Analysis of electrode impedance and its subcomponents for lateral wall, mid-scala, and perimodiolar electrodes in cochlear implants

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.

Keywords:

• Access resistance
• Polarization impedance
• Warburg capacitance
• Faraday resistance
• Cochlear implants

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Notes on contributors

Aniket A. Saoji

Aniket A. Saoji is an Associate Professor of Otolaryngology in the Department of Otolaryngology-Head and Neck Surgery at the Mayo Clinic Alix School of Medicine. He is the Director of the Cochlear Implant Program at Mayo Clinic, Rochester, Minnesota.

Madison Graham

Madison Graham is a clinical Audiologist in the Division of Audiology at the Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota.

Amy Stein

Amy Stein is a Principal Research Audiologist in the Clinical Product Development Department at Advanced Bionics LLC.

Kanthaiah Koka

Kathaiah Koka is a Principal Research Scientist in the Department of Research and Technology at Advanced Bionics LLC.