What is an electromyogram?

An electromyogram, or EMG, is a test that checks how your muscles respond to messages sent by your nerves. The test measures the activity of your muscles in response to small amounts of electricity passed through a needle to your muscles.

When is it used?

An electromyogram can help diagnose problems such as:

• Nerve damage or injury caused by a compressed disk in your neck or back
• Nerve problems in your hand from carpal tunnel syndrome
• Muscle or movement problems, such as muscle twitching that you cannot control
• 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 this procedure?

• You may or may not need to take your regular medicines the day of the procedure. Tell your healthcare provider about all medicines and supplements that you take. Some products may increase your child’s risk of side effects. Ask your healthcare provider if you need to avoid taking any medicine or supplements before the procedure.
• Tell your healthcare provider if you have any food, medicine, or other allergies such as latex, or if you have a pacemaker.
• Ask if there is anything you should avoid before the test, like smoking cigarettes or any food or drink containing caffeine.
• On the day of the test, take a shower to remove oil from your skin. Don’t put any lotions or creams on your skin before the test.
• Follow any other instructions your healthcare provider gives you.
• Ask any questions you have before the procedure. You should understand what your healthcare provider is going to do. You have the right to make decisions about your healthcare and to give permission for any tests or procedures.

What happens during the procedure?

An EMG can be done at a hospital or in a testing center. First you may be given a sedative to relax you. Your healthcare provider will insert several small needles attached to wires through your skin into the muscles where you are having symptoms. The wires record the electrical activity of the muscles. Your muscles may be tested when they are resting, when contracting gently, and when contracting forcefully. The test can be slightly painful when the electricity passes through the wires to the muscles.

The test takes 30 to 60 minutes, depending on how many of your muscles are being tested.

What happens after the procedure?

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

Ask your healthcare provider:

• How and when you will hear your test results
• How long it will take to recover
• If there are activities you should avoid and when you can return to your normal activities
• How to take care of yourself at home
• What symptoms or problems you should watch for and what to do if you have them

Make sure you know when you should come back for a checkup. Keep all appointments for provider visits or tests.