Electromyograpy (EMG)/ Nerve Conduction Study (NCS) Info
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Nerve Conduction Study/Needle EMG Test
An electromyography (EMG) and nerve conduction studies (NCS) test help evaluate and treat problems related to your nerves or muscles. A nerve conduction study (NCS) is a medical diagnostic test commonly used to evaluate the function of the motor and sensory nerves of the human body, especially the ability of electrical conduction. Nerve conduction velocity (NCV) is a common measurement made during this test. The term NCV often is used to mean the actual test. This may be misleading. Velocity is only one measurement in the test suite. If your physician has recommended these tests for you, please read the following information.
What does Electroymyography (EMG) mean?
Electromyography (EMG) simply means measuring the electrical activity of the muscles. Normal muscles give off a certain size, shape and sound of electrical signal. Muscles that have a damaged nerve give off very different electrical signals. Therefore, analyzing the abnormal electrical signals in your muscles will help your doctor locate the specific site, nature and extent of any nerve damage.
For further information, please view Dr. Bamshad's video seminar below-
Electrodiagnostics - The Basics
How do I prepare for the test?
You may eat regularly and take all normal medications prior to the test. Wear loose clothing. Be aware that you may be asked to change into a hospital gown or shorts if needed.
Do not apply any lotions, creams or oils on the day of your test. These materials make it difficult for the tape to adhere to your skin.
The entire test may take up to 1 hour or longer, depending on what areas need to be tested. Be sure to allow extra time to check in and complete paperwork.
What problems are diagnosed by EMG?
EMG is used to diagnose any problem relating to nerves in the spine, arms or legs. These conditions usually cause pain, numbness, tingling or muscle weakness in part of the body. Examples of some of these conditions include:
- Pinched nerves in the neck or back, from disc problems or arthritis
- Compressed nerves in the wrist (carpal tunnel syndrome, at the elbow, knee or other areas)
- Neuropathies, such as numbness in the hands and feet, due to diabetes
How is an Electromyography (EMG) done?
While you are lying in a comfortable position on the table, a tiny needle is inserted into your affected muscle. Electrical signals are recorded at rest and as you slightly flex the muscle. A series of different muscles will be tested.
What is the Nerve Conduction Study (NCS) test?
NCS testing is almost always done along with the Electromyography (EMG) exam. In fact, when doctors say “EMG”, it is short for EMG and NCS testing together. This test evaluates nerves by measuring how fast the electrical impulse travels through them. Certain nerve diseases cause electrical signals to be transmitted more slowly than normal. This test helps your doctor determine the site, nature and extent of any nerve damage.
How is the NCS test done?
While you are resting on the table, several small recording wires will be attached to your hand or foot. A small electric stimulator will be placed on your skin close to the wires, then an electrical impulse will be given. After traveling down the nerve, the signal is recorded by the electrode wires and printed on a graph. The small shock may tingle or make your muscles twitch momentarily, but this is not harmful.
Is the needle EMG test painful?
There is some discomfort when the needle is inserted, but not so much that sedatives or anesthesia is needed. Being calm with relaxed muscles during the test will help decrease any possible discomfort.
Are the electrical impulses given during the NCS test painful?
Again, there is some discomfort, but it is mostly a brief tingling sensation. Once the test is underway, most people find it easier than expected.
What can I expect after the test?
You may experience some small areas of muscular soreness. However most people have no difficulty returning to their regular daily activities, including work. Results of the test will be shared with you, either immediately after the test or when you return to see your referring doctor.