Dry needling versus magnesium sulfate iontophoresis of active trigger points of the axioscapular muscle in neck pain: a single blind randomized controlled trial

Objective: To compare the effects of dry needling (DN) and magnesium sulfate (MgSO4) iontophoresis on pressure pain threshold (PPT), neck disability, pain intensity and muscle activity/amplitude in patients with upper-trapezius active myofascial trigger points (MTrPs) and neck pain. Methods: Sixty subjects with neck pain and cervical myofascial pain syndrome (MPS) of the upper trapezius muscles were randomly assigned into a DN group that received DN and stretching of all cervical muscles, an iontophoresis group that received MgSO4 iontophoresis and stretching of all cervical muscles or a control group C that received only stretching of all cervical muscles. The subjects received the treatment twice a week for 4 weeks. PPT, Arabic neck disability index (ANDI), pain intensity visual analogue scale (VAS) and cervical muscle amplitude (assessed by electromyography and expressed as a normalized root mean square (RMS)) were measured before and after completion of the treatment. Results: In the within-group analysis, there were statistically significant differences pre- versus post-treatment in all variables in both experimental groups (p < 0.05) but no significant differences in the control group with the single exception of pain intensity. In the between-group analysis post-treatment, there were statistically significant differences between all three groups. Compared with the iontophoresis group, the DN group showed significant improvements in VAS (mean difference (MD) −2.0, 95% confidence interval (CI) −2.84 to −1.36; p < 0.01), RMS (MD −1.32, 95% CI −1.79 to −0.85; p < 0.001), ANDI (MD −2.60, 95% CI −4.50 to −0.70; p = 0.004) and PPT (MD 1.48, 95% CI 1.01–1.95; p < 0.001). Conclusion: DN and MgSO4 iontophoresis both had positive effects on PPT, ANDI, VAS and muscle amplitude in the treatment of neck pain subjects with upper-trapezius MTrPs. DN had a superior effect than MgSO4 iontophoresis for all outcomes studied.