Electromyography (EMG) is used to determine the cause of pain by evaluating the condition of muscles and nerves. For example, this test can reveal whether a nerve is being pinched in the spine or the periphery of the body (such as arms or legs). It can also identify pain states and diseases specific to the muscle itself.
In an EMG test, a small needle with an electrode is inserted in the muscle to measure and record its electrical activity. Based on the pattern of multiple muscle responses, the physician can identify the cause of the pain.
A Nerve Conduction Study (NCS) is the second portion of what is usually called an EMG test. NCS is a means of activating nerves to gauge their response. In this study, small electrical shocks are sent through the nerve, and electrodes are placed on the skin to record the signal.
Mount Sinai's Pain Management and Integrative Medicine physicians perform these diagnostic tests in our office, with each test typically lasting about an hour. The combined results of EMG and NCS tests give the physician a comprehensive clinical picture of the cause and characteristics of a patient's pain, which can be more helpful than an MRI in assessing the origin of the discomfort and determining the best treatment plan.