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，但使用相同设备的患者之间观察到巨大的结果差异。这些结果表明，患者依赖的因素显著影响CI接受者的语音识别。我们注意到了电刺激异位部位的生理学证据，这可能会产生竞争性的神经活动，并可能与表现下降有关。生理观察是指在固定电极上刺激时，不同记录部位的耳壳内诱发电位的系统性潜伏期移位。出现这种现象的受试者经常报告说，当有人说话时，会出现相互竞争的噪音和咕噜声/类似回声的声音，这些声音令人讨厌和/或扰乱了语音识别。潜伏期漂移现象最常在语音识别能力一般到较差的CI使用者的心尖接触上观察到。基于这些和其他结果，我们假设在典型使用期间，在CI设备的刺激过程中可能会出现两个空间上分离的激发点。这个为期两年的探索性项目的主要目标是测试异位激发部位假说的具体预测，并评估可将异位激发的发生降至最低的替代刺激方法。这些数据将提供有关外周缺陷对患者表现的影响的新信息，以及可能改善CI接受者结果的替代优化参数。这项工作按照三个具体目标组织，包括(1)检验假设，即在耳蜗尖诱发异位兴奋的电极数量越多，受试者的语音识别分数越低，与设备类型无关；(2)检验异位兴奋假说，通过检测各种刺激模式对增强和/或减弱异位兴奋的影响，通过测试脑干中继核团神经反应的预测潜伏期偏移，并将解剖变化与异位兴奋迹象的发生率相关联；以及(3)评估被确定为最大限度地减少异位激活的刺激模式在结合基于脉动的语音处理策略时是否改善了语音识别。 公共卫生相关性：该项目将增加对特定患者的生理解剖学特征的了解，这些特征可能在很大程度上决定或限制单个人工耳蜗植入患者的预后水平。这一知识将导致患者特定的配对策略和定制的声音处理器设计，使信息编码与电极神经接口的性质最佳匹配。具体地说，这个项目将专注于神经激活的继发性异位部位的发生，这可能发生在人工耳蜗电刺激过程中。我们将探讨它的产生机制及其对语音识别的影响。最后，将对旨在防止异位刺激发生的程序进行评估。

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.