Evaluation of streamlined programming procedures for the Nucleus cochlear implant with the Contour electrode array

The objective of this study was to evaluate streamlined programming procedures for the Nucleus cochlear implant system with the Contour electrode array.

Phase 1 involved an examination of the clinical MAPs for the first 103 recipients implanted with the Contour electrode array in the Melbourne Cochlear Implant Clinic, to examine the ability to predict the entire MAP based on a smaller number of clinically determined T- and/or C-levels. In phase 2, a subset of the streamlined procedures was selected and clinically evaluated, using speech perception and subjective preference measures. In the first study, the clinical MAP was compared with a MAP based on interpolating across three behavioral T-levels and three behavioral C-levels in a group of newly implanted subjects. The second study investigated the use of a single interpolated profile as the basis to creating the entire MAP. Initial evaluation compared the clinical MAP with two streamlined MAPs, one in which the C-level profile was derived from interpolation across a subset of T-levels and one in which the T-level profile was derived from interpolation across a subset of C-levels. In this case, the interpolated profile was based on five behavioral measures. Subsequently, the use of either three or a single T-level measure as the basis for the interpolated T-level profile was evaluated. Eighteen subjects, who were experienced with the clinical MAP before enrollment in the study, participated in the initial evaluation. The subjects were selected to include a group whose RMS deviation from clinical MAP levels, as determined in Phase 1, was greater than that of the wider population.

The Phase 1 analysis showed that as expected, larger differences were observed between the clinical and derived MAP levels as interpolation was applied across fewer measured electrodes and that the use of a single interpolated profile to create the entire MAP resulted in the greatest deviation. No significant group mean difference was found in speech perception scores for newly implanted subjects when mapped with the clinical versus the streamlined MAP based on three behavioral T- and three behavioral C-level measures. For some individual subjects, scores were higher with the streamlined MAP. Subjective reports from the comparative performance questionnaire were consistent with these findings. No significant group mean difference in speech perception scores was found in comparing the clinical MAP with the streamlined MAPs based on a single interpolated T- or C-level profile created from five behavioral measures. Individual effects were observed; however, there was no consistent finding across subjects. The use of three rather than five behavioral T-level measures in the procedure did not result in significantly lower group mean scores; however, significantly poorer scores were obtained for three of the 10 individual subjects. The use of a MAP based on a single behavioral measure did result in poorer speech perception scores when compared with the MAP based on five behavioral T-level measures. These findings were consistent with subjective results from the performance questionnaires administered to determine preference for program across a range of listening situations.

Two streamlined programming procedures are recommended for use in the clinical setting: (1) interpolating across three measured T-levels and three measured C-levels and (2) interpolating across five measured T- or C-levels and using the interpolated profile for fitting of the alternative profile.