Calculation of the Faradaic Impedance of the Electrode-Tissue Interface Improves Prediction of Behavioral T/C Levels in Cochlear Implant Patients

BACKGROUND: Fitting of cochlear implants is a labor-intensive process, and therefore automated fitting procedures are being sought. The objective of this study was to evaluate if decomposition of the complex impedance of the electrode-tissue interface could provide additional parameters that show im...

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Bibliographic Details
Published in:Journal of International Advanced Otology 2023-09, Vol.19 (5), p.368-375
Main Authors: Zarowski, Andrzej, Leblans, Marc, Molisz, Andrzej, Sismono, Fergio, Dinther, Joost van, Offeciers, F. Erwin
Format: Article
Language:English
Subjects:
Automation
Cochlear implants
Electrodes
Electrolytes
Implants, Artificial
Medical research
Medicine, Experimental
Original
Otolaryngology
Patients
Prosthesis
Statistical analysis
Transplants & implants
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Summary:BACKGROUND: Fitting of cochlear implants is a labor-intensive process, and therefore automated fitting procedures are being sought. The objective of this study was to evaluate if decomposition of the complex impedance of the electrode-tissue interface could provide additional parameters that show improved correlation with the behavioral T/C levels. METHODS: A new method for decomposing the complex impedance of the electrode-tissue interface was developed and tested in 18 patients in a prospective study in a tertiary otologic referral center. RESULTS: The averaged near-field Faradaic resistance (RF) calculated in study subjects shows a very strong correlation (R (2) = 0.80) with the behavioral C levels and can be used for automated fitting in most patients. The standard deviation for the T levels and the C levels calculated for each of the electrode contacts in all study subjects is in the range of 10-15 CL and 15-20 CL, respectively. These higher values of the standard deviations are caused by a few outliers who require that additional parameters have to be added to the metric equation, allowing for the automated prediction of the T/C levels. CONCLUSION: A new method for deriving information from the electrode impedance measurements shows excellent correlation of the Faradaic resistance with the behavioral T/C levels in most patients and can be very useful for fitting cochlear implants based on objective measures. Since some patients still show discrepancies between the predicted T/C levels based on the [R.sub.F] calculation, additional parameters have to be added to the metric equation, allowing for automated prediction of the T/C levels. KEYWORDS: Cochlear implants, Faradaic, impedance, corresponding circuit, behavioral, T/C level
ISSN:1308-7649
2148-3817
DOI:10.5152/iao.2023.23695