[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.

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.

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.

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.

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.

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.

Evaluation of an automated auditory brainstem response in a multi-stage infant hearing screening.

An automated auditory brainstem response (AABR) method, the Maico MB-11 with BERAphone, has been developed for hearing screening in newborns. The aim of this study was to test the validity of this automated ABR screening method in a multistage newborn hearing screening (NHS). We applied a "five level" protocol using transient evoked otoacoustic emission (TEOAE), AABR-MB-11 with BERAphone and conventional auditory brainstem response (ABR). TEOAE, AABR, and conventional ABR testing were performed by ENT specialists experienced in neonatal screening techniques. Among the 8,671 newborns tested (males 3,889; females 4,782), only 42 newborns were lost to follow-up and the final false-positive rate was of 0.03%. Our experience highlights that for the neonatal period, conventional auditory brainstem response is the most reliable method for assessing the hearing level and minimizing the false-positive rate. Although AABR (performed by ENT specialists experienced in neonatal screening techniques) is easy to use, fast and with a good compliance, the device is unable to provide accurate and certain diagnosis on the degree of hearing loss to allow a proper treatment.

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.

Electrocochleography: a review of recording approaches, clinical applications, and new findings in adults and children.

Research related to expanding and improving the clinical use of electrocochleography (ECochG) has been ongoing for 25 yr at the University of Kansas Medical Center. This article presents highlights of findings from our laboratory during this period that have contributed to current ECochG recording approaches and clinical applications. A review of new data related to improving the sensitivity of ECochG in the diagnosis of Ménière's disease, the use of an ear canal recording approach for improving auditory brain stem response testing in newborns, and technical aspects related to recording the cochlear microphonic in newborns also will be presented.

Clinical significance of the summating potential-action potential ratio and the action potential latency difference for condensation and rarefaction clicks in Meniere's disease.

OBJECTIVES: This study was aimed to elucidate the diagnostic significance of the summating potential (SP)-action potential (AP) ratio and the AP latency difference between condensation and rarefaction clicks (AP con-rar difference) in Meniere's disease. METHODS: The AP and SP were recorded transtympanically in 67 patients with definite Meniere's disease. The SP/AP ratio and the AP con-rar difference were assessed in terms of 1) their interrelationship, 2) their relationship to hearing level, and 3) the rate of occurrence of abnormal values according to the stages of Meniere's disease. RESULTS: No correlation was found between the SP/AP ratio and the AP con-rar difference. Neither the SP/AP ratio in general nor the AP con-rar difference was correlated with the hearing level. However, enhanced values of the SP/AP ratio (0.35 or higher) were moderately correlated with the hearing level (r = 0.51), and their occurrence rate was 55.2%. An increased AP con-rar difference (0.13 ms or longer) was not correlated with the hearing level, and its occurrence rate was 50.2%; it appeared most frequently at stage 3 (p <0.05). CONCLUSIONS: An enhanced SP/AP ratio might not always indicate the presence of endolymphatic hydrops associated with an increase in endolymphatic pressure. An increased AP con-rar difference might reflect the presence of a biased basilar membrane resulting from an increased endolymphatic pressure, and hence it is diagnostically essential to simultaneously evaluate the SP/AP ratio and the AP con-rar difference.

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.

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.

Recording of electrically evoked auditory brainstem responses (E-ABR) with an integrated stimulus generator in Matlab.

Electrical auditory brainstem responses (E-ABRs) of subjects with cochlear implants are used for monitoring the physiologic responses of early signal processing of the auditory system. Additionally, E-ABR measurements allow the diagnosis of retro-cochlear diseases. Therefore, E-ABR should be available in every cochlear implant center as a diagnostic tool. In this paper, we introduce a low-cost setup designed to perform an E-ABR as well as a conventional ABR for research purposes. The distributable form was developed with Matlab and the Matlab Compiler (The Mathworks Inc.). For the ABR, only a PC with a soundcard, conventional system headphones, and an EEG pre-amplifier are necessary; for E-ABR, in addition, an interface to the cochlea implant is required. For our purposes, we implemented an interface for the Combi 40+/Pulsar implant (MED-EL, Innsbruck).

A flexible research platform for multi-channel auditory steady-state response measurements.

The possibilities of currently commercially available auditory steady-state response (ASSR) devices are mostly limited to avoid unintentional misuse and to guarantuee patient safety as such. Some setups, e.g. do not allow the application of high intensities or the use of own stimuli. Moreover, most devices generally only allow data collection using maximal two EEG channels. The freedom to modify and extend the accompagnying software and hardware is very restricted or inexistent. As a result, these devices are not suited for research and several clinically diagnostic purposes. In this paper, a research platform for multi-channel ASSR measurements is presented, referred to as SOMA (setup ORL for multi-channel ASSR). The setup allows multi-channel measurements and the use of own stimuli. It can be easily extended to facilitate new measurement protocols and real-time signal processing. The mobile setup is based on an inexpensive multi-channel RME soundcard and software is written in C++. Both hardware and software of the setup are described. An evaluation study with nine normal-hearing subjects shows no significant performance differences between a reference and the proposed platform. SOMA presents a flexible and modularly extensible mobile high-end multi-channel ASSR test platform.

ABR recordings in newborns using an ear canal electrode.

