Wee A S
Department of Neurology, University of Mississippi Medical Center, Jackson, Mississippi, USA.
Electromyogr Clin Neurophysiol. 2001 Mar;41(2):71-7.
The median nerves of six normal subjects were electrically stimulated at different locations on the wrist in a bipolar fashion. The evoked compound sensory nerve action potentials (CSNAPs) were recorded at the index finger. Electrical stimuli consisted of constant-current monophasic rectangular pulses. Initially, the nerve was stimulated with a cathodal current and a just supramaximal CSNAP was obtained. Then, at the same stimulus location, the nerve was excited with an anodal current. A just supramaximal response in the anodal-CSNAP was obtained, or until a maximum current of 100 mA was delivered. CSNAPs obtained from anodal excitation required several times more electrical stimulus intensity when compared to those derived from cathodal stimulation. Morphologically, they were similar, except the onset latency of the anodal-CSNAPs was approximately 0.2 to 0.3 msec early compared to that derived from cathodal stimulation. This implies that during anodal excitation, the site of nerve depolarization was not located underneath the anode, but was situated at some distance from it. Also, it appears that a minimum nerve length (10 mm or more) should be exposed to the anodal current in order to induce depolarization. A very localized application of the anodal stimulus often failed to elicit nerve depolarization.
对6名正常受试者的正中神经在腕部不同位置进行双极电刺激。在示指记录诱发的复合感觉神经动作电位（CSNAPs）。电刺激由恒流单相矩形脉冲组成。最初，用阴极电流刺激神经并获得刚好超最大的CSNAP。然后，在相同刺激位置，用阳极电流刺激神经。获得刚好超最大的阳极CSNAP反应，或直至施加100 mA的最大电流。与阴极刺激获得的CSNAP相比，阳极刺激获得的CSNAP需要几倍的电刺激强度。形态学上，它们相似，只是阳极CSNAP的起始潜伏期比阴极刺激获得的潜伏期早约0.2至0.3毫秒。这意味着在阳极刺激期间，神经去极化部位不在阳极下方，而是位于距阳极一定距离处。此外，似乎阳极电流应作用于至少10 mm或更长的神经长度才能诱导去极化。阳极刺激的非常局部的应用常常不能引起神经去极化。
