BACKGROUND High frequency alternating current (HFAC) stimulation have been shown to produce a peripheral nerve conduction block. Currently, all the studies applying HFAC stimulation in clinical studies, have employed frequencies below 10 kHz. The main aim of this work was to investigate the neuromodulatory effect of transcutaneous 20 kHz stimulation on somatosensory and pain thresholds, and maximal handgrip strength. METHODS A randomized, crossover, single-blinded, placebo-controlled trial was conducted following recruitment of fourteen healthy volunteers. Transcutaneous stimulation at 20 kHz and sham stimulation were applied over the ulnar and median nerves of fourteen healthy volunteers for 20 min. Maximal handgrip strength (MHS), mechanical detection threshold (MDT) and pressure pain threshold (PPT) were registered prior to, during (15 min), immediately after the end (20 min), and 10 min following stimulation. RESULTS The 20 kHz stimulation showed a lower MHS during the stimulation at the 15 min (30.1 kgs SE 2.8) and at 20 min (31.8 kgs, SE 2.8) when compared to sham stimulation (35.1 kgs, SE 3.4; p < 0.001 and 34.2 kgs, SE 3.4; p = 0.03, respectively). The 20 kHz stimulation resulted in a slight increase in MDT at 15 min (0.25 mN; 0.25-2.00) when compared to the sham stimulation (0.25 mN; 0.25-0.25; p = 0.02), and no effects were showed for PPT. CONCLUSIONS High-frequency stimulation at 20 kHz suggests a partial block of nerve activity. Studies in subjects with neurological disorders characterized by nerve hyperactivity are needed to confirm the clinical impact of this non-invasive electrical stimulation technique. TRIAL REGISTRATION NCT, NCT02837458. Registered on 12 April 2017.

中文翻译：

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20 kHz交流电刺激：对运动阈值和体感阈值的影响。

背景技术已经示出了高频交流电（HFAC）刺激产生周围神经传导阻滞。当前，所有在临床研究中应用HFAC刺激的研究都采用了10 kHz以下的频率。这项工作的主要目的是研究经皮20 kHz刺激对体感和疼痛阈值以及最大握力的神经调节作用。方法在招募了14名健康志愿者后，进行了一项随机，交叉，单盲，安慰剂对照试验。对20名健康志愿者的尺神经和中神经施加20 kHz的经皮刺激和假刺激。在操作前，操作中（15分钟）记录最大握力（MHS），机械检测阈值（MDT）和压力疼痛阈值（PPT），结束后立即（20分钟），以及刺激后10分钟。结果与假刺激（35.1 kgs，SE 3.4; p <0.001和34.2）相比，20 kHz刺激在15 min（30.1 kgs SE 2.8）和20 min（31.8 kgs，SE 2.8）刺激期间显示出较低的MHS。 kgs，SE 3.4； p ＝ 0.03）。与假刺激（0.25 mN; 0.25-0.25; p = 0.02）相比，20 kHz刺激在15分钟时的MDT略有增加（0.25 mN; 0.25-2.00），并且对PPT无影响。结论20 kHz的高频刺激提示神经活动部分受阻。需要对以神经活动亢进为特征的神经系统疾病受试者进行研究，以确认这种非侵入性电刺激技术的临床影响。NCT试用注册，NCT02837458。