Electrodiagnostic Testing

Venu Akuthota

Updated 5/2009

Electrodiagnostic (EDX) studies (sometimes called EMG for electromyography) are a commonly used technique to test the function of muscles and nerves. These studies are ordered by physicians to help determine the cause of back or neck pain, numbness/tingling and strength loss. Commonly diagnosed conditions include “pinched nerves” (radiculopathies), peripheral nerve injuries and muscle disease.

They are usually two parts: one testing nerves (referred to as “nerve conduction studies”) and the other testing muscles (referred to as “electromyography”). These studies allow the NASS physician to learn how nerve and muscles are functioning. This testing process often helps to narrow down the possible causes of back/body pain and muscle weakness.

Nerve Conduction Studies

The NASS doctor performs these studies by placing sensors over nerves in the arms and legs and then stimulating those nerves with small electric sensations. Most patients report that these studies are “uncomfortable” but not necessarily painful. The doctor is able to see how fast or slow nerves are functioning. Comparisons are made to averages to see if see the nerves are working properly.

Electromyography (EMG)

EMG is performed by placing small needles in the muscles of the arm, leg or back to directly evaluate the electrical activity caused by a muscle contraction. Most patients state that the needles feel like a small cramp or a splinter in the muscle. EMG allows the NASS physician to evaluate how well muscles are functioning. In addition, the EMG study can help determine if muscles are receiving the proper signal from nerves.

When would my NASS doctor consider an electrodiagnostic study?

This study is considered when the reason for pain or tingling or weakness is not clear. This study can also be used to determine the severity of a nerve injury or how badly a nerve is being pinched in the neck or back. Occasionally other conditions can mimick a pinched nerve in the back or neck. Electrodiagnostic studies can also help determine if other conditions are occurring.

What should my NASS doctor know about me to determine if I should have an EDX?

The doctor performing the electrodiagnostic test will ask questions about the nature of your pain, tingling and weakness. This will help them determine which nerves and muscles to test. The NASS physician may also ask questions about other conditions which may affect the nerves and muscles, such as diabetes and thyroid problems. Your NASS doctor should know if you have ever had a neck or back surgery.

Are there any reasons I should not have an EDX study?

If you are on blood thinning medications, such as aspirin, plavix, heparin or warfarin (Coumadin), the NASS physician may not perform certain portions of the test. If that information is absolutely necessary, you may be asked to stop blood thinning medication prior to the electrodiagnostic test. If you have a pacemaker or similar device, certain portions of the test may not be able to performed.