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.
A randomized controlled study on the effect of two different treatments (FREMS AND TENS) in myofascial pain syndrome.
Myofascial pain syndrome (MPS) is a frequent cause of chronic muscoloskeletal pain. Transcutaneous electrical nerve stimulation (TENS) is one of the most frequently employed treatments in MPS. The aim of this study is to compare the short and medium-term effects of frequency modulated neural stimulation (FREMS) to those of TENS in MPS.
                Forty subjects with upper trapezius MPS were randomly allocated to 1 of 2 groups, treated with either FREMS (n=19) or TENS (n=21). Each treatment consisted in 10 sessions lasting 20 min each. Patients were evaluated before treatment, at 1 week, and at 1 and 3 months after the end of treatment. Clinical evaluation included parameters for measurement of pain levels using the neck pain and disability visual analogue scale (NPDVAS) and algometry, evaluation of myofascial trigger point characteristics and measurement of the range of cervical movement (range of motion, ROM).
                The FREMS group showed a significant improvement in the NPDVAS, algometry, in myofascial trigger point characteristics, and in the ROM (homolateral rotation, controlateral rotation, bending and extension) after the end of treatment and at 1 and 3 months follow-up evaluation. The TENS group showed significant improvement in the same outcome measures except for algometry and cervical extension, but these improvements were maintained only at the 1 month follow-up evaluation. However, were not observed statistically significant differences between FREMS of TENS in many of outcome measures.
                Both FREMS and TENS have positive short-term effects on MPS. But, medium-term effects were achieved only with FREMS.