Patient Info
The EMG Test
What is an EMG?
An EMG, which is an electromyogram, may be ordered to see if you have a pinched nerve in the back or the neck. If you have tingling or numbness in your arms or legs, an EMG may also show if you have nerve pressure there. The EMG measures the electrical activity in muscles. Muscles normally receive constant electrical signals from healthy nerves.
During this test, the doctor uses acupuncture-like needles to record electrical sounds from the various muscles in the arm or leg. If a muscle does not receive normal signals from a sick nerve, it broadcasts abnormal noise signals through the needle to a sound amplifier to help the doctor identify if a muscle is not correctly working with the nerve attached to it.
Who will complete your EMG test?
The EMG is performed by a specialized physician, the Electromyographer, who has completed extensive training and certification in EMG/NCV testing, usually a Physiatrist, who is a specialist in Physical Medicine and Rehabilitation, or a Neurologist. Sometimes, parts of the test (the nerve conductions) are performed by a nurse or technician. The quality of the results and the time required to finish is quite dependent on the skill and training of the physician administering the test.
How long does the EMG test take to complete?
Usually, and EMG takes anywhere from 15 to 30 minutes, depending on how extensive a test is required.
What kind of preparations are necessary for an EMG?
Few preparations are needed on the day you have an EMG. You can drive yourself to and from the test, and no fasting or other dietary changes are required before the test.
Do medications interfere with the EMG test?
With few exceptions, you may continue taking medication prescribed by your physician as ordered. However, if you are taking a blood thinner, you should mention this to the office only if you are having an EMG done. There are no medication precautions for the NCV test.
Is pain medication or sedation usually needed for the test?
Some patients take two Tylenol tablets after the test for discomfort. Because the test requires help by the patient for best results and is usually well tolerated, no sedation is given.
How soon will I find out the results?
The results are usually ready later that day, or the next day in complicated cases. Your results would be sent to the referring physician or other specialists in a detailed report.
The NCV Test
What is a NCV test?
A nerve conduction velocity test (NCV) is an electrical test that is used to detect nerve conditions. In this test, the nerve is electrically stimulated while a second electrode detects the electrical impulse 'down stream' from the first. This is usually done with surface patch electrodes that are placed on the skin over the nerve at various locations. One electrode stimulates the nerve with a very mild electrical impulse. The resulting electrical activity is recorded by the other electrodes. The distance between electrodes and the time it takes for electrical impulses to travel between electrodes are used to calculate the speed of impulse transmission, which is the nerve conduction velocity. A decreased speed of transmission indicates nerve disease. A nerve conduction velocity test is often done at the same time as an electromyogram (EMG) in order to exclude or detect muscle conditions.
When is a nerve conduction velocity test used?
The NCV test can be used to detect true nerve disorders such as neuropathy, or conditions whereby muscles are affected by nerve injury such as carpal tunnel syndrome. Normal body temperature must be maintained for the NCV test, because low body temperatures slow nerve conduction.
How long does the NCV test take to complete?
Testing usually takes less than 30 minutes depending on the number of nerves tested.
Is the NCV test safe?
Yes. The small amount of current delivered to the nerve is always at a very safe level. Patients wearing pacemakers or other electrical devices need not worry since this current will rarely interfere.
How uncomfortable is the NCV test?
The stimulation may be mildly uncomfortable but this is typically brief when testing is done by an experienced physician. Most patients comment that the test was far easier to complete than expected.
What is involved in preparation for the NCV test?
You may be given instructions about how to prepare for a nerve conduction velocity test. It's wise to keep the area to be tested warm, dry and free of lotions provides the best result. Skin temperature should be warm if possible for the test, because low body temperatures slow nerve conduction and falsely change test results.
What if your NCV test result is normal?
Normal results from a NCV test only mean that there is no evidence of measurable damage or disease in the nerve. This test does not measure pain. In a small number of cases, nerve disease may still exist despite normal results. This is because other healthy fibers in the same nerve may show a normal reaction time.
What if you have any other questions before the test?
Any other questions or concerns can be answered when your physician or medical professional before you test.
