An electromyogram (EMG) is a test that measures the electrical discharges made by the muscles. It can determine whether muscle weakness or paralysis is due to a nerve problem or to a problem with the muscle itself.
During an electromyogram, a thin needle is placed in a muscle to measure its electrical activity at rest and during use. The needle is attached to a machine with a viewing screen (like a TV) that displays electrical activity in the muscles as waves on the screen.
Last Revised: November 30, 2011
Author: Healthwise Staff
Medical Review: Anne C. Poinier, MD - Internal Medicine & Colin Chalk, MD, CM, FRCPC - Neurology
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