Feasibility of Near-infrared Spectroscopy to Measure Cortical Pain Pathway (Brain) Activation During Dry Needling

This study supports a line of ongoing investigation aimed at improving the diagnosis, management, and treatment of chronic pain after musculoskeletal injury. Continued progress in this arena requires novel methods to measure central nervous system (brain) mechanism of action and its role in identification of the unique transition of musculoskeletal injury to chronic pain. The purpose of this study is to use near-infrared spectroscopy (NIRS) to measure changes along cortical pain pathways in the brain related to true and sham dry needling treatment. Specific Aim #1: The investigators will compare the cortical pain pathway response during dry needling treatment to sham dry needling treatment using NIRS in two groups of patients with chronic shoulder pain. The investigators hypothesize that decreased cortical activity will be seen in the dorsolateral prefrontal cortex (DLPFC) in those treated with true dry needling compared to those treated with sham dry needling. Specific Aim #2: The investigators will evaluate whether the cortical pain pathway response (imaged using NIRS) during dry needling predicts 1-week improvement in shoulder muscle response, local hypoalgesia, and self-reported pain and disability in the group of patients that received true dry needling treatment. The investigators hypothesize that decreased cortical activity in the DLPFC will be associated with improvements in shoulder muscle response, local hypoalgesia, and self-reported pain and disability in those treated with true dry needling.