EMG and Nerve Conduction Study

Numbness, tingling and weakness in an arm or leg can come from a pinched nerve in the spine, a trapped nerve at the elbow or wrist, or damage to many nerves at once. An EMG and nerve conduction study tests how your nerves and muscles are actually working, which helps pinpoint where the problem is.

These are two tests that are usually done together:

• Nerve conduction study (NCS): small sticky pads are placed on the skin, and mild electrical pulses are used to measure how fast and how strongly signals travel along a nerve.
• Electromyography (EMG): a very thin needle is placed into several muscles to record their electrical activity at rest and when you tighten them.

The tests are performed by a neurologist or a physical medicine and rehabilitation specialist.

EMG and nerve conduction studies can show:

• Where a nerve is trapped, such as carpal tunnel syndrome at the wrist, cubital tunnel syndrome at the elbow, or peroneal nerve compression at the knee
• Whether a nerve root is pinched in the spine, as in cervical radiculopathy or sciatica
• Peripheral neuropathy, which affects many nerves
• How severe the nerve damage is and whether it is recent or long-standing

Dr. Grunch uses these tests to make sure surgery is aimed at the right spot. They help tell apart a pinched nerve in the neck from a trapped nerve at the wrist or elbow, and they show how urgently a nerve needs to be freed. See our guide to pinched nerves and nerve pain.

• Shower the day of the test and do not put lotion, oil or cream on your arms or legs.
• Tell the tester if you take a blood thinner, have a pacemaker or defibrillator, or have hemophilia. You usually do not need to stop a blood thinner for this test.
• Wear loose clothing that can be pushed up above your elbows or knees.
• Eat and take your medicines as usual.
• Keep your hands and feet warm; cold limbs can affect the results.

For the nerve conduction study, you will feel quick tingling or tapping sensations from the electrical pulses, like a static shock. For the EMG, a thin needle is placed into several muscles one at a time, and you will be asked to relax and then tighten each muscle. The needle can feel like a pinch or ache. The whole test takes about 30 to 90 minutes depending on how many nerves and muscles are checked.

You can drive and go back to normal activities right away. Muscles may be a little sore or bruised for a day or two. The specialist sends a report to Dr. Grunch, and she or one of her physician assistants will go over the results with you.

EMG and nerve conduction studies are very safe. Minor bruising or soreness at the needle sites is the most common side effect. Infection and bleeding are rare.

Does an EMG hurt?

The nerve conduction part feels like quick static shocks. The EMG needle can feel like a pinch or ache in the muscle. Most people find it uncomfortable but very manageable, and it is over in under an hour or so.

Why do I need an EMG if I already had an MRI?

An MRI shows structure, like a disc pressing on a nerve. An EMG shows how the nerve is actually working and where it is injured, which helps confirm that the problem on the MRI is the one causing your symptoms.

Can an EMG tell the difference between carpal tunnel and a pinched nerve in the neck?

Yes. That is one of its most important uses, and some people have both.

Do I need to stop my blood thinner?

Usually not, but tell the person doing the test that you take one.

If Dr. Grunch has ordered an EMG or nerve conduction study for you and you have questions, call 470-293-9800 or contact us. You can also ask general questions any time through our “Ask Us Anything” chat. For questions about scheduling, cost or arrival time for the test itself, call the imaging center where it is booked.

Related: All imaging and diagnostic tests · Carpal tunnel syndrome · Cervical radiculopathy

This information is for educational purposes only and is not medical advice. It does not replace individualized care from a licensed physician. Please talk to your provider about your symptoms and follow the instructions from your imaging center.