What is an EMG/NCS?

What is an EMG/NCS?


What is an EMG/NCS?

EMG or electromyography is a test that examines the nerves and muscles of the body. 

The test may include nerve conduction studies (NCS), needle electromyography or evoked potentials. Prior to the test the physician will perform an examination to determine what aspects of the test are needed.

Why do I need an EMG?

Doctors order this test to help determine the cause of the patient’s symptoms. The test is extremely important in making a proper diagnosis and treatment plan.

EMG/NCS testing also measures the severity of the patient’s condition. A negative test suggests symptoms are not severe, and conservative care can continue. A positive test indicates that the electrical conduction of the nerve is being physically affected. Aggressive treatment is most likely recommended.

How long does it take?

The test typically takes 30 – 45 minutes. Occasionally the test can last up to 1 hour. 

How will the test affect me?

There are no long lasting side effects. Patients may experience mild muscle soreness for a short period of time. 

After the test patients can return to normal activity.

How can I prepare for the test?

Patients should alert their physician if they are taking any type of blood thinning medication or if they have a pace maker, neurostimulator or ventricular defibrillator. Normal medications may continue. Although pain medication and other medications will not affect the results patients should bring a list of their medications to the test.

Patients need to take a bath or shower prior to the test to remove the natural oils from the skin. DO NOT USE LOTIONS ON THE DAY OF THE TEST.

When will I receive the results of the test?

Results may be discussed on the day of the test or an additional appointment will be scheduled for further discussion.

How are the tests performed?

    The test examines the electrical signals of your muscles. A thin needle (pin) is placed in several muscles in the affected region. The doctor looks at the monitor and listens to the signals.
    NCS examines how well the nerve conduction is in a signal. A small electrical potential is produced (i.e. shock) causing a mild tingling sensation. Several nerves may be tested.

Will it hurt?

This is the most common question. The NCS feels like getting shocked with static electricity. The EMG feels like a sharp poke followed by a deep muscle ache. The test can be uncomfortable at times, but not unbearable. Patients may experience mild muscle soreness for a short period of time.

What are the risks of this test?  

All procedures involve some risks. Anytime the skin is broken by a needle, there is a risk of infection, pain at the site, swelling, bruising or bleeding. 

If the procedures are performed near the chest wall, a pneumothorax (dropped lung) may occur. This would require hospitalization and/or further treatment. This is the most serious complication. These complications are rare and every effort is made to avoid them. 

Dr. Rebecca Aronson
Dr. Rebecca Aronson
Dr. Aronson is a board-certified physician in Physical Medicine and Rehabilitation (PM&R), with a special interest in electrodiagnostic medicine. She received her medical degree from Arizona College of Osteopathic Medicine and residency training from the National Rehabilitation Hospital in Washington DC. Dr. Aronson has over 10 years of experience in the field of PM&R and enjoys diagnosing and treating patients with musculoskeletal ailments.

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