AO Journal Group: Comparison of Physiological and Behavioral Measures for Two Cochlear Implant Arrays

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This article review was submitted Michelle L. Hughes, Ph.D., who is the Coordinator for the Cochlear Implant Program for the Boys Town National Research Hospital and a Contributing Editor for Audiology Online in the area of cochlear implants.

Article:

Polak, M., Hodges, A. & Balkany, T. (2005). ECAP, ESR and subjective levels for two different Nucleus 24 electrode arrays. Otology & Neurotology, 26, 639-645. www.otology-neurotology.com

Summary:

This study compared two physiologic measures to behavioral programming levels for subjects with two different cochlear implant electrode arrays. The purpose of the study was to determine whether physiologic measures relate to behavioral measures in a different way for two electrode array designs. Physiologic measures consisted of electrically evoked compound action potential (ECAP) thresholds and electrically evoked stapedial reflex thresholds (ESRTs). Behavioral levels consisted of threshold (T-level) and maximum comfort levels (C-levels) for the 250-pps SPEAK speech processing strategy for 15 adults implanted with the Nucleus 24M straight array and 15 adults implanted with the Nucleus 24R(CS) Contour array.

The results showed no difference in T-levels, C-levels, ECAP thresholds, or ESRTs between the two device types. Mean C-levels were 192 programming units (PU) for the straight array and 196 PU for the Contour array. Mean T-level was 160 PU for both groups. Mean ESRT and ECAP threshold was 193 PU and 182 PU, respectively, for the straight array and 192 PU and 183 PU, respectively, for the Contour. For both electrode array groups, ESRTs were strongly correlated with C-level (r = 0.93 for straight array; r = 0.95 for Contour array) and ECAP thresholds fell at about two-thirds of the behavioral dynamic range. The results from this study suggest that objective measures can be used to set behavioral levels in the same way for either the Nucleus straight or Contour electrode array.