Case Western Reserve University, Cleveland, OH, USA.
Med Biol Eng Comput. 2011 Feb;49(2):241-51. doi: 10.1007/s11517-010-0679-x. Epub 2010 Oct 2.
This study investigates a novel technique for blocking a nerve using a combination of direct and high frequency alternating currents (HFAC). HFAC can produce a fast acting and reversible conduction block, but cause intense firing at the onset of current delivery. We hypothesized that a direct current (DC) block could be used for a very brief period in combination with HFAC to block the onset firing, and thus establish a nerve conduction block which does not transmit onset response firing to an end organ. Experiments were performed in rats to evaluate (1) nerve response to anodic and cathodic DC of various amplitudes, (2) degree of nerve activation to ramped DC, (3) a method of blocking onset firing generated by high frequency block with DC, and (4) prolonged non-electrical conduction failure caused by DC delivery. The results showed that cathodic currents produced complete block of the sciatic nerve with a mean block threshold amplitude of 1.73 mA. Ramped DC waveforms allowed for conduction block without nerve activation; however, down ramps were more reliable than up ramps. The degree of nerve activity was found to have a non-monotonic relationship with up ramp time. Block of the onset response resulting from 40 kHz current using DC was achieved in each of the six animals in which it was attempted; however, DC was found to produce a prolonged conduction failure that likely resulted from nerve damage.
本研究探讨了一种使用直流和高频交流电（HFAC）组合阻断神经的新方法。HFAC 可产生快速作用且可逆的传导阻滞，但在电流传递开始时会引起强烈放电。我们假设，直流电（DC）阻断可以在非常短的时间内与 HFAC 结合使用，以阻断起始放电，从而建立一种不会将起始反应放电传递到终末器官的神经传导阻滞。在大鼠中进行了实验，以评估（1）神经对各种幅度的阳极和阴极 DC 的反应，（2）对斜坡 DC 的神经激活程度，（3）用 DC 阻断高频阻断产生的起始放电的方法，以及（4）DC 传递引起的长时间非电传导失败。结果表明，阴极电流产生完全阻断坐骨神经的阻断阈值平均幅度为 1.73 mA。斜坡 DC 波形允许在不激活神经的情况下进行传导阻断；然而，下斜坡比上斜坡更可靠。发现神经活动的程度与上斜坡时间呈非单调关系。在尝试的六只动物中的每一只中都实现了用 DC 阻断 40 kHz 电流产生的起始反应，但发现 DC 会产生长时间的传导失败，这可能是由于神经损伤引起的。
