Electrophysiological and Ultrasound Quantitative Biomarkers for Myofascial Pain

This is an observational study that is intended to determine the capacity of three technologies to serve as diagnostic biomarkers for myofascial pain syndrome. Investigators will seek patients with myofasical pain syndrome as well as healthy subjects for this study. Electrical impedance myography (EIM), myofiber threshold tracking (TT) excitability testing, and ultrasound with shear wave elastography (SWE) measurements will be obtained from the trapezius muscle (the muscle that extends over the back of the neck and shoulders). These measurements will be repeated within 2-5 days to assess repeatability of these methods.