gms | German Medical Science

Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants

Medical University of Hannover

01.06. bis 04.06.2005, Hannover

Impedance variability during the programming of the speech processor

Meeting Abstract

  • corresponding author F. Toth - University of Szeged, Department of Otolaryngology, Szeged
  • J.G. Kiss - University of Szeged, Department of Otolaryngology, Szeged
  • J. Jarabin - University of Szeged, Department of Otolaryngology, Szeged
  • L.A. Nagy - University of Szeged, Department of Otolaryngology, Szeged
  • A. Szamoskozi - University of Szeged, Department of Otolaryngology, Szeged
  • A. Torkos - University of Szeged, Department of Otolaryngology, Szeged
  • J. Czigner - University of Szeged, Department of Otolaryngology, Szeged
  • J. Jori - University of Szeged, Department of Otolaryngology, Szeged

Medical University of Hannover, Department of Otolaryngology. Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants. Hannover, 01.-04.06.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05omci008

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/omci2005/05omci008.shtml

Veröffentlicht: 31. Mai 2005

© 2005 Toth et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Introduction

The most important step during the fitting of the speech processor is to determine the electrical comfort and threshold levels, which implies a series of psychophysical measurements. The intensity of the current that evokes hearing experience (hearing threshold level) and that evokes a tolerable loudness hearing comfort level) must carefully be determined on all electrodes. The electrodes implanted into the inner ear get surrounded with connective tissue which in turn lowers their impedance. According to our experience some impedance change takes place even during the process of speech processor fitting. Our aim was to demonstrate this effect.

Materials and Methods

We carried out impedance telemetry measurements on 76 cochlear implant patients before the fitting and right after it. 59 out of 76 patients used Nucleus 24 channel implants and 17 of them used MED-EL 12 channel implants. Measurements were taken during a two year period at every fitting.

Results

As a result we got that regardless of the type of the implant the impedance of the intracochlear electrodes decreased in most of the cases during fitting. The change shows some variability depending on the position of the electrodes and on the patient.

Conclusions

The change of the impedance causes the change of the electrical threshold- and comfort levels, since the same hearing sensation can only be reached with a stimulus with a different amplitude. This is why it is so important to bear this change in mind.