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Individual low-frequency hearing preservation results as related to audiogram thresholds shifts for 1-month post-activation are shown here for all subjects.
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Objectives
Electrocochleography (ECochG) recordings during cochlear implantation have shown promise in estimating the impact on residual hearing. The purpose of the study was (1) to determine whether a 250-Hz stimulus is superior to 500-Hz in detecting residual hearing decrement and if so; (2) to evaluate whether crossing the 500-Hz tonotopic, char...
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Introduction
Intracochlear electrocochleography (ECochG) is increasingly being used to measure residual inner ear function in cochlear implant (CI) recipients. ECochG signals reflect the state of the inner ear and can be measured during implantation and post-operatively. The aim of our study was to apply an objective deep learning (DL)-based algori...
Purpose of Review
To summarize the literature on scalar translocation of cochlear implant (CI) electrode arrays (EAs), including diagnosis, prevention, and clinical implications of such.
Recent Findings
Rates of translocation vary by EA design, with lateral wall (straight) EAs having rates ranging from 5 to 22% and pre-curved (perimodiolar) having...
Background: Various representations exist in the literature to visualize electrocochleography (ECochG) recordings along the basilar membrane (BM). This lack of generalization complicates comparisons within and between cochlear implant (CI) users, as well as between publications. This study synthesized the visual representations available in the lit...
In recent years, tools for early detection of irreversible trauma to the basilar membrane during hearing preservation cochlear implant (CI) surgery were established in several clinics. A link with the degree of postoperative hearing preservation in patients was investigated, but patient populations were usually small. Therefore, this study's aim wa...
Citations
... The responses can be measured at both extracochlear and intracochlear sites, whereby the latter is now achievable through direct recordings with the CI's electrode array. ECochG recordings in cochlear implants have demonstrated potential relevance in monitoring cochlear function during and after insertion of the CI electrode [7][8][9][10][11][12][13][14][15][16][17][18][19], detecting intracochlear trauma [20][21][22][23], optimizing the electrode's placement [24,25], estimating hearing thresholds [26][27][28][29], investigating different etiologies of hearing loss [30][31][32][33], and predicting postoperative preservation of hearing [12,[34][35][36][37][38][39][40][41][42] and CI speech perception outcomes [43][44][45][46][47][48][49][50]. ...
... Instead, they showed the growth functions of the amplitude of ECochG, ECochG responses recorded from a single location before and after insertion, or ECochG thresholds for different stimuli, amongst others. The remaining 74 studies [9][10][11][12][13]15,[17][18][19][20][21]24,25,34,35,37,[39][40][41][42]48, were included for review and are described in detail in Table S1 in the Supplementary Materials (https://github.com/OtoBM). The included articles contained 60 (81.1%) human studies, 11 (14.9%) ...
Background: Various representations exist in the literature to visualize electrocochleography (ECochG) recordings along the basilar membrane (BM). This lack of generalization complicates comparisons within and between cochlear implant (CI) users, as well as between publications. This study synthesized the visual representations available in the literature via a systematic review and provides a novel approach to visualize ECochG data in CI users. Methods: A systematic review was conducted within PubMed and EMBASE to evaluate studies investigating ECochG and CI. Figures that visualized ECochG responses were selected and analyzed. A novel visualization of individual ECochG data, the ZH-ECochG Bode plot (ZH = Zurich), was devised, and the recordings from three CI recipients were used to demonstrate and assess the new framework. Results: Within the database search, 74 articles with a total of 115 figures met the inclusion criteria. Analysis revealed various types of representations using different axes; their advantages were incorporated into the novel visualization framework. The ZH-ECochG Bode plot visualizes the amplitude and phase of the ECochG recordings along the different tonotopic regions and angular insertion depths of the recording sites. The graph includes the pre- and postoperative audiograms to enable a comparison of ECochG responses with the audiometric profile, and allows different measurements to be shown in the same graph. Conclusions: The ZH-ECochG Bode plot provides a generalized visual representation of ECochG data, using well-defined axes. This will facilitate the investigation of the complex ECochG potentials generated along the BM and allows for better comparisons of ECochG recordings within and among CI users and publications. The scripts used to construct the ZH-ECochG Bode plot are provided by the authors.
... Furthermore, they could result from contact between the electrode array and the basilar membrane instead of cochlear trauma (Kiefer et al., 2006), although impingement of the basilar membrane can also cause postoperative hearing loss. The advancement of the recording electrode beyond the site of response generation along the basilar membrane may additionally result in amplitude decreases (Walia et al., 2022). Amplitude variations in the summated responses to alternating-polarity stimuli (SUM response) could also result from cochlear trauma, basilar membrane fixation, or changing contributions of hair cells and neural structures to the ECochG responses (van Gendt et al., 2020). ...
