The standardization of electrically evoked stapedial reflex test (ESRT) and NRT test in terms of T level in cochlear implant patients

Main purpose of this study was to obtain standardization in the clinical use of ESRT, NRT and T Level in cochlear implant users. The relationship between ESRT, NRT and T Level was examined, as were the affects of stimulation parameters (pulse width, rate) in these measurements. The study was comprised of 54 users, aged from 7 to 71 years. Participants used Nucleus Freedom, 24 Contour and 24M Cochlear implants. NRT and ESRT measurements were performed and T Level determined. Measurements were performed using apical (22, 20), medial (10) and basal (5) electrodes. Pulse width proved much more affected in Freedom. T-NRT values were between T-NRT and ESRT in all models. T-NRT and T Level tended to rise from basal to apical. Stimulation rate did not affect test values significantly. The correlation between t-NRT and T Level was mildly significant and highest in Freedom. The correlation between t-NRT and ESRT was highly significant for all implants. Results suggest that when fitting a speech procesor with objective measurements test parameters, diffirences between implant models should be considered. Key Words: Cochlear implant, ECAP, NRT, electrically evoked stapedial reflex test, ESRT, T level.