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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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Processing of artifact in electrically evoked action potentials

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  • corresponding author M. Sainz - Dpto. Cirugía y sus Especialidades, Universidad de Granada, 18071 Granada, Spain
  • A. de la Torre - Dpto. Electrónica y Tecn. Comp., Universidad de Granada, 18071 Granada, Spain
  • C. Roldán - Servicio ORL, Hospital Universitario S. Cecilio, 18012 Granada, Spain
  • I. Álvarez - Dpto. Electrónica y Tecn. Comp., Universidad de Granada, 18071 Granada, Spain
  • H. Spitzer - Institute of Applied Physics, University Innsbruck, Austria
  • H. Schößer - Med-El Medical Electronics, Worldwide Headquarters, Innsbruck, Austria
  • K. Veekmans - Med-El Medical Electronics, Worldwide Headquarters, Innsbruck, Austria
  • J.M. Ortigosa - Dpto. Electrónica y Tecn. Comp., Universidad de Granada, 18071 Granada, Spain

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. Doc05omci087

The electronic version of this article is the complete one and can be found online at: http://www.egms.de/en/meetings/omci2005/05omci087.shtml

Published: May 31, 2005

© 2005 Sainz 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

Electrically evoked compound action potentials (ECAP) are strongly affected by stimulation artifact. In this study we analyze and compare different methods to process the stimulation artifact affecting the electrically evoked compound action potentials.

Materials and Methods

The methods for artifact processing considered are based on (1) the use of masked responses to subtract the artifact to the contaminated response; (2) the use of a tri-phase stimulus in order to control the transitory to the electrical perturbation in the vicinity of the stimulation electrode; and (3) the application of numerical methods to compensate for the stimulation artifact. In this analysis we include ECAP recordings from 5 patients implanted with a MED-EL Pulsar device. The responses were recorded by means of the auditory response telemetry incorporated in this cochlear implant.

Results

Even though the masking method sometimes provides appropriate cancellation of the artifact, since the artifact for a couple of stimuli is different to that for a single stimulus, sometimes the artifact is not appropriately cancelled and a false ECAP response appears. The use of tri-phase stimulus provides a more appropriate cancellation of the artifact because the electrical perturbation after the stimulation can be reduced with an appropriate configuration of this stimulus. This procedure does not produce false ECAP responses. Numerical methods must be carefully applied because the selection of an improper function to fit the response results in false ECAPs.

Conclusions

Tri-phase stimuli is a promising method for artifact cancellation in electrically evoked compound action potentials.