Electromyography or EMG is a diagnostic procedure that measures muscle response or electrical activity in response to nerve’s stimulation of the muscle. The EMG measures the electrical activity of the muscle during the rest, slight contraction and forceful contractions periods. The EMG uses electrodes to transmit or detect electrical activity to help identify neuromuscular abnormalities. During the test, one or more needle electrodes penetrate the skin into the muscle to record the electrical activity. Once the electrode(s) have been inserted into the muscle being exanimated, the physician may ask you to contract a muscle such as bending an arm or leg. That information will be displayed on an oscilloscope (a monitor that that shows the electrical activity in the form of waves) as well as graphs, sounds or numerical values that your physician can interpret.
The Nerve Conduction Study (NCS), another part of an EMG, are electrodes that are taped onto the skin to measure the frequency, strength and speed of conduction of an electrical traveling between two or more points. NCS are typically performed at the same time as the EMG is and can predict nerve damage.