Long-term electrode impedance changes and failure prevalence in cochlear implants

Newbold, Carrie; Risi, Frank; Hollow, Rod; Yusof, Yusmeera; Dowell, Richard C.

doi:10.3109/14992027.2014.1001076

Cited by 16 publications

(10 citation statements)

References 17 publications

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“…Due to the longer waiting period in the conventional 4‐week activation group, impedance may have already reached a steady level before our first postoperative evaluation. Although there was no measurement data during the first month after the implantation in the control group, this result suggested a shorter period to reach stable impedance level than the previous studies . Dose the early electrical stimulation help to stabilise the surround environment of the electrode array is still unknown.…”

Section: Discussioncontrasting

confidence: 57%

“…11 Within several hours after the electrode insertion, a cell cover composed of inflammatory cells, protein adsorption, macrophages and fibroblasts will form around the electrodes, which will lead to increased impedance. When early activation occurs 24 hours after surgery, electrical stimulation causes the formation of a hydride layer, which increases the array surface and triggers cell escape from the surface of the contacts, 12 thereby dramatically decreasing the impedance. In our study, impedance in the early activation group achieved steady level at 2 weeks after cochlear implantation.…”

Section: Oscillations Of Impedancementioning

confidence: 99%

“…Although there was no measurement data during the first month after the implantation in the control group, this result suggested a shorter period to reach stable impedance level than the previous studies. 2,3,9,12 Dose the early electrical stimulation help to stabilise the surround environment of the electrode array is still unknown. Further study including the serial histology changes may provide stronger evidence.…”

Section: Oscillations Of Impedancementioning

confidence: 99%

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Feasibility of early activation after cochlear implantation

Sun

Chang

Hsu

et al. 2019

Clinical Otolaryngology

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Objectives The purpose of the study is to investigate feasibility of early activation after cochlear implantation by evaluating long‐term impedance change and speech perception. Design Case‐control study Setting Between July 2015 and December 2016, we prospectively enrolled 20 subjects for early activation (within 24 hours after cochlear implantation). On the other hand, from November 2013 to July 2015, 20 age‐ and sex‐matched control subjects from the database of cochlear implantees treated with conventional activation schedule (4 weeks after surgery) were retrospectively enrolled. Participant Forty patients who underwent cochlear implantation surgeries. Main outcome measures The series impedance and speech perception score of both groups were compared. Results No statistical difference in long‐term follow‐up between the two groups was found using GEEs and multivariate analysis. In the early activation group, impedance reached a steady level by the 2nd postoperative week, and the hearing perception ability significantly improved by the 4th postoperative week. Conclusion This comparative study illustrated sequential impedance data during early activation (24 hours) and conventional activation (4 weeks) after CI surgery. There were no major complications in either group, and the safety of early activation with respect to impedance changes, postoperative residual hearing preservation and speech perception scores were non‐inferior to that of the conventional group. Therefore, in this study, we established the feasibility of early activation 24 hours after cochlear implantation.

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Section: Discussioncontrasting

confidence: 57%

Section: Oscillations Of Impedancementioning

confidence: 99%

Section: Oscillations Of Impedancementioning

confidence: 99%

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Feasibility of early activation after cochlear implantation

Sun

Chang

Hsu

et al. 2019

Clinical Otolaryngology

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“…A high impedance electrode may also make it difficult to monitor skin hydration levels over time, which can hinder both sweat-based measurements, and investigations of certain skin diseases [ 12 ]. Finally, in long-term monitoring and ambulatory applications, impedance stability is highly desirable, as changes in the electrode response as a result of increased impedance may be detrimental to diagnostic accuracy [ 13 , 14 ]. The issue of maintaining a low-impedance skin–electrode interface to enable clean and meaningful recording of skin-based biopotentials has been discussed in several previous works [ 7 , 15 , 16 , 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

Time Evolution of the Skin–Electrode Interface Impedance under Different Skin Treatments

Murphy

Scheid

Hendricks

et al. 2021

Sensors

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A low and stable impedance at the skin–electrode interface is key to high-fidelity acquisition of biosignals, both acutely and in the long term. However, recording quality is highly variable due to the complex nature of human skin. Here, we present an experimental and modeling framework to investigate the interfacial impedance behavior, and describe how skin interventions affect its stability over time. To illustrate this approach, we report experimental measurements on the skin–electrode impedance using pre-gelled, clinical-grade electrodes in healthy human subjects recorded over 24 h following four skin treatments: (i) mechanical abrasion, (ii) chemical exfoliation, (iii) microporation, and (iv) no treatment. In the immediate post-treatment period, mechanical abrasion yields the lowest initial impedance, whereas the other treatments provide modest improvement compared to untreated skin. After 24 h, however, the impedance becomes more uniform across all groups (<20 kΩ at 10 Hz). The impedance data are fitted with an equivalent circuit model of the complete skin–electrode interface, clearly identifying skin-level versus electrode-level contributions to the overall impedance. Using this model, we systematically investigate how time and treatment affect the impedance response, and show that removal of the superficial epidermal layers is essential to achieving a low, long-term stable interface impedance.

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“…This metric provides important clinical information about the device and individual electrode function, in both intra and post-operative patient's appointments. In today's CI standard of care, it is mainly used to investigate the electrode's overall function (Paasche et al, 2006), detect problems such as short-circuit or open circuit (Goehring et al, 2013), guide audio-processors fitting (Khater et al, 2015), and determine power consumption (Newbold et al, 2015). For example, intra-operatively this measure checks the integrity of the device after surgical manipulation.…”

Section: Introductionmentioning

confidence: 99%

Measuring the Electrical Status of the Bionic Ear. Re-thinking the Impedance in Cochlear Implants

Lella

Parreño

Fernandez

et al. 2020

Front. Bioeng. Biotechnol.

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As in any biophysical electrode-tissue environment, impedance measurement shows a complex relationship which reflects the electrical characteristics of the medium. In cochlear implants (CIs), which is mostly a stimulation-oriented device, the actual clinical approach only considers one arbitrary time-measure of the impedance. However, to determine the main electrical properties of the cochlear medium, the overall impedance and its subcomponents (i.e., access resistance and polarization impedance) should be described. We here characterized, validated and discussed a novel method to calculate impedance subcomponents based on CI measurement capabilities. With an electronic circuit of the cochlear electrode-tissue interface and its computational simulation, the access resistance and polarization impedance were modeled. Values of each electrical component were estimated through a custom-made pulse delivery routine and the acquisition of multiple data points. Using CI hardware, results fell within the electronic components nominal errors (± 10%). Considering the method's accuracy and reliability, it is readily available to be applied in research-clinical use. In the man-machine nature of the CI, this represents the basis to optimize the communication between a CI electrode and the spiral ganglion cells.

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Long-term electrode impedance changes and failure prevalence in cochlear implants

Abstract: A relatively low incidence of electrode failures were recorded for the Nucleus devices of these recipients. Electrode impedance dropped for all array types after 8 to 12 years of device use.

Cited by 16 publications

References 17 publications

Feasibility of early activation after cochlear implantation

Feasibility of early activation after cochlear implantation

Time Evolution of the Skin–Electrode Interface Impedance under Different Skin Treatments

Measuring the Electrical Status of the Bionic Ear. Re-thinking the Impedance in Cochlear Implants

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