Department of Neurology
Department of Neurosurgery
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The EMG: Electromyography Test
University of Iowa Department of Neurology
Peer Review Status: Internally Peer Reviewed
Creation Date: Unknown
Last Revision Date: June 2003
An EMG evaluates the health of your muscles by measuring electrical activity. A thin, small electrode (needle) is inserted into one of your muscles, which is evaluated at rest and at various degrees of contraction.
What is it?
- evaluates the health of your muscles by measuring electrical activity
- a small thin electrode (needle) is inserted into one of your muscles, which is then evaluated at rest and at various degrees of contraction
How long does it take?
- 1-1/2 to 2 hours combined with NCV
Why is an EMG performed?
- if you are experiencing weakness in your arms, legs, hands, or face
- can determine whether weakness is due to muscle disease, nerve disease or disease of the junction between nerve and muscle
Does it hurt?
- you may experience some pain when the needle is inserted into each of the muscles being tested. Some discomforts should be expected during this test.
- the EMG is not acupuncture or a skin treatment of any kind. Nothing is injected into or under your skin.
Where is it conducted?
- the Electromyography Lab
- Lower Level of Carver Pavilion
How many EMGs are conducted each year?
What should you do to prepare for the test?
- eat normal meals
- continue taking prescribed medications unless your doctor gives other instructions
- tell your doctor if you are taking a "blood thinner" such as coumadin, heparin, or aspirin, or if you bruise easily or have hemophilia
How is the EMG performed?
- before the EMG begins, a doctor will give you a brief neurological exam to check your nervous system and muscles
- you will then lie on an examination table
- the doctor will insert a needle electrode into the muscle
- your muscle will then be evaluated at rest. During this phase, the needle is moved several times so that various sections of the muscle can be tested. This may cause some discomfort.
- you will be asked to flex your muscles slightly, and then as hard as you can, and additional measurements will be taken
- the number of muscles to be tested depends in the problem you have and what is found during the test
After the test
- you may return to your hospital room or go home, unless given other instructions from the doctor
- there might be a slight tenderness in the muscles that were tested, but this should go away in a few hours. Your muscles may also ache for 1 or 3 days
- you will learn the test results either from the doctor before you leave, or from a copy of the letter sent to your personal physician