Definition

A nerve conduction study (NCS) measures the speed and strength of electrical activity in a nerve. The test can gather details about the structure and function of muscles and nerves.

Electromyogram of Shoulder—Used with a Nerve Conduction Study
Electromyogram EMG

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Reasons for Test

A NCS is most often done to:

  • Find out the cause of pain, cramping, numbness, or weakness
  • Find out if nerves are working the right way
  • Tell apart muscle and nerve problems
  • Check if a nerve is recovering from injury

Possible Complications

There are no major problems from this test.

What to Expect

Prior to Test

The care team may meet with you to talk about:

  • Any allergies you may have
  • Current medicines, herbs, and supplements that you take and whether you need to stop taking them before the test
  • Whether you need to avoid smoking, food, and certain drinks for 2 to 3 hours before the test
  • Avoiding using any creams, moisturizers, or powders on your skin before the test

Description of Test

Your skin will be cleaned. Electrodes will be taped to the skin along the nerves that are being studied. One electrode will stimulate the nerve with a mild electrical impulse. It will cause the nerves to activate. The electrodes will measure the current that travels down the nerve pathway. The current will be slower and weaker if the nerve is damaged. An electrical impulse will be used at different places to find the site of any damage.

Nerve conduction studies are often done along with electromyography (EMG).

How Long Will It Take?

About 30 to 90 minutes

Will It Hurt?

The test areas may be sore. This will go away in an hour or two.

Results

The doctor will study the details from the test. A report should be ready within a few days.

Call Your Doctor

Call your doctor if you have any questions or concerns after the test.

If you think you have an emergency, call for medical help right away.

RESOURCES:

American Chronic Pain Association
http://www.theacpa.org

National Institute of Neurological Disorders and Stroke
http://www.ninds.nih.gov

CANADIAN RESOURCES:

Canadian Neurological Sciences Federation
http://www.cnsfederation.org

Chronic Pain Association of Canada
http://www.chronicpaincanada.com

REFERENCES:

Electrodiagnostic testing. American Academy of Orthopaedic Surgeons website. Available at: http://orthoinfo.aaos.org/topic.cfm?topic=A00270. Accessed October 1, 2020.

Nerve conduction studies. Johns Hopkins website. Available at: https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/nerve-conduction-studies. Accessed October 1, 2020.

Peripheral neuropathy. EBSCO DynaMed website. Available at:https://www.dynamed.com/condition/peripheral-neuropathy. Accessed October 1, 2020.

Spinal diagnostics: nerve conduction studies. Cedars Sinai website. Available at: https://www.cedars-sinai.org/health-library/diseases-and-conditions/s/spinal-diagnostics-nerve-conduction-studies.html. Accessed October 1, 2020.

Last reviewed September 2020 by EBSCO Medical Review Board Rimas Lukas, MD  Last Updated: 10/1/2020