By Dr. Glen Halvorson
Glen Halvorson M.S., M.D. is well known in his field for his extensive research and practice of electromyography. So we sat down with him for a few questions about electromyography.
Q: What is an EMG?
A: The letters “EMG” stand for electromyography. As opposed to an EKG, which is an electrical test of the heart, an 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. As such, I don’t personally use “EMG.” When I write for such tests, I use the term, “EDx” which is an electrodiagnostic exam. This comprises both muscle and nerve testing.
Q. What should patients know about EMGs?
A: Let’s start with what the test does. And EMG is a test of normal vs. abnormal electrical activity in the muscles and nerves. If you have pain, numbness, burning, weakness or tingling, symptoms of nerve irritation these may come from either peripheral nerve or nerve root injury.
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. We treat many people with radiating nerve-like pain when structural lesions of the spine such as herniated discs, bone spurs, and/or degenerative arthritic narrowing cause pain by pressing on nerve roots. In simple terms: if a person has a pinched nerve in the spine or extremity, I can do a test to determine where it is pinched, how severely it is pinched and if there is evidence of permanent or temporary damage. I can also distinguish between injury to motor versus sensory nerves as well as differentiating 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.
Q: Are there side effects or any issues patients should look for following an EMG?
A: No, an EMG is a safe procedure. There is some mild discomfort involved. The test should take between 30-90 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 we require is no lotion, cream or body oil used prior to the test because we are sticking electrodes on the skin to record the nerve responses. From a practical perspective, if you wear a short sleeve shirt and shorts, patients probably don’t have to get into a gown.
Q: Is an EMG typically covered by insurance?
A: Some insurance do not require pre-authorization for in-clinic procedures. Others do. It is highly variable. Sometimes you can get immediate authorization over the phone, and for others it might be a few days to a couple of weeks. Evidence-based guidelines for who, what, and when to test are established by the AANEM. Medicare guidelines pretty much follow the AANEM guidelines verbatim, which have been established by medical experts in the fields of neurology, who specialize in electrodiagnostic medicine.
Dr. Glen Halvorson is board certified in electrodiag- nosis with the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM). He is a former oral examiner for the national EMG board and former Arizona State physician representative to the AANEM for 10 years. He is a Qualified Medical Examiner for the State of California. As medical director of a Medicare licensed independent testing facility he has interpreted in the past three years over ten thousand nerve tests of patients with primarily diabetic neuropathy.