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Electromyography (EMG) measures and records the electrical activity of a muscle. The test can record a muscle's electrical activity at rest or during a muscle contraction.
An EMG is often done with nerve conduction studies . These studies can analyze the electrical activity in your nerves.
Reasons for Test
EMG is most often done to:
- Aid in diagnosing the source of pain, cramping, or weakness
- Differentiate between true muscle weakness and limitations due to pain
- Determine if muscles and nerves are working properly
- Distinguish between muscle and nerve disorders
Problems from the procedure are rare, but all procedures have some risk. Your doctor will review potential problems, like:
- Pain or bruising at the needle insertion site
- Infection at the needs insertion site
What to Expect
Prior to Test
Make sure you talk to your doctor about the medications you are taking. You may be asked to adjust certain medications up to a week before the test, such as:
- Aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs)
- Blood thinners
On the day before and day of the test:
- 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. You will have to change into a hospital gown.
- Tell your doctor if you have a pacemaker or other implanted device.