Electromyography (EMG)

Electromyography (EMG) is a test that assesses the health of the muscles and the nerves controlling the muscles. 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 and nerves.

 

The test is performed by inserting a needle electrode through the skin into the muscle. The electrical activity of the muscles is detected by the electrode and displayed on an oscilloscope. The activity may also be heard through a speaker.

 

After placement of the electrodes, you may be asked to contract the muscle. The presence, size and shape of the wave form produced on the oscilloscope provide information about the ability of the muscle to respond when the nerves are stimulated.

 

No special preparation is usually necessary for the test. There may be some discomfort with the insertion of the electrodes and the area may feel tender or bruised for a few days following the test.