What is electromyography (EMG)?
Electromyography (EMG) is a diagnostic test. Your doctor may order this test to help evaluate the health and function of your nerves and muscles. An EMG may be recommended if you symptoms such as have muscle weakness or numbness and tingling.
When is electromyography (EMG) necessary?
Results from these tests help your healthcare provider diagnose a wide range of conditions, disorders, and injuries affecting the nerves and muscles.
How does electromyography (EMG) work, and what can I expect on the day of testing?
The EMG study usually includes two parts: 1) Nerve Conduction Studies (NCS) and 2) Needle electrode examination (NEE).
During the first part of the test (NCS), small discs are placed on the skin to record nerve function. Mild electrical stimulation is then applied over the skin to test the ability of the nerves to carry the electrical impulse to the recording discs. You can think of your nerves as being similar to electrical cables. A damaged cable will prevent electricity from running through it and powering the devices it is attached to (such as your TV). In a similar way, damaged nerves will prevent electrical signals from running through and being recorded by the discs attached to your skin.
During the second part of the test (NEE), a tiny needle is placed into muscles to directly test the function and health of the muscles. A mild pinprick sensation may be felt when the needle is placed into the muscle. During this part of the testing, no electrical stimulation is delivered through the needle and nothing is injected through the needle tip. You can think of the needle as being similar to a microphone. It is only a recording device. The needle is attached via a cable to a computer which allows your physician to both hear and see what your muscle is doing both at rest and with movement.
How do I prepare for electromyography (EMG)?
Before you have an EMG, you should:
- Bathe or shower. Wear comfortable, loose-fitting clothing.
- Avoid putting cream, lotion or perfume on your skin. Creams and lotions can affect the test’s accuracy.
- Tell your provider if you’re taking blood thinner medication (anticoagulants) such as warfarin. Blood thinners may increase your risk of bleeding after an EMG. But don’t stop taking your medication without talking to your provider.
What should I expect after electromyography (EMG)?
You may have sore or tender muscles for a few days after the test. The muscle soreness isn’t usually severe and should get better in less than a week. You may also see some bruising where the needles entered your skin.
What are the risks of electromyography (EMG)?
EMG is generally safe. Complications are rare. Some people (especially people who take blood thinner medications) may bleed after the test. Rarely, infections can occur where the needles entered the skin.
When should I know the results of an electromyography (EMG) test?
You can expect to receive the results of the test typically within 24 to 48 hours after testing is completed.
When should I call my doctor about electromyography (EMG)?
Call your provider if you have:
- Bleeding that doesn’t stop.
- Severe pain or tenderness where the needles entered the skin.
- Redness, warmth, swelling or a fever. These may be signs of an infection.
A note from Cleveland Clinic
If you have signs of muscle disease, nerve damage or injury, an EMG test will help your provider deliver an accurate diagnosis. It also helps your provider plan treatment. Before an EMG test, be sure to tell your provider if you’re taking blood thinner medications. These drugs can increase your risk of bleeding after the test.