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Performing Repeated Intraoperative Impedance Telemetry Measurements during Cochlear Implantation

Published: August 4th, 2023



1Department of Otorhinolaryngology-Head and Neck Surgery, Ruhr-University Bochum, St. Elisabeth-Hospital Bochum, 2Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, 3International Graduate School of Neuroscience (IGSN), Ruhr-University Bochum, 4Technical University of Munich, 5Department of Otorhinolaryngology, TUM School of Medicine, Klinikum rechts der Isar, 6MED-EL, 7Department of Otorhinolaryngology and Head & Neck Surgery, Antwerp University Hospital, 8Department of Otorhinolaryngology-Head and Neck Surgery, Medical University Innsbruck

Here we present a protocol to conduct repeated impedance telemetry measurements during cochlear implantation (CI). They may allow conclusions on the electrode's and implant's function. Repeated impedance measurements enable objective feedback on whether the electrode is positioned inside the perilymph or outside the inner ear.

Impedance measurements are routinely performed during cochlear implantation (CI) after finalized electrode insertion. They may allow conclusions on the electrode's and implant's function. In the postoperative setting, the analysis of impedance changes enables the identification of scarring or inflammation processes around the electrode. Recent studies report associations between impedance telemetry and the site of stimulation. Consequently, repeated impedance measurements during cochlear implant electrode insertion may enable objective feedback on whether the electrode is positioned inside the perilymph or outside the inner ear. With the presented novel method, impedances can be measured in real-time during cochlear implantation. This protocol systematically explains how to perform repeated impedance recordings during CI surgery. These repeated measurements are challenging since they depend on multiple intraoperative methodological factors starting with the draping of the patient. Thus, for successful recordings, a standardized procedure is mandatory. In this article, we comprehensively illustrate the system setup and procedure of performing intraoperative measurements during CI surgery.

Preserving residual hearing is an increasing topic of interest in cochlear implantation (CI) surgery, and the indication has changed towards candidates with functional residual hearing. Thus, measurements that may objectify the position of the electrode array and the resulting potential intracochlear damage during surgery are becoming increasingly important. CI-users with successfully preserved hearing have been shown to have superior hearing performance with the implant after surgery, even when stimulated electrically-only1. Some of them may additionally benefit from acoustic stimulation (electro-acoustic stimulation; EAS). Perioperative heari....

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This protocol was approved by the local Ethics Committee in accordance with the Helsinki Declaration (Ruhr-University Bochum: Reg.-No.: 21-7373; Medical University Innsbruck Reg.-No.: 1060/2021). Informed consent was obtained from all participants.

1. Preparation for the surgery

  1. Make sure to obtain audiological testing reports, including pure-tone audiometry, objective testing (e.g., brainstem evoked response audiometry, speech testing), and vestibular diagnostics .......

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For repeated impedance measurements during cochlear implantation, a standardized procedure is mandatory to achieve the highest possible reproducibility. The major aspects that have been considered to play an important role are the video quality as well as the insertion angle. Both may impede the visualization of the electrode contacts entering the round window and thus, the interpretation of the video for future analyses. Further, the placement of the receiver coil is crucial to prevent interruptions during insertion and.......

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Repeated impedance measurements are a promising approach to gain real-time feedback from the cochlea during the insertion process. They indicate which electrode contacts are positioned inside the perilymph or not. With the here presented novel method for flexible lateral wall electrodes (MED-EL, Innsbruck, Austria)7, impedances may be measured in real-time during cochlear implantation utilizing the inserting electrode array. However, for reliable measurements, a standardized procedure is cruc.......

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NameCompanyCatalog NumberComments
AudacityOpen source editor software
Coil cableAny appropriate brandImplant interface
ComputerAny appropriate brand
Electrode arrayMED-EL, FlexSoft, Flex28
IM SoftwareMED-EL
MAX Interface USBAny appropriate brandInterface connection
OcteniseptSCHÜLKE & MAYR GmbHN/A
Open Broadcaster SoftwareOpen source recording software
Spongostan EthiconN/AResorbable sponge
Ultracain 1% Suprarenin, SanofiN/ALocal anesthesia

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