Analgesic effects of a capacitive-resistive monopolar radiofrequency in patients with myofascial chronic neck pain: a pilot randomized controlled trial

BACKGROUND: To date, there is a lack of prior studies on the use of capacitive resistive monopolar radiofrequency (RF) to treat neck pain. The objective of this study was to investigate the immediate effect of capacitive resistive monopolar radiofrequency (RF=448 kHz), in comparison with a placebo, on (1) reducing neck pain intensity at myofascial trigger points (MTrP), (2) decreasing neck disability and (3) improving cervical range of motion (CROM). METHODS: A randomized, double-blind, placebo-controlled trial (NCT02353195) was carried out. Patients with myofascial chronic neck pain (N=24) with active MTrP in one upper trapezius muscle were randomly divided into two groups: a radio-frequency group, which received eight sessions of a monopolar capacitive resistive radio-frequency application over the upper trapezius muscle, and a placebo group (PG), which received eight sessions of placebo radio-frequency over the same muscle. Visual analog scale (VAS), CROM and Neck Disability Index (NDI) were evaluated after the first session and after the eight sessions. RESULTS: The Wilcoxon test for VAS showed statistically significant differences between baseline, immediately after the first session and after eight sessions (p<.001). No significant differences for PG were found. No differences were observed between groups. NDI improved in both groups after eight sessions, but no differences were found between groups (p<.05). ANOVA for time factor showed statistically significant changes in the right cervical rotation in both groups (F=4.112; p=.026) after eight sessions. CONCLUSIONS: Even though there were no differences between both groups, the monopolar capacitive, resistive RF could have a potential effect on pain intensity.