Introduction:
Percutaneous electrotherapy is a therapeutic alternative in musculoskeletal conditions. Percutaneous micro- electrolysis (MEP) stands out as treatment for tendinopathies and musculoskeletal pain, such as myofascial trigger points (MTrPs), although more studies are needed to support it. The study aimed to investigate MEP effectiveness in reducing pain pressure threshold (PPT) and pain intensity (PI) in MTrPs.

Methods:
A randomized controlled clinical trial was performed at Physiotherapy Laboratory of Andrés Bello University and in- volved 48 volunteers with MTrPs in upper trapezius muscle, randomly assigned to the experimental or control group. Both groups received baseline ultrasound treatment. In the experimental group, MEP intervention was applied with 3 re-evaluation sessions (on days 1, 3, and 7). Direct current was delivered with an acupuncture needle directly to MTrPs, and PPT and PI were re-evaluated before and after the application. The main outcomes were PPT and PI differences (PPTdiff and PIdiff) between evaluation sessions.

Results:
TMEP implied positive changes, increasing PPT (PPTdiff1-1, p = 0.0000; PPTdiff2-1, p = 0.0000; PPTdiff3-1, p = 0.0000) and decreasing PI (PIdiff1-1, p = 0.0001; PIdiff2-1, p = 0.0001; PIdiff3-1, p = 0.0008) in the experimental group. Significant differ- ences were observed in PPT in the second re-evaluation session compared with the control group (PPTdiff2-1, p = 0.0032).

Conclusions:
MEP is a good analgesic treatment for MTrPs compared with therapeutic ultrasound, although neither of these therapies seems to be better than the other in a long term. They improve PPT and PI, so MEP can be considered effective alter- native treatment for MTrPs pain.