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.

What Happens During These Tests?

• 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 with the needle.

• NCS checks how quickly impulses travel between nerves. To do this, mild electrical currents are applied to the skin on some parts of your body.

• 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.

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 had neck or back surgery. You may also be asked questions about your overall health.

Before the 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. But know that you may be asked to change into a hospital gown. The entire test will take about 60 minutes. Be sure to allow extra time to check in.