EMG (Electromyography)

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An EMG test determines the health and function of the muscles and nerves that control movement. Using electrodes to detect, evaluate, and record the electrical signals transmitted to your muscles and nerve cells. It helps diagnose the extent of nerve and muscle damage and locate where the damage has occurred or if it's reversible. The EMG test is a diagnostic tool that helps neurologists detect neuromuscular abnormalities.

An EMG test is used to evaluate conditions and disorders as follows: 

  • Involuntary muscle twitching
  • Sciatica
  • Muscular dystrophy
  • Myasthenia gravis
  • Carpal tunnel syndrome
What happens during EMG?

Small needles are inserted into the muscle through the skin. Electrodes in the needles detect electrical stimulation in the muscle and display the results in the form of waves on a monitor. Sometimes, an audio amplifier is available to record the sound of electrical signals. 

You may be asked to contract the muscle being tested (by lifting or bending the arm). A forceful contraction of muscle activates fibers that elevate stronger electrical signals. A healthy muscle shows an electrical signal during contraction and not during rest. However, a damaged muscle or muscle with lost nerve input shows abnormal electrical patterns during contraction and electrical signals during rest. 

Some discomfort may occur with needle insertion and soreness after muscle contractions.

What does the EMG detect?

You may be recommended EMG & NCV tests altogether to diagnose the cause behind an unexplained muscle weakness. One of the reasons could be multiple sclerosis, herniated disc, muscular dystrophy, carpal tunnel syndrome, etc.


  • Avoid using any creams or lotions on the day of the test.
  • Smoking should be avoided for at least three hours before the procedure.
  • Don't wear clothing that obstructs your doctor's view of the area being evaluated.
  • If you are taking blood thinners or anticoagulants, inform the doctor performing the test before it is done.
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