穴位TENS对正常年轻人热痛阈特异性抑制作用的研究

A study of the specific inhibitory effects of acupoints TENS on heat pain threshold in normal young subjects

目的 探讨经皮神经电刺激疗法 (TENS)对人体实验性热痛阈及实验性振动阈的影响 ,从而阐明TENS作用机理。方法 2 0名正常人 ,年龄在 2 0～ 3 9岁。随机分为TENS组和空白刺激组。每位受试者左手合谷穴和大鱼际区接受 3 0minTENS(2 0 0 μs ,10 0Hz ,2～ 3倍感觉阈 )或空白刺激 ,分别采用MedocTSA 2 0 0 1和MedocVSA 3 0 0对受试者左手鱼际区的热痛阈和振动阈进行测定。并分别在TENS或空白刺激前的3 0、2 0、10min及刺激后 0、10、2 0、3 0、40、5 0min记录热痛阈和振动阈。采用逐步回归分析法对结果进行分析。结果 本研究显示与空白刺激相比 ,3 0min的TENS治疗后即刻 ,即 0min(P =0 .0 0 2 )和 2 0min(P =0 .0 0 4)热痛阈显著增高 ,增高值分别为 0 .81℃及 1.5 4℃。而同一治疗方案在同一人群中对振动阈无改变。结论 TENS作用于针灸穴位具有镇痛的特异性 ,而对其他感觉如振动觉无改变。换言之 ,TENS可能通过激活粗纤维传导 ,抑制细纤维传导的痛觉 。

Objective To delineate the influence of acupoint TENS on pain threshold and vibrotactile sensation in human subjects. Methods Twenty normal, young subjects were randomly allocated into TENS and placebo groups. The conventional TENS (200 μs pulses at 100 Hz and 2 3 times sensory threshold) or placebo stimulation was applied to the acupuncture points (LI4) on each subject' s left hand. Heat pain and vibrotactile thresholds were measured using Medoc TSA 2001 and VSA 3000, respectively, on the thenar eminence of each subject's left hand. These assessments were done at 30, 20 and 10 min before and 0, 10, 20, 30, 40 and 50 min after 30 min of TENS or placebo treatment. Results In comparison with placebo stimulation, a significant increase in heat pain threshold, by 0.81℃and 1.54℃, was demonstrated at 0 ( P =0.002) and 20 min ( P =0.004), respectively, after 30 min of TENS application. No significant difference in vibrotactile threshold was found between the two groups. Conclusion The results demonstrated that, the effect of the acupoints TENS was to reduce pain rather than the vibrotactile sensibility. This might be attributed to the activation of the large fibers transmitting tactile sensations (especially the vibration) and the inhibition of the fine fibers transmitting the pain sensation.