Electrocochleography triggered intervention successfully preserves residual hearing during cochlear implantation: Results of a randomised clinical trial

Bester, Christofer; Collins, Aaron M.; Razmovski, Tayla; Weder, Stefan; Briggs, Robert; Wei, Benjamin; Zakaria, Anis; Gérard, Jean-Marc; Mitchell‐Innes, Alistair; Tykocinski, Michael; Kennedy, Richard; Iseli, Claire; Dahm, Markus; Ellul, Simon; O’Leary, Stephen

doi:10.1016/j.heares.2021.108353

Cited by 25 publications

(31 citation statements)

References 23 publications

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“…The CM amplitude drop is only a rough approximation for intracochlear trauma that may affect hearing outcomes. Despite that, CM amplitude drops can be predictive of decline in residual hearing as shown in the current study and other recent studies (O'Leary et al, 2020;Bester et al, 2021;Lenarz et al, 2022). Importantly, CM activity is related to outer hair cell activity but not necessarily hearing ability; thus, there may be hair cells measured by the CM that are not innervated by functional spiral ganglion cells (Fontenot et al, 2019).…”

Section: Limitationssupporting

confidence: 40%

“…We hypothesized that a drop in CM amplitude for 250-Hz was more predictive of hearing preservation than changes in CM amplitude for 500-Hz stimulus. Several recent studies (Harris et al, 2017a;O'Connell et al, 2017;Ramos-Macias et al, 2019;Bester et al, 2021;Lenarz et al, 2022;Walia et al, 2022) have explored intraoperative CM amplitude drops during insertion and its correlation with postoperative behavioral thresholds with no clear consensus on any reliable or significant correlation. Universally, across all prior studies, 500-Hz was used for the acoustic stimulus throughout the insertion.…”

Section: Discussionmentioning

confidence: 99%

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Is Characteristic Frequency Limiting Real-Time Electrocochleography During Cochlear Implantation?

et al. 2022

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ObjectivesElectrocochleography (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, characteristic frequency (CF) place partly explains the problems experienced using 500-Hz.DesignMultifrequency ECochG comprising an alternating, interleaved acoustic complex of 250- and 500-Hz stimuli was used to elicit cochlear microphonics (CMs) during insertion. The largest ECochG drops (≥30% reduction in CM) were identified. After insertion, ECochG responses were measured using the individual electrodes along the array for both 250- and 500-Hz stimuli. Univariate regression was used to predict whether 250- or 500-Hz CM drops explained low-frequency pure tone average (LFPTA; 125-, 250-, and 500-Hz) shift at 1-month post-activation. Postoperative CT scans were performed to evaluate cochlear size and angular insertion depth.ResultsFor perimodiolar insertions (N = 34), there was a stronger linear correlation between the largest ECochG drop using 250-Hz stimulus and LFPTA shift (r = 0.58), compared to 500-Hz (r = 0.31). The 250- and 500-Hz CM insertion tracings showed an amplitude peak at two different locations, with the 500-Hz peak occurring earlier in most cases than the 250-Hz peak, consistent with tonotopicity. When using the entire array for recordings after insertion, a maximum 500-Hz response was observed 2–6 electrodes basal to the most-apical electrode in 20 cases (58.9%). For insertions where the apical insertion angle is >350 degrees and the cochlear diameter is <9.5 mm, the maximum 500-Hz ECochG response may occur at the non-apical most electrode. For lateral wall insertions (N = 14), the maximum 250- and 500-Hz CM response occurred at the most-apical electrode in all but one case.ConclusionUsing 250-Hz stimulus for ECochG feedback during implantation is more predictive of hearing preservation than 500-Hz. This is due to the electrode passing the 500-Hz CF during insertion which may be misidentified as intracochlear trauma; this is particularly important in subjects with smaller cochlear diameters and deeper insertions. Multifrequency ECochG can be used to differentiate between trauma and advancement of the apical electrode beyond the CF.

