EMG (electromyography) is a method of examination of the health status of the structures by measuring the electrical properties of the muscles, nerves and nerve roots. EMG examination has two parts: examination of nerves and examination of muscles. Depending on the diagnosis, both or only one of them may be needed.
- Examination of Nerves: Some nerves selected in the arms, legs or other parts of the body are stimulated by electric current via an electrode placed on the skin. Electricity creates an unpleasant but tolerable feel where it is supplied. The electrical activities that occur in the nerve after stimulation are measured in various ways. Measurements are taken from 5 to 10 nerves in such a way during an EMG examination.
- Examination of Muscles: A needle-shaped electrode is placed in a selected muscle in the arms, legs, or other body parts to examine the electrical activity of the muscle. The electrode used is similar in size and appearance to injection needles. These electrodes are for single-use, a new needle is used for each patient, and this needle is then disposed of after examination (in some examinations such as single-fiber EMG, the electrodes are not disposable and re-used after sterilization). Pain during insertion of the electrode needle is similar to the pain experienced during intramuscular drug injection, but pain is less because no substance is injected during the EMG. Examination of each muscle takes a few minutes. The needle is held in the muscle within this period. The direction and location of the needle can be displaced several times for recording from different locations within the muscle. These procedures are usually painless or cause tolerable mild pain. The number of muscles to be examined in an EMG examination depends on the presumptive diagnosis; usually 1 to 10 muscle is examined.
EMG examinations are not performed for patients who have a high blood clotting disorder or who use medication that prevents blood clotting. Other than this, EMG can be performed for all age groups and for everyone; the presence of a pacemaker or neurostimulator does not prevent the EMG.
Duration of the examination takes 15 minutes to 1.5 hours depending on the scope of the procedure planned to be performed.
EMG has no expected side effects and no known lasting damage except the pain induced by electrical stimulation and the needle used. Rarely, an intramuscular temporary accumulation of blood might occur. Very rarely, during examination of some of the deep body muscles, adjacent tissues and organs may have temporary adverse effects.
There is no further examination replacing a one-on-one EMG examination. However, in some cases, depending on the nature of the disorder, the information that is expected to be obtained by EMG examination may be obtained in part by some other examination methods.