Hearing Preservation After Cochlear Reimplantation Using Electrocochleography: A Case Report.

Studies have shown that hearing preservation is possible in the context of reimplantation, but residual hearing could not be predicted or expected in these cases. We describe a case in which a patient with mild to profound sensorineural hearing loss who underwent cochlear implantation with a lateral wall array and had hearing preserved postoperatively. She developed facial nerve stimulation which was unresponsive to reprogramming. Using electrocochleography to measure intracochlear trauma during the insertion process, the patient underwent reimplantation with a perimodiolar electrode and hearing was preserved postoperatively. This case demonstrates the potential to use electrocochleography for hearing preservation during reimplantation. Laryngoscope, 131:2348-2351, 2021.

Búsqueda de criterios de normalidad de potenciales evocados auditivos de tronco cerebral y potenciales evocados auditivos de estado estable con estímulo en campo libre / Search for normality criteria of auditory brain responses and auditory steady state response with free-field stimulation

Objetivo: Conocer los umbrales de normalidad de las pruebas de ABR y ASSR en campo libre comparadas con los auriculares de inserción. Métodos: Estudio observacional descriptivo de una serie de casos de niños sin hipoacusia en el periodo de tiempo entre abril de 2016 y enero de 2017, a los que se realiza ABR y ASSR convencionales utilizando auriculares de inserción y mediante campo libre. Resultados: Fueron valorados 54 oídos con criterios absolutos de normalidad. La edad media fue de 16,7 meses (DE = 5,7) con un rango de edad comprendido entre los 6 y los 24 meses. La evocación del potencial de acción a 70 dBs en campo libre mostró una media de onda I de 3,47ms (DE = 0,59 ms), onda II de 4,01 (DE = 0,31), onda III de 5,97 (DE = 0,61), onda IV de 6,71 (DE=0,67) y onda V de 8,22 (DE = 0,51). Se encuentra una diferencia estadísticamente significativa (p < 0,05) en el valor otenido con auriculares de inserción o en campo libre en la onda I (diferencia media 1,91), en la onda III (1,88), en la onda IV (1,69) y en la onda V (1,95), siendo mayores en campo libre. No se encuentran diferencias estadísticamente significativas en las interlatencias. Las respuestas en el ASSR mediante campo libre presentaron un incremento de 1,56 min en comparación a los auriculares de inserción. Conclusiones: Los umbrales obtenidos en ABR mediante campo libre son superponibles a los realizados con auriculares de inserción, únicamente se diferencian en el aumento de las latencias, manteniendo las interlatencias, ocasionado por el retraso de estimulación del oído debido a la distancia entre la fuente sonora y el tímpano. Ambas pruebas son realizables mediante campo libre lo que permitiría aplicarlas de manera rutinaria y a pacientes donde no se les pueden realizar las convencionales

Objective: To discover the thresholds of normality of the tests of ABR and ASSR in free-field stimulation compared with headphones. Methods: Descriptive study of a series of cases of children without hearing loss carried out between April 2016 and January 2017. The ABR and conventional ASR were performed using insert headphones and free-field stimulation. Results: Fifty-four ears were evaluated with absolute criteria of normality. The mean age was 16.7 months (SD = 5.7). The evocation of the action potential at 70 dBs in the free-field showed a mean on wave I of 3.47ms, on wave II of 4.01, on wave III of 5.97, on wave IV of 6.71 and on wave V of 8.22. There is a statistically significant difference (p<.05) between the value obtained with insert earphones and the free-field on wave I (mean difference 1.91), on wave III (1.88), on wave IV (1.69) and on wave V (1.95), their being higher in stimulus in free field. There were no statistically significant differences in the interlatencies. The responses in the ASSR with free-field showed an increase of 1.56 minutes compared to the headphones. Conclusions: The thresholds obtained in ABR by free-field were differentiated from those obtained by headphones in the increase of latencies, caused by delayed stimulation of the ear due to the distance between the sound source and the eardrum. Both tests are feasible by free-field stimulation, which would allow them to be applied routinely to patients on whom conventional tests cannot be performed

The Clinical Benefit of Device Therapy for Meniere's Disease in Adults: Systematic Review and Meta-Analysis.

