My provider has ordered an EMG/NCS test. Now what?
What is an EMG/NCS test?
EMG stands for electromyography and NCS stands for nerve conduction studies. It is a two-part test. First, small, completely safe, electrical shocks are applied to the skin, one nerve at a time. The specially trained technician has many years of experience. Recordings are made to determine the health of the nerves. Next, a specially trained physician performs electromyography by inserting a thin needle into several muscles of the arm or leg, one at a time, and records the natural electrical activity present at rest and with slight activation of the muscle.
What does an EMG/NCS test for?
The test is used to assess the health of muscle tissue and the peripheral nervous system, which includes all the nerves outside the brain and the spinal cord. It evaluates common conditions such as carpal tunnel syndrome and peripheral neuropathy. The test is also used to look for damage to the nerve roots that exit the spinal cord and become pinched by disc or bony material of the spine (radiculopathy). The test is also used to evaluate for rarer conditions such as ALS (Lou Gehrig’s disease), muscle disease (myopathy) and myasthenia gravis.
Why is my provider ordering the test?
When your doctor heard about your problem, he/she thought it could be caused by a nerve or muscle condition that EMG/NCS can be helpful to diagnose. Providers usually make a mental list of the possible causes for a patient’s problem. This test helps narrow that list.
How long will it take?
It depends on what your provider has ordered. If only one arm or one or both legs are being tested, it will likely take one hour, start to finish. If both arms are ordered, plan for 1½ hours. Keep in mind, the needle part (electromyography) will only take five minutes or so for most patients.
Does it hurt?
For almost everyone, the test is only mildly painful. Some people read online or are told by their provider, most of whom have never had the test or seen it done, that the test is painful and then come to the test anxious. I’ve even had people hyperventilating when I open the door. Others say they lost sleep worrying about the test. I want to relieve your anxiety about an EMG/NCS. Almost everyone says it was not nearly as bad as what they have heard or read. Part of the reason the test has a bad reputation is that many years ago the needles used to be much larger. Technology has allowed them to be much smaller without compromising quality, and comfort has dramatically improved.
How big is the needle?
The needle used is very thin. I tell people it is similar to the size of an acupuncture needle, not like a blood drawing needle. Also, we have the option of using a cooling spray just before inserting the needle to help reduce pain.
How should I prepare?
Although usually no specific preparation is necessary, you can do a few things beforehand. Do not use moisturizers on your skin for a few days before the test so that tape used during the test will stick. If having studies on the arms, consider wearing a shirt with short sleeves that can push up to the point of the shoulder; otherwise, we will need for you to change into a gown. A T-shirt works well. Wear clothing that is easy to remove if you are having studies done on your legs. It’s a good idea to empty your bladder just before beginning the test for comfort. The test can easily be stopped if you need to urinate.
When will I know the results?
Going over the results and deciding the next steps in diagnosis and treatment is ultimately up to the provider who sent you. We will generally discuss whether the test showed abnormalities or not, and for common and non-life threatening conditions such as carpal tunnel, tell you what was found and what your provider will likely do next. Some serious or complex diagnoses need to be discussed by your referring clinician.
Providers usually make a mental list of the possible causes for a patient’s problem. The EMG/NCS test helps narrow that list.