Scheperle Rachel A
Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA 52242, United States.
J Otol. 2017 Mar;12(1):18-28. doi: 10.1016/j.joto.2017.01.001. Epub 2017 Jan 7.
Electrically evoked compound action potential (eCAP) amplitudes elicited at suprathreshold levels were assessed as a measure of the effectiveness of cochlear implant (CI) stimulation. Twenty-one individuals participated; one was excluded due to facial stimulation during eCAP testing. For each participant, eCAPs were elicited with stimulation from seven electrodes near the upper limit of the individual's electrical dynamic range. A reduced-channel CI program was created using those same seven electrodes, and participants performed a vowel discrimination task. Consistent with previous reports, eCAP amplitudes varied across tested electrodes; the profiles were unique to each individual. In 6 subjects (30%), eCAP amplitude variability was partially explained by the impedance of the recording electrode. The remaining amplitude variability within subjects, and the variability observed across subjects could not be explained by recording electrode impedance. This implies that other underlying factors, such as variations in neural status across the array, are responsible. Across-site mean eCAP amplitude was significantly correlated with vowel discrimination scores (r = 0.56). A single eCAP amplitude measured from the middle of the array was also significantly correlated with vowel discrimination, but the correlation was weaker (r = 0.37), though not statistically different from the across-site mean. Normalizing each eCAP amplitude by its associated recording electrode impedance did not improve the correlation with vowel discrimination (r = 0.52). Further work is needed to assess whether combining eCAP amplitude with other measures of the electrode-neural interface and/or with more central measures of auditory function provides a more complete picture of auditory function in CI recipients.
将阈上水平诱发的电诱发复合动作电位（eCAP）幅度作为人工耳蜗（CI）刺激效果的一项指标进行评估。21名个体参与研究；1名因在eCAP测试期间出现面部刺激而被排除。对于每位参与者，在其电动态范围上限附近的七个电极进行刺激来诱发eCAP。使用相同的七个电极创建了一个通道减少的CI程序，参与者执行元音辨别任务。与之前的报告一致，eCAP幅度在各测试电极间存在差异；其分布模式因人而异。在6名受试者（30%）中，eCAP幅度变异性部分可由记录电极的阻抗来解释。受试者内部剩余的幅度变异性以及受试者间观察到的变异性无法通过记录电极阻抗来解释。这意味着其他潜在因素，如阵列中神经状态的变化，是其原因所在。跨位点的平均eCAP幅度与元音辨别分数显著相关（r = 0.56）。从阵列中部测量的单个eCAP幅度也与元音辨别显著相关，但相关性较弱（r = 0.37），尽管与跨位点平均值在统计学上无差异。将每个eCAP幅度除以其相关记录电极阻抗进行归一化处理，并未改善与元音辨别之间的相关性（r = 0.52）。需要进一步开展工作，以评估将eCAP幅度与电极 - 神经界面的其他测量指标和/或与听觉功能的更中枢性测量指标相结合，是否能更全面地反映CI接受者的听觉功能。
