Negative or positive EMG results aren’t really meaningful ways to describe the data.
Risks and Contraindications
Both EMG and NCS are low-risk.
With EMG, there is a slight risk of getting an infection or bleeding where the electrodes were inserted.
Illustration by Cindy Chung for Verywell Health
Precautions may need to be taken.
You may have to pay a co-pay and/or co-insurance.
There may be a technician to help attach the surface electrodes as well.
Illustration by Cindy Chung, Verywell
The NCS usually comes first when both are done.
Pre-Test
You will likely need to fill out a consent form before you have this test.
Next steps include:
The neurologist will find the nerve(s) that are going to be tested.
Preparation for an EMG will occur after NCS is complete.
The procedure is then repeated for each area your healthcare provider wants to test.
EMG is normally performed right after the NCS.
Activity is measured and translated as waves on a screen, and static-like noises are played on a speaker.
The neurologist who does the test listens to these sounds and watches the monitor to detect abnormalities.
When your test is complete, the electrode will be removed.
You should be able to get dressed, if necessary, and go home right away.
Your healthcare provider may give you specific instructions, depending on your medical condition.
These may be signs of an infection.
NCS and EMG Test Results
Positive EMG test results are just one part of data interpretation.
The EMG and NCS are not always straightforward and may not always lead to just one possible diagnosis.
However, the tests can reduce the number of diagnostic possibilities.
Myelin and Axon Function
Myelin helps action potentials travel faster.
With problems related to myelin (myelinopathy), conduction velocity is decreased.
Next steps will vary greatly, depending on the cause or your symptoms.
Your healthcare provider will let you know how to proceed.
If you want a second opinion, ask for a referral.
Summary
The electromyography (EMG) test is used to evaluate nerve and muscle function.
An EMG often is used with a nerve conduction study.
Remember that while EMG and NCS are helpful diagnostic tools, they are only one piece of the puzzle.
Talk with your healthcare provider about your results and treatment plan.
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