From the Department of Anesthesiology.
Institute of Diagnostic Radiology and Neuroradiology, University Medicine of Greifswald, Greifswald, Germany.
Anesth Analg. 2018 Jun;126(6):2085-2092. doi: 10.1213/ANE.0000000000002820.
Transcutaneous vagus nerve stimulation (TVNS) is a promising treatment for acute and chronic pain. However, experimental studies yielded controversial results. We examined if TVNS reduces the perceived intensity of repetitive painful heat stimulation and temporal summation of pain (TSP) in healthy volunteers in comparison with placebo and sham stimulation, as well as no intervention.
In 4 sessions, 90 heat pulse stimuli at individual pain tolerance temperature were applied to the ventral forearm of 49 healthy volunteers (25 women) using a Contact Heat Evoked Potential Stimulator thermode (Medoc, Ramat Yishai, Israel). Pain intensity was assessed with verbal ratings on a numeric pain scale (0-100) at every tenth heat pulse. After the first session in which pain intensities without intervention were evaluated, participants completed 3 sessions in a single-blinded randomized crossover manner: (1) sham stimulation applied at the earlobes, (2) placebo stimulation (inactive device), or (3) TVNS applied at the cymbas conchae. Primary data were analyzed using analysis of variance for repeated measures and t test for paired samples.
Pain intensity decreased during all interventions as compared to no intervention (ηp = 0.22, P < .001; mean difference TVNS versus no intervention 9.5; 95% confidence interval [CI], 3.6-15.4; P < .001). Hypoalgesic effect of TVNS was better than that of placebo and sham in men before the onset of TSP (mean differences for TVNS versus placebo 6.2; 95% CI, 0.2-12.1; TVNS versus sham 6.2; 95% CI, 0.2-12.1; P < .05). In women, TSP response under TVNS was decreased if compared to no intervention (median difference, 7.5; 95% CI, 3.5-15.0; P = .003).
TVNS, placebo, and sham stimulation exerted comparable effects under experimental heat pain stimulation. Only in male participants, TVNS was superior to sham and placebo conditions in the reduction of heat pain before the onset of TSP.
经皮迷走神经刺激（TVNS）是一种有前途的治疗急性和慢性疼痛的方法。然而，实验研究结果存在争议。我们研究了在健康志愿者中，与安慰剂和假刺激相比，TVNS 是否能降低重复疼痛热刺激和疼痛时间总和（TSP）的感知强度，以及与不干预相比是否能降低感知强度。
在 4 个疗程中，使用 Medoc（Ramat Yishai，以色列）的 Contact Heat Evoked Potential Stimulator 热电极将 90 个热脉冲刺激施加到 49 名健康志愿者（25 名女性）的腹侧前臂，每个脉冲的个体疼痛耐受温度。在不干预的情况下，每 10 个热脉冲评估一次疼痛强度，并在数字疼痛量表上进行口头评分（0-100）。在第一次不干预评估疼痛强度的疗程后，参与者以单盲随机交叉方式完成 3 个疗程：（1）耳垂假刺激，（2）安慰剂刺激（无效装置），或（3） cymbas conchae 应用 TVNS。主要数据采用重复测量方差分析和配对样本 t 检验进行分析。
与不干预相比，所有干预措施均能降低疼痛强度（ηp = 0.22，P <.001；TVNS 与不干预相比的平均差异为 9.5；95%置信区间 [CI]，3.6-15.4；P <.001）。在 TSP 发作前，与安慰剂和假刺激相比，TVNS 在男性中的镇痛效果更好（TVNS 与安慰剂的平均差异为 6.2；95%CI，0.2-12.1；TVNS 与假刺激的平均差异为 6.2；95%CI，0.2-12.1；P <.05）。在女性中，与不干预相比，TVNS 下的 TSP 反应减弱（中位数差异为 7.5；95%CI，3.5-15.0；P =.003）。
在实验性热痛刺激下，TVNS、安慰剂和假刺激均产生类似的效果。仅在男性参与者中，在 TSP 发作前，TVNS 优于假刺激和安慰剂条件，能降低热痛。
