Nerve Conduction Study

A nerve conduction study tests how fast your nerves send signals to your muscles. The study is usually done at the same time as an EMG, a test that measures the electrical activity of your muscles.

Using these two tests, doctors can measure the speed and strength of electrical signals in your nerves and muscles, helping them diagnose health problems in these areas and more effectively treat your nerve and muscle pain.

A nerve conduction study, or NCS, is a test your doctor may use to diagnose damaged and destroyed nerves and come up with a pain relief plan. An NCS tests how fast your nerves send signals to your muscles.

The NCS is usually done with an electromyogram (e-LEK-tro-MY-oh-GRAM), or EMG, which measures the electrical activity of your muscles. Using the information from the NCS, your doctor or another pain management specialist can help find relief for your pain symptoms.

Both the nerve conduction study and EMG test use patches (electrodes) to send electricity through parts of your body. Doctors can measure the speed and strength of this electrical signal to test your nerves and muscles. They can diagnose problems you may have from the test results and recommend solutions and treatments for pain.

Your doctor will start the nerve conduction test by putting patches on your skin. Some of these patches create a small electrical current that stimulates your nerves. Other patches measure the reaction of the nerve.

By measuring the distance between the patches and the time it takes for nerve signals to travel between them, your doctor can measure the speed of the nerve signals and the health of your nerves.

The nerve conduction study is generally a safe test. However, there are some minor risks associated with this test:

• You can get an infection where the needle was inserted. Your doctor will talk with you about steps you can take to prevent infection.
• You may have bleeding at the place where the needle was inserted. If bleeding does not stop after the test, you should tell your doctor.

The benefit of the nerve conduction test is a better understanding of the health of your nerves. This test can also benefit you by helping diagnose nerve issues.

In a similar way, the EMG test will benefit you by giving more information about how well your muscles work and respond to nerve signals.

Together, these tests can give your doctor important information about problems with your nerves and muscles. Your doctor or pain management specialist can then use the information about your nerves and muscles to help manage your pain.

Talk to your doctor about any medical conditions you have before the nerve conduction study or EMG test.

Preparation guidelines

Follow your doctor’s instructions to prepare for your procedure:

• Tell your doctor if you use a cardiac defibrillator or pacemaker, because the test can interfere with these devices.
• Your doctor may ask you to avoid caffeine and nicotine, because these drugs can interfere with the test results.
• Do not use lotion or cream on the day of the test. These can interfere with the gel that is used to attach the electrodes.

Different doctors may perform the tests in different ways, but in general, this is how nerve conduction and EMG tests are done:

Nerve conduction test

1. Two patches (electrodes) are placed on your skin. These patches will record the electrical activity of your nerves. One patch is placed near the muscle that is being studied, and another patch is placed farther away.
2. A paste or gel will be placed on your skin between the two patches. This gel helps the electricity pass between the two patches.
3. A small amount of electricity will be applied to the patch, and a machine will measure how long it takes for your nerves to respond.
4. When the nerve conduction test is finished, the gel and patches will be removed.

EMG test

1. You may be given a medicine to numb the area that is being tested.
2. A very thin needle with an electrode will be inserted into your muscle. A patch (electrode) will be placed on your skin.
3. Your doctor will send a small amount of electricity between the electrodes. This will help measure electrical activity in your muscle.
4. You may be asked to relax your muscles for one test, and then flex them for a second test.
5. When the EMG test is finished, the needle and patch will be removed.

Your doctor will talk to you about how long it will take to process the information from the test. You may receive a call with your test results, or you may have to schedule a follow-up appointment to discuss your results.

Usually, no follow-up tests are needed. Your doctor will contact you with test results, or to schedule a follow-up appointment for further tests or exams.

• MedlinePlus