小儿耳蜗植入后电诱发复合动作电位的阈值及其临床应用

目的：研究应用神经反应遥测（neural response telemetry,NRT)技术，测试电诱发复合动作电位（electrically-evoked compound action potential,ECAP)阈值以指导小儿人工耳蜗映射调图的策略与时机。方法：应用NRT3．0软件对辐值增长函数进行线性拟合，确定ECAP阈值。比较6例儿童植入者在术后1、2、3个月ECAP阈值的变化，同时比较了7例儿童术中、术后ECAP阈值的差异。结果：ECAP幅值增长函数在接近阈值或进入饱和时不再呈线性。术后ECAP阈值保持稳定。各导电极的术中ECAP阈值比术后阈值平均高约15CL，二者有显著性相关（R2＝0．9154）。结论：应选取幅值增长函数的直线段部分进行拟合以确定ECAP阈值。术后应用ECAP阈值指导小儿映射调图时，测试一次ECAP阈值即可。术中ECAP阈值可用作开机时映射图的C值。

Electrically evoked compound action potential thresholds of pediatric cochlear implant recipients and its clinical application]

OBJECTIVE: To investigate the possibility of using pediatric cochlear implant mapping protocol, to estimate the psychophysical levels based on the electrically evoked compound action potential (ECAP) threshold measured with the neural response telemetry (NRT) capabilities of cochlear corporation's CI24M device. METHODS: ECAP amplitude growth functions were regressed via NRT 3.0 software to determine ECAP threshold. 6 pediatric cochlear implant recipients' ECAP thresholds 1, 2 and 3 months after surgery were compared, meanwhile, intraoperative and postoperative ECAP thresholds in 7 pediatric recipients were compared. RESULTS: The ECAP amplitude growth functions were not linear when ECAP was close to threshold or saturation. There were no significant difference among the ECAP thresholds 1, 2 and 3 months after surgery. The average intraoperative ECAP threshold of 22 electrodes was 15 CL greater than postoperative threshold. It showed high relationship between them (R2 = 0.9154). CONCLUSION: ECAP threshold should be determined by regression of data from linear part of amplitude growth function. Only one NRT trial should be assessed when mapping protocol based on ECAP threshold to estimate pediatric map parameter. The intraoperative ECAP threshold can act as C-level at the initial mapping. Key words cochlear implant, electrically evoked compound action potential, mapping.