Electrode impedance changes after implantation of a dexamethasone-eluting intracochlear array

Needham, Karina; Stathopoulos, Dimitra; Newbold, Carrie; Leavens, Jason; Risi, Frank; Manouchehri, Shahram; Durmo, Irfan; Cowan, Robert

doi:10.1080/14670100.2019.1680167

Cited by 18 publications

(18 citation statements)

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“…This outcome was limited to the basal region where DEX was administered. The neuroprotective effect of chronic stimulation has been described in the literature [42] and was also reported in other studies discussed in this review [19,20,31,33], but by mimicking the clinical situation in CI patients, the added value of DEX was demonstrated in a preclinical model. To extend the therapeutic effect over the entire cochlea, drug-eluting electrodes seem to be a more complete and feasible delivery method.…”

Section: Discussionsupporting

confidence: 57%

“…Two types of impedance measures were recorded following cochlear implantation by Needham et al [33]. Mean monopolar impedance measures, representing the device power requirements, were higher in the DEX-eluting group immediately at implantation (p = 0.002) and stayed greater in comparison with controls during the 4 week observation period (p = 0.001).…”

Section: Drug-eluting Electrodementioning

confidence: 99%

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Inner Ear Pharmacotherapy for Residual Hearing Preservation in Cochlear Implant Surgery: A Systematic Review

et al. 2022

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Cochlear implantation initiates an inflammatory cascade in which both acute insertion trauma and chronic foreign body reaction lead to intracochlear fibrosis and loss of residual hearing. Several strategies have been proposed to attenuate the local reactive process after implantation, including intracochlear drug delivery. The present study gives an overview of what is being investigated in the field of inner ear therapeutics and cochlear implant surgery. The aim is to evaluate its potential benefit in clinical practice. A systematic search was conducted in PubMed, Embase, and Cochrane Library databases identifying comparative prospective studies examining the effect of direct inner ear drug application on mechanical cochlear trauma. Both animal and human studies were considered and all studies were assessed for quality according to the validated risk of bias tools. Intracochlear administration of drugs is a feasible method to reduce the local inflammatory reaction following cochlear implantation. In animal studies, corticosteroid use had a significant effect on outcome measures including auditory brainstem response, impedance, and histological changes. This effect was, however, only durable with prolonged drug delivery. Significant differences in outcome were predominantly seen in studies where the cochlear damage was extensive. Six additional reports assessing non-steroidal agents were found. Overall, evidence of anti-inflammatory effects in humans is still scarce.

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Section: Discussionsupporting

confidence: 57%

Section: Drug-eluting Electrodementioning

confidence: 99%

Inner Ear Pharmacotherapy for Residual Hearing Preservation in Cochlear Implant Surgery: A Systematic Review

et al. 2022

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“…A similar pattern of post-implantation cochlear tissue response has been seen in several animal models of cochlear implantation, including guinea pig, cat, mouse and sheep (Clark et al, 1975;Claussen et al, 2019;Kaufmann et al, 2020;O'Leary et al, 2013). Deleterious CI outcomes have been associated with the cochlear tissue response and neo-ossification, including poorer word recognition scores (Kamakura & Nadol, 2016), impedance increases with subsequent poorer battery life and decreased dynamic range (Needham et al, 2020;Wilk et al, 2016) and loss of residual acoustic hearing after cochlear implantation (Quesnel et al, 2016;Scheperle et al, 2017). A wide variety of inflammatory cells, including lymphocytes, macrophages, eosinophils and peri-implant foreign body giant cells are consistently seen within the intracochlear tissue response as well as other parts of the cochlea (O'Malley et al, 2017).…”

Section: Introductionmentioning

confidence: 61%

Chronic Cochlear Implantation with and without Electric Stimulation in a Mouse Model Induces Robust Cochlear Influx of CX3CR1^+/GFP Macrophages

