Electromyography (EMG) and Nerve Conduction Studies

Electromyography (EMG) and nerve conduction studies are tests that check how well your muscles and the nerves that control them are working. These nerves control your muscles by sending out electrical signals to make your muscles move. As your muscles react by tightening (contracting), they give off electrical activity, which can then be measured.

An EMG test looks at the electrical signals your muscles make when they are at rest and when used. A healthy muscle should not give off any electrical signals when you aren't moving it. If your muscle is damaged, it may show electrical activity while at rest or activity that is not normal while using it.; A nerve conduction study measures how fast and how well your body's electrical signals move along your nerves.

A damaged nerve has a slower and weaker signal. This test can help check for nerve damage.; EMG tests and nerve conduction studies can help find out if you have a health condition that has damaged your muscles or nerves or how they work together. These tests can be done separately, but they are usually done at the same time.

Why this test is done

You may need these tests if you have symptoms of a muscle or nerve disorder. These symptoms include:

• Muscle weakness
• Tingling or numbness in arms, legs, hands, feet, and/or face
• Muscle cramps, spasms, and/or twitching
• Paralysis of any muscles

How to prepare

Tell your provider if you have a pacemaker or cardiac defibrillator. Special steps will need to be taken before the test if you have one of these devices.

Tell your provider if you take blood thinner medicines. If you're taking blood thinners, you may need to watch for more bleeding from the needle.

Wear loose, comfortable clothing for easy access to the test area. It can be easily removed if you need to change into a hospital gown.

Make sure your skin is clean. Don't use lotions, creams, or perfumes for a day or two before the test. They can change the results of the test.

Other names for this test

electrodiagnostic study, EMG test, electromyogram, NCS, nerve conduction velocity, NCV