OBJECTIVES: This study aimed to assess the clinical benefit of device therapy on controlling the symptoms of Meniere's disease (MD). MATERIALS AND METHODS: We searched PubMed, Embase, the Cochrane Library, China National Knowledge Internet, and Wanfang Data before January 13, 2018. We selected randomized controlled clinical trials, case-controlled studies, and cohort studies that dealt with outcomes of device therapy for the treatment of MD. RESULTS: Sixteen trials met our inclusion criteria. The use of device therapy resulted in improved vertigo control, which was described as a reduction in the number of vertigo days by month (weighted mean difference [WMD]: 3.15, 95% confidence interval [CI]: 2.00-4.31), in the number of vertigo episodes by month (WMD: 7.37, 95% CI: 2.40-12.35), and in the vertigo visual analog score (WMD: 41.51, 95% CI: 34.68-48.34). In addition, the overall complete vertigo control (class A) rate was 50% (95% CI: 37%-64%). The device therapy also reduced the number of sick days by month (WMD: 4.56, 95% CI: 2.15-6.97), and the functional level improved (WMD: 2.66, 95% CI: 2.15-3.17). The electrocochleographic parameters decreased. The device therapy proved beneficial for hearing changes (WMD: 3.19, 95% CI: 0.66-5.71). No publication bias was found in the funnel plot and the results of Egger's test. CONCLUSION: This study showed that the device therapy might reduce vertigo attacks and sick days in patients with MD. Additionally, the function level and hearing level may improve after the device therapy. In addition, the decrease in electrocochleographic parameters showed that inner ear electrophysiology improved after device therapy.

Search for normality criteria of auditory brain responses and auditory steady state response with free-field stimulation. / Búsqueda de criterios de normalidad de potenciales evocados auditivos de tronco cerebral y potenciales evocados auditivos de estado estable con estímulo en campo libre.

OBJECTIVE: To discover the thresholds of normality of the tests of ABR and ASSR in free-field stimulation compared with headphones. METHODS: Descriptive study of a series of cases of children without hearing loss carried out between April 2016 and January 2017. The ABR and conventional ASR were performed using insert headphones and free-field stimulation. RESULTS: Fifty-four ears were evaluated with absolute criteria of normality. The mean age was 16.7 months (SD=5.7). The evocation of the action potential at 70 dBs in the free-field showed a mean on wave I of 3.47ms, on wave II of 4.01, on wave III of 5.97, on wave IV of 6.71 and on wave V of 8.22. There is a statistically significant difference (p<.05) between the value obtained with insert earphones and the free-field on wave I (mean difference 1.91), on wave III (1.88), on wave IV (1.69) and on wave V (1.95), their being higher in stimulus in free field. There were no statistically significant differences in the interlatencies. The responses in the ASSR with free-field showed an increase of 1.56minutes compared to the headphones. CONCLUSIONS: The thresholds obtained in ABR by free-field were differentiated from those obtained by headphones in the increase of latencies, caused by delayed stimulation of the ear due to the distance between the sound source and the eardrum. Both tests are feasible by free-field stimulation, which would allow them to be applied routinely to patients on whom conventional tests cannot be performed.

Electrococleografía extratimpánica en una población normal. Estudio descriptivo / Extra-tympanic electrocochleography in a normal population. A descriptive study

Introducción y objetivos: La electrococleografía extratimpánica es un registro elecrofisiológico que refleja la actividad eléctrica acontecida en la cóclea tras un estímulo sonoro. Se obtiene mediante la aplicación del estímulo en el conducto auditivo externo y el registro de la actividad eléctrica mediante electrodos de superficie. Dada la escasa literatura existente acerca de la exploración electrococleográfica normal en nuestro medio, este estudio busca regularizar los valores obtenidos mediante esta exploración en sujetos sin enfermedad otoneurológica y explicar detalladamente el proceso mediante el cual se obtiene el registro. Métodos: Exploración mediante electrococleografía extratimpánica de 60 oídos sin enfermedad otoneurológica y análisis estadístico de los resultados obtenidos. De ellos, 30 oídos fueron explorados a 90dB mientras que otros 30 oídos fueron estimulados a 80dB. Resultados: Se muestran los valores medios de amplitud y latencia del potencial de sumación y del potencial de acción, así como las latencias medias de la onda I y la onda II. Asimismo, se presenta el cálculo del cociente potencial de sumación/potencial de acción. Obtenidos estos resultados se comparan en función de la intensidad del estímulo, del sexo del paciente, del oído estudiado y del grupo etario. Conclusiones: Este estudio recopila datos sobre la electrococleografía en una población normal. Los valores obtenidos están en el rango de los valores normales de otros países, expuestos en la literatura internacional. Estos datos pueden ser muy útiles como referencia a la hora de valorar exploraciones en pacientes con dolencias que afectan la estructura o la función coclear (AU)

