What to expect at the appointment
On the day of your exam, do not use any creams, moisturizers or powders on your skin. If you have any bleeding disorders, let the examining provider know prior to testing. If you take blood thinners, even any aspirin or aspirin-like medications let the examining provider know. You may be asked to stop blood thinners and aspirin products prior to your examination. If you have a pacemaker let us know.
How to prepare
No lotions or creams
The lotions and creams make if more difficult to make good contact with the skin and can interfere with the test. We have alcohol wipes if we need to remove the lotions.
EMG/NCS of arms
For tests on the arms we recommend either wearing a loose fitting top or tank top so we can access the shoulders and neck.
EMG/NCS of legs
Please come with loose fitting shorts to change into. We also have a gown to change into if that is more comfortable.
lectromyography (EMG) measures muscle response or electrical activity in
response to a nerve’s stimulation of the muscle. The test is used to help detect neuromuscular abnormalities. During the test, one or more small needles (also called electrodes) are inserted through the skin into the muscle. The electrical activity picked up by the electrodes is then displayed on an oscilloscope (a monitor that displays electrical activity in the form of waves). An audio-amplifier is used so the activity can be heard.
EMG measures the electrical activity of muscle during rest, slight contraction and forceful contraction. Muscle tissue does not normally produce electrical signals during rest. When an electrode is inserted, a brief period of activity can be seen on the oscilloscope, but after that, no signal should be present.
After an electrode has been inserted, you may be asked to contract the muscle, for example, by lifting or bending your leg. The action potential (size and shape of the wave) that this creates on the oscilloscope provides information about the ability of the muscle to respond when the nerves are stimulated. As the muscle is contracted more forcefully, more and more muscle fibers are activated, producing action potentials.
A related procedure that may be performed is nerve conduction study (NCS). NCS is a measurement of the amount and speed of conduction of an electrical impulse through a nerve. NCS can determine nerve damage and destruction, and is often performed at the same time as EMG. Both procedures help to detect the presence, location, and extent of diseases that damage the nerves and muscles.