Knost B, Flor H, Birbaumer N, Schugens M M
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Germany.
Psychophysiology. 1999 Nov;36(6):755-64.
The effect of level of muscle tension on the perception of painful stimuli was assessed in 13 chronic back pain patients, 14 subjects at high risk for chronic back pain, and 14 matched healthy controls. Subjects received painful intracutaneous electric stimuli to the forearm or the lower back while they produced either high or low muscle tension levels. Visual analog scale (VAS) ratings of acute pain were obtained after each trial. Electroencephalograms, electromyograms, skin conductance levels, and blood pressure were measured during the trials. Although subjective pain ratings were not significantly affected by muscle tension levels, the chronic pain patients displayed elevated N150 and N150/P260 amplitudes of the somatosensory-evoked potentials in the low as compared to the high muscle tension condition. The high risk group showed a trend toward higher N150 amplitudes in the low as compared to the high tension condition. The results of this study partially support the hypothesis that increases in muscle tension might serve as a pain-reducing mechanism in chronic pain patients and those at risk for chronicity, thus leading to a vicious pain-tension cycle.
在13名慢性背痛患者、14名慢性背痛高危受试者和14名匹配的健康对照者中，评估了肌肉紧张程度对疼痛刺激感知的影响。受试者在产生高或低肌肉紧张水平时，接受对前臂或下背部的皮内电刺激。每次试验后获得急性疼痛的视觉模拟量表（VAS）评分。在试验期间测量脑电图、肌电图、皮肤电导水平和血压。虽然主观疼痛评分没有受到肌肉紧张程度的显著影响，但与高肌肉紧张状态相比，慢性疼痛患者在低肌肉紧张状态下体感诱发电位的N150和N150/P260波幅升高。高危组在低紧张状态下与高紧张状态相比，显示出N150波幅有升高的趋势。本研究结果部分支持了这样的假设，即肌肉紧张程度增加可能是慢性疼痛患者和慢性疼痛高危人群的一种疼痛减轻机制，从而导致疼痛-紧张的恶性循环。
