1 Department of Speech and Hearing Sciences, University of Washington, Seattle, WA, USA.
2 Massachusetts Eye and Ear, Department of Otolaryngology, Harvard Medical School, Boston, MA, USA.
Trends Hear. 2019 Jan-Dec;23:2331216519862987. doi: 10.1177/2331216519862987.
Modeling data suggest that sensitivity to the polarity of an electrical stimulus may reflect the integrity of the peripheral processes of the spiral ganglion neurons. Specifically, better sensitivity to anodic (positive) current than to cathodic (negative) current could indicate peripheral process degeneration or demyelination. The goal of this study was to characterize polarity sensitivity in pediatric and adult cochlear implant listeners (41 ears). Relationships between polarity sensitivity at threshold and (a) polarity sensitivity at suprathreshold levels, (b) age-group, (c) preimplantation duration of deafness, and (d) phoneme perception were determined. Polarity sensitivity at threshold was defined as the difference in single-channel behavioral thresholds measured in response to each of two triphasic pulses, where the central high-amplitude phase was either cathodic or anodic. Lower thresholds in response to anodic than to cathodic pulses may suggest peripheral process degeneration. On the majority of electrodes tested, threshold and suprathreshold sensitivity was lower for anodic than for cathodic stimulation; however, dynamic range was often larger for cathodic than for anodic stimulation. Polarity sensitivity did not differ between child- and adult-implanted listeners. Adults with long preimplantation durations of deafness tended to have better sensitivity to anodic pulses on channels that were estimated to interface poorly with the auditory nerve; this was not observed in the child-implanted group. Across subjects, duration of deafness predicted phoneme perception performance. The results of this study suggest that subject- and electrode-dependent differences in polarity sensitivity may assist in developing customized cochlear implant programming interventions for child- and adult-implanted listeners.
建模数据表明，对电刺激极性的敏感性可能反映了螺旋神经节神经元的外周过程的完整性。具体来说，对阳极（正）电流的敏感性优于对阴极（负）电流的敏感性可能表明外周过程退化或脱髓鞘。本研究的目的是描述儿科和成年人工耳蜗植入者（41 耳）的极性敏感性。在阈值处的极性敏感性与（a）阈上水平的极性敏感性、（b）年龄组、（c）耳聋前植入时间、（d）语音感知之间的关系。在阈值处的极性敏感性定义为在响应两个三相脉冲中的每一个时测量的单通道行为阈值之间的差异，其中中央高幅度相为阴极或阳极。对阳极的响应比对阴极的响应的阈值较低可能表明外周过程退化。在大多数测试的电极上，阈值和阈上敏感性对于阳极刺激比对于阴极刺激更低；然而，阴极刺激的动态范围通常比阳极刺激更大。儿童和成人植入者之间的极性敏感性没有差异。植入前耳聋时间较长的成年人在与听神经接口估计较差的通道上对阳极脉冲的敏感性往往更好；在儿童植入组中没有观察到这种情况。在所有受试者中，耳聋持续时间预测语音感知表现。本研究的结果表明，个体和电极依赖性的极性敏感性差异可能有助于为儿童和成人植入者开发定制的人工耳蜗编程干预措施。
