OBJECTIVE Electrical neuromodulation is a clinically effective therapeutic instrument, currently expanding into newer indications and larger patient populations. Neuromodulation technologies are also moving towards less invasive approaches to nerve stimulation. In this study, we investigated an enhanced transcutaneous electrical nerve stimulation (eTENS) system that electrically couples a conductive nerve cuff with a conventional TENS electrode. The objectives were to better understand how eTENS achieves lower nerve activation thresholds, and to test the feasibility of applying eTENS in a human model of peripheral nerve stimulation. APPROACH A finite element model (FEM) of the human lower leg was constructed to simulate electrical stimulation of the tibial nerve, comparing TENS and eTENS. Key variables included surface electrode diameter, nerve cuff properties (conductivity, length, thickness), and cuff location. Enhanced neural excitability was predicted by relative excitability (RE > 1), derived using either the activating function (AF) or the nerve activation threshold (MRG model). MAIN RESULTS Simulations revealed that a localized 'virtual bipole' was created on the target nerve, where the isopotential surface of the cuff resulted in large potential differences with the surrounding tissue. The cathodic part (nerve depolarization) of the bipole enhanced neural excitability, predicted by RE values of up to 2.2 (MRG) and 5.5 (AF) when compared to TENS. The MRG model confirmed that action potentials were initiated at the cathodic edge of the nerve cuff. Factors contributing to eTENS were larger surface electrodes, longer cuffs, cuff conductivity (>1×103 S m-1), and cuff position relative to the cathodic surface electrode. SIGNIFICANCE This study provides a theoretical basis for designing and testing eTENS applied to various neural targets and data suggesting function of eTENS in large models of nerve stimulation. Although eTENS carries key advantages over existing technologies, further work is needed to translate this approach into effective clinical applications.

中文翻译：

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通过局部虚拟双极杆实现增强的经皮电神经刺激：人类胫神经刺激的计算研究。

目的电神经调节是一种临床上有效的治疗仪器，目前正在扩展到更新的适应症和更大的患者人群中。神经调节技术也正朝着侵入性较小的神经刺激方法发展。在这项研究中，我们研究了增强的经皮电神经刺激（eTENS）系统，该系统将传导性神经套囊与传统的TENS电极电耦合。目的是更好地了解eTENS如何达到较低的神经激活阈值，并测试将eTENS应用于人周围神经刺激模型的可行性。方法建立人小腿的有限元模型（FEM），以比较TENS和eTENS来模拟胫神经的电刺激。关键变量包括表面电极直径，神经袖套的特性（导电性，长度，厚度）和袖套位置。神经兴奋性的增强是通过相对兴奋性（RE> 1）预测的，可以通过激活功能（AF）或神经激活阈值（MRG模型）得出。主要结果模拟结果表明，在目标神经上形成了局部“虚拟双极”，袖带的等势面导致与周围组织的巨大电势差。双极的阴极部分（神经去极化）增强了神经兴奋性，与TENS相比，RE值预测高达2.2（MRG）和5.5（AF）。MRG模型证实了动作电位是在神经套的阴极边缘处引发的。造成eTENS的因素包括较大的表面电极，较长的袖带，袖带电导率（> 1×103 S m-1），和袖带相对于阴极表面电极的位置。意义该研究为设计和测试适用于各种神经靶标的eTENS提供了理论基础，并暗示了eTENS在大型神经刺激模型中的功能。尽管eTENS具有优于现有技术的关键优势，但仍需要进一步的工作才能将该方法转化为有效的临床应用。