Effects of Intramuscular Electrical Stimulation on Pain and Dysfunction Following Upper Trapezius Trigger Points

Introduction: The purpose of the present study was to investigate the effects of single-session intramuscular electrical stimulation (IMES) on pain and dysfunction following active trigger points in the upper trapezius muscle. 
Materials and Methods: Volunteers (30 females) with active trigger points in the upper trapezius muscle were randomly divided into two IMES and placebo groups. For the IMES group, a needle was inserted into the trigger point, and electrical stimulation was applied to generate a pain-free contraction. For the placebo group, the intervention procedure was exactly the same, but there was no electrical stimulation. Pain by visual analog scale (VAS), pain pressure threshold (PPT), range of motion (ROM), and disability by neck disability index (NDI) were assessed as main outcome measures before, immediately after, and one week after conducting intervention by another blinded researcher. 
Results: The VAS scales were improved in both groups but were significantly lower in the IMES group one week after treatment. The PPT and ROM scores were substantially higher in the IMES group one week after the treatment. The NDI indexes significantly reduced for both groups, with no significant differences between them. 
Conclusion: IMES effectively improves pain, PPT, ROM, and NDI, following trigger points in the upper trapezius muscle. Further studies are required to investigate the IMES’s long-term effects.