What is an Electromyography (EMG)?

Electromyography, called “EMG”, tests the electrical activity of the muscle at rest and flexed (contracted). Certain muscle disorders, such as a pinched nerve, neuropathies and muscle diseases, change the electrical activity of the muscles.

The testing involves the use of surface electrodes (small round metal discs) for nerve testing and small, fine needle electrodes for muscle testing. The electrodes are placed in different locations on your body and connected with small wires to a computer. The computer records the responses of the nerves and muscles on a chart called the electromyograph.

What happens during testing?

To measure nerve responses, the technician will touch a small stimulator to your skin. This will produce a small shock-like sensation. These stimuli are not harmful but could be somewhat uncomfortable and are used to determine if the nerves are functioning correctly.

What happens during muscle testing?

When measuring muscle activity, a tiny disposable needle is inserted into the muscle being studied. When the needle is inserted, the computer records the muscles reaction. The “resting” activity is recorded first. In the next stage you are asked to gradually increase the tightening or contracting of the muscle. During the test the needle electrode may be moved to another part of the muscle.

What should I expect after the test?

There are no side effects from this test. There may be some discomfort afterwards in the areas tested, but this will be temporary.

The results will be studied by a neurologist who is a specialist in nerve and muscle diseases. The report of the findings will be sent to your physician who will discuss them with you.