Comparison of Neural Response Telemetry Threshold with Behavioral Response in Cochlear Implant / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: Electrically evoked compound action potential thresholds recorded using neural response telemetry can be used to set MAP thresholds (T-levels) and maximum comfort levels (C-levels) especially in children implanted with the Nucleus 24 device. However, the thresholds and C-levels change over time and the relationship between neural response telemetry (NRT) measurements and behavioral levels in children may also change. The purpose of this study was to apply the neural response threshold to the behavioral levels at the beginning (up to first 6 months). SUBJECTS AND METHOD: The neural response telemetry test was administered in 23 patients (mean age was 16.8) with Nucleus 24 device. Four intra-cochlear electrodes (electrodes 5, 10, 15, and 20) were tested. The behavioral threshold and the maximum comfort level at immediate, 1, 2, 3 and 6 months post-implantation were compared with the neural response threshold. RESULTS: Among 23 patients, 15 had their NRT thresholds within their dynamic range in the 6 months post-mapping period. Although the time when NRT thresholds comes within the dynamic range may differ from patient to patient, it was common finding that this occurred after 2 months of post-mapping in most of the patients. CONCLUSION: During the first few months of post-implantation, care must be exercised when interpreting NRT measurements.