Introduction and objectives: Extra-tympanic electrocochleography is an electrophysiological register obtained after stimulating the cochlea with an audible stimulus. This stimulus is applied using an earphone over the external auditory canal, while the electrical activity is registered by surface electrodes. There are few studies that analyse normal electrocochleography in our environment. Thus, the main objective of our study was to regularize the values obtained with electrocochleography in ears without any otoneurological diseases. We explain in detail the process of obtaining the register. Methods: Sixty healthy ears were studied by extratympanic electrocochleography. Statistical results were analysed. While 30 ears were studied with a stimulus at 90dB, another 30 ears were studied with a stimulus at 80dB. Results: Summating potential and action potential latencies and amplitudes were measured. Summating potential/action potential ratios were calculated. Wave I and wave II latencies were also determined. These results were analysed in function of stimulus intensity, patient gender, patient age group and ear side studied. Conclusions: This study collected extra-tympanic electrocochleography data in a normal population and the results were in the range of other international studies obtained in other countries. These data can be used as a reference to evaluate illnesses that affect cochlear structure or functions (AU)

[Electrocochleography using Transtympanic, Ear Drum and Ear Canal Electrode in Diagnosis of Morbus Menière]. / Elektrokochleografie mit Trommelfell-, Gehörgangs- und transtympanaler Elektrode bei V.a. Morbus Menière.

OBJECTIVE: Aim of this study was to explore the clinical value of non-invasive recordings of electrocochleography in comparison to the use of invasive electrodes for the diagnosis of endolymphatic hydrops in patients with suspicious Morbus Menière. MATERIAL AND METHODS: 15 patients with clinical suspicion of Morbus Menière underwent electrocochleography with transtympanic needle-electrode as well as tympanic membrane electrode. 10 patients received electrocochleography with transtympanic needle-electrode and ear canal electrode. A control group of 12 healthy adults was evaluated using tympanic membrane electrode. The negative electrode was placed on the ipsilateral mastoid, the ground electrode in the middle of the forehead. For stimulation broadband click stimulus as well as long tone bursts of 1, 2 and 4 kHz were applied. In addition the impedance of the electrode was registered. RESULTS: While transtympanic electrocochleography gave reliable results in 100% of these cases, extratympanic recordings often manifested poor wave morphology. The electrocochleographic measures following stimulation with 1 and 2 kHz long tone bursts were the best measures to identify endolymphatic hydrops. This was the case with transtympanic as well as with tympanic membrane electrodes. There was no correlation between impedance and wave morphology. CONCLUSIONS: For the evaluation of Morbus Menière non-invasive electrocochleography showed good results using a tympanic canal electrode with 1 and 2 kHz tone bursts. Yet in unclear cases transtympanic electrocochleography should be preferred.

A flexible and inexpensive high-performance auditory evoked response recording system appropriate for research purposes.

Recording auditory evoked responses (AER) is done not only in hospitals and clinics worldwide to detect hearing impairments and estimate hearing thresholds, but also in research centers to understand and model the mechanisms involved in the process of hearing. This paper describes a high-performance, flexible, and inexpensive AER recording system. A full description of the hardware and software modules that compose the AER recording system is provided. The performance of this system was evaluated by conducting five experiments with both real and artificially synthesized auditory brainstem response and middle latency response signals at different intensity levels and stimulation rates. The results indicate that the flexibility of the described system is appropriate to record AER signals under several recording conditions. The AER recording system described in this article is a flexible and inexpensive high-performance AER recording system. This recording system also incorporates a platform through which users are allowed to implement advanced signal processing methods. Moreover, its manufacturing cost is significantly lower than that of other commercially available alternatives. These advantages may prove useful in many research applications in audiology.

Superiority of tympanic ball electrodes over mastoid needle electrodes for intraoperative monitoring of hearing function.

