Nerves use electrical impulses to coordinate muscle movement in our bodies. Diseases affecting the muscles and nerves can result in abnormal electrical activity.
Electromyography (EMG) is a diagnostic test used to detect nerve and muscle disorders and to evaluate the functioning of muscles. It records the electrical activity produced by the muscles, during rest and contraction. Your doctor may arrive at a diagnosis based on the results of the EMG along with information from your medical history, physical and neurological examinations, and results from other tests.
EMG testing can be used for the diagnosis of a variety of disorders that damage muscle tissue, nerves, or the junctions between nerve and muscles. An EMG can also be used to evaluate the cause of weakness, paralysis, and muscle twitching.
Prior to the procedure
You will be instructed not to use lotion on your skin prior to the procedure. Please take all your usual medications on the day of the procedure.
Electromyography is performed by an EMG technologist or a doctor. It may be conducted in a doctor’s office, hospital or clinic. During the test, you will be asked to lie down on a table or bed so that the muscles being tested are relaxed. An EMG normally takes about 20 to 40 minutes. A needle electrode is inserted into the muscle, connected by wires to a recording machine. You may feel a quick, sharp pain during the insertion of the electrode. The doctor then records your readings with the muscle at rest and under contraction. The needle electrode may be moved several times to record the electrical activity in different areas of the muscle. On the computer screen the electrical activity may be depicted as wavy and spiky lines. Electrical impulses may also be monitored through a speaker, in which the electrical signals are denoted by a popping sound or monitored on video. After the test, the needle electrode is removed.
Some soreness and a tingling sensation may persist for 1 or 2 hours after electromyography. Certain factors or conditions may interfere with the test results. These tests are usually avoided in individuals with swelling, bleeding, or obesity.
EMG can be used for the diagnosis of a variety of disorders that damage muscle tissue, nerves, or the junctions between nerve and muscle.