Intramuscular Electrical Stimulation on Upper Trapezius With Trigger Points

Myofascial trigger points (MTrPs) are defined as discrete areas of tenderness in tautbands of skeletal muscles that are painful. The upper trapezius (UT) muscle has beenfound to be often affected by MTrPs, which can result in altered sensory‐motor function.MTrPs may be related to pressure pain sensitivity and alterations in the upper trapeziusmuscle activity. A reduction in PPTs and increased electromyographic (EMG) activity ofthe UT muscle with MTrPs can be respectively interpreted as increased pain receptorssensitization and motor endplate activity.In routine clinical practice, exercises, TrP injections, medications, and alternativetherapies such as acupuncture dry needling (DN) are used to treat MTrPs. In recent years,some studies have reported that intramuscularly delivered electrical stimulation is apotential resource for the management of myofascial pain syndrome (MPS). Evidence fromthe literature suggests that IMES is effective in conditions such as adhesive capsulitis,MPS, and other non‐traumatic musculoskeletal disorders.In routine neuromuscular electrical stimulation, conventional electrode placement (CEP)is used, in which an active cathode pole is placed in the peripheral target tissue and areference anode is placed over the spinal level for peripheral pain modulation. Inverseelectrode placement (IEP) is a alternate electrode placement method in which a cathodepole is placed over the spinal level and an anode pole over the distal parts of thelimbs. IEP model experiments on MPS and non‐traumatic shoulder pain disorders achievedsignificant clinical outcomes for shoulder pain and associated functional disabilities.Although IMES is effective in reducing the pain threshold and changing EMG activity, thedifference between the effects of IMES based on IEP and CEP on PPT and EMG activity(%MVIC) remains unknown. In line with previous study findings, this study hypothesizedthat IMES using IEP would achieve significant changes in the PPT, EMG activity, musclelength, and pain severity of the UT muscle with TrPs compared with IMES using CEP andSham‐IMES