Electrodiagnostic medicine is medical subspecialty. Specially trained physicians use information from a patient’s history and physical exam, along with the results from tests they conduct to record and analyze electrical impulses between muscles and nerves, to diagnose, evaluate and treat neuromuscular, musculoskeletal, and nervous system disorders. Here are some frequently asked questions (FAQs) patients may have about an electrodiagnostic appointment. If you have other questions, please discuss them with your physician or locate a Board certified physician through the ABEM directory.
Neuromuscular medicine is the practice of medicine that involves the care of adult and pediatric patients with disorders of the peripheral nervous system (PNS) and its connections with the central nervous system. The PNS includes the motor and sensory neurons, peripheral nerves, neuromuscular junctions, and muscles. The care of patients with neuromuscular symptoms and signs includes physical examination, clinical investigation, diagnosis, management, and counseling for patients and their families. Neuromuscular medicine requires training and knowledge beyond that expected of a general neurologist or physiatrist. Electrodiagnostic medicine is a part of neuromuscular medicine.
Who performs the needle electromyogram (EMG) and nerve conduction study?
The AANEM’s policy is that an appropriately trained doctor should do all needle EMG testing. A trained technologist under a doctor’s supervision can perform nerve conduction studies.
What kind of medical training do doctors who perform EMGs have?
Doctors who perform EMGs go to 4 years of medical school then have 3 or 4 more years of training in a residency program. Most work as neurologists or physical medicine and rehabilitation doctors. Medical training helps the doctor decide which tests to perform based on your symptoms. It teaches doctors what can go wrong with the human body and how to tell the difference between these problems.
Why am I being sent to the EMG Lab for tests?
You are being sent to the EMG lab because you have numbness, tingling, pain, weakness, or muscle cramping. Some of the tests that the EMG doctor may use to diagnose your symptoms are nerve conduction studies, needle EMGs, and evoked potentials. The EMG doctor will examine you to decide which tests to do.
What does an NCS show?
Nerve conduction studies show how well the body’s electrical signals are traveling to a nerve. This is done by applying small electrical shocks to the nerve and recording how the nerve works. These shocks cause a quick, mild, tingling feeling. The doctor may test several nerves.
What happens during a needle EMG?
For this test, a small, thin needle is put in several muscles to see if there are any problems. A new needle is used for each patient, and it is thrown away after the test. There may be a small amount of pain when the needle is put in. The doctor tests only the muscles necessary to decide what is wrong. The doctor will look at and listen to the electrical signals that travel from the needle to the EMG machine. The doctor then uses his medical knowledge to determine what could be causing your problem.
What is an Evoked Potential?
Evoked potentials are painless tests that check the nerve pathways through the spinal cord or from the eyes and ears. The signals for these tests can come from small electrical shocks, light pulses, or clicks of sound in the ears. The nerve responses are recorded over the scalp and other areas of skin.
How long will these tests take?
The tests usually take 20 to 90 minutes. You can do any of your normal activities, like eating, driving, and exercising, before the tests. There are no lasting side effects. You also can do your normal activities after the tests.
How should I prepare for the tests?
Tell the EMG doctor if you are taking aspirin, blood thinners (like Coumadin®), have a pacemaker, or have hemophilia. Take a bath or shower to remove oil from your skin. Do not use body lotion on the day of the test. If you have myasthenia gravis, ask your EMG doctor if you should take any medications before the test.
When will I know the test results?
The EMG doctor will discuss your test results with you or send them to your regular doctor. After the exam, check with the doctor who sent you to the lab for the next step in your care.
What other tests may be recommended?
Depending on your symptoms, your physician may recommend neuromuscular ultrasound, biopsies, or genetic testing.
What is a muscle biopsy?
A needle muscle biopsy is a short procedure to remove a small piece of muscle tissue using a hollow needle. Once in the laboratory, the muscle cells are checked for various proteins, which may be responsible for neuromuscular disorders.
What is NM ultrasound?
Neuromuscular ultrasound is an emerging diagnostic field which focuses on traumatic and bad changes in your tendons and joints. Recent advances allow doctors to see these with ultrasound to help diagnose neuromuscular disorders.