(EMG)En Español (Spanish Version)
This test measures and records the electrical activity that muscles generate at rest and in response to muscle contraction.
EMG of the Shoulder
© 2008 Nucleus Medical Art, Inc.
Reasons for Procedure
Electromyography (EMG) is often done at the same time as nerve conduction studies, which help to diagnosis peripheral nerve disorders.
EMG is most often done to:
- Aid in diagnosing the source of pain, cramping, or weakness in the muscles and nerves
- Differentiate between true muscle weakness and limitations due to pain
- Determine if muscles are working properly
- Distinguish between muscle and nerve disorders
Risk Factors for Complications During the Procedure
- Hemophilia and other bleeding disorders
- Use of blood-thinning medications
What to Expect
Prior to Procedure
Your doctor will likely do the following:
- Medical history
- Review your medications
- Physical exam
- Neurological exam
In the days leading up to the test:
- Avoid aspirin, aspirin-containing products, or anti-inflammatory drugs (eg, ibuprofen) for one week before the EMG
- Ask your doctor if you need to stop taking any of your medications
- If you have myasthenia gravis, ask if you should take any medication before the test
- If directed to, avoid cigarettes, coffee, tea, and soft drinks for 2-3 hours before the test
- Take a bath or shower before the test.
- On the day before, do not use lotion or oil
- Wear comfortable clothing, but expect to change into a hospital gown
Description of the Procedure
The doctor inserts a small needle electrode into a muscle at rest and moves the needle in the muscle. Each movement of the needle and muscle contraction produces a waveform. This waveform is recorded and analyzed. The test is repeated on different muscles and limbs.
No special activities or procedures
How Long Will It Take?
Will It Hurt?
You may have pain when the electrodes are inserted, which feels like an injection into the muscle. After the test, you may have muscle aches and discomfort for several days. Warm compresses and pain medication may help.
- Increased pain
Average Hospital Stay
- Resume any medication you stopped before the test
- Resume normal activities as tolerated
The doctor doing the EMG may discuss the results with you. Also, a report will be sent to your regular doctor, who will recommend treatment based on the tests, the exam, and your symptoms.
National Institutes of Health
National Institute of Neurological Disorders and Stroke
BC Health Guide
Medical encyclopedia: electromyography. National Library of Medicine website. Available at: http://www.nlm.nih.gov/medlineplus. Accessed August 1, 2003.
What to expect during your EMG test. American Association of Neuromuscular & Electrodiagnostic Medicine website. Available at: http://www.aanem.org/index.cfm?. Updated March 2005. Accessed June 5, 2008.
Young RR, Hutton JT, Homan RV. Gait and movement disorders. American Academy of Neurology website. Available at: http://www.aan.com/familypractice/html/chp8.htm. Accessed June 5, 2008.
Last reviewed November 2007 by Judy Chang, MD, FAASM
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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