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Influence of the Insertion Depth of the Cochlear Implant Electrode on the Intra-Operative Electrophysiological Results in the Treatment with CI532 Implants
Do the insertion depth of the electrode array with an attempt to optimize the perimodiolar position by the so-called pull-back technique (Basta et al., 2010) and the cochlea-close fixation method with the "Kiel knot" influence the intra-operative electrophysiological results in cochlear implant recipients?
In 31 post-lingual deaf adults with complete round-window insertion into the Scala tympani (without scale dislocation or tip fold-over) with a CI532 implant, the ECAP (electrically evoked compound action potential) thresholds at insertion depth of 1st marker, after array pull-back to the 3 rd marker as well as after fixation and CI electrode impedances were analysed intra-operatively, and compared with previous Kiel studies with CI512/CI RE (CA).
Statistically significant lower ECAP thresholds at the insertion depth marker ring 3 compared to marker 1 for the single electrodes E1 – 5, E8 and E10 – 12 (p < 0.05). In the basal electrodes E1 – 5 significantly higher ECAP thresholds compared to CI512/CI RE (CA). Apical lower electrode impedances in CI532 compared to CI512/CI RE (CA). There was no influence by the fixation method "Kiel Knot".
In comparison with results of CI512/CI RE (CA) (at middle marker), the CI532 electrode at insertion depth at 1. marker has basal higher ECAP thresholds which increase further after retraction to the 3 rd marker, so that the pull-back technique is not recommended. Further investigation will require whether there is an optimal CI insertion depth for the CI532, and whether withdrawing perimodiolar preformed CI electrodes have a positive impact on speech intelligibility with respect to electrophysiology.
23 April 2019 (online)
© 2019. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).
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