The immediate effectiveness of electrical nerve stimulation and electrical muscle stimulation on myofascial trigger points.

This study is designed to investigate the immediate effectiveness of electrotherapy on myofascial trigger points of upper trapezius muscle. Sixty patients (25 males and 35 females) who had myofascial trigger points in one side of the upper trapezius muscles were studied. The involved upper trapezius muscles were treated with three different methods according to a random assignment: group A muscles (n = 18) were given placebo treatment (control group); group B muscles (n = 20) were treated with electrical nerve stimulation (ENS) therapy; and group C muscles (n = 22) were given electrical muscle stimulation (EMS) therapy. The effectiveness of treatment was assessed by conducting three measurements on each muscle before and immediately after treatment: subjective pain intensity [(PI) with a visual analog scale], pressure pain threshold [(PT) with algometry], and range of motion [(ROM) with a goniometer] of upper trapezius muscle (lateral bending of cervical spine to the opposite side). When the effectiveness of treatment was compared with that of the placebo group (group A), there was significant improvement in PI and PT in group B (P < 0.01) but not in group C (P > 0.05). The improvement of ROM was significantly more in group C (P < 0.01) as compared with that in group A or group B. When each group was divided into two additional subgroups based on the initial PI, it was found that ENS could reduce PI and increase PT significantly (P < 0.05), but did not significantly (P > 0.05) improve ROM, as compared with the placebo group for both subgroups. EMS could significantly (P < 0.05) improve ROM, but not PT, better than the placebo groups, for either subgroup. It could reduce PI significantly more (P < 0.05) than placebo controls only for the subgroup with mild to moderate pain, but not with severe pain. For pain relief, ENS was significantly better (P < 0.05) than EMS; but for the improvement of ROM, EMS was significantly better (P < 0.05) than ENS. It is concluded that ENS is more effective for immediate relief of myofascial trigger point pain than EMS, and EMS has a better effect on immediate release of muscle tightness than ENS.

Difference in pain relief after trigger point injections in myofascial pain patients with and without fibromyalgia.

OBJECTIVE: To compare responses to trigger point (TrP) injection between patients having both myofascial pain syndrome (MPS) caused by active TrPs and fibromyalgia syndrome (FMS) and patients with MPS due to TrPs but without FMS. DESIGN: Prospective design blinded measurement, before- after trial. SETTING: A pain control medical clinic. PATIENTS: Group 1: MPS + FMS; Group 2: MPS only. All patients (9 in each group) had active TrPs in the upper trapezius muscle. INTERVENTION: Myofascial TrP injection with 0.5% xylocaine. MAIN OUTCOME MEASURES: Subjective pain intensity (PI), pain threshold (PT), and range of motion (ROM) were assessed before, immediately after, and 2 weeks after TrP injection. RESULTS: In a comparison of preinjection measures to immediate postinjection measures, only ROM was significantly improved (p < .05) in Group 1 patients; all three parameters were significantly improved (p < .05) in the Group 2 patients who had only MPS. Two weeks after injection, both groups showed significant improvement (p < .05) in all three measured parameters as compared to preinjection measurements. In a comparison of the two groups, the immediate effectiveness of TrP injection was significantly less (p < .05) in Group 1 than in Group 2 for all three parameters. Two weeks after injection, the degree of improvement in PT or ROM (but not PI) was not significantly different between two groups. Postinjection soreness (different from myofascial pain) was more severe, developed sooner, and lasted longer in Group 1 than in Group 2. CONCLUSION: Trigger point injection is a valuable procedure for pain relief for patients in both group. Patients with FMS are likely to experience significant but delayed and attenuated pain relief following injection of their active TrPs compared to myofascial pain patients with similar TrPs but without FMS. Also, FMS patients are likely to experience significantly more postinjection soreness for a longer period of time.