OBJECT: Recording the auditory brainstem response (ABR) is a common method for monitoring the integrity of auditory pathways during surgery in the cerebellopontine angle. Electrocochleography (ECochG) is an alternative means of intraoperative neuromonitoring. In the present study the authors compared the practicability and prognostic significance of these two methods by performing simultaneous recordings in the operating room. METHODS: Between 2006 and 2011, 125 patients (mean age 55 years) underwent surgery in the cerebellopontine angle. Seventy-one percent of the patients presented with a hearing deficit, and 37% had useful hearing but with slight functional impairment. Auditory brainstem response was recorded with a subdermal needle electrode at the mastoid. For ECochG recording, a noninvasive ball electrode was attached to the tympanic membrane. Amplitudes obtained from both ECochG and ABR audiometry were compared and correlated to pre- and postoperative hearing deficits. RESULTS: Simultaneous intraoperative monitoring via ABR and ECochG was possible in 114 cases (91%). Postoperatively, 42% of patients showed some degree of new hearing deficit, whereas 4% had improvement. The mean amplitudes in ECochG monitoring were significantly higher (0.18 ± 0.04 µV) than the ABR potentials (0.08 ± 0.006 µV; p < 0.05). All waves recorded at the mastoid needle electrode could be recognized in the potentials of the tympanic ball electrode. Hearing outcome correlated more reliably with the relative amplitude changes in Waves III and V in ECochG (III: p = 0.0008, V: p = 0.0015) than in ABR monitoring (III: p = 0.2075, V: p = 0.0398). CONCLUSIONS: Intraoperative monitoring of the auditory system by recording with noninvasive tympanic ball electrodes is more practicable than with subcutaneous needle electrodes at the tragus. Since there is also a reliable correlation between ECochG and clinical outcome, the method can replace common ABR recording during surgery in the cerebellopontine angle.

Development of an ultra low noise, miniature signal conditioning device for vestibular evoked response recordings.

BACKGROUND: Inner ear evoked potentials are small amplitude (<1 µVpk) signals that require a low noise signal acquisition protocol for successful extraction; an existing such technique is Electrocochleography (ECOG). A novel variant of ECOG called Electrovestibulography (EVestG) is currently investigated by our group, which captures vestibular responses to a whole body tilt. The objective is to design and implement a bio-signal amplifier optimized for ECOG and EVestG, which will be superior in noise performance compared to low noise, general purpose devices available commercially. METHOD: A high gain configuration is required (>85 dB) for such small signal recordings; thus, background power line interference (PLI) can have adverse effects. Active electrode shielding and driven-right-leg circuitry optimized for EVestG/ECOG recordings were investigated for PLI suppression. A parallel pre-amplifier design approach was investigated to realize low voltage, and current noise figures for the bio-signal amplifier. RESULTS: In comparison to the currently used device, PLI is significantly suppressed by the designed prototype (by >20 dB in specific test scenarios), and the prototype amplifier generated noise was measured to be 4.8 nV/Hz @ 1 kHz (0.45 µVRMS with bandwidth 10 Hz-10 kHz), which is lower than the currently used device generated noise of 7.8 nV/Hz @ 1 kHz (0.76 µVRMS). A low noise (<1 nV/Hz) radio frequency interference filter was realized to minimize noise contribution from the pre-amplifier, while maintaining the required bandwidth in high impedance measurements. Validation of the prototype device was conducted for actual ECOG recordings on humans that showed an increase (p < 0.05) of ~5 dB in Signal-to-Noise ratio (SNR), and for EVestG recordings using a synthetic ear model that showed a ~4% improvement (p < 0.01) over the currently used amplifier. CONCLUSION: This paper presents the design and evaluation of an ultra-low noise and miniaturized bio-signal amplifier tailored for EVestG and ECOG. The increase in SNR for the implemented amplifier will reduce variability associated with bio-features extracted from such recordings; hence sensitivity and specificity measures associated with disease classification are expected to increase. Furthermore, immunity to PLI has enabled EVestG and ECOG recordings to be carried out in a non-shielded clinical environment.

A low cost setup for behavioral audiometry in rodents.