The objective to preserve residual hearing during cochlear implantation has recently led to the use of intracochlear electrocochleography (ECochG) as an intraoperative monitoring tool. Currently, a decrease in the amplitude of the difference between responses to alternating-polarity stimuli (DIF response), predominantly reflecting the hair cell response, is used for providing feedback. Including other ECochG response components, such as phase changes and harmonic distortions, could improve the accuracy of surgical feedback. The objectives of the present study were (1) to compare simultaneously recorded stepwise intracochlear and extracochlear ECochG responses to 500 Hz tone bursts, (2) to explore patterns in features extracted from the intracochlear ECochG recordings relating to hearing preservation or hearing loss, and (3) to design support vector machine (SVM) and random forest (RF) classifiers of acoustic hearing preservation that treat each subject as a sample and use all intracochlear ECochG recordings made during electrode array insertion for classification. Forty subjects undergoing cochlear implant (CI) surgery at the Oslo University Hospital, St. Thomas’ Hearing Implant Centre, or the University Hospital of Zurich were prospectively enrolled. In this cohort, DIF response amplitude decreases did not relate to postoperative acoustic hearing preservation. Exploratory analysis of the feature set extracted from the ECochG responses and preoperative audiogram showed that the features were not discriminative between outcome classes. The SVM and RF classifiers that were trained on these features could not distinguish cases with hearing loss and hearing preservation. These findings suggest that hearing loss following CI surgery is not always reflected in intraoperative ECochG recordings.
... Even so, hearing loss shortly after the surgery ranging from partial to complete implies traumatic events of varying degrees [21]. Despite a strong hypothetical framework, the expected relationship (i.e., poorer hearing preservation in cases when ECochG amplitude declined during insertion) has been observed in some but not all data sets, and a substantial amount of unexplained variability exists [16,[22][23][24][25][26][27]. Scalar translocation is one of the more extreme traumatic events that can occur during electrode array insertion. ...
... While many of these approaches are promising, they are not yet available with manufacturer systems or are not available to be used in real time as feedback. Evoking the ECochG using multiple frequencies and comparing associated response patterns is currently feasible [24,25,38,39]. While theoretical advantages exist, whether or not those advantages improve real-time interpretation (and ultimately post-operative outcomes) remains unknown. ...
... Selecting adjacent electrodes in succession was anticipated to be a sufficient recording site adjustment given the length of the Flex 24 and 26 arrays and spacing across electrodes (1.74 and 1.9 mm, respectively). Although maximal ECochG responses evoked with a 500-Hz stimulus have been recorded up to six electrodes away from the most apical site for modiolar-hugging arrays, the maximum response has been observed primarily at the apical electrode for lateral wall arrays [25]. A single case involving a Cochlear Slim 20 array where a maximum was recorded at a more basal site (electrode 20 of 22) occurred for the subject with the deepest insertion angle (385°) [25]. ...
This study evaluates intracochlear electrocochleography (ECochG) for real-time monitoring during cochlear implantation. One aim tested whether adjusting the recording electrode site would help differentiate between atraumatic and traumatic ECochG amplitude decrements. A second aim assessed whether associations between ECochG amplitude decrements and post-operative hearing loss were weaker when considering hearing sensitivity at the ECochG stimulus frequency compared to a broader frequency range. Eleven adult cochlear implant recipients who were candidates for electro-acoustic stimulation participated. Single-frequency (500-Hz) ECochG was performed during cochlear implantation; the amplitude of the first harmonic of the difference waveform was considered. Post-operative hearing preservation at 500 Hz ranged from 0 to 94%. The expected relationship between ECochG amplitude decrements and hearing preservation was observed, though the trend was not statistically significant, and predictions were grossly inaccurate for two participants. Associations did not improve when considering alternative recording sites or hearing sensitivity two octaves above the ECochG stimulus frequency. Intracochlear location of a moving recording electrode is a known confound to real-time interpretation of ECochG amplitude fluctuations, which was illustrated by the strength of the correlation with ECochG amplitude decrements. Multiple factors contribute to ECochG amplitude patterns and to hearing preservation; these results highlight the confounding influence of intracochlear recording electrode location on the ECochG.
... Sin embargo, durante la inserción de los electrodos, el potencial microfónico coclear también cambia de amplitud por la tonotopía coclear 24 . De esta forma, la caída de amplitud del potencial microfónico coclear durante la inserción de los electrodos podría explicarse por la tonotopía coclear, y no necesariamente ser sinónimo de daño mecánico de la estructura coclear. ...
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.
