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Saoji AA, Graham M, Stein A, Koka K. Analysis of electrode impedance and its subcomponents for lateral wall, mid-scala, and perimodiolar electrodes in cochlear implants. Cochlear Implants Int 2021; 23:87-94. [PMID: 34895078 DOI: 10.1080/14670100.2021.2000734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVE Electrode impedances play an important role in cochlear implant patient management. During clinical visits, electrode impedances are calculated from a single point voltage waveform. In the present study, multipoint electrode impedance analysis was performed to study electrode impedance and its subcomponents in patients with three different types of cochlear implant electrode arrays. DESIGN Voltage waveforms were measured at six different time points during the cathodic phase of a biphasic pulse in forty-seven cochlear implant patients with perimodiolar, mid-scala, or lateral wall electrode arrays. Multipoint electrode impedances were used to determine access resistance and polarization impedance. RESULTS Access resistance of approximately 5 kΩ was calculated across the three different electrode arrays. Mid-scala electrodes showed a smaller increase in impedances as a function of pulse duration compared to the other electrodes. Patients with lower impedances showed higher capacitance and lower resistance, suggesting that differences in electrochemical reaction at the electrodes' surface can influence impedances in cochlear implants. CONCLUSIONS Analysis of cochlear implant electrode impedances and their subcomponents provides valuable information about resistance to the flow of current between stimulating and return electrodes, and build an understanding of the contribution of electrochemical processes used to deliver electrical stimulation to the auditory nerve.
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Affiliation(s)
- Aniket A Saoji
- Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic School of Medicine, Rochester, MN, USA
| | - Madison Graham
- Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic School of Medicine, Rochester, MN, USA
| | - Amy Stein
- Research and Technology, Advanced Bionics, Valencia, CA, USA
| | - Kanthaiah Koka
- Research and Technology, Advanced Bionics, Valencia, CA, USA
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Saoji AA, Adkins WJ, Graham MK, Carlson ML. Does early activation within hours after cochlear implant surgery influence electrode impedances? Int J Audiol 2021; 61:520-525. [PMID: 34278935 DOI: 10.1080/14992027.2021.1942569] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE This study aims to determine if early device activation can influence cochlear implant electrode impedances by providing electrical stimulation within hours after cochlear implant surgery. DESIGN Electrode impedances were measured intraoperatively, at device activation, and one-month after device activation in three groups: users whose devices were activated (1) on the same day (Same Day), (2) the next day (Next Day), and (3) 10-14 days (Standard), after cochlear implant surgery. STUDY SAMPLE Electrode impedances are reported in fifty-one patients implanted with a Cochlear™ Nucleus® Cochlear Implant. RESULTS Compared to intraoperative levels, impedances dropped within hours for the Same Day activation group (p < 0.001) and continued dropping on the next day after surgery (p < 0.001). Similarly, electrode impedances were significantly (p < 0.001) lower at device activation for the Next Day group as compared to their intraoperative measurements. For Standard activation, impedances increased significantly from intraoperative levels, prior to device activation (p < 0.001). One-month after initial activation, impedances were not statistically different between the Same Day, Next Day, and Standard activation groups. CONCLUSIONS Early device activation does not influence long-term impedances in a clinically meaningful manner.
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Affiliation(s)
- Aniket A Saoji
- Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic School of Medicine, Rochester, MN, USA
| | - Weston J Adkins
- Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic School of Medicine, Rochester, MN, USA
| | - Madison K Graham
- Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic School of Medicine, Rochester, MN, USA
| | - Matthew L Carlson
- Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic School of Medicine, Rochester, MN, USA
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Huang SH, Shmoel N, Jankowski MM, Erez H, Sharon A, Abu-Salah W, Nelken I, Weiss A, Spira ME. Immunohistological and Ultrastructural Study of the Inflammatory Response to Perforated Polyimide Cortical Implants: Mechanisms Underlying Deterioration of Electrophysiological Recording Quality. Front Neurosci 2020; 14:926. [PMID: 32982683 PMCID: PMC7489236 DOI: 10.3389/fnins.2020.00926] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/11/2020] [Indexed: 12/12/2022] Open
Abstract
The deterioration of field potential (FP) recording quality and yield by in vivo multielectrode arrays (MEA) within days to weeks of implantation severely limits progress in basic and applied brain research. The prevailing hypothesis is that implantation of MEA platforms initiate and perpetuate inflammatory processes which culminate in the formation of scar tissue (the foreign body response, FBR) around the implant. The FBR leads to progressive degradation of the recording qualities by displacing neurons away from the electrode surfaces, increasing the resistance between neurons (current source) and the sensing pads and by reducing the neurons’ excitable membrane properties and functional synaptic connectivity through the release of pro-inflammatory cytokines. Meticulous attempts to causally relate the cellular composition, cell density, and electrical properties of the FBR have failed to unequivocally correlate the deterioration of recording quality with the histological severity of the FBR. Based on confocal and electron microscope analysis of thin sections of polyimide based MEA implants along with the surrounding brain tissue at different points in time after implantation, we propose that abrupt FP amplitude attenuation occurs at the implant/brain-parenchyma junction as a result of high seal resistance insulation formed by adhering microglia to the implant surfaces. In contrast to the prevailing hypothesis, that FP decrease occurs across the encapsulating scar of the implanted MEA, this mechanism potentially explains why no correlations have been found between the dimensions and density of the FBR and the recording quality. Recognizing that the seal resistance formed by adhering-microglia to the implant constitutes a downstream element undermining extracellular FP recordings, suggests that approaches to mitigate the formation of the insulating glial could lead to improved recording quality and yield.
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Affiliation(s)
- Shun-Ho Huang
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Harvey M. Kruger Family Center for Nanoscience, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nava Shmoel
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Harvey M. Kruger Family Center for Nanoscience, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maciej M Jankowski
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel.,Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Hadas Erez
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Aviv Sharon
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Wesal Abu-Salah
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Israel Nelken
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.,Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Aryeh Weiss
- Faculty of Engineering, Bar-Ilan University, Ramat Gan, Israel
| | - Micha E Spira
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel.,The Harvey M. Kruger Family Center for Nanoscience, The Hebrew University of Jerusalem, Jerusalem, Israel
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Needham K, Stathopoulos D, Newbold C, Leavens J, Risi F, Manouchehri S, Durmo I, Cowan R. Electrode impedance changes after implantation of a dexamethasone-eluting intracochlear array. Cochlear Implants Int 2019; 21:98-109. [DOI: 10.1080/14670100.2019.1680167] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Karina Needham
- The HEARing CRC, Carlton, Australia
- Department of Audiology and Speech Pathology, The University of Melbourne, Carlton, Australia
- Otolaryngology, Department of Surgery, The University of Melbourne, East Melbourne, Australia
| | - Dimitra Stathopoulos
- The HEARing CRC, Carlton, Australia
- Department of Audiology and Speech Pathology, The University of Melbourne, Carlton, Australia
| | - Carrie Newbold
- The HEARing CRC, Carlton, Australia
- Department of Audiology and Speech Pathology, The University of Melbourne, Carlton, Australia
- Otolaryngology, Department of Surgery, The University of Melbourne, East Melbourne, Australia
| | - Jason Leavens
- Cochlear Ltd, Macquarie University, Sydney, Australia
| | - Frank Risi
- Cochlear Ltd, Macquarie University, Sydney, Australia
| | | | - Irfan Durmo
- Cochlear Ltd, Macquarie University, Sydney, Australia
| | - Robert Cowan
- The HEARing CRC, Carlton, Australia
- Department of Audiology and Speech Pathology, The University of Melbourne, Carlton, Australia
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