Long-Term Measures of Electrode Impedance and Auditory Thresholds for the Ineraid Cochlear Implant

Dorman, Michael F.; Smith, Luke; Dankowski, Korine; McCandless, Geary A.; Parkin, James L.

doi:10.1044/jshr.3505.1126

Cited by 58 publications

(37 citation statements)

References 9 publications

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“…Relative to adults, children demonstrated greater threshold instability during the first few months after implantation, with thresholds typically increasing during that period (Hughes et al, 2001). Although others have reported general, long term, stability of psychophysical measures (e.g., Dorman et al, 1992;Waltzman et al, 1991;Hughes et al, 2001), the ECAP provides an objective measure of the periphery, that unlike psychophysical or central electrophysiological measures is not prone to the effects of neural plasticity or learning. Indeed, ECAP-based measures could conceivably be used as a means of providing baseline measures for assessing central plasticity.…”

Section: Stability Of Evoked Potentials Assessed Over Timementioning

confidence: 93%

The clinical application of potentials evoked from the peripheral auditory system

et al. 2008

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Section: Stability Of Evoked Potentials Assessed Over Timementioning

confidence: 93%

The clinical application of potentials evoked from the peripheral auditory system

et al. 2008

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“…For example, using a scaled down DBS electrode in a primate model electrical stimulation resulted in a significant but reversible decrease in impedance magnitude. Electrical impedance changes as a result of electrical stimulation have also been documented in humans with cochlear implants [29,30].…”

Section: Neurostimulation and Impedance Changementioning

confidence: 98%

“…Regarding current delivery, tissue activation volume, and stimulation thresholds, the effect of voltagecontrolled stimulation is dependent on the electrode-tissue interface impedance [9,20,29,35,36]. In one example of impedance changes that might affect voltage-controlled stimulation, transient unusually high electrode impedance has been documented in DBS electrodes reactivated after a period of time, which subsequently normalized spontaneously [32].…”

Section: Clinical Correlations Of Electrode-tissue Impedancementioning

confidence: 99%

Long-Term Surface Electrode Impedance Recordings Associated with Gliosis for a Closed-Loop Neurostimulation Device

Sillay

Ondoma

Wingeier³

et al. 2018

Ann Neurosci

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Background: Closed-loop neurostimulation is a novel alternative therapy for medically intractable focal epilepsy for patients who are not candidates for surgical resection of a seizure focus. Electrodes for this system can be implanted either within the brain parenchyma or in the subdural space. The electrodes then serve the dual role of detecting seizures and delivering an electrical signal aimed at aborting seizure activity. The Responsive Neurostimulation (RNS®) system (Neuropace, Mountain View, CA, USA) is an FDA-approved implantable device designed for this purpose. Objective: One of the challenges of the brain machine interface devices is the potential for implanted neurostimulator devices to induce progressive gliosis, apart from that associated with the minimal trauma at implantation. Gliosis has the potential to alter impedances over time, thereby affecting the clinical efficacy of these devices, and also poses a challenge to the prospects of in vivo repositioning of depth electrodes. We present a clinical case with 3-year follow-up and pathology. Methods: Single-case, retrospective review within a randomized trial with specific minimum follow-up and impedance measurements. Results: Impedance changes in the surface electrode over time were observed. Surgical pathological findings revealed significant gliosis in the leptomeninges of the cortices. Conclusion: We report, for the first time, long-term impedance recordings from a surface electrode associated with pathologic findings of gliosis at the Neuropace device-tissue interface in a patient who was enrolled in the multicenter RNS System Pivotal Clinical Investigation. Further study is required to elucidate the temporal relationship of pathological findings over time. Impedance changes were more complex than can be explained by a progressive or transient pathological mechanism. Further effort is required to elucidate the relationship between impedance change and seizure event capture.

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“…This is evident from the data presented in Table 2, where threshold variations for medial arrays are generally greater than for lateral arrays. Some evidence supporting this observation can be found in threshold current reductions over time, reported by PFINGST (1990) (who used arrays that positioned electrode contacts in the region between the modiolus and the middle of the scala tympani) and DORMAN et al (1992) (for patients using the Ineraid cochlear implant), whereas unchanged EABR thresholds over time were reported for Nucleus implant users (BROWN et al, 1995).…”

Section: Highest Potential Deviation and Electric Field Intensity Formentioning

confidence: 74%

“…10-20 kll (DE SAUVAGE et al, 1997;DORMAN et al, 1992), dominates resistive changes caused by encapsulation tissue (roughly hundreds of ohms) in the neighbouring cochlear tissue.…”

Section: Highest Potential Deviation and Electric Field Intensity Formentioning

confidence: 99%

Modelling encapsulation tissue around cochlear implant electrodes

Hanekom

2005

Med. Biol. Eng. Comput.

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The objective of the study was to explore the effect of electrode encapsulation by fibrous scar tissue on electrical potential distributions and auditory nerve fibre excitation patterns. A finite element model in combination with an auditory nerve fibre model was used to predict changes in threshold currents and auditory nerve fibre excitation patterns. The model showed that electrical potentials at the target nerve fibres and the electrode contacts changed in the presence of encapsulation tissue. This led to changes in threshold currents and spread of excitation. The effect of electrode encapsulation on threshold currents and spread of excitation depended on the thickness of the perilymph layer separating the fibrous tissue encapsulation and the electrode array, nerve fibre survival status, electrode geometry and configuration, and array location. Model results suggested that arrays located close to the modiolus were most sensitive to threshold changes caused by electrode encapsulation (changes were between -0.26 and 2.41 dB), whereas encapsulation of an electrode array had less effect on threshold currents when the array was located in a lateral position in the scala tympani (changes were between -0.64 and 1.5 dB). For medially located arrays, changes in the spread of excitation varied between an increase of 0.21 mm and a decrease of 0.33 mm along the length of the basilar membrane, and an increase of 0.18 mm and a decrease of 0.66 mm along the length of the basilar membrane were calculated for laterally located arrays.

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Long-Term Measures of Electrode Impedance and Auditory Thresholds for the Ineraid Cochlear Implant

Cited by 58 publications

References 9 publications

The clinical application of potentials evoked from the peripheral auditory system

The clinical application of potentials evoked from the peripheral auditory system

Long-Term Surface Electrode Impedance Recordings Associated with Gliosis for a Closed-Loop Neurostimulation Device

Modelling encapsulation tissue around cochlear implant electrodes

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