What is an EMG or NCS?
Electrodiagnostic studies include electromyography (EMG); nerve conduction studies (NCS); and evoked potentials (EP). Like imaging studies, these studies cannot confirm the presence or absence of pain. They are most useful in evaluating a patient when pain is present with an observed neurological deficit. Electromyography (EMG) is the most commonly used test to assess the function of the nerve roots leaving the spine. The test is done by inserting tiny electrodes into the muscles of the arm or leg. By looking for abnormal electrical signals in the muscles, the EMG reveals nerve irritation, or pinching of the nerve, as it leaves the spinal canal. Think of how you test the wiring on a lamp. If you place a working bulb into the lamp, and the bulb lights up, you assume that the wiring is okay. However, what if the bulb does not light up? You may safely assume that something is probably wrong with the wiring, like the lamp is unplugged, or a short circuit has occurred. By relating the muscl