Introduction:
Preservation of residual hearing after cochlear implantation allows for electroacoustic stimulation, which leads to better music appreciation, noise localization, and speech comprehension in noisy environments. Real-time intraoperative electrocochleography (rt-ECochG) monitoring has shown promise in improving residual hearing rates. Four-point impedance (4PI) is being explored as a potential biomarker in cochlear implantation that has been associated with fibrotic tissue response, hearing loss, and dizziness. In this study, we explore whether monitoring both rt-ECochG intraoperatively and postoperative 4PI improves predictions of the preservation of residual hearing.
Methods:
This was a prospective cohort study. Adults with residual acoustic hearing underwent cochlear implantation with intraoperative intracochlear electrocochleography (ECochG) monitoring. The surgeon responded to a drop in ECochG signal amplitude of greater than 30% by a standardized manipulation of the electrode with the aim of restoring the ECochG. At the end of the procedure, the ECochG signal was categorized as being maintained or having dropped more than 30%. 4PI was measured on 1 day, 1 week, and 1 and 3 months after cochlear implantation. Residual hearing was measured by routine pure-tone audiogram at 3 months postoperatively. The ECochG category and 4PI impedance values were entered as factors in a multiple linear regression predicting the protection of residual hearing.
Results:
Twenty-six patients were recruited. Rt-ECochG significantly predicted residual hearing at 3 months (t test; mean difference, 37.7%; p = 0.002). Inclusion of both 1-day or 3-month 4PI in a multiple linear regression with rt-ECochG markedly improved upon correlations with residual hearing compared with the rt-ECochG-only model (rt-ECochG and 1-d 4PI model, R2 = 0.67; rt-ECochG and 3-mo 4PI model, R2 = 0.72; rt-ECochG-only model, R2 = 0.33).
Conclusions:
Both rt-ECochG and 4PI predict preservation of residual hearing after cochlear implantation. These findings suggest that the biological response of the cochlea to implantation, as reflected in 4PI, is an important determinant of residual hearing, independent of the acute effects on hearing during implant surgery seen with rt-ECochG. We speculate that 4PI relates to inflammation 1 day after implantation and fibrosis at 3 months.
Objectives
Our recent empirical findings have shown that the auditory nerve compound action potential (CAP) evoked by a low-level tone burst originates from a narrow cochlear region tuned to the tone burst frequency. At moderate to high sound levels, the origins shift to the most sensitive audiometric regions rather than the extended high-frequency regions of the cochlear base. This means that measurements evoked from extended high-frequency sound stimuli can shift toward the apex with increasing level. Here we translate this study to understand the spatial origin of acoustically evoked responses from ears that receive cochlear implants, an emerging area of research and clinical practice that is not completely understood. An essential step is to first understand the influence of the cochlear implant in otherwise naive ears. Our objective was to understand how function of the high-frequency cochlear base, which can be excited by the intense low-frequency sounds that are frequently used for objective intra- and postoperative monitoring, can be influenced by the presence of the cochlear implant.
Design
We acoustically evoked responses and made measurements with an electrode placed near the guinea pig round window. The cochlear implant was not utilized for either electrical stimulation or recording purposes. With the cochlear implant in situ, CAPs were acoustically evoked from 2 to 16 kHz tone bursts of various levels while utilizing the slow perfusion of a kainic acid solution from the cochlear apex to the cochlear aqueduct in the base, which sequentially reduced neural responses from finely spaced cochlear frequency regions. This cochlear perfusion technique reveals the spatial origin of evoked potential measurements and provides insight on what influence the presence of an implant has on acoustical hearing.
Results
Threshold measurements at 3 to 11 kHz were elevated by implantation. In an individual ear, thresholds were elevated and lowered as cochlear implant was respectively inserted and removed, indicative of “conductive hearing loss” induced by the implant. The maximum threshold elevation occurred at most sensitive region of the naive guinea pig ear (33.66 dB at 8 kHz), making 11 kHz the most sensitive region to acoustic sounds for guinea pig ears with cochlear implants. Conversely, the acute implantation did not affect the low-frequency, 500 Hz thresholds and suprathreshold function, as shown by the auditory nerve overlapped waveform. As the sound pressure level of the tone bursts increased, mean data show that the spatial origin of CAPs along the cochlear length shifted toward the most sensitive cochlear region of implanted ears, not the extended high-frequency cochlear regions. However, data from individual ears showed that after implantation, measurements from moderate to high sound pressure levels originate in places that are unique to each ear.
Conclusions
Alterations to function of the cochlear base from the in situ cochlear implant may influence objective measurements of implanted ears that are frequently made with intense low-frequency sound stimuli. Our results from guinea pigs advance the interpretation of measurements used to understand how and when residual acoustic hearing is lost in human ears receiving a cochlear implant.
