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Definition
By Mayo Clinic staffElectromyography (EMG) is a diagnostic procedure to assess the health of muscles and the nerve cells that control them (motor neurons).
Motor neurons transmit electrical signals that cause muscles to contract. An EMG translates these signals into graphs, sounds or numerical values that a specialist interprets.
An EMG uses tiny devices called electrodes to transmit or detect electrical signals.
During a needle EMG, a needle electrode inserted directly into a muscle records the electrical activity in that muscle.
A nerve conduction study, another part of an EMG, uses electrodes taped to the skin (surface electrodes) to measure the speed and strength of signals traveling between two or more points.
EMG results can reveal nerve dysfunction, muscle dysfunction or problems with nerve-to-muscle signal transmission.
- Ropper AH, et al. Adams & Victor's Principles of Neurology. 9th ed. New York, N.Y.: The McGraw-Hill Companies; 2009. http://www.accessmedicine.com/content.aspx?aID=3641135&searchStr=electromyography. Accessed Dec. 18, 2012.
- Horowitz SH. Overview of electromyography. http://www.uptodate.com/home. Accessed Dec. 18, 2012.
- FAQ: Patient information. American Association of Neuromuscular & Electrodiagnostic Medicine. http://www.aanem.org/Education/Patient-Resources/Learn-About-an-EMG.aspx. Accessed Dec. 18, 2012.
- Overview of peripheral nervous system disorders. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merckmanuals.com/professional/neurologic_disorders/peripheral_nervous_system_and_motor_unit_disorders/overview_of_peripheral_nervous_system_disorders.html?qt=peripheral%20nervous%20system%20disorders&alt=sh#v1045423. Accessed Jan. 15, 2013.
- Carpal tunnel syndrome fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/carpal_tunnel/detail_carpal_tunnel.htm. Accessed Jan. 15, 2013.
- What are pleurisy and other pleural disorders? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/pleurisy/. Accessed Jan. 17, 2013.
- What is hemophilia? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/hemophilia/. Accessed Jan. 18, 2013.
- Barbara Woodward Lips Patient Education Center. About your electromyography (EMG) examination. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2008.
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