears in the control group (p=0.05). However, no relationship was found in latencies of p13, n23, and interpeak latency among groups classified by the stage of Meniere's disease. In the patients with Meniere's disease, the mean interaural amplitude difference (IAD) ratio was 23.9+/-16.9%. The IAD ratio of patients with Meniere's disease was larger than that of the control group, but it is statistically insignificant (p=0.133). CONCLUSION: Prolonged p13 latency of VEMP was a pathognomic finding for Meniere's disease in this study.

Role of Vestibular Evoked Myogenic Potentials to Elevate the Sensitivity of Objective Tests in Early Meniere's Disease

BACKGROUND AND OBJECTIVES: Diagnosis of Meniere's disease (MD) is based on detailed medical history and audiometry in addition to electrocochleography (ECoG). However, the sensitivity of ECoG is rather low and the diagnosis seems to be rather obscure if the patient is evaluated after resolution of acute symptom, especially in early stage of disease without substantial hearing loss. In such cases, if a patient complains recurrent episodes within short term period, any objective result would be beneficial to initiate medical treatment such as diuretics. Since the saccule is the main target organ in MD, authors suppose vestibular evoked myogenic potential (VEMP) test combined with ECoG may elevate the diagnostic sensitivity in MD. Aim of study is to evaluate the possibility of this suggestion. MATERIALS AND METHOD: Thirty-four patients of unilateral MD who have hearing loss less than 40 dB and onset of first attack within 1 year were included in this study. They underwent VEMP, caloric test and ECoG. Abnormal rates of each test and results of combination were analyzed according to the group of MD. RESULTS: Patients with abnormal results in VEMP, ECoG and calorict tests were 29%, 15% and 35%, respectively. Patients showed abnormal results either in VEMP or ECoG were 41% in all MD and 72% in definite group. CONCLUSIONS: To get higher objective evidence of cochleovestibulopahty in early MD, interpretation of VEMP result in addition to ECoG and caloric test seems to be beneficial.

Clinical Significance of the Extratympanic Electrocochleography / 대한이비인후과학회지

Electrocochleography(ECoG) is used to evaluate the cochlear function in patients with Meniere's disease. Endolymphatic hydrops is widely accepted as the underlying pathological finding in Meniere's disease and may cause the elevation of the ratio of summating potential amplitude to action potential amplitude. So, SP/AP amplitude ratio has been suggested as a diagnostic indicator for Meniere's disease. A variety of electrode locations have been employed to record the precise cochlear potentials better. In this study, we peformed extratympanic ECoG with an electrode(TIP trode(R)) that was placed in contact with the ear canal wall in normal subjects and Meniere's patients. The SP/AP amplitude ratio and the SP amplitude measured in the ears of patients with bilateral Meniere's disease and in the involved ear of patients with unilateral Meniere's disease were significantly larger than in the ears of normal subjects. In the contralateral ear of patients with unilateral Meniere's disease, the SP/AP amplitude ratio was significantly larger than in the ears of normal subjects; however, it was below the level for the diagnostic criteria of endolymphatic hydrops in Meniere's disease. This study suggests that ECoG can be a useful tool for the diagnosis of Meniere's disease and the early detection of incipient Meniere's disease in the contralateral ear of a patient with unilateral Meniere's disease.