Electromyography (EMG) is a diagnostic test administered to people who may be experiencing muscle or nerve pain, including cramping, tingling, numbness, or weakness.
An EMG involves needle electrodes inserted into the muscle being tested. The test is used to measure electrical activity in particular muscles when contracted. The test is also used to identify whether electrical activity is present when it shouldn’t be (that is, when the muscle is at rest). An EMG can identify whether the problem you are experiencing is with your muscle.
EMGs usually are performed at the same time as a nerve conduction study (NCS), in which electrodes are placed on top of the skin and used to send electrical signals to the muscle being tested. This test measures how fast and strong signals travel from one location to another. It can identify whether the problem is with your signaling of your nerves, rather than the muscle itself.
Preparing for an EMG
It is recommended that you avoid using moisturizers before an EMG. You should also avoid drinking caffeinated beverages at least 2 – 3 hours prior to testing. It is also inadvisable not to smoke before an EMG.
Your doctor should be notified of the medications you take, whether you use a pacemaker, an implanted device that helps to regulate your heartbeat, if you have epilepsy, or any metal implants in your body. Otherwise, follow your doctor’s instructions if any other preparation is needed based on your current health. You may be advised to wear loose clothing, depending on the area being tested.
What Happens During an EMG
An EMG and NCS may be administered by a physician, technologist, or a lab coordinator.
During an EMG, a needle electrode will be inserted into the muscle being tested. The insertion is generally not painful. The end of the needle will pick up signals from contracted muscles and measures and records that activity on a special device, which may emit audible clicks or numerical values, depending on the device being used.
Because an EMG typically occurs in conjunction with a nerve conduction study, an electrode sticker is placed some distance from the muscle, and it deliver a minor electrical current, which should prompt the muscle to work. You may experience minor discomfort as the signals are sent, but it generally doesn’t cause pain.
The combined tests usually take no more than an hour, depending on the body area being tested.
An EMG can help diagnose a variety of neuromuscular problems.
When an electrical activity is noted in resting muscles, it may mean you have a muscle disorder, a connective nerve disorder, or inflammation due to an injury. If responses from the stimulated muscles are abnormal, it could indicate a large number of issues such as a herniated disc or carpal tunnel syndrome. Your doctor will use the results of your EMG together with other factors before making a diagnosis.
Now you know what happens before, during, and after electromyography (EMG), you may wonder if you need to take one. Do you think you might have some sort of nerve or muscle disorder? SC Internal Medicine Associates and Rehabilitation offers a variety of on-site diagnostic services, including electromyography. Call us at (803) 749-1111 or request an appointment now.