Clinical Definition

An EMG, or electromyogram, is a test that measures electrical activity of the muscles and the nerves that control them during a two-part examination. It is part of an evaluation to help to detect causes of numbness, paralysis and spasm as well as facial and extremity pain. In the first part, the ability of nerves to transmit electrical impulses to muscles is measured, with the help of a small, brief electrical stimulus. Then, a needle electrode exam measures the electrical activity in muscles.

In Our Own Words

An EMG will tell you if there is a problem with the nerves, with the muscle, or if the electrical activity of the muscle is normal. This helps a physician evaluate the cause, and in some cases prognosis, of numbness, paralysis, spasms, weakness or pain in the limbs and extremities, as well as in other areas of musculature, such as in the head, neck and shoulders.
The two-part test includes measuring the ability of the nerves to transmit electrical impulses to the muscles and evaluation of the electrical activity in the muscles. The test includes a small electrical stimulus and then the insertion of a very thin needle into the muscles.
Special instructions are given to patients about discussing with their doctor their current medication regimen, their medical history and other details.