We cannot make any definite statements on the efficacy and clinical usefulness of electrotherapy modalities for neck pain. Since the quality of evidence is low or very low, we are uncertain about the estimate of the effect. Further research is very likely to change both the estimate of effect and our confidence in the results. Current evidence for PEMF, rMS, and TENS shows that these modalities might be more effective than placebo but not other interventions. Funding bias should be considered, especially in PEMF studies.  Galvanic current, iontophoresis, electric muscle stimulation(EMS), and static magnetic field did not reduce pain or disability. Future trials on these interventions should have larger patient samples and include more precise standardization and description of all treatment characteristics.
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.