Electromyography (EMG)

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Electromyography (EMG) measures and records the electrical activity of a muscle. The test can record a muscle's electrical activity at rest or during a muscle contraction.

An EMG is often done with nerve conduction studies. These studies can analyze the electrical activity in your nerves.

EMG is most often done to:

  • Aid in diagnosing the source of pain, cramping or weakness
  • Differentiate between true muscle weakness and limitations due to pain
  • Determine if muscles and nerves are working properly
  • Distinguish between muscle and nerve disorders

What to Expect

Your doctor inserts a small needle electrode into your muscle at rest. You’ll be asked to rest or contract the muscle. The needle picks up electrical activity and produces a waveform, which your doctor will record and analyze. Your doctor will repeat the test on different muscles and limbs.

The test takes between 30-90 minutes. You may have some pain when your doctor inserts the needle electrodes, and you may have muscle aches and discomfort for several days. Warm compresses and pain medication may help.

Your doctor will discuss treatment options with you based on the test results.

After Test

You’ll be able to leave once the test is done. Once you are home:

  • Resume any medications you stopped before the test
  • Resume normal activities as tolerated

Possible Complications

Problems from the procedure are rare. Your doctor will review potential problems, like:

  • Bleeding
  • Pain or bruising at the needle insertion site
  • Infection at the needle insertion site

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Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.