Artikel
On the variability of intracochlear measured threshold profiles of electrically evoked compound action potentials of cochlear implant patients
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Veröffentlicht: | 8. Juli 2008 |
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Gliederung
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Introduction: The thresholds of electrically evoked compound action potentials (ECAP) are increasingly used to program speech processors of cochlear implant patients. The AutoNRTTM of Cochlear provides a quite reliable system to automatically derive the ECAP-thresholds. However, occasionally occurring variations in this profile are not reflected in the profile of the C(“comfort”)-levels [Ref. 1].
Methods: At the MHH all patients supplied with a Nucleus RE24-CA „Freedom“-implant are routinely subject to AutoNRT measurements, which are evaluated across the entire electrode array (22 electrodes). In this work the variability of the ECAP-profiles is further researched. It is analysed, if the variations can be explained either by so called T-tails, either by measurement uncertainties, or if they remain stable over time.
Results: Two classes of temporal variations can be identified: A) A displacement of the entire profile, B) An alteration of the thresholds of single electrodes. In one case, both the average ECAP-threshold and the C-level increases up to more then 30CL within 3 months. In another case, a particular ECAP-threshold alters about 90CL, whereas the corresponding C-level only changes about 20CL.
Conclusion and outlook: Although T-tail effects could be detected, they cannot sufficiently explain the observed variability of the ECAP-profile.
References
- 1.
- Gärtner L, Büchner A, Battmer RD, Lenarz T. Anpassung von Cochlea-Implantat-Patienten unter Anwendung eines automatischen Systems zur Aufzeichnung und Auswertung von elektrisch evozierten Summenaktionspotentialen. GMS Curr Posters Otorhinolaryngol Head Neck Surg. 2007;3:Doc71 (20070425). Verfügbar unter: http://www.egms.de/en/journals/cpo/2007-3/cpo000336.shtml