The objective of this study was to improve the sensitivity of ABR recordings in newborns via a procedure that utilizes the ear canal as a recording site. Conventional recordings were compared to ear canal recordings of the ABR in 45 normally-hearing newborns who passed their newborn hearing screening. Responses were obtained at stimulus levels of 80, 60, 40, and 20 dBnHL using forehead (+) to ear canal (-), versus forehead (+) to mastoid (-) electrode configurations. ABR parameters evaluated included measurement of component amplitudes of wave I and V, absolute latencies of I and V, the I-V interwave interval, and amplitude ratio. At stimulus levels of 80, 60, and 40 dBnHL, wave I amplitude was significantly larger using the ear canal configuration. This investigation shows that the amplitude of wave I is significantly larger and easier to identify when the ear canal is used as one of the recording sites in comparison to more conventional scalp (mastoid) recordings.

Cochlear microphonic potential recorded by transtympanic electrocochleography in normally-hearing and hearing-impaired ears.

The cochlear microphonic is a receptor potential believed to be generated primarily by outer hair cells. Its detection in surface recordings has been considered a distinctive sign of outer hair cell integrity in patients with auditory neuropathy. This report focuses on the results of an analysis performed on cochlear microphonic recorded by transtympanic electrocochleography in response to clicks in 502 subjects with normal hearing threshold or various degrees of hearing impairment, and in 20 patients with auditory neuropathy. Cochlear microphonics recorded in normally-hearing and hearing-impaired ears showed amplitudes decreasing by the elevation of compound action potential Cochlear microphonic responses were clearly detected in ears with profound hearing loss. After separating recordings according to the presence or absence of central nervous system pathology (CNS+ and CNS-, respectively), cochlear microphonic amplitude was significantly higher in CNS+ than in CNS- subjects with normally-hearing ears and at 70 dB nHL compound action potential threshold. Cochlear microphonic responses were detected in all auditory neuropathy patients, with similar amplitudes and thresholds to those calculated for normally-hearing CNS- subjects. Cochlear microphonic duration was significantly higher in auditory neuropathy and normally-hearing CNS+ patients compared to CNS- subjects. Our results show that: 1. cochlear microphonic detection is not a distinctive feature of auditory neuropathy; 2. CNS+ subjects showed enhancement in cochlear microphonic amplitude and duration, possibly due to efferent system dysfunction; 3. long-lasting, high frequency cochlear microphonics with amplitudes comparable to those obtained from CNS- ears were found in auditory neuropathy patients. This could result from a variable combination of afferent compartment lesion, efferent system dysfacilitation and loss of outer hair cells.

Surgical monitoring with auditory evoked potentials.

This comprehensive review of surgical monitoring with auditory evoked potentials (AEPs) includes a detailed discussion of techniques used for recording brainstem auditory evoked potentials, direct eight-nerve potentials, and electrocochleograms. The normal waveform of these different potentials is discussed, and the typical patterns of abnormalities seen with different insults to the peripheral or central auditory pathways are presented. The mechanisms most probably responsible for changes in AEPs during surgical procedures are analyzed. A critical analysis is made of what represents a significant change in AEPs. Also considered is the predictive value of intrasurgical changes of AEPs. Finally, attempts are made to determine whether AEPs monitoring can assist the surgeon in the prevention of postsurgical complications.

Intrasubject test-retest variability in clinical electrocochleography.

Seventeen healthy volunteers without a history of auditory or vestibular difficulty and with normal screening audiometry had bilateral (34 ears) electrocochleography performed repeatedly at 1-week intervals. Each subject had from four to seven electrocochleograms performed on each ear. Measurements were made in the external auditory canal using a gold-foil "TIPtrode." Amplitude and latency for the summating potential (SP) and action potential (AP) were measured and SP/AP ratios were calculated. Averages and standard deviations for amplitude, latency, and SP/AP ratios were computed. The average SP/AP ratio was 0.22 with a standard deviation of 0.06. The range was 0.04 to 0.50. The average difference between the highest and lowest SP/AP ratio for a given individual was 0.155 (i.e., the range 0.03 to 0.31) with a standard deviation of 0.07. These normative data are useful in assessing the results of dehydration electrocochleography and in establishing how much test-retest variation is required to suggest pathology.

Noninvasive electrodes for electrocochleography in the chinchilla.

This study compares noninvasive vs invasive electrodes for electrocochleography in chinchillas. Summating potential (SP) amplitude, action potential (AP) amplitude, and AP threshold, recorded with five types of noninvasive electrodes, were compared with simultaneous bulla recordings. Noninvasive electrodes included a needle electrode over the bulla, gold Tiptrode (Etymotic Research, Elk Grove Village, Ill), Enhancer I (Nicolet Instrument Corp, Madison, Wis), Coats (Lifetech Inc, Austin, Tex) electrode, and a locally constructed tympanic membrane (TM) electrode. Stimuli included 100-microsecond clicks and 6000-Hz tone bursts (with a 1 millisecond rise/fall time and a 5 millisecond plateau). Stimuli were initially presented at 110 dB peak equivalent sound pressure level for the clicks and 100 dB peak equivalent sound pressure level for the tone bursts. Intensity was then decreased in 10-dB decrements until no replicable AP activity was observed. The TM damping for the TM electrode was measured with 0.5, 1, 2, 4, and 6 kHz and click stimuli. The AP was clear and replicable for all electrodes used in the study, although the amplitude was substantially less for the noninvasive electrodes as opposed to the invasive electrode. The invasive electrode provided the largest amplitude SP recording, but SP could generally be clearly recorded with the needle electrode, Enhancer I, and the Coats electrode. The TM electrode and gold Tiptrode provided SP recordings less consistently. The AP threshold could be recorded with all the electrodes in the study and was generally within 10 dB of threshold recorded invasively. Electrode variables, including ease of electrode placement and potential injury, were examined. The Tiptrode and Enhancer I electrodes posed relatively few problems during placement.(ABSTRACT TRUNCATED AT 250 WORDS)