Electromyography (EMG) and Nerve Conduction Studies

Reviewed

EMG and nerve conduction studies are tests that check how well your muscles and the nerves that control them are working. An EMG test looks at the electrical signals your muscles make when at rest and when used. A nerve conduction study measures how fast and how well your body's electrical signals move along your nerves. These tests can help find out if you have a health condition that has damaged your muscles or nerves or how they work together.

Preparation and collection

Tell your provider if you have a pacemaker or cardiac defibrillator (special steps will be needed). Tell your provider if you take blood thinner medicines (you may need to watch for more bleeding from the needle). Wear loose, comfortable clothing. Make sure your skin is clean; do not use lotions, creams, or perfumes for a day or two before the test.

Understanding this test

Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.

  • EMG may cause mild pain or discomfort when the needle electrode is inserted; if pain becomes very uncomfortable it may change test results.
  • NCS may cause a mild tingling feeling (like mild static electricity) during the electrical pulse.
  • The muscles tested may be sore for a few days after the test, and there may be some bruising where needles were placed.
  • Results are not diagnostic on their own; your provider will consider your symptoms, medical history, and other test results.

What to do next

If your results are not normal, it can be a sign of many different conditions. Your provider will consider your symptoms, medical history, and the results of other tests to determine the cause. Talk to your provider about what your results mean.

Evidence source

U.S. National Library of Medicine: Electromyography (EMG) and Nerve Conduction Studies

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