Increase in cochlear implant electrode impedances with the use of electrical stimulation

Abstract

Objective

Electrode impedances play a critical role in cochlear implant programming. It has been previously shown that impedances rise during periods of non-use, such as the post-operative recovery period. Then when the device is activated and use is initiated, impedances fall and are typically stable. In this study, we report a new pattern where electrode impedances increase with device use and decrease with device rest.

Design

Electrode impedances were measured three to four times every day over a span of 1–3 months for two cochlear implant patients.

Study sample

Two patients with a Nucleus cochlear implant participated in this study.

Results

Both subjects in this study show wide fluctuations in electrode impedances. By taking serial electrode impedance measurements throughout a day of use, we observe that electrode impedances consistently increase with device use and decrease with device rest.

Conclusion

In this study, we report two cases of electrode impedances increasing as a function of device use. Numerous management strategies were employed to reduce this effect but none prevailed; a clear pathophysiologic mechanism remains elusive. Further study into the cause of this electrode impedance pattern is warranted to establish a management strategy for these cochlear implant users.

Keywords:

• Electrode impedances
• cochlear implants
• rising pattern

Acknowledgment

The authors would like to thank our patients who invested their time and effort in generating such a detailed time series of electrode impedances. We are grateful to Dr. Jillian Crosson from Cochlear Americas for providing the equipment to perform these measurements.

Disclosure statement

Dr. Aniket A. Saoji is a consultant for Advanced Bionics and Envoy Medical. Dr. Colin L W Driscoll is a consultant for Advanced Bionics, Cochlear Corporation and Envoy Medical.

Institutional review board approval

This study was approved by the Mayo Clinic Institutional Review Board (#19-005759).

Additional information

Funding

The research hardware used in this study was provided by Cochlear Corporation.