Electromyography (EMG) / Nerve Conduction Velocity (NCV)
This test is used to test the nerves and muscles in your entire lower extremity. Your doctor will usually order this test when he suspects that there may be some type of problem with the nerve supply to your foot and leg. Commonly the EMG/NCV test is used to diagnosis one of the following: Tarsal Tunnel Syndrome, Peripheral Neuropathy, Neuromuscular disorders, Nerve palsy or Paralysis, and Radioculopathy. Your doctor typically will refer you to either a hospital or a neurologist to have the test preformed.
The EMG portion of the test is used to record the electrical activity in your muscles. It can diagnose diseases of the nerves and muscles. It can detect conditions such as tarsal tunnel syndrome, inflamed muscles and pinched nerves. A tiny needle, called an electrode, is inserted directly into a specific muscle belly. The electrode then records the activity during the insertion, while the muscle is at rest, and while the muscle contracts. Nerve and muscle diseases alter the pattern of electrical activity in these muscles, which is record both audibly and on a computer screen. After the first muscle is tested, the electrode may be inserted into another muscle. Muscles chosen for the testing vary with the patient's symptoms and may be modified, depending on the results from the first muscles tested. Total testing time may range from just a few minutes to more than an hour, depending upon how many muscles are tested. After the exam, you may feel tenderness in the tested muscles. There is a slight risk of minor, localized inflammation in muscles during the test. This usually lasts only a few hours. Other common patient complaints are pain with insertion of the electrode.
Most of the time the Nerve Conduction Velocity Test will accompany the EMG Test. The NCV evaluates the health of the peripheral nerve by recording how fast electrical impulse travels through it. A peripheral nerve transmits information between the spinal cord and the muscles. You will be resting on a cart or bed and electrodes will be taped to your skin. A stimulator will be held against your skin, which sends out a small electrical charge along the nerve. You may feel a tingle or your muscles may twitch but this shock is not harmful. Each test will take only a few minutes. After the exam the electrodes will be removed and your skin cleaned. The time between the stimulation and response will be recorded to determine how quickly and thoroughly that the impulse is sent. A number of nervous system diseases may reduce the speed of this impulse. Each nerve test takes just a few minutes to an hour, depending upon how many nerves are being tested.
While the hospital or neurologist’s office will give you instructions for the day of the examination, a few general preparations will help. Eat normally and take medication as you usually would. If you are taking a blood thinner, make sure you inform the testing facility and ask the ordering physician about the use of the medication and the timing of the test. Bath or shower the morning of the examination. Avoid bath oils or any skin lotions or emollients the day of the examination.
A typical EMG/NCV of the lower extremity takes approximately 45 minutes. This test is an important tool for diagnosing diseases of the nervous system, you can help ensure the best results if you relax and cooperate with the technicians. Make sure that you ask any questions that you have about the test before it is performed. Your physician will discuss the results with you. If you have any further questions regarding why this test was ordered for you, please ask your physician.