Efficacy of Acupuncture Treatment on Myofascial Pain Syndrome in Upper Trapezius

Upper trapezius myofascial pain syndrome is one of the most common musculoskeletal impairments. Hyper-irritable pain can be intensified due to muscle contraction either at rest or during movement. In traditional Chinese medicine, the Jian Jing (GB21) acupoint is most commonly used to treat pain, neck stiffness, shoulder tension, and headaches. Subjects were recruited for this study at the local outpatient center and randomly assigned into an experimental group with 40-mm-long acupuncture needling or a placebo group with 2.5-mm-long auricular needling. A pressure pain algometer was used to measure the pressure pain threshold (PPT) before and after needling, and two sets of electromyography (EMG) electrodes were attached on both shoulders to measure the trapezius muscle activity during a shoulder shrug motion. The PPT and EMG data were recorded and analyzed to compare different needling depths in suppressing the muscular pain. Twenty-four participants completed the 3-week experiment. The outcomes indicated that there was no substantial difference in PPT pre- and post-treatment between groups. The root-mean-square and integrated EMG activities showed significant decreases during the shrugging motion after each 20-mm-deep acupuncture treatment for the experimental group, but not in the placebo group with the 2.5-mm-deep surface acupuncture. Although the pain tolerance threshold showed a tendency towards improvement, it was not statistically significant, while the placebo group showed almost no treatment effect. Comparing the effects of insertion depth i.e., acupuncture and auricular surface needling, the EMG data indicate that deep acupuncture is an effective treatment for the management of trapezium myofascial pain as it can ameliorate the muscle fatigue of the upper trapezius due to prolong unchanged posture.