In auditory animal research it is crucial to have precise information about basic hearing parameters of the animal subjects that are involved in the experiments. Such parameters may be physiological response characteristics of the auditory pathway, e.g. via brainstem audiometry (BERA). But these methods allow only indirect and uncertain extrapolations about the auditory percept that corresponds to these physiological parameters. To assess the perceptual level of hearing, behavioral methods have to be used. A potential problem with the use of behavioral methods for the description of perception in animal models is the fact that most of these methods involve some kind of learning paradigm before the subjects can be behaviorally tested, e.g. animals may have to learn to press a lever in response to a sound. As these learning paradigms change perception itself (1,2) they consequently will influence any result about perception obtained with these methods and therefore have to be interpreted with caution. Exceptions are paradigms that make use of reflex responses, because here no learning paradigms have to be carried out prior to perceptual testing. One such reflex response is the acoustic startle response (ASR) that can highly reproducibly be elicited with unexpected loud sounds in naïve animals. This ASR in turn can be influenced by preceding sounds depending on the perceptibility of this preceding stimulus: Sounds well above hearing threshold will completely inhibit the amplitude of the ASR; sounds close to threshold will only slightly inhibit the ASR. This phenomenon is called pre-pulse inhibition (PPI) (3,4), and the amount of PPI on the ASR gradually depends on the perceptibility of the pre-pulse. PPI of the ASR is therefore well suited to determine behavioral audiograms in naïve, non-trained animals, to determine hearing impairments or even to detect possible subjective tinnitus percepts in these animals. In this paper we demonstrate the use of this method in a rodent model (cf. also ref. (5)), the Mongolian gerbil (Meriones unguiculatus), which is a well know model species for startle response research within the normal human hearing range (e.g. (6)).

Validation of a new TEOAE-AABR device for newborn hearing screening.

OBJECTIVE: Because newborn hearing screening (NHS) programs are currently implemented in an increasing number of countries, physiological NHS technologies have to be continuously optimized. This study validates a new TEOAE-AABR screening device. DESIGN: TEOAE and AABR screenings were performed in 299 ears with both the new NHS device and a well-established and validated one. Furthermore, 49 ears, suspected of having a hearing loss, underwent the screenings and an additional diagnostic ABR. STUDY SAMPLE: One hundred and fifty newborns and infants were included in the study (median age 1.0 months, range 0-54 months; among them 39 babies from neonatal intensive care units). RESULTS: Screening with both devices resulted in a concordance of κ =.98 for TEAOE measurements and .96 for AABR measurements. The mean measurement durations were significantly shorter for the new device than for the established one for both TEOAE (15.4 vs. 17.2 s) and AABR (26.6 vs. 32.7 s). CONCLUSIONS: The algorithm of the new screening device is as valid as that for the established one. The shorter test durations with the new device facilitate hearing screenings and allow for a higher number of valid measurements in restless children than with former comparable procedures.

Hearing threshold prediction with Auditory Steady State Responses and estimation of correction functions to compensate for differences with behavioral data, in adult subjects. Part 1: Audera and CHARTR EP devices.

BACKGROUND: The objective of the study was the evaluation and comparison of hearing threshold values extrapolated from Auditory Steady State Responses, using 2 commercial systems and the estimation of correction factors applicable to the ASSR data. MATERIAL/METHODS: One hundred ten subjects participated to the study. All subjects were initially examined with otoscopy, pure-tone audiometry and admittance. Data were acquired by 2 clinical systems the Audera (Viasys) and the CHARTR EP (ICS), using identical protocols. The acoustic stimuli consisted of single carrier frequencies at 1000, 2000 and 4000 Hz modulated at 40 Hz. RESULTS: The data show that the threshold estimates from both devices differ significantly from the measured behavioral thresholds. The ICS device presented significantly larger mean-ASSR estimated hearing level values at the tested frequencies, implying an underestimation of the hearing threshold. Both sets of prediction errors overestimated hearing levels for the normal group. The prediction errors were in all cases greater for the Audera than for the ICS. CONCLUSIONS: The errors encountered in the estimates of the 2 widely-used commercial devices suggest that the current ASSR protocols are not ready for a wide-range use and that significant developments in the area of threshold prediction/precision are necessary. If, on the other-hand, the ASSR predicted threshold is used on a purely consulting basis, as in hearing-aid fitting, then such errors might be acceptable in a clinical setting.

ABR-based newborn hearing screening with MB11 BERAphone® using an optimized chirp for acoustical stimulation.

