Comparison of EAP thresholds with MAP levels in the nucleus 24 cochlear implant: Data from children

Objective: The purpose of this study is to examine the relationship between the electrically evoked compound action potential (EAP) thresholds and the MAP thresholds (T-levels) and maximum comfort levels (C-levels) in childre n implanted with the Nucleus 24 device. Design: EAP thresholds were measured using the Neural Response Telemetry sy stem of the Nucleus 24 device. Twenty children implanted with the Nucleus 2 4 cochlear implant participated in this study. EAP thresholds were compared with the behavioral measures of T- and C-level used to construct the MAP t hese children used on a daily basis. For these subjects, both EAP and MAP T - and C-levels were obtained the same visit, which occurred at 3 to 5 mo po stconnection. Results: EAP thresholds were shown to fall between MAP T- and C-level for 1 8 of 20 subjects tested; however, considerable variability across subjects was noted. On average, EAP thresholds fell at 53% of the MAP dynamic range. Correlations between EAP threshold and MAP T- and C-level improved substan tially when combined with behavioral measures obtained from one electrode i n the array. Conclusions: Moderate correlations were found between EAP thresholds and MA P T- and C-levels for the children participating in this study. However, a technique is described for improving the accuracy of predictions of MAP T- and C-levels based on EAP data combined with a small amount of behavioral i nformation.