Fitting In Children Cochlear Implantees Using Neural Response Imaging And Evoked Stapedius Reflex

Objective:In order to give help for cochlear implantees to set the parameter of the speech processor,especially among infants,loners or multiple-deformity,we evaluate the clinic application of electrically evoked stapedius reflex(ESR) or neural responses imagine(NRI) under Fidelity 120 encoded strategy.Four cochlear electrodes(3,7,11 and 15) are stimulated as tested electrodes.We measure most comfortable level(M-levels),evoked stapedius reflex threshold(ESRT) and neural responses imagine threshold(tNRI).We aimed to answer the following research questions:in children using cochlear implants,1) is it feasible to record the NRI and ESR after the time of cochlear implantation? 2) What is the relation between tNRI and ESRT and electrodes location? 3) What is the relation between tNRI and ESR thresholds and M-levels? 4) What is the regression equation between tNRI and ESR thresholds and M-levels? Methods:Subject selection criteria were as following:cochlear implantees must have used Fidelity 120 HiRes 90K implant (Advanced Bionics Corporation,Sylmar,CA) and switched on at least 6 months, considerable ability of communication and experience of loudness scaling.A total of 20 prelingual children participated in the present study,and the mean age is 6.5 years(rang:3 to 13).M-levels were procured by perceptual measures,NRI threshold were measured by Soundwave 1.4 software,biphasic pulses(32 Ks per phase with no interphase gap,30 Hz stimulation rate,300 dB automatic gain control,128 frequency stratum super stratum) are delivered using monopolar coupling.The NRI amplitude is plotted as a function of stimulus intensity.A regression line is drawn,and the intersection point is defined as threshold NRI (tNRI),where ECAP amplitude is accepted as zero.All measurements were recorded using the alternating subtraction technique.We use tone burst stimulate the test electrode in SoundWave 1.4 software,and use a probe by otoflex 100 middle ear analysator place in the ear contralateral of the implanted ear to record ESR,we begin stimulating electric current from M-levels.If the baseline excursions exceed 0.05mmho,we judge the ESR is occurrence,and the minimum stimulating electric current is the ESRT,which can evoke the ESR.One-Way analysis of variance was used among for complete ESR threshold and NRI threshold,and linear correlation was used between ESR threshold or NRI threshold and M-levels all four test electrodes.Result:1) ESR was present in 70 of 80 electrodes(87.5%), and NRI was present in 75 of 80 electrodes(93.75%).2) the tendency general average of ESR threshold and NRI threshold is increase from apical part to basal part in cochlea,but One-Way analysis of variance indicated non-significant effect in ESRT and tNRI over electrode location(F=0.072,df=3/66,P＞0.05 and F=0.442,df=3/71,P＞0.05).3) there are strong linear correlation between ESRT and tNRI threshold and M-levels(r=0.91,P＜0.01) in four test electrodes.The regression equations are M=23.774+0.869ESRT and M=53.331+0.986tNRI between ESRT and tNRI and M-levels.Conclusion:ESR and NRI are easy and simply objective measures,and could provide helpful reference for the setting of M-levels.