Electromyogram (EMG)

What is an electromyogram?

An electromyogram, or EMG, is a test that checks the response of muscles to messages sent by the nerves. The test measures the electrical activity of muscles in response to stimulation.

When is it used?

An electromyogram can help diagnose problems such as:

• nerve damage or injury caused by a compressed disk in the neck or back
• nerve compression from carpal tunnel syndrome in the hand
• muscle or movement problems, such as involuntary muscle twitching
• muscle weakness from nerve disorders or diseases such as muscular dystrophy
• nerve problems caused by conditions such as diabetes, pernicious anemia, and heavy metal poisoning.

How do I prepare for an electromyogram?

Tell your health care provider before the test if:

• You have any bleeding problems.
• You have a pacemaker.
• You have allergies.
• You are taking any medicines.

On the day of the test, take a shower to remove body oil and do not use body lotion.

How is the test done?

First you may be given a sedative to relax you. Your health care provider will insert several small needle electrodes through your skin into the muscles being tested. The electrodes record the electrical activity of the muscles. Muscles may be tested when they are resting, when contracting gently, and when contracting forcefully. The test takes about 30 to 60 minutes to perform, depending on the number of muscles being tested.

What happens after the test?

The muscles may feel tender or bruised for a few days after the test.

How will I get the test result?

Ask your health care provider when and how you will get the result of your test.