Article
Cochlear microphonics for monitoring the function of the inner ear – Comparison of intra- and extracochlear recordings
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Published: | September 7, 2016 |
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Introduction: In the last years new cochlear implant (CI) electrodes were developed which aim to preserve the residual hearing during implantation. This is successful in most of the cases. Nevertheless it is desirable to have a monitoring during the insertion of the electrode. The aim is to identify critical steps as well as to modify the ongoing insertion procedure immediately if necessary.
Method: Within the insertion of hearing preserving electrodes cochlear microphonics (CMs) were recorded. This took place at different times during the insertion. Up to now in 28 patients CMs were recorded extracochlearly using a cotton wick electrode placed at the promontory wall. Furthermore, in three patients the CMs were recorded intracochlearly using special recording contacts in the tip of the CI electrode (MedEl, based on the Flex20-electrode). The stimulation was done acoustically using insert earphones and tone bursts (250 Hz, 500 Hz, 1 kHz, 2 kHz and 4 kHz).
Results: Extracochlearly in most of the patients peaks of up to 0.5 uV were detected in the according spectrum at maximum stimulation. Intracochlearly peaks of up to 20 uV were found.
Conclusion: Altogether the recording of CMs during the CI insertion is possible. With intracochlear recordings the amplitudes are by far higher than with extracochlear recordings. For a more detailed analysis the obtainment of additional data sets is necessary.
Supported by: DFG Cluster of Excellence Hearing4 All