Electromyography

Your health care provider inserts a very thin needle electrode through your skin into one of your muscles. The electrode on the needle picks up the electrical activity given off by your muscles. This activity appears on a nearby monitor and may be heard through a speaker. After placement of the electrodes, you may be…

No special preparation is usually necessary. Avoid using any creams or lotions on the day of the test. Body temperature can affect the results of this test. If it is extremely cold outside, you may be told to wait in a warm room for a while before the test is performed. If you are taking blood thinners or…

You may feel some pain or discomfort when the needles are inserted. But most people are able to complete the test without problems. Afterward, the muscle may feel tender or bruised for a few days.

EMG is most often used when a person has symptoms of weakness, pain, or abnormal sensation. It can help tell the difference between muscle weakness caused by the injury of a nerve attached to a muscle, and weakness due to a muscle or other nervous system disease.

There is normally very little electrical activity in a muscle while at rest. Inserting the needles can cause some electrical activity, but once the muscles quiet down, there should be little electrical activity detected. When you flex a muscle, activity begins to appear. As you contract your muscle more, the…

An EMG can detect problems with your muscles during rest or activity. Disorders or conditions that cause abnormal results include the following: Alcoholic neuropathy (damage to nerves from drinking too much alcohol) Amyotrophic lateral sclerosis (ALS; disease of the nerve cells in the brain and spinal cord that…

Risks of this test include: Bleeding (minimal) Infection at the electrode sites (rare)

Katirji B. Clinical electromyography. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 36. Preston DC, Shapiro BE. Basic overview of electromyography. In: Preston DC, Shapiro BE, eds. Electromyography and…