[Comparison of neural response telemetry thresholds with behavioral T/C levels]

Abstract

Objective: To provide an objective method to estimate T-levels and C-levels using neural response telemetry (NRT) thresholds for children, from whom we can not get accurate responses because they are very young or have other disabilities, by comparing NRT thresholds and T/C levels.

Methods: Seventy patients implanted with the nucleus CI24M multiple cochlear implant system participated in this study. 329 electrodes were tested. The software used in this study was NRT 2.04. Monopolar stimulation mode was used during NRT threshold measurement. No. 3, 5, 10, 15, 20 electrodes were tested for each patient. The T-levels and C-levels were obtained at the same visit.

Results: 92.7% of all the tested electrodes recorded NRT responses. There were variations in the amplitudes and thresholds of NRT responses across subjects and electrodes. NRT thresholds fell within the different points of the MAP dynamic range. The mean of NRT thresholds was shown to fall between the mean of T-levels and C-levels. The NRT thresholds and T/C levels reduced from basal to apical ends of the cochlear.

Conclusions: Considerable variability across subjects was noted. So it is difficult to estimate T-levels and C-levels accurately by testing only NRT thresholds only. NRT technology provides a new objective method for estimating T-levels and C-levels for children who are unable to cooperate with audiologists during mapping after operation. The new NRT technology should be improved in the future.