What Is EMG (Electromyography)? When Is It Performed?

Created: 07.07.2025  ·  Last Updated: 30.07.2026  ·  Category: Neurology  ·  Prepared by the Academic Hospital Web and Medical Editorial Board.

What Is EMG (Electromyography)?

EMG (Electromyography) is a diagnostic test that measures the electrical activity of muscles and nerves. Electrical signals produced by muscles at rest and during voluntary contraction are evaluated to obtain information about muscle- or nerve-related problems.

EMG is especially useful in neurologic disorders as an auxiliary method for diagnosis and differential diagnosis. It may also help guide treatment planning and, in some cases, follow-up.

Important Information: EMG does not use radiation. However, if needle EMG is planned, blood thinner use, bleeding disorders, infection risk or the presence of a pacemaker/electronic medical device should be reported to the healthcare team before the test.

When Is EMG Performed?

EMG is used in the diagnosis of many muscle and nervous system problems. It may be requested to identify the source of symptoms and help create the correct treatment plan in the following situations:

  • Numbness and tingling in the hand, arm, leg or face
  • Muscle weakness
  • Muscle twitching, cramps or spasms
  • Nerve entrapment such as carpal tunnel syndrome
  • Nerve compression related to lumbar or cervical disc herniation
  • Neuromuscular disorders such as ALS, polyneuropathy or myopathy

If these symptoms are present, consulting a neurology specialist is important for proper evaluation.

You can contact us to evaluate whether EMG is needed for numbness, tingling, muscle weakness or suspected nerve entrapment.

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How Is EMG Performed?

EMG usually consists of two parts. Which parts are performed depends on the patient’s symptoms and the nerve-muscle problem the physician wants to investigate.

  1. Nerve conduction study (NCS): Small electrodes are placed on the skin. Low-voltage electrical stimuli are applied to the nerves, and the speed and quality of nerve responses are measured.
  2. Needle EMG: A fine needle electrode is inserted into the selected muscle. Electrical signals generated at rest and during contraction are recorded, allowing assessment of the muscle and the nerve controlling it.

EMG results are evaluated by a neurology specialist. According to the result, a diagnosis may be made, differential diagnosis may be supported or further testing may be requested.

What Should Be Considered Before EMG?

  • You may shower before the test; however, the skin should not have lotion, cream or oil on it.
  • The test usually does not require fasting.
  • People taking blood thinners or those with bleeding disorders should inform their doctor before the test.
  • If you have a pacemaker or another implanted electronic medical device, you should inform the technologist or neurology specialist before EMG.
  • Previous surgeries, current infections and medications should be shared with the healthcare team.

The Need for EMG Is Determined by Neurology Evaluation

In numbness, tingling, muscle weakness, cramps or suspected nerve entrapment, EMG may help the diagnostic process.

Frequently Asked Questions

How long does EMG take?
Depending on the body region and the scope of the examination, an EMG test usually takes between 30 minutes and 1 hour.
Is EMG safe?
EMG is a diagnostic test that does not use radiation. Nerve conduction studies use low-voltage electrical stimulation, and needle EMG uses fine needle electrodes. Blood thinner use, bleeding disorders or pacemakers/electronic medical devices should be reported beforehand.
Is EMG painful?
Short electrical stimuli during nerve conduction studies may cause discomfort. During needle EMG, a fine needle electrode may cause brief pinching or soreness; most patients can tolerate the procedure.
Do I need to fast before EMG?
Fasting is usually not required before EMG. The skin should be clean and dry, and lotions or oils should not be used. Medications and implanted medical devices should be reported to the healthcare team.
Academic Hospital note: EMG evaluation should consider symptom location and duration, numbness/tingling, muscle weakness, suspected nerve entrapment, medications, blood thinner use and the presence of electronic medical devices together. You can book an appointment for evaluation.

References

  1. Mayo Clinic. Electromyography (EMG)
  2. Cleveland Clinic. EMG (Electromyography): Purpose, Procedure & Results
  3. Cleveland Clinic. Nerve Conduction Study