OBJECTIVE: At our center, the Maico MB11 BERAphone(®) device is used for newborn hearing screening based on Auditory Brainstem Responses (ABR). In 2006, an optimized chirp stimulus was implemented in the device to increase the reliability and quality of the screening method. In 2002, an automated response detection algorithm had been implemented. This study analyzes the screening results using the MB11 BERAphone(®) device with the implemented chirp stimulus and automated response detection method. METHODS: The data presented were collected in the well-baby nursery as part of the newborn hearing screening program following a two stage screening protocol. To focus the study on the typical routine screening, data from at-risk babies were not included. Overall, data from 6866 babies (3604 males and 3262 females) screened from March 2006 to April 2011 were analyzed in this study. RESULTS: Out of the 6866 babies screened, 6607 passed bilaterally prior to hospital discharge (defined as 1st stage in this hearing screening program). Therefore, the pre-discharge pass rate of the hearing screening with the MB11 BERAphone(®) device was 96.2%. The resulting referral rate was 3.8%. The median test time per ear (excluding time for preparation and data reporting) was 28s with a range of 15-112s (5-95th percentile). The number of infants referred for 2nd stage, post-discharge re-screening was 259. Of this group, 71 passed bilaterally and 188 failed the re-screening in one or both ears. Therefore, including both the pre-discharge and post-discharge screening results, the bilateral pass rate was 97.3% and 2.7% were referred for diagnostic evaluation. Diagnostic testing was performed on all of the 188 infants who were referred. Results showed that 47 of these babies had hearing loss. This equates to a positive predictive value for a refer result of 25%. The observed prevalence of hearing impairment in our population was 0.684%. Diagnostic results for 141 of the referred newborns proved that they had normal hearing. That is, 141 out of 6866 newborns had a false-positive result with the MB11 BERAphone(®) screening. Therefore, the device had a specificity of 97.9%. During the time period of this study, no baby who passed the hearing screening was later found to have hearing impairment, suggesting a sensitivity of 100%. However, due to the limited number of newborns and the short time period after screening for the more recently screened babies, a reliable estimate of the sensitivity cannot be yet made from our program statistics. The theoretical sensitivity of the MB 11 device is 99.9%. CONCLUSIONS: The Maico MB11 BERAphone(®) is a reliable device for auditory brainstem response newborn hearing screening and it provides results within a very short time. Due to the implemented method for automatic detection of ABR, the use of the device does not require an experienced examiner, allowing it to be used by trained technicians in locations outside the department of audiology such as the well-baby nursery.

Cross-phaseogram: objective neural index of speech sound differentiation.

We introduce a new approach, the cross-phaseogram, that captures the brain's ability to discriminate between spectrotemporally dynamic speech sounds, such as stop consonants. The goal was to develop an analysis technique for auditory brainstem responses (ABRs) that taps into the sub-millisecond temporal precision of the response but does not rely on subjective identification of individual response peaks. Using the cross-phaseogram technique, we show that time-varying frequency differences in speech stimuli manifest as phase differences in ABRs. By applying this automated and objective technique to a large dataset, we found these phase differences to be less pronounced in children who perform below average on a standardized test of listening to speech in noise. We discuss the theoretical and practical implications of our results, and the extension of the cross-phaseogram method to a wider range of stimuli and populations.

Electrical compound action potentials recorded with automated neural response telemetry: threshold changes as a function of time and electrode position.

OBJECTIVE: Since the introduction of neural response telemetry (NRT) for the Nucleus 24 cochlear implant (CI24), researchers and clinicians have investigated the feasibility of using the electrically evoked compound action potential (ECAP) threshold to objectively predict psychophysical measurements that are used in the programming of the speech processor. The ability to substitute objective for behavioral measurements, particularly measurements made at the time of surgery, would greatly facilitate programming the MAP for young children and other individuals who are not able to provide reliable behavioral data required for MAP programming. There have been a number of studies that have examined characteristics of the ECAP measured at the time of surgery and postoperatively; however, all the available published data are based on the CI24. With the introduction of the Nucleus Freedom device, an automated NRT (AutoNRT) program became available, which was capable of measuring ECAP thresholds at lower levels than was previously possible with NRT software associated with the CI24 device. It was hypothesized that the enhancements to the NRT program may improve the predictability of postoperative measurements from intraoperatively recorded ECAP thresholds. The purpose of this study was to track ECAP thresholds obtained using AutoNRT as a function of time and electrode position. DESIGN: ECAP thresholds were recorded from 71 children and adults implanted with the Nucleus Freedom device using the AutoNRT test protocol. ECAP thresholds were obtained at the time of surgery, at initial stimulation, and 3 mos poststimulation. Five electrodes located at basal, middle, and apical positions in the cochlea were tested at each time interval and thresholds were compared. RESULTS: Significant differences were found in ECAP thresholds measured with AutoNRT as a function of both time and electrode position. Basal electrodes had higher ECAP thresholds than apical electrodes and that relationship was consistent for each time period. Thresholds for all electrodes decreased between surgery and initial stimulation and remained relatively stable at 3 mos poststimulation. ECAP thresholds were consistently lower for children compared with adults at each time point. Mid-array electrodes (11 and 16) showed the least amount of change over time. CONCLUSIONS: AutoNRT thresholds demonstrated significant change over time, limiting the ability to use intraoperatively recorded ECAP thresholds to predict postoperative measurements. In this study, electrodes 11 and 16 showed the least amount of change in ECAP threshold over time and therefore would be the best choices for estimating postoperative ECAP thresholds. Although not an ideal solution, mid-array ECAP thresholds obtained intraoperatively may prove to be helpful in creating a first MAP when no other behavioral or electrophysiological data are available.

