WHAT IS ELECTRODIAGNOSTIC TESTING (EMG/NCS)?

What is it?
Electrodiagnostic testing provides information about muscles and nerves helping the physician arrive at a diagnosis. The idea of EMG is not all that different than EKG. In EKG electrodes record the electrical activity of the heart. In EEG, the same thing can be done to record electricity within the brain. Technology has made it possible to record electrical activity of muscles and nerves (other electrical tissues) throughout the body.

How does it work?
The study consists of two portions: nerve conduction studies (NCVs) and electromyography (EMG). In nerve conduction studies, electrical impulses are given at various points along the course of specific nerves. The evoked response of those nerves to the electrical stimulus is recorded by the machine. The consultant will use the information outlined along with the history and exam to formulate a clinical impression.

In the EMG portion of the test, a needle electrode is introduced into specific muscles, one at a time, in order to receive both visual and auditory information about the electrical functioning of that muscle and the nerve which supplies it. In other words the electromyographer looks at the screen and listens to “static” noises which come from the muscle being studied.

The test generally takes between 30-60 minutes, although there are exceptional cases which require more or less time. For a good part of that time, the patient feels absolutely nothing while the electromyographer is setting up, measuring, calculating, and thinking.

What does a normal test consist of?
Unlike EKGs, there is no standard EMG study. The specific complaints (the history) which the patient gives and the physical examination determine how the doctor will begin his study. Ongoing results of the first nerves or muscles studied determine how to proceed and how extensive the test will be in order to come to a conclusion. As soon as the doctor has sufficient data to come to an intelligent conclusion, the test is completed.

Are there any side effects?
The electrical impulses and needle examination can both be somewhat uncomfortable. However, generally there is no risk from the procedure and no side effects. The patient might have occasional local muscle soreness for several hours following the test. Pain killers are virtually never needed and the patient is fully awake during the procedure. The only exception to this would be children, who are sometimes sedated to assure that they are able to lie still and cooperate with the test.

Regular medications and “pain killers” may be taken without any effect on the test results. It is important not to use any skin lotions or creams on the day of the test.

Cost?
Charges will vary depending on the extent of the test, generally between $300 and $600. The fee is usually covered by most insurance carriers. Some insurances, particularly HMOs, will require preauthorization.

Conclusion:
In summary, electromyography is a test whereby through use of electrical impulses and needle examination, responses can be recorded and interpreted to gain better understanding about muscles and nerves function in diseases. Along with a history and exam, it assists in arriving at a diagnosis. It is safe, no-invasive, well tolerated, and involves no medication or significant side effects.