Objective
To evaluate the predictive value of intracochlear electrocochleography (ECochG) for identifying tip fold‐over during cochlear implantation (CI) using the slim modiolar electrode (SME) array.
Study Design
Prospective cohort study.
Setting
Tertiary referral center.
Methods
From July 2022 to June 2023, 142 patients, including adults and children, underwent intracochlear ECochG monitoring during and after SME placement. Tone‐bursts were presented from 250 Hz to 2 kHz at 108 to 114 dB HL. A fast Fourier transform (FFT) allowed for frequency‐specific evaluation of ECochG response. ECochG patterns during insertion and postinsertion were evaluated using sensitivity and specificity analysis to predict tip fold‐over. Intraoperative plain radiographs served as a reference standard.
Results
Fifteen tip fold‐over cases occurred (10.6%) with significant ECochG response (>2 µV). Sixty‐one cases without tip fold‐over occurred (43.0%) with significant ECochG response. All tip fold‐overs had both a nontonotopic postinsertion sweep and nonrobust active insertion pattern. No patients with robust insertion or tonotopic sweep patterns had tip fold‐over. Sensitivity of detecting tip fold‐over when having both nonrobust insertion and nontonotopic sweep patterns was 100% (95% confidence inteval [CI] 78.2%‐100%), specificity was 68.9% (95% CI 55.7%‐80.1%), and the overall accuracy was 72.0% (95% CI 60.5%‐81.7%).
Conclusion
Intracochlear ECochG monitoring during cochlear implantation with the SME can be a valuable tool for identifying properly positioned electrode arrays. In cases where ECochG patterns are nonrobust on insertion and nontonotopic for electrode sweeps, there may be a concern for tip fold‐over, and intraoperative imaging is necessary to confirm proper insertion.
Importance
Cochlear implantation produces remarkable results in postlingual deafness, although auditory outcomes vary. Electrocochleography (ECochG) has emerged as a valuable tool for assessing the cochlear-neural substrate and evaluating patient prognosis.
Objective
To assess whether ECochG-total response (ECochG-TR) recorded at the best-frequency electrode (BF-ECochG-TR) correlates more strongly with speech perception performance than ECochG-TR measured at the round window (RW-ECochG-TR).
Design, Setting, and Participants
This single-center cross-sectional study recruited 142 patients from July 1, 2021, to April 30, 2022, with 1-year follow-up. Exclusions included perilymph suctioning, crimped sound delivery tubes, non–native English speakers, inner ear malformations, nonpatent external auditory canals, or cochlear implantation revision surgery.
Exposures
Cochlear implantation.
Main Outcomes and Measures
Speech perception testing, including the consonant-nucleus-consonant (CNC) words test, AzBio sentences in quiet, and AzBio sentences in noise plus 10-dB signal to noise ratio (with low scores indicating poor performance and high scores indicating excellent performance on all tests), at 6 months postoperatively; and RW-ECochG-TR and BF-ECochG-TR (measured for 250, 500, 1000, and 2000 Hz).
Results
A total of 109 of the 142 eligible postlingual adults (mean [SD] age, 68.7 [15.8] years; 67 [61.5%] male) were included in the study. Both BF-ECochG-TR and RW-ECochG-TR were correlated with 6-month CNC scores (BF-ECochG-TR: r = 0.74; 95% CI, 0.62-0.82; RW-ECochG-TR: r = 0.67; 95% CI, 0.54-0.76). A multivariate model incorporating age, duration of hearing loss, and angular insertion depth did not outperform BF-ECochG-TR or RW-ECochG-TR alone. The BF-ECochG-TR correlation with CNC scores was significantly stronger than the RW-ECochG-TR correlation ( r difference = −0.18; 95% CI, −0.31 to −0.01; z = −2.02). More moderate correlations existed between 6-month AzBio scores in noise, Montreal Cognitive Assessment (MoCA) scores ( r = 0.46; 95% CI, 0.29-0.60), and BF-ECochG-TR ( r = 0.42; 95% CI, 0.22-0.58). MoCA and the interaction between BF-ECochG-TR and MoCA accounted for a substantial proportion of variability in AzBio scores in noise at 6 months ( R ² = 0.50; 95% CI, 0.36-0.61).
Conclusions and Relevance
In this case series, BF-ECochG-TR was identified as having a stronger correlation with cochlear implantation performance than RW-ECochG-TR, although both measures highlight the critical role of the cochlear-neural substrate on outcomes. Demographic, audiologic, and surgical factors demonstrated weak correlations with cochlear implantation performance, and performance in noise was found to require a robust cochlear-neural substrate (BF-ECochG-TR) as well as sufficient cognitive capacity (MoCA). Future cochlear implantation studies should consider these variables when assessing performance and related interventions.