Click- and chirp-evoked human compound action potentials.

In the experiments reported here, the amplitude and the latency of human compound action potentials (CAPs) evoked from a chirp stimulus are compared to those evoked from a traditional click stimulus. The chirp stimulus was created with a frequency sweep to compensate for basilar membrane traveling wave delay using the O-Chirp equations from Fobel and Dau [(2004). J. Acoust. Soc. Am. 116, 2213-2222] derived from otoacoustic emission data. Human cochlear traveling wave delay estimates were obtained from derived compound band action potentials provided by Eggermont [(1979). J. Acoust. Soc. Am. 65, 463-470]. CAPs were recorded from an electrode placed on the tympanic membrane (TM), and the acoustic signals were monitored with a probe tube microphone attached to the TM electrode. Results showed that the amplitude and latency of chirp-evoked N1 of the CAP differed from click-evoked CAPs in several regards. For the chirp-evoked CAP, the N1 amplitude was significantly larger than the click-evoked N1s. The latency-intensity function was significantly shallower for chirp-evoked CAPs as compared to click-evoked CAPs. This suggests that auditory nerve fibers respond with more unison to a chirp stimulus than to a click stimulus.

Using concha electrodes to measure cochlear microphonic waveforms and auditory brainstem responses.

During electrocochleography, that is, ECochG or ECoG, a recording electrode can be placed in the ear canal lateral to the tympanic membrane. We designed a concha electrode to record both sinusoidal waveforms of cochlear microphonics (CMs) and auditory brainstem responses (ABRs). The amplitudes of CM waveforms and Wave I or compound action potentials (CAPs) recorded at the concha were greater than those recorded at the mastoid but slightly lower than those recorded at the ear canal. Wave V amplitudes recorded at the concha were greater than those recorded at the ear canal but lower than those recorded at the mastoid. There was not a significant difference between the amplitudes recorded at the concha and at the ear canal. For CM and Wave I or CAP, the latency recorded at the concha was longer than at the canal but shorter than at the mastoid; for Wave V, the reverse was true. However, these differences were not statistically significant and may be due to the distance to response generators. Aside from the advantages that the regular ECoG has over otoacoustic emission (OAE) testing, the concha electrode was also easier and safer to place and may be suitable for children, newborn screening, participants with canal conditions, and remote clinics which could have concerns with the availability and cost of a canal electrode. Using concha electrodes, we also experienced fewer postauricular artifacts than when using a mastoid electrode.

Padronização do potencial evocado auditivo de tronco encefálico utilizando um novo equipamento / Standardization of brainstem auditory evoked potential using a new device

TEMA: padronização do Potencial Evocado Auditivo de Tronco Encefálico (PEATE) utilizando um novo equipamento. OBJETIVO: padronizar as respostas do PEATE utilizando de um novo equipamento desenvolvido (NED) no Brasil. MÉTODOS: análise das latências absolutas, interpicos e das amplitudes das ondas do PEATE, por meio de um novo equipamento desenvolvido para estudar grupos de ouvintes normais (91 adultos) e outro com perda neurossensorial (15 adultos) com perda auditiva neurossensorial bilateral entre o equipamento EP15 / Interacoustis e o NED. Utilizando o clique não filtrado, com duração de 100 microssegundo (µs), totalizando 2.000 estímulos, na polaridade rarefeita, frequência de estimulação de 13,1 cliques/s, intensidade de 80 decibels de nível de audição normalizado (dB NAn), com janela de 10 milissegundos e filtro passa-banda entre 100 e 3000 Hertz (Hz). Nível de significância de 0,05. RESULTADOS: as médias das latências absolutas e interpicos em 76 ouvintes normais no NED foram: onda I=1,50, III=3,57, V=5,53, I-III=2,06, III-V=1,96 e I-V=4,02. Ao separar por gênero houve diferença estatisticamente significante para as latências absolutas das ondas III e V e nos interpicos I-III e I-V. Valor médio da amplitude da onda I=0,384 microvolt (μV) e da onda V=0,825 μV. Não existiu diferença estatisticamente significante ao comparar as latências absolutas e interpicos entre dois equipamentos no mesmo indivíduo. CONCLUSÃO: os componentes do PEATE com o NED em ouvintes normais foram similares quanto às orelhas, com latências menores estatisticamente significantes nas mulheres. As latências do PEATE no mesmo indivíduo com o NED foram semelhantes às obtidas com o EP15 / Interacoustis. Foram obtidos os valores de normalidade para o PEATE em adultos ouvintes normais.

