Your muscles and nerves are full of electrical signals. Specifically, your nerves send signals to your muscles to tell them to move. If your doctor wants to see how the signals in your nerves and muscles are working, they’ll recommend you get an electromyogram (EMG) and nerve conduction study (NCS).
Types of Electromyography Tests
An EMG test checks how healthy your muscles are. It examines the electrical signals your muscles make—both when you’re using them and resting them.
A nerve conduction study is similar to an EMG test, but slightly different. This test looks at how well the electrical signals travel from your nerves to your muscles.
These tests are both part of a subspecialty of physical medicine and rehabilitation called electrodiagnostic medicine. In other words, the tests use electricity to help diagnose conditions that involve your nerves or your muscles.
Your doctor will likely perform them during the same visit. There is no recovery time involved with either test. You’ll be able to do whatever activities you had scheduled.
The tests typically take up to an hour.
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What Does an EMG Test Feel Like?
Whether EMG tests are painful is a topic of some discussion. Studies find that people expect EMG tests to be more painful than they actually are. In reality, while an EMG test does involve needles and some discomfort, most patients find it easy to tolerate.
The EMG electrode is about the size of an acupuncture needle, so it’s hair-like and goes under the skin easily. Plus, to help with EMG testing of hand and foot muscles, doctors apply a freezing spray to the area to lessen discomfort.
Don’t let fear of pain stop you from getting a test that can help doctors diagnose and treat you.
Here’s how an EMG test works:
- You’ll sit or lie comfortably while your provider puts a very thin needle with an electrode into your muscle. It may sting and be a bit uncomfortable.
- After measuring your muscle at rest, your provider may ask you to move the muscle, such as bending your arm.
- The electrode measures your muscle’s electrical activity. A machine records this activity and shows it on a monitor. You will also “hear” your muscles, meaning that you hear the echo of waves being sent through that muscle.
- If you need the test in more than one muscle, your provider will take the electrode out and repeat the process.
What Does a Nerve Conduction Study Feel Like?
A nerve conduction study doesn’t use needles. It does, however, use small electrical pulses.
Here’s what to expect with this test:
- You’ll sit or lie comfortably while your provider places electrodes on your skin. They’ll put the electrodes over the nerve they’re studying.
- They’ll send a mild electrical pulse to the electrodes. This is what stimulates the nerve to send a signal to your muscle. The pulse might feel like a tingling in your muscle.
- Your provider will measure how long it takes your muscle to respond to the signal from the nerve.
What Conditions Does Electromyography Help Diagnose?
EMG and nerve conduction studies are invaluable tests for diagnosing dozens of nerve and muscle conditions. Some of these conditions are due to injuries. Other are inherited disorders.
Doctors often use electromyography to diagnose (or rule out) conditions such as:
- Carpal tunnel syndrome, a common condition that affects the wrist and hand
- Nerve injuries in the neck and back, such as herniated disc
- Sciatic nerve problems, which can cause weakness, numbness, or tingling in the leg
- Neuromuscular disorders such as polyneuropathy and ALS (Lou Gehrig’s disease)
- Muscular dystrophy, or other conditions that cause muscle weakness (called myopathies)
- Neuromuscular diseases, such as myasthenia gravis – a nerve-related autoimmune disorder that causes weakness of the voluntary muscles
There are other conditions that can cause abnormal results. Your doctor will go over your results with you and talk about next steps.
Electrodiagnostic Medicine at UPMC
Physicians at the UPMC Department of Physical Medicine and Rehabilitation are leaders in electrodiagnostic medicine. Chairing and participating in many national committees in this area of medicine, doctors then use this expertise to treat patients locally.
They offer cutting-edge techniques like diagnostic ultrasound, in combination with electrodiagnostic medicine practices, to give patients the best chance of an accurate and informed diagnosis.
To schedule your electrodiagnostic services at the department of physical medicine and rehabilitation, you will need a prescription from your health care provider. Please call 412-647-5424 to schedule. To learn more about electromyography, visit our website.
U.S. National Library of Medicine. Medline Plus. Electromyograpy. Link.
At UPMC, we strive to improve your function after injury or illness. We help people recover from functional, pain-related, and neurological conditions, with both inpatient and outpatient care available. We are dedicated to providing you with exceptional clinical care and focused on developing new technologies and treatments to help you achieve mobility and maintain independence. Find a provider near you.