Nerve Conduction and EMG Studies

Electrodiagnostic Testing (Nerveconduction testing and Needle EMG) or EMG Studies

An electrodiagnostic test is a neurodiagnostic test that measures the electrical activity of a muscle during contraction and relaxation. An electrodiagnostic test generally consists of two parts: nerve conduction studies and needle EMG. Nerve conduction studies are useful in detecting nerve-related problems, such as nerve entrapment (carpal tunnel syndrome), or more widespread nerve dysfunction. The needle EMG is useful for identifying problems arising from a “pinched nerve” in the spine, as well as, diseases of the muscles themselves. Both parts of the test are usually needed for the physician to obtain meaningful results. The results of this test help your doctor determine the cause of your symptoms and select the best treatment for you.

What happens during a nerve conduction test and needle EMG?

You will be asked to lie on an exam table, either on your back or stomach depending on the areas to be tested. Small, flat discs called electrodes will be taped to the surface of your skin. A small electrical current is used to stimulate the nerve. Since the level of electricity used during the test is very low (similar to that of static electricity), the test is very safe. Repeated small, short stimulations of varied intensity are administered. The electrical activity will be recorded on a computer connected to the EMG machine. The second part of the test involves the placement of a sterile, disposable, very thin needle electrode through the skin and into the muscle. The needle is a specialized recording device that directly records the muscle’s natural electrical activity at rest and during muscle contraction. Analysis of this activity gives important information about the health of each muscle tested as well as the controlling nerves. The stimulation of the nerve and the prick of the needle will be slightly uncomfortable, but lying still and remaining as relaxed as possible will help.

The entire test can last anywhere from 30 minutes to an hour depending on the number of areas to be tested. The results of the nerve conduction study and EMG will be discussed with you at your next appointment. Little preparation is needed before these examinations. Make sure not to place any skin lotions or moisturizers on before your examination. Wearing loose fitting clothing may also be helpful. Please inform the examiner if you take blood thinners or have a pacemaker.

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