Electrical Impulses Provide Insight?

By Jon Konzen, DO
Neurology
Chippewa Valley Neurosciences, Eau Claire

In evaluating issues of pain, numbness, or weakness of the neck, back, arms or legs, your physician may request that you undergo an ÒEMGÓ study. What is it and what does it evaluate?

EMG stands for electromyography. This is a diagnostic test that looks at problems with the nerves and muscles of the body that may produce pain, numbness or weakness. The test is usually done by a specialist, such as a neurologist or physiatrist, who has had specialized training in electromyography. This procedure is a two part test. The first part of the study consists of attaching small skin electrodes to various parts of the body under examination. A small electrical stimulus is given to the skin surface, feeling much like rubbing your feet on the carpet and getting a Òstatic electric shockÓ. This will in turn cause an electrical signal to travel down a nerve to another point on the skin, where an electrode is attached to record how well the nerve is functioning.

Nerves are connected to muscles. When there is a problem in the nerve, it often produces changes in the muscle to which it is attached; thus, the second part of the study. This is the needle examination. The needle does not inject anything nor deliver any stimulus. It is a recording electrode and will be ÒlisteningÓ to the muscle for abnormalities.

There are many problems for which an EMG study is ordered including: nerve compression, or pinching of the nerve at the wrist, such as carpal tunnel syndrome. Other areas of compression can include the neck or back, in which case, the pinching is called a radiculopathy. An EMG can not only tell if the compression exists, but how severe it is. This is important in advanced states, as it may be able to identify a correctable condition before it produces permanent and irreversible damage.

In addition to compression, the test can define other types of problems such as muscle disease called myopathies. These include muscular dystrophy. The test may also be done if the connection between the nerve and the muscle is suspected to be abnormal, or to determine that the problem is not nerve or muscle related.

The most common question regarding EMG is whether or not the study hurts. The study may involve some discomfort; however, it is short lasting and should not require any anesthesia. Most studies take about one hour to complete. The study can be done on patients who are on coumadin, as well as, on patients that have cardiac pacemakers in place.

After the study is completed, the examining physician will review the data and send the results, with a report, to the referring physician. The results are usually available the same day as the test. The patient will get the final results from his or her referring physician. In some cases, the findings on the study may require that the patient see another physician, if specialized treatment is required. For example, if the findings on the test show significant carpal tunnel syndrome, then a surgical referral may be necessary.

For more information, call Dr. Jon Konzen, Chippewa Valley Neurosciences Eau Claire » 715.831.0811