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  4. Real-time Localization of Cochlear-Implant Electrode Arrays Using Bipolar Impedance Sensing

Real-time Localization of Cochlear-Implant Electrode Arrays Using Bipolar Impedance Sensing

AUTHORS

Bruns Trevor L. , Riojas Katherine E. , Labadie Robert F. , Webster Robert J. . IEEE Transactions on Bio-Medical Engineering. 2022 ; 69(2). 718-724

ABSTRACT

Objective: Surgeons have no direct objective feedback on cochlear-implant electrode array (EA) positioning during insertion, yet optimal hearing outcomes are contingent on placing the EA as close as feasible to viable neural endings. This paper describes a system to non-invasively determine intracochlear positioning of an EA, without requiring any modifications to existing commercial EAs themselves.

Methods: Electrical impedance has been suggested as a way to measure EA proximity to the inner wall of the cochlea that houses auditory nerve endings-the modiolus. In this paper, we extend prior work and demonstrate for the first time the relationship between bipolar access resistance and proximity of the EA to the modiolus (E-M proximity). We also evaluate two methods for producing direct, real-time estimates of E-M proximity from bipolar impedance measurements.

Results: We show that bipolar access resistance is highly correlated with E-M proximity and can be approximately modeled by a power law function. This one dimensional model is shown to be capable of producing accurate real-time estimates of E-M proximity, but its simplicity also limits the potential for future improvement. To address this challenge, we propose a new prediction approach based on a recurrent neural network, which generated an overall prediction accuracy of 93.7%.

Conclusion: Bipolar access resistance is highly correlated with E-M proximity, and can be used to estimate EA positioning.

Significance: This work shows how impedance sensing can be used to localize an EA during insertion into the small, enclosed cochlear environment, without requiring any modifications to existing clinically used EAs.

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