Electromyography (EMG)Medical Author:
J Stephen Huff, MD
Medical Editor:
Michael D Burg, MD
Medical Editor:
Francisco Talavera, PharmD, PhD
Medical Editor:
James S Cohen, MD
Electromyography (EMG) IntroductionElectromyography, or EMG, involves testing the electrical activity of muscles. Often, EMG testing is performed with another test that measures the conducting function of nerves. This is called a nerve conduction study. Because both tests are often performed at the same office visit and by the same personnel, the risks and procedures generally apply to both tests. Muscular movement involves the action of muscles and nerves and needs an electrical current. This electrical current is much weaker than the one in your household wiring. In some medical conditions the electrical activity of the muscles or nerves is not normal. Finding and describing these electrical properties in the muscle or nerve may help your doctor diagnose your condition. EMG may aid with the diagnosis of nerve compression or injury (such as carpal tunnel syndrome), nerve root injury (such as sciatica), and with other problems of the muscles or nerves. Less common medical conditions include amyotrophic lateral sclerosis, myasthenia gravis, and muscular dystrophy. Viewer Comments & ReviewsElectromyography (EMG) - ResultsThe eMedicineHealth physician editors ask:What did the results of your electromyography (EMH) determine? |
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Electromyography (EMG)
Electromyogram (EMG) and Nerve Conduction Studies »
Test Overview
An electromyogram (EMG) measures the electrical activity of muscles at rest and during contraction. Nerve conduction studies measure how well and how fast the nerves can send electrical signals.
Nerves control the muscles in the body with electrical signals called impulses. These impulses make the muscles react in specific ways. Nerve and muscle problems cause the muscles to react in abnormal ways.
If you have leg pain or numbness, you may have these tests to find out how much your nerves are being affected. These tests check how well your spinal cord, nerve roots, and nerves and muscles that control your legs are working.
Why It Is Done
An EMG is done to:
- Find diseases that damage muscle tissue, nerves, or the junctions between nerve and muscle. These problems may include a herniated disc, amyotrophic lateral sclerosis (ALS), or myasthenia gravis (MG).
- Find the cause of weakness, paralysis, or muscle twitchin...
Read the Electromyogram (EMG) and Nerve Conduction Studies article »
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Since the measuring device has been constructed by the observer . . . we have to remember that what we observe is not nature itself but nature exposed to our method of questioning.
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