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

Sources of ASSR artefacts at high stimulation levels in normal hearing subjects

Meeting Abstract

  • corresponding author L.H.M. Mens - Department of Otorhinolaryngology, University Medical Centre Nijmegen, the Netherlands
  • B.M.A. Luijten - Department of Otorhinolaryngology, University Medical Centre Nijmegen, the Netherlands
  • C.S. van der Reijden - Department of Otorhinolaryngology, University Medical Centre Nijmegen, the Netherlands
  • A.F.M. Snik - Department of Otorhinolaryngology, University Medical Centre Nijmegen, the Netherlands

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. Doc05omci004

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/omci2005/05omci004.shtml

Veröffentlicht: 31. Mai 2005

© 2005 Mens 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

To identify non-physiological sources of false-positive ASSRs at high stimulus levels (110 and 120 dB SPL).

Materials and Methods

The ASSR was recorded in normal hearing adults who did not hear the stimulus by using headphones with blocked housing placed behind the ears and adequate masking of the stimulus through insert phones. Tones of 0.5 and 2 kHz were presented simultaneously at both sides at 110 or 120 dB SPL for 4.4 minutes. The tones were 100% amplitude modulated and 20% frequency modulated ("Mixed-Mode" stimulus) or only amplitude modulated but expanded with multiple carriers ("Extended Stürzebecher" stimulus). Both 40 and 90 Hz modulation was tested. The EEG was recorded in six derivations simultaneously. Two electrodes were deliberately altered to produce a medium to high impedance. All recordings were made using two different amplifiers and two different types of headphones.

Results

Preliminary results showed many artefacts, which were caused by a malfunctioning amplifier. After replacement of the amplifier, results from the first subjects showed only a small number of artefacts under all conditions.

Conclusions

The possibility of artefacts is highly disturbing for clinicians, especially testing subjects at risk for large hearing losses. Apart from the specific false-positive rate found with this equipment, the significance of this study is that it proposes a method for each centre to verify the validity of ASSR testing at high stimulus levels as far as non-physiological sources of artefacts are concerned (that is, disregarding potential physiological responses of non-auditory origin).