Electromyography, or EMG, involves testing the electrical activity of muscles. Often, EMG testing is performed with another test that measures the conducting function of nerves. This is called a nerve conduction study. Because both tests are often performed at the same office visit and by the same personnel, the risks and procedures generally apply to both tests.
Muscular movement involves the action of muscles and nerves and needs an electrical current. This electrical current is much weaker than the one in your household wiring.
In some medical conditions the electrical activity of the muscles or nerves is not normal. Finding and describing these electrical properties in the muscle or nerve may help your doctor diagnose your condition.
EMG may aid with the diagnosis of nerve compression or injury (such as carpal tunnel syndrome), nerve root injury (such as sciatica), and with other problems of the muscles or nerves. Less common medical conditions include amyotrophic lateral sclerosis, myasthenia gravis, and muscular dystrophy.
People usually have a small amount of discomfort during EMG testing because of pin insertion. Disposable needles are used so there is no risk of infection.
During nerve conduction studies, small electrodes are taped to the skin or placed around fingers. You typically experience a brief and mild shock, which may be a bit unpleasant. Most people find it only slightly annoying.
During EMG, small pins or needles are inserted into muscles to measure electrical activity. The needles are different than needles used for injection of medications. They are small and solid, not hollow like hypodermic needles. Because no medication is injected, discomfort is much less than with shots.
You will be asked to contract your muscles by moving a small amount during the testing.
With nerve conduction studies, small electrodes will be taped to your skin or placed around your fingers. You typically will experience a mild and brief tingling or shock, which may be a bit unpleasant.
The person who administers the test will explain the procedure. Often muscle activity is monitored through a speaker during the test, which may make a popping or soft roaring noise. The EMG technician will be looking at an oscilloscope, which looks like a small TV set during the procedure.
Testing may take 30-60 minutes.
Detect and evaluate damage to the peripheral nervous system, which includes all the nerves that lead away from the brain and spinal cord and the smaller nerves that branch out from those nerves. Nerve conduction studies are often used to help diagnose nerve disorders, such as carpal tunnel syndrome or Guillain-Barré syndrome. Identify the location of abnormal sensations, such as numbness, tingling, or pain.