Ectopic Stimulation Factors Limiting Cochlear Implant Outcomes

描述（由申请人提供）：平均而言，不同人工耳蜗（CI）系统的患者语音识别水平高度相似，但在使用相同器械的患者中观察到较大的结果差异。这些结果表明，显着的患者依赖性因素影响CI收件人的语音识别。我们已经注意到电刺激的异位部位的生理证据，可能会产生竞争性神经活动，并可能与性能下降。生理学观察结果是在固定电极上刺激的不同记录部位存在脑内诱发电位的系统潜伏期偏移。呈现这种现象的受试者通常报告竞争噪声和咕噜声/回声样声音，这些声音在某人说话时发生，并且对语音识别是恼人的和/或破坏性的。潜伏期移位现象最常观察到的是对具有平均至较差的语音识别的CI用户的顶端接触的刺激。基于这些和其他结果，我们假设在典型使用期间，在CI器械刺激期间可能发生两个空间上分离的兴奋部位。在这个探索性的为期两年的项目的主要目标是测试异位兴奋部位假说的具体预测，并评估替代刺激方法，可以尽量减少异位兴奋的发生。这些数据将提供新的信息外周功能障碍对患者的性能和替代优化参数，可能会改善CI收件人的结果的影响。这项工作是按照沿着三个具体目标组织的，包括（1）检验这样一个假设，即在顶端耳蜗中具有引起异位兴奋的更多数量的电极的受试者具有较低的语音识别分数，与设备类型无关;（2）通过检查各种刺激模式对增强和/或减弱异位兴奋的影响来检验异位兴奋假说，通过测试在脑干中继核的神经反应的预测的潜伏期偏移，以及将解剖学变化与异位兴奋的迹象的发生率相关联;以及（3）评估被识别为使异位激活最小化的刺激模式在被并入基于脉动的语音处理策略中时是否改善语音识别。 公共卫生相关性：该项目将增加对患者特定生理解剖特征的了解，这些特征可能在很大程度上决定或限制个体人工耳蜗植入患者的结局水平。这一知识将导致患者特定的拟合策略和定制声音处理器设计，其最佳地匹配信息编码与电极神经接口的性质。具体而言，该项目将重点关注人工耳蜗电刺激期间可能发生的神经激活的继发异位部位的发生。我们将探讨其产生的机制及其对语音识别的影响。最后，将评估旨在防止异位刺激发生的程序。

DESCRIPTION (provided by applicant): On average, patient speech recognition levels across different cochlear implant (CI) systems are highly similar, yet large outcome variation is observed across patients with the same device. These results indicate significant patient-dependent factors influence speech recognition in CI recipients. We have noted physiological evidence of an ectopic site of electrical stimulation that may produce competing neural activity and may be associated with diminished performance. The physiological observation is the presence of systematic latency shifts of intracochlear evoked potentials across different recording sites for stimulation on a fixed electrode. Subjects presenting with this phenomenon often report competing noise and grunt/echo-like sounds which occur when someone is speaking and are annoying and/or disruptive to speech recognition. The latency-shift phenomenon is observed most often with stimulation on apical contacts of CI users with average-to-poor speech recognition. Based on these and other results, we hypothesize that there are two, spatially-separate sites of excitation which may occur during stimulation with a CI device during typical use. The primary goals in this exploratory two-year project are to test specific predictions of the ectopic excitation site hypothesis and to evaluate alternative stimulation methods which may minimize the occurrence of ectopic excitation. These data will provide new information about the effects of peripheral deficits on patient performance and alternative optimization parameters that may improve the outcomes of CI recipients. The work is organized along three specific aims, including (1) to test the hypothesis that subjects with a greater number of electrodes eliciting ectopic excitation in the apical cochlea have lower speech recognition scores, independent of device type; (2) to test the ectopic excitation hypothesis by examining the effects of various stimulus modes on enhancing and/or diminishing ectopic excitation, by testing for predicted latency shifts of neural responses at brainstem relay nuclei, and correlating anatomical variation with the incidence of signs of ectopic excitation; and (3) to evaluate whether stimulation modes identified to minimize ectopic activation improve speech recognition when incorporated into pulsatile-based speech processing strategies. PUBLIC HEALTH RELEVANCE: This project will increase knowledge of patient-specific, physio-anatomical characteristics that may largely determine or limit outcome level in individual cochlear implant patients. This knowledge will lead to patient-specific fitting strategies and custom sound processor designs which best match information coding to the nature of the electrode nerve interface. Specifically, this project will focus on the occurrence of a secondary ectopic site of neural activation that may occur during electrical stimulation with a cochlear implant. The mechanisms of generation and consequences of its occurrence on speech recognition will be explored. Finally, procedures designed to prevent the occurrence of ectopic stimulation will be evaluated.