Functional monitoring of peripheral nerves from electrical impedance measurements.
Functional monitoring of peripheral nerves from electrical impedance measurements.
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DOI：
10.1016/j.jphysparis.2017.05.003
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发表时间：
2016-11-01
期刊：
影响因子：
--
通讯作者：
David, Olivier
中科院分区：
文献类型：
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作者：
Fouchard, Alexandre;Coizet, Veronique;David, Olivier
适用于周围神经的医用电刺激器使用多接触袖带电极（MCC）提供选择性神经接口。然而，神经假体目前由于无法定位感兴趣的区域而受到限制。到目前为止，MCC要么用于刺激，要么用于记录，它也可以作为一种传导手段，通过阻抗测量来表征神经。在这项研究中，我们探讨了使用电阻抗（EI）测量作为体内功能神经监测技术的可行性。监测范式包括以复合动作电位（CAP）形式同步记录诱发的内源性活动和来自EI探针的叠加正弦信号。对鼠类的坐骨神经进行测量，选择其分支为腓神经和胫神经，每节使用单触点和多触点电极。在刺激阶段，记录显示CAP具有一致的纤维传导速度。在刺激和正弦扰动的耦合阶段，使用单接触电极类型提取特定频率（例如2.941kHz）的阻抗变化，并与先前记录的CAP在时间上一致。使用MCC，也记录了局部诱发的CAP，但信噪比（SNR）过低，无法区分预期的相关阻抗变化，并推断出神经内阻抗空间变化的图像。在体内进行的测量可以区分诱发的CAP和相关的阻抗变化，具有很强的时间相关性。这表明功能性EI监测的可行性，旨在检测与神经活动相关的阻抗变化。进一步的工作需要改进体内系统，即在信噪比方面，并集成新的多接触设备，以便向具有空间局部阻抗变化检测的EI断层扫描发展。最终，通过这些方法可以识别出刺激的目标区域。
Medical electrical stimulators adapted to peripheral nerves use multicontact cuff electrodes (MCC) to provide selective neural interfaces. However, neuroprostheses are currently limited by their inability to locate the regions of interest to focus. Intended until now either for stimulation or recording, MCC can also be used as a means of transduction to characterize the nerve by impedancemetry. In this study, we investigate the feasibility of using electrical impedance (EI) measurements as an in vivo functional nerve monitoring technique. The monitoring paradigm includes the synchronized recording of both the evoked endogenous activity as compound action potentials (CAP) and the superimposed sine signal from the EI probe. Measurements were conducted on the sciatic nerve of rodents, chosen for its branchings towards the peroneal and tibial nerves, with both mono- and multi-contact per section electrodes. During stimulation phases, recordings showed CAP with consistent fiber conduction velocities. During coupled phases of both stimulation and sine perturbation, impedance variations were extracted using the mono-contact electrode type for certain frequencies, e.g. 2.941kHz, and were temporally coherent with the previous recorded CAP. Using a MCC, localized evoked CAP were also recorded but the signal to noise ratio (SNR) was too low to distinguish the expected associated impedance variation and deduce an image of impedance spatial changes within the nerve. The conducted in vivo measurements allowed to distinguish both evoked CAP and associated impedance variations with a strong temporal correlation. This indicates the feasibility of functional EI monitoring, aiming at detecting the impedance variations in relation to neural activity. Further work is needed to improve the in vivo system, namely in terms of SNR, and to integrate new multicontact devices in order to move towards EI tomography with the detection of spatially-localized impedance variations. Eventually, regions that are interesting to be targeted by stimulation could be identified through these means.