Janko Martin, Trontelj Jože V
Institute of Clinical Neurophysiology, The University Medical Centre, Zaloška c.7, 61105 Ljubljana Yugoslavia.
Pain. 1980 Oct;9(2):219-230. doi: 10.1016/0304-3959(80)90009-3.
With the aim of studying peripheral physiological mechanisms involved in transcutaneous electrical nerve stimulation (TENS) for the suppression of pain, the authors have examined 14 healthy volunteers in the perceptual part and 8 in the microneurographic part of this study. For pain suppressing stimulation they have used ring electrodes and stimulators capable of producing rectangular, sine wave, triangular and hybrid wave forms. Pain was induced with electrical stimuli on the distal phalanx of the middle finger. TENS with rectangular, sine wave and triangular pulses activates mainly A beta, but also some A delta fibres. Pain suppressing capacity of different wave forms used was the same and was achieved with stimuli close to the threshold for pain. Pain was most effectively diminished when noxious and pain suppressing stimuli were applied to the same finger; this effect was smaller with the two stimuli on neighbouring fingers and very weak when pain suppressing stimulus was applied to the contralateral hand. Increases in stimulus frequency resulted in an increased and variable latency as well as intermittent blocking of those spike components which had been near threshold at low frequency stimulation. This interpreted as being due to local changes in excitation threshold. In surface-recorded averaged electroneurograms this effect was seen as amplitude decrement and increased response duration, but was not due to impulse transmission failure in A delta fibres as seen microneurographically. On continuous high frequency stimulation, the intensity of sensation elicited diminished, although there was no change in the microneurogram. The authors conclude that the peripheral contribution to the analgesic effects of TENS seems to be unimportant.
为了研究经皮电神经刺激（TENS）抑制疼痛所涉及的外周生理机制，作者在本研究的知觉部分检查了14名健康志愿者，在微神经图部分检查了8名健康志愿者。对于疼痛抑制刺激，他们使用了环形电极和能够产生矩形、正弦波、三角波和混合波形的刺激器。通过对中指远端指骨施加电刺激来诱发疼痛。矩形、正弦波和三角波脉冲的TENS主要激活Aβ纤维，但也激活一些Aδ纤维。所使用的不同波形的疼痛抑制能力相同，且通过接近疼痛阈值的刺激来实现。当将有害刺激和疼痛抑制刺激施加于同一手指时，疼痛最有效地减轻；当两种刺激施加于相邻手指时，这种效果较小，而当疼痛抑制刺激施加于对侧手时，效果非常微弱。刺激频率增加会导致潜伏期增加且变化不定，以及低频刺激时接近阈值的那些锋电位成分出现间歇性阻滞。这被解释为是由于兴奋阈值的局部变化所致。在表面记录的平均神经电图中，这种效应表现为振幅减小和反应持续时间增加，但并非如微神经图所见的Aδ纤维冲动传导失败所致。在持续高频刺激时，尽管微神经图没有变化，但所引发的感觉强度减弱。作者得出结论，TENS镇痛作用的外周贡献似乎并不重要。
