Muscle & Nerve Testing
An electromyogram (EMG) is an electrical test of skeletal muscle. There are two aspects of this test: the first is the muscle test, called the EMG. The second tests the nerves – specifically the peripheral motor nerves and the sensory nerves. This test is called a nerve conduction study, or NCS. When someone refers a patient for an EMG, common usage of the term incorporates both tests.
What should I know about EMG?
An EMG is a test of normal vs. abnormal electrical activity in the muscles and nerves. If you have pain, numbness, burning, weakness, tingling, or other symptoms of nerve irritation, they may be coming from an injury to either your peripheral nerves or a nerve root. An EMG helps determine which and can be a very useful tool in determining your treatment options.
When your nerves come out of the spinal cord, they are called nerve roots. From there they divide into nerve branches that become peripheral nerves. Many patients have radiating, nerve-like pain caused by pressure on nerve roots. This can occur when there are structural lesions of the spine such as herniated discs, bone spurs, or degenerative arthritic narrowing. In simple terms, if a person has a pinched nerve in the spine or extremity, an electromyogram can determine where it is pinched, how severely it is pinched, and if there is evidence of permanent or temporary damage. It can also distinguish between an injury to different types of nerves as well as differentiate nerve trauma from nerve disease.
The value of the testing is in trying to accurately determine location and severity of the injury and give the referring/ treating physician this information. From there, the physician can best determine whether the patient needs a procedure and what kind of procedure.
Are there any side effects or issues patients should look for following an EMG?
An electromyogram is a very safe diagnostic exam. There is some mild discomfort involved. The test typically takes between 20-30 minutes depending on the complexity of the test and number of abnormal findings.
Patients can take all of their medications prior to testing. The only restriction required is that no lotion, cream, or body oil be used prior to the test because electrodes will be stuck to the skin to record the nerve responses. From a practical perspective, if you wear a short-sleeved shirt and shorts, you may not have to get into a gown.