What is an electromyogram?

An electromyogram (EMG) is a test that measures the electrical activity of the nerves and muscles. The study consists of two parts:

  1. The first part of the test involves nerve conduction studies (NCS) that are performed by a technologist. This part measures the ability of nerves to transmit (send) electrical impulses, or messages, to their respective muscles. This part involves a small and brief electrical stimulus.
  2. The second part of the test is called needle electrode examination, which is performed by a doctor who specializes in EMG. This part examines and measures the electrical activity in muscles. This involves inserting a very thin gauge needle that acts like a microphone into the muscle. Nothing is pushed in or pulled out through the needle. A number of muscles are examined this way, based on the clinical problem.

For both parts of the test, the patient may feel some uncomfortable sensations.

Why do patients need to have an electromyogram?

An EMG can help doctors learn the cause of numbness or paralysis, muscle weakness or spasms, and the cause of pain in the arms, hands, legs, feet, and face. The results will allow the ordering physician to decide how to treat the disorder.

Things to know about an EMG at Cleveland Clinic main campus site and its satellites:

  • Patients have both NCS and needle examination when an EMG is ordered.
  • The length of stay is 1 to 3 hours, based on the clinical problem, for both parts of the test at all EMG sites. Please plan to stay accordingly.
  • Precautions: If any of the following precautions apply, please call the main campus lab at 216.444.5544, Monday through Friday, between the hours of 7:30 a.m. and 5:00 p.m. Let them know if:
    • You have had symptoms for less than three weeks.
    • You are taking medications such as:
      • Mestinon® (pyridostigmine bromide)
      • Coumadin® (crystalline warfarin sodium)
      • Lovenox® (enoxaparin)
      • Heparin
      • Xarelto (rivaroxaban)
      • Eliquis (apixaban)
      • Pradaxa (dabigatran)
    • You have any bleeding disorder.
    • You have any electrical internal devices implanted (defibrillators, internal pain stimulators, deep brain stimulators, etc.).
    • The patient is a child who needs sedation for the procedure.
  • Patients will be asked to change into a gown, but may leave undergarments on.
  • Patients do not need to fast before this study.
  • Hygiene: Bathing is recommended to make sure that there are no oils, lotions, creams, or perfume on the skin. Please do not apply any of these items before the test. This will ensure the best results during the test.
  • Results are available to the ordering physician in three business days.

Last reviewed by a Cleveland Clinic medical professional on 12/06/2016.


  • American Association of Neuromuscular & Electrodiagnostic Medicine. Types of Tests Accessed 11/30/2016.

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