Electromyography (EMG) is a diagnostic test that measures muscle response or electrical activity in response to a nerves stimulation of the muscle. The test is used to help detect neuromuscular abnormalities and can reveal nerve dysfunction, muscle dysfunction, or problems with nerve-to-muscle signal transmission. During the test, one or more small needles (also called electrodes) are inserted through the skin into the muscle. The electrical activity picked up by the electrodes is then displayed on an oscilloscope (a monitor that displays electrical activity in the form of waves). An audio-amplifier is used so the activity can be heard. EMG measures the electrical activity of the muscle during rest, slight contraction, and forceful contraction.

A related procedure that may be performed is nerve conduction study (NCS). NCS is a measurement of the amount and speed of conduction of an electrical impulse through a nerve. NCS can determine nerve damage and destruction and is often performed at the same time as EMG. Both procedures help to detect the presence, location, and extent of diseases that damage the nerves and muscles.

EMG tests and nerve conduction studies can both help find out if you have a disorder of your muscles, nerves, or both. These tests can be done separately, but they are usually done at the same time. Your doctor may order an EMG test if you experience any symptoms such as muscle weakness, numbness, tingling, or pain. EMG testing usually takes anywhere from 30 to 90 minutes, depending on the condition being tested and findings of the study. EMG testing is extremely safe, but talk with your doc...