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

Evolution of Neural Response Imaging and psychophysics measurements over time

Meeting Abstract

  • corresponding author J. Guiraud - Department of Audiology and Otorhinolaryngology, CNRS UMR 5020, Lyon
  • E. Truy - Department of Head and Neck Surgery, Edouard Herriot Hospital, Lyon
  • L. Arnold - Advanced Bionics, Cambridge
  • P. Boyle - Advanced Bionics, Cambridge
  • L. Collet - Department of Audiology and Otorhinolaryngology, CNRS UMR 5020, Lyon

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. Doc05omci077

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/omci2005/05omci077.shtml

Veröffentlicht: 31. Mai 2005

© 2005 Guiraud 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

Neural Response Imaging (NRI) consists in measuring evoked compound action potentials (eCAPs) from the auditory nerve in cochlear implanted patients. It has been shown to relate to implant program levels (e.g. [1], [2]). However, evolution over time of this relationship has been less investigated and should nevertheless be taken into consideration as plastic properties of neural circuits may alter it.

Materials and Methods

Six children and four adults using HiResolution programs participated to the study. Measurements were done at first fitting of their implant, one week later, and at one, three and six months of implant use. NRI and most comfortable levels (M) were recorded at apical, medial and basal cochlear sites with Soundwave clinical software. 30 Hz rate stimulation was performed with biphasic, 32 µs width pulses for NRI measurement. The alternate polarity approach was used for artefact reduction. The M levels were measured with patients' programs parameters using a bracketing method.

Results

NRI couldn't be recorded from three patients: two of them had no NRI and one encountered an artifact problem. Visual NRI threshold (1stNRI) and extrapolated NRI threshold (tNRI) were considered. A Spearman correlation test showed that they both were significantly correlated over time, while M weren't. A repeated measures Analysis of Variance (ANOVA) showed that 1stNRI  and tNRI increased significantly over time for basal and apical electrodes only, while the M levels increased significantly for all electrode positions.

Conclusions

Correlation between tNRI and 1stNRI show that the algorithm to calculate the extrapolated NRI threshold is well written. A bigger sample of patients is required to investigate the relationship between tNRI, 1stNRI and M levels over time. NRI and behavioral data are still being collected.


References

1.
Firszt JB, Runge-Samuelson CL, Raulie J (2003). Comparisons of ECAP and High Resolution programming levels in the Clarion CII using single and multi-electrode stimulation techniques. Poster presented at the Conference on implantable auditory prostheses. Pacific Grove, CA, August, 2003.
2.
Novak MA, Overstreet EH, Thomas JF, Rotz LA, Black JM (2003). EABR and ECAP thresholds and growth function slopes: correlations with HiResolution program settings. Poster presented at the Conference on implantable auditory prostheses. Pacific Grove, CA, August, 2003.