Sanderson Alan P, Rogers Edward T F, Verschuur Carl A, Newman Tracey A
Institute of Sound and Vibration Research, Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom.
Institute for Life Sciences and Optoelectronics Research Centre, University of Southampton, Southampton, United Kingdom.
Front Neurosci. 2019 Jan 15;12:1048. doi: 10.3389/fnins.2018.01048. eCollection 2018.
Neuroprostheses designed to interface with the nervous system to replace injured or missing senses can significantly improve a patient's quality of life. The challenge remains to provide implants that operate optimally over several decades. Changes in the implant-tissue interface may precede performance problems. Tools to identify and characterize such changes using existing clinical measures would be highly valuable. Modern cochlear implant (CI) systems allow easy and regular measurements of electrode impedance (EI). This measure is routinely performed as a hardware integrity test, but it also allows a level of insight into the immune-mediated response to the implant, which is associated with performance outcomes. This study is a 5-year retrospective investigation of MED-EL CI users at the University of Southampton Auditory Implant Service including 176 adult ears (18-91) and 74 pediatric ears (1-17). The trend in EI in adults showed a decrease at apical electrodes. An increase was seen at the basal electrodes which are closest to the surgery site. The trend in the pediatric cohort was increasing EI over time for nearly all electrode positions, although this group showed greater variability and had a smaller sample size. We applied an outlier-labeling rule to statistically identify individuals that exhibit raised impedance. This highlighted 14 adult ears (8%) and 3 pediatric ears (5%) with impedance levels that deviated from the group distribution. The slow development of EI suggests intra-cochlear fibrosis and/or osteogenesis as the underlying mechanism. The usual clinical intervention for extreme impedance readings is to deactivate the relevant electrode. Our findings highlight some interesting clinical contradictions: some cases with raised (but not extreme) impedance had not prompted an electrode deactivation; and many cases of electrode deactivation had been informed by subjective patient reports. This emphasizes the need for improved objective evidence to inform electrode deactivations in borderline cases, for which our outlier-labeling approach is a promising candidate. A data extraction and analysis protocol that allows ongoing and automated statistical analysis of routinely collected data could benefit both the CI and wider neuroprosthetics communities. Our approach provides new tools to inform practice and to improve the function and longevity of neuroprosthetic devices.
旨在与神经系统接口以替代受损或缺失感官的神经假体能够显著提高患者的生活质量。然而，挑战依然存在，即要提供能在几十年内最佳运行的植入物。植入物与组织界面的变化可能先于性能问题出现。利用现有临床测量方法来识别和表征此类变化的工具将具有极高价值。现代人工耳蜗（CI）系统便于对电极阻抗（EI）进行轻松且定期的测量。此测量通常作为硬件完整性测试来执行，但它也能让我们对植入物的免疫介导反应有所洞察，而这种反应与性能结果相关。本研究是对南安普顿大学听觉植入服务中心的MED - EL CI使用者进行的为期5年的回顾性调查，包括176只成人耳朵（18 - 91岁）和74只儿童耳朵（1 - 17岁）。成人EI的趋势显示，顶端电极处的EI有所下降。在最靠近手术部位的基底电极处则出现了上升。儿童队列中，几乎所有电极位置的EI随时间都在增加，不过该组的变异性更大且样本量较小。我们应用了一种异常值标记规则来统计识别出阻抗升高的个体。这凸显了14只成人耳朵（8%）和3只儿童耳朵（5%）的阻抗水平偏离了群体分布。EI的缓慢变化表明耳蜗内纤维化和/或骨生成是潜在机制。对于极端阻抗读数的常规临床干预是停用相关电极。我们的研究结果凸显了一些有趣的临床矛盾之处：一些阻抗升高（但非极端）的病例并未促使电极停用；而许多电极停用的情况是由患者主观报告告知的。这强调了在临界病例中需要改进客观证据来指导电极停用，我们的异常值标记方法就是一个很有前景的候选方法。一种允许对常规收集的数据进行持续自动统计分析的数据提取和分析方案可能会使CI及更广泛的神经假体领域都受益。我们的方法提供了新工具来指导实践并改善神经假体装置的功能和使用寿命。
