Objective: To evaluate whether or not large diameter myelinated muscle afferents contribute to the pathophysiology and spontaneous electromyographic activity(SEA) of myofascial trigger points (MTrPs).Method: Twenty healthy subjects, with a latent MTrP in brachioradial muscle on one forearm and no symptom of musculoskeletal pain, volunteered for this two-session study. Every subject was required to participate two sessions of this study. The first session was to study local pain, referred pain and SEA evoked from a MTrP in the brachioradial muscle in subjects at the time of pre-compression, 20min following compression, and 10min after de-compression. The second session of this study was to measure pressure pain threshold (PPT) and pressure threshold for eliciting referred pain (PTRP) 1 week after the first session of study at both MTrP region and non-MTrP region that was chosen on the brachioradial muscle of another forearm and also at the time of pre-compression, 20min following compression, and 10min after de-compression. The ischemic compression block (ICB) of large diameter myelinated muscle afferents was obtained with a 7cm wide toumiquet applied around the bicep brachialis muscle of upper arm proximal to the brachioradial muscle in 20 healthy subjects.Result: The VAS peak values of the local pain and referred pain, average amplitude and frequency of the intermittent spike activity of SEA significantly decreased after ICB and that PPT and PTRP at MTrP region significantly increased after ICB. These changes retumed to the level of pre-compression after de-compression. However,PPT at non-MTrP region had no significant difference pre-compression, 20 min following compression and de-compression.Conclusion: These results suggest that large diameter muscle afferents may be involved in mechanical hyperalgesia and SEA at MTrP.%目的:研究大直径有髓鞘肌肉传入纤维是否参与了肌筋膜激痛点(MTrP)的痛觉增敏和自发性肌电活动.方法:20名青年志愿者均可在肱桡肌上找到潜在的MTrP,参与本项目两部分的实验.用7cm宽的袖带对一侧肱桡肌进行施加压力20min以引起缺血压迫阻滞(ICB)大直径有髓鞘的肌肉传入纤维.第一部分研究受试者肱二头肌受压至缺血前,压迫阻滞20min后及解除压迫10min后,肱桡肌MTrP局部疼痛、牵涉痛及自发性电活动的改变;第二部分在1周后,研究受试者肱二头肌受压至缺血前,压迫阻滞20min后及解除压迫10min后,肱桡肌MTrP与对侧肱桡肌相应部位non-MTrP(非激痛点)的压力疼痛阈值(PPT)与牵涉痛阈值(PTRP)的改变.结果:ICB后MTrP的局部疼痛、牵涉痛及自发性电位活动的波幅及频率均明显降低,解除压迫后恢复至未压迫前水平;MTrP的PPT和PTRP均在ICB后明显升高,解除压迫后又降低;ICB后,MTrP的PPT仍然低于非MTrP区.结论:大直径的有髓鞘的肌肉传入纤维参与了MTrP的机械性痛觉增敏和自发性电活动.
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