Motor neurons are the nerve cells that transmit the electrical signals that cause your muscles to contract. An EMG test uses tiny electrodes to transmit these signals to a machine, which translates them into graphs, sounds, or numerical values that a neurologist can read and interpret.
EMG testing is done on muscles when they’re at rest, slightly contracted, and forcefully contracted. Normally, muscle doesn’t produce electrical signals when it’s at rest. As it’s contracted, the electrical activity increases, with forceful contractions producing the greatest amount of electrical activity.
An EMG is one of the go-to diagnostic tools for patients who have signs and symptoms of a nerve or muscle disorder. Common symptoms that lead to EMG testing include:
EMG results are often the definitive link to either confirming or ruling out a range of muscle or nerve conditions, such as:
During your EMG, you’re asked to remove any objects containing metal, such as jewelry or your glasses, because they can interfere with the test. You may also be asked to wear a hospital gown. Depending on your symptoms and the affected muscles, your neurologist at The Neurology Group may place surface electrodes at various places on your skin, or they may insert tiny needle electrodes through your skin and into the muscle.
As the electrode measures the electrical activity of your muscle, you’re able to either see it on a screen or hear it through a speaker. Your doctor gives you instructions during the test about when you should rest the muscle, and when and how forcefully you should contract it.
Take a shower shortly before your test to remove the natural oils from your skin, and don’t apply any lotions or creams. Because body temperature can affect the results of an EMG, you may need to warm up after you arrive for your appointment, if you’re having your test during the winter months.
If you have a pacemaker or a cardiac defibrillator, take blood-thinning medications, or have hemophilia, let your neurologist know before you have the test. The test is also safe to take if you are pregnant, but let your neurologist know before you have the test.