ELECTROMYOGRAPHY

Patient having nerve conduction testing done

ELECTROMYOGRAPHY (EMG, Nerve Conduction, Electromyogram)

Definition

Electromyography (EMG) and nerve conduction testing (NCS) studies the function of individual nerves and muscles. Several means may be employed but usually include measurement of nerve and muscle response to electrical stimulation and measurement of spontaneous muscle electrical activity.

What's it used for?

These tests are used for any dysfunction of nerve and muscle including pinching or compression of a specific nerve, inherited or acquired nerve dysfunction and inherited or acquired muscle dysfunction. Symptoms which might be due to these type of problems include tingling, numbness, pain, weakness and muscle cramping. Testing typically takes from 20 minutes to 90 minutes, depending on the problem your doctor is testing for. Test results are sent to your doctor.

Preparation

Since most testing involves the arms or legs, you should make sure that these areas are easily accessible for testing. Creams or lotions interfere with the measurement of the electrical activity and should be avoided. Take a bath or a shower to remove the natural oils from your skin. If you have Myesthenia Gravis ask your doctor if you should take your medication the day of the test. Tell your doctor if you are taking any blood thinners such as aspirin, warfarin or coumadin, if you have Hemophilia, or if you have a pacemaker.

What are the Side Effects?

There are no lasting side effects from the tests, but the testing itself can sometimes be uncomforatable. The NCSs involve small electrical shocks to the nerve which may cause a quick tingling of pricking feeling along with an involuntary twitch of the arm or leg.

EMG studies usually use a thin needle inserted into several muscles. These needles are usually disposable and a new one is used for each patient. Like any needle, some discomfort may be felt.

Where is it done?

Nerve conduction and EMG testing can be done in doctor's offices or hospitals where the appropriate equipment is available.

R. O'Brien MD