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Section: Limitationssupporting

confidence: 40%

Section: Discussionmentioning

confidence: 99%

Is Characteristic Frequency Limiting Real-Time Electrocochleography During Cochlear Implantation?

et al. 2022

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“…Consequently, most losses of residual hearing occurred intraoperatively or in the early postoperative phase. Reasons can be a traumatic electrode insertion (9,23,24) or an inflammatory response with resulting scar tissue formation (12)(13)(14). In addition, the presence of the electrode array can influence the mechanical properties of the cochlea and, thus, residual hearing thresholds (25,26).…”

Section: Discussionmentioning

confidence: 99%

Cochlear Implant Electrode Impedance as Potential Biomarker for Residual Hearing

Wimmer

Sclabas²,

Caversaccio³

et al. 2022

Front. Neurol.

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Introduction and ObjectivesAmong cochlear implant candidates, an increasing number of patients are presenting with residual acoustic hearing. To monitor the postoperative course of structural and functional preservation of the cochlea, a reliable objective biomarker would be desirable. Recently, impedance telemetry has gained increasing attention in this field. The aim of this study was to investigate the postoperative course of the residual acoustic hearing and clinical impedance in patients with long electrode arrays and to explore the applicability of impedance telemetry for monitoring residual hearing.MethodsWe retrospectively analyzed records of 42 cochlear implant recipients with residual hearing covering a median postoperative follow-up of 25 months with repeated simultaneous pure tone audiometry and impedance telemetry. We used a linear mixed-effects model to estimate the relation between clinical electrode impedance and residual hearing. Besides the clinical impedance, the follow-up time, side of implantation, gender, and age at implantation were included as fixed effects. An interaction term between impedance and follow-up time, as well as subject-level random intercepts and slopes, were included.ResultsLoss of residual hearing occurred either during surgery or within the first 6 post-operative months. Electrode contacts inserted further apically (i.e., deeper) had higher impedances, independent of residual hearing. The highest impedances were measured 1 month postoperatively and gradually decreased over time. Basal electrodes were more likely to maintain higher impedance. Follow-up time was significantly associated with residual hearing. Regardless of the time, we found that a 1 kΩ increase in clinical impedance was associated with a 4.4 dB deterioration of residual hearing (p < 0.001).ConclusionPure tone audiometry is the current gold standard for monitoring postoperative residual hearing. However, the association of clinical impedances with residual hearing thresholds found in our study could potentially be exploited for objective monitoring using impedance telemetry. Further analysis including near-field related impedance components could be performed for improved specificity to local immune responses.

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“…If ECochG signal drops occur during electrode insertion (usually measured by the CM amplitude), preliminary evidence suggests that the surgical response may affect the inner ear function. A randomized study showed that when the CM amplitude decreased by 30% or more (related to the initial maximum amplitude), a slight withdrawal of the electrode resulted in a significant improvement of postoperative residual hearing 21 . However, the definition of a detrimental drop is unclear; another publication reported a CM decrease of 61% (or more) at a slope steepness of 0.2 µV/ s (or more) to be significant 9 .…”

Section: Discussionmentioning

confidence: 99%

Performing Intracochlear Electrocochleography During Cochlear Implantation

Schuerch

Waser

Mantokoudis

et al. 2022

JoVE

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Electrocochleography (ECochG) measures inner ear potentials generated in response to acoustic stimulation of the ear. These potentials reflect the residual function of the cochlea. In cochlear implant candidates with residual hearing, the implant electrode can directly measure ECochG responses during the implantation process. Various authors have described the ability to monitor the inner ear function by continuous ECochG measurements during the surgery. The measurement of ECochG signals during surgery is not trivial. There are no interpretable signals in up to 20% of cases. For a successful recording, a standardized procedure is recommended to achieve the highest measurement reliability and avoid possible pitfalls. Therefore, seamless collaboration between the CI surgeon and CI technician is key. This video consists of an overview of the system setup and a stepwise procedure of performing intracochlear ECochG measurements during CI surgery. It shows the surgeon's and the CI technician's roles in the process, and how a smooth collaboration between the two is made possible.

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Electrocochleography triggered intervention successfully preserves residual hearing during cochlear implantation: Results of a randomised clinical trial

Cited by 25 publications

References 23 publications

Is Characteristic Frequency Limiting Real-Time Electrocochleography During Cochlear Implantation?

Is Characteristic Frequency Limiting Real-Time Electrocochleography During Cochlear Implantation?

Cochlear Implant Electrode Impedance as Potential Biomarker for Residual Hearing

Performing Intracochlear Electrocochleography During Cochlear Implantation

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