Version July 2025
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What are nerve conduction and electromyography tests? —
These tests are done to see how well nerves and muscles work. Normally, nerves send signals to muscles to make them move.
●Nerve conduction studies – This records the electrical activity of nerves at rest and when stimulated.
●Electromyography, or "EMG" – This looks at the electrical activity of a muscle at rest and when it contracts.
Doctors often order these tests together, but they can be done by themselves. Nerve conduction and EMG tests are done for many reasons. For example, they can:
●Find the cause of symptoms like numbness or weakness
●Learn if a problem is with the nerves, muscles, or both
●Check to see if a nerve or muscle problem is getting better
How do I prepare for these tests? —
The doctor or nurse will tell you if you need to do anything special to prepare.
Before the tests, your doctor will do an exam. They will also ask you about your "health history." This involves asking you questions about any health problems you have or had in the past, past surgeries, and any medicines you take. Tell them about:
●Any medicines you are taking – This includes any prescription or "over-the-counter" medicines, plus any herbal supplements. It helps to write down and bring a list of your medicines, or bring a bag with all your medicines with you.
●Any allergies you have
●Any bleeding problems you have – Certain medicines, including some herbs and supplements, can increase the risk of bleeding. Some health conditions also increase this risk.
●If you have a pacemaker, defibrillator, or other medical device
You might also get information about:
●If you need to stay away from cold temperatures before the test – If it is cold outside, wait in a warm room for a bit before the test. Being cold can slow down nerve activity and might affect the test results.
●Taking a bath or shower before the test – Do not use body lotions, creams, or ointments before the test.
●Avoiding smoking or vaping and caffeine for several hours before the test
Ask the doctor or nurse if you have questions or if there is anything you do not understand.
What happens during a nerve conduction test? —
When it is time for the test:
●The doctor will clean the skin over your nerves or muscles.
●They will place small patches called "electrodes" on your skin.
●They will put a small amount of electrical current through the electrodes. This stimulates your nerves.
●The electrodes send information to a computer. This tells how fast the signal from the electrode travels along your nerve and how strong the signals are.
●The doctor might check different spots along the path of a nerve.
●You might feel slight pain or tingling during the test.
●A nerve conduction test takes between 30 and 90 minutes.
What happens during an EMG? —
When it is time for the test:
●The doctor will clean your skin over your muscles.
●They will place an electrode with a very thin needle through your skin and into your muscle.
●The electrode will pick up electrical activity made by your muscles. The activity is tracked by a computer.
●The doctor will test your muscle when it is still and when it moves. You might hear crackles or pops during the test when your muscles move.
●The electrodes send a signal to a computer about how fast the signal from the electrode travels along the nerve and how strong the signals are.
●You might have some mild pain or bruising from this test.
●An EMG takes between 30 and 90 minutes.
What happens after the tests? —
Most people can go home right away. You might get your results the same day, or it might take a little longer for an expert to read them. Your doctor or nurse will tell you when to expect the results.
If your tests show any abnormal results, your doctor or nurse will talk to you about what to do next.
What are the risks of nerve conduction and EMG tests? —
Your doctor will talk to you about all the possible risks, and answer your questions.
A nerve conduction study has very few risks.
Risks of having an EMG might include:
●Pain
●Bleeding
●Infection
●A collapsed lung (called "pneumothorax")
●Electrical injury
When should I call the doctor? —
If you had an EMG, call for advice if you have:
●A fever of 100.4°F (38°C) or higher, or chills
●Very bad pain, redness, drainage, bleeding, or swelling where the needle went into your skin
●Chest pain or trouble breathing
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