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Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants

Medical University of Hannover

01.06. bis 04.06.2005, Hannover

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Measurement of Neural Spread of Excitation and Perceptual Channel Determination: an Objective Way of Excluding Electrodes from a User's Program?

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  • corresponding author J. Guiraud - Unité CNRS UMR 5020 Laboratoire 'Neurosciences et Systèmes Sensoriels, Lyon, France ; Service d'Audiologie et d'Explorations Orofaciales, Hôpital Edouard Herriot, Lyon, France
  • A. Norena - 1) Unité CNRS UMR 5020 Laboratoire 'Neurosciences et Systèmes Sensoriels, Lyon, France; 2) Service d'Audiologie et d'Explorations Orofaciales, Hôpital Edouard Herriot, Lyon, France
  • E. Truy - 1) Unité CNRS UMR 5020 Laboratoire 'Neurosciences et Systèmes Sensoriels, Lyon, France; 2) Service d'Audiologie et d'Explorations Orofaciales, Hôpital Edouard Herriot, Lyon, France
  • L. Arnold - Advanced Bionics Clinical Research Department, Croydon, United Kingdom
  • P. Boyle - Advanced Bionics Clinical Research Department, Croydon, United Kingdom
  • L. Collet - 1) Unité CNRS UMR 5020 Laboratoire 'Neurosciences et Systèmes Sensoriels, Lyon, France; 2) Service d'Audiologie et d'Explorations Orofaciales, Hôpital Edouard Herriot, Lyon, France

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. Doc05omci078

The electronic version of this article is the complete one and can be found online at: http://www.egms.de/en/meetings/omci2005/05omci078.shtml

Published: May 31, 2005

© 2005 Guiraud et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

Text

Introduction

When programming cochlear implants it is important to consider the user’s ability to discriminate between different pitches. Each electrode should be distinct from its neighbours both spatially and temporally. This work’s objective was to determine whether neural spread of excitation measure and pitch ranking may be used to improve a program by identifying electrodes to switch off.

Materials and Methods

Spread of excitation was measured using the cochlear mapping approach implemented in the Neural Response Imaging test bench. Stimulation waveforms were 32 µs per phase biphasic pulses delivered at 75% of the subject’s dynamic range, at a 30 Hz rate. Using software written to identify perceptual channels the subject was asked to identify the higher of two pitches produced by automatic adjustment of the current delivered simultaneously to pairs of adjacent electrode.

Results

Perceptual channel testing in the mid region showed 3 intermediate channels between electrodes 8 and 9. Apical testing was less conclusive. Basal testing was not performed due to partial insertion. Interesting cochlear mapping results were also obtained .

Conclusions

These results confirmed the theoretical ability to create intermediate channels. The provision of additional channels could be useful for this subject where only twelve electrodes were inserted into the cochlea. Further work is required to investigate the relationship between pitch ranking, spatial spread and performance.