Claussen

Quevedo

Higgins

et al. 2021

Preprint

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BackgroundCochlear implantation is an effective auditory rehabilitation strategy for those with profound hearing loss, including those with residual low frequency hearing through use of hybrid cochlear implantation techniques. Post-mortem studies demonstrate the nearly ubiquitous presence of intracochlear fibrosis and neo-ossification following cochlear implantation. Current evidence suggests post-implantation intracochlear fibrosis is associated with delayed loss of residual acoustic hearing in hybrid cochlear implant (CI) recipients and may also negatively influence outcomes in traditional CI recipients. This study examined the contributions of surgical trauma, foreign body response and electric stimulation to intracochlear fibrosis and the innate immune response to cochlear implantation and the hierarchy of these contributions.MethodsNormal hearing CX3CR1+/GFP mice underwent either round window opening (sham), acute CI insertion or chronic CI insertion with no, low- or high-level electric stimulation. Electric stimulation levels were based on neural response telemetry (NRT), beginning post-operative day 7 for 4 hours per day. Subjects (n=3 per timepoint) were sacrificed at 4 hours, 1,4,7,8,11,14 and 21 days. An unimplanted group (n=3) served as controls. Cochleae were harvested at each time-point and prepared for immunohistochemistry with confocal imaging. The images were analyzed to obtain CX3CR1+ macrophage cell number and density in the lateral wall (LW), scala tympani (ST) and Rosenthal’s canal (RC).ResultsA ST peri-implant cellular infiltrate and fibrosis occurred exclusively in the chronically implanted groups starting on day 7 with a concurrent infiltration of CX3CR1+ macrophages not seen in the other groups. CX3CR1+ macrophage infiltration was seen in the LW and RC in all experimental groups within the first week, being most prominent in the 3 chronically implanted groups during the second and third week. There were no significant differences in macrophage infiltration related to levels of electric stimulation.ConclusionsThe cochlear immune response was most prominent in the presence of chronic cochlear implantation, regardless of electric stimulation level. Further, the development of intracochlear ST fibrosis was dependent on the presence of the indwelling CI foreign body. An innate immune response was evoked by surgical trauma alone (sham and acute CI groups) to a lesser degree. These data suggest that cochlear inflammation and intrascalar fibrosis after cochlear implantation are largely dependent on the presence of a chronic indwelling foreign body and are not critically dependent on electrical stimulation. Also, these data support a role for surgical trauma in inciting the initial innate immune response.

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“…17 In addition, the use of a dexamethasone-eluting Cochlear Contour Advance electrode has been shown to determine different impedance values than standard electrodes. 34,35 These data suggest that intracochlear inflammation is present, and it can be modulated and it may influence impedance levels.…”

Section: Discussionmentioning

confidence: 84%

Long-Term Impedance Trend in Cochlear Implant Users with Genetically Determined Congenital Profound Hearing Loss

et al. 2022

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Background Impedance is a basic parameter registered at any cochlear implant (CI) fitting section. It is useful in monitoring electrode functioning and the status of the surrounding anatomical structures. Purpose The main aim of this study is to evaluate the 5-year impedance-value trend in patients affected by congenital genetically determined profound hearing loss implanted with Cochlear Nucleus devices. Research Design Observational, retrospective, monocentric study. Study Sample Twenty-seven consecutive patients (9 females: 12.0 ± 7.6 years old; range: 4.2–40.4) with genetic diagnosis of GJB2 mutation causing congenital profound hearing loss who underwent cochlear implantation from 2010 to 2020 with good auditory benefit. Intervention Impedance values of the CIs were obtained from the CIs' programming software that registers those parameters for each follow-up section of each patient. Data Collection and Analysis Impedance values were measured over time (activation, 6, 12, 24, and 60 months after cochlear implantation), for each of the 22 electrodes, in common ground, monopolar 1, monopolar 2, and monopolar 1 + 2 stimulation modes. Results A significant variation was found between CI activation and 6-month follow-up. This difference was found for each of the 22 electrodes. Electrodes 1 to 4 showed higher impedance values compared with all other electrodes in each time interval. Repeated-measures analysis of variance ruled out significant variations in impedance values from 6-month to 5-year follow-up. Conclusions Impedance values were extremely stable after activation, at least for the first 5 years. In these cases, even minimal impedance variations should be carefully evaluated for their possible implications on hearing performance.

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Electrode impedance changes after implantation of a dexamethasone-eluting intracochlear array

Cited by 18 publications

References 32 publications

Inner Ear Pharmacotherapy for Residual Hearing Preservation in Cochlear Implant Surgery: A Systematic Review

Inner Ear Pharmacotherapy for Residual Hearing Preservation in Cochlear Implant Surgery: A Systematic Review

Chronic Cochlear Implantation with and without Electric Stimulation in a Mouse Model Induces Robust Cochlear Influx of CX3CR1^+/GFP Macrophages

Long-Term Impedance Trend in Cochlear Implant Users with Genetically Determined Congenital Profound Hearing Loss

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Electrode impedance changes after implantation of a dexamethasone-eluting intracochlear array

Cited by 18 publications

References 32 publications

Inner Ear Pharmacotherapy for Residual Hearing Preservation in Cochlear Implant Surgery: A Systematic Review

Inner Ear Pharmacotherapy for Residual Hearing Preservation in Cochlear Implant Surgery: A Systematic Review

Chronic Cochlear Implantation with and without Electric Stimulation in a Mouse Model Induces Robust Cochlear Influx of CX3CR1+/GFP Macrophages

Long-Term Impedance Trend in Cochlear Implant Users with Genetically Determined Congenital Profound Hearing Loss

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Chronic Cochlear Implantation with and without Electric Stimulation in a Mouse Model Induces Robust Cochlear Influx of CX3CR1^+/GFP Macrophages