BACKGROUND: standardization of Brainstem Auditory Evoked Potential (BAEP) using a new device. AIM: to standardize BAEP responses using a new device developed (NDD) in Brazil. METHOD: analysis of absolute latencies, interpeaks and wave amplitudes of BAEP, using a new device developed to study normal-hearing groups (91 adults) and individuals (15 adults) with bilateral neurosensory hearing loss. Responses obtained in the EP15 hearing device/Interacoustics and the NDD were compared. For this, the following paramenters were used: non-filtered click of 100 microsecond (µs), totaling 2000 stimuli in rarefied polarity, stimulation frequency of 13.1 clicks/s, intensity of 80 decibels normalized hearing level (dB nHL), with a window of 10 milliseconds and bandpass filter between 100 and 3000 Hertz (Hz). Significance level was set at 0.05. RESULTS: absolute latency and interpeak means for 76 normal-hearing individuals with the NDD were: wave I=1.50, III=3.57, V=5.53, I-III=2.06, III-V=1.96 and I-V=4.02. When analyzing results according to gender, there was a statistically significant difference for the absolute latencies of waves III and V and in interpeaks I-III and I-V. Mean amplitude value of wave I=0.384 microvolt (µV) and of wave V=0.825 µV. There was no statistically significant difference between the absolute latencies and interpeaks of the two devices in the same individual. CONCLUSION: the components of BAEP with the NDD in normal-hearing subjects were similar regarding the tested ears, with statistically lower latencies in women. The BAEP latencies in the same individual with NDD were similar to those obtained with the EP15 / Interacoustics. Normal values of BAEP were obtained in normal-hearing adults.

MB11 BERAphone) hearing screening compared to ALGOportable in a Dutch NICU: a pilot study.

OBJECTIVE: Since 2001 all Dutch Neonatal Intensive Care Units use a highly reliable automated auditory brainstem response (AABR) newborn hearing screening device, the (ALGOportable). A more recent AABR newborn hearing screening device, the MB11 BERAphone, does not make use of disposable ear couplers and has a different algorithm, a possible advantage with regard to a faster response acquisition. Use of the MB11 BERAphone is therefore potentially more cost effective and faster. This study compares test results and suitability of the MB11 BERAphone to the ALGOportable as reference AABR hearing screening test for newborns during neonatal intensive care admission. METHODS: In 54 NICU graduates [median GA 31 2/7 weeks, median BW 1760 g] 55 (110 ears) hearing screening test results and total test time were examined with both the MB11 BERAphone and ALGOportable. Test time was measured from the start of the procedure, including child preparation, until a bilateral result (pass/refer) was obtained. RESULTS: The median postconceptional age of testing was 34 3/7 weeks (range 30-41 6/7). In 3 ears MB11 BERAphone screening failed due to continuous myogenic activity. In 104/107 ears final results were congruent [87/107 (81%) pass; 17/107 (16%) refer] leaving an incongruity in 3 ears of 2 infants: MB11 BERAphone "refer" and ALGOportable "pass". Diagnostic investigative audiology confirmed a 35dB unilateral conductive hearing loss in 1 child. At 15 months of age speech and language development in the other child was normal. When using the ALGO portable as reference test, the sensitivity of the MB11 BERAphone is 100% (17/17), specificity 97% (87/90). The mean MB11 BERAphone test time was slightly, but not significantly, shorter 11.4 min (SD 6.6) than with the ALGOportable 13.9 (p<0.08). CONCLUSION: The MB11 BERAphone is a reliable and feasible hearing screening device for use with NICU graduates under NICU circumstances. It is potentially more cost effective than the ALGOportable.