Electromyogram (EMG) and Nerve Conduction Studies

EMG (Electromyography), Nerve Conduction Studies

Why It Is Done

An electromyogram (EMG) is done to:

• Find diseases that damage muscle tissue, nerves, or the junctions between nerve and muscle (neuromuscular junctions). These disorders may include a herniated disc, amyotrophic lateral sclerosis (ALS), or myasthenia gravis (MG).
• Find the cause of weakness, paralysis, or muscle twitching. Problems in a muscle, the nerves supplying a muscle, the spinal cord, or the area of the brain that controls a muscle can cause these symptoms. The EMG does not show brain or spinal cord diseases.

Nerve conduction studies are done to:

• Find damage to the peripheral nervous system, which includes all the nerves that lead away from the brain and spinal cord and the smaller nerves that branch out from those nerves. Nerve conduction studies are often used to help find nerve disorders, such as carpal tunnel syndrome or Guillain-Barré syndrome.

Both EMG and nerve conduction studies can help diagnose a condition called post-polio syndrome that may develop months to years after a person has had polio.

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Author:	Jan Nissl, RN, BS	Last Updated: September 1, 2006
Medical Review:	Patrice Burgess, MD - Family Medicine Barrie J. Hurwitz, MD - Neurology
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