Electromyography and Nerve Conduction Studies
Testing Your Muscle and Nerve Function
Electromyography (EMG) and nerve conduction studies (NCS) are tests that measure muscle and nerve function. In most cases, both tests are performed. NCS is most often done first.
During NCS, mild electrical currents are applied to the skin on some parts of your body. This is done to see how quickly impulses travel between nerves.
EMG assesses muscle function. To do this, a fine needle is placed under your skin into the muscle being tested. This is repeated on other muscles. The needle allows the electrical activity in your muscles to be measured. No electrical currents are applied to the needle. During each test, wavy lines (waveforms) appear on a screen or on paper. These lines show how well your nerves and muscles work. These waveforms help to determine your test results.
Before Your Test
Prepare for your test as instructed. Shower or bathe, but don’t use powder, oil, or lotion. Your skin should be clean and free of excess oil. Wear loose clothes. Be aware that you may be asked to change into a hospital gown.
The entire test will take about 1 hour. Be sure to allow extra time to check in.
Don’t use lotion, oil, or powder after you shower or bathe.
Let the Technologist Know
For your safety and for the success of your test. tell the technologist if you:
- Have any bleeding problems
- Take blood thinners (anticoagulants) or other medications, including aspirin
- Have any immune system problems
- Have bad neck or back surgery
You may also be asked questions about your overall health.
During Your Test
You will be asked to lie on an exam table with a blanket over you.
Nerve Conduction Study (NCS)
Small metal disks (electrodes) will be attached to your skin on the area of your body being tested. This will be done using water based gel or paste. A doctor or technologist will apply mild electrical currents to your skin. Your muscles will twitch, but the test won’t harm you. Currents may again be applied to the same area or the test may continue on other parts of your body.
Most of the electrodes will be removed for EMG. The doctor will clean the area being tested with alcohol. A fine needle will be inserted into the muscles in this region. When the needle is inserted, you may feel as if your skin is being pinched. Try to relax and do as instructed.
After Your Test
Before you leave, all electrodes will be removed. You can then get right back to your normal routine. If you feel tired or have some discomfort, take it easy. If you were told to stop taking any medications for your test, ask when you can start taking them again.
Your doctor will let you know when your test results are ready.