What is an electromyogram (EMG)?

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So your doctor ordered an EMG.  What is that?  EMG stands for electromyogram or simply a study to look at the electrical activity of the muscles.  This is actually only part of the examination.  The other part of the study is what is commonly referred to as the NCS or nerve conduction studies.  Nerve conduction studies are a way for the examiner to evaluate the ability of your nerves to appropriately conduct electricity.  Nerves are like the electrical wiring in your house.  They are the electrical wires in our bodies.  They are what carry the signals to our muscles to tell them to contract when you need to use them, such as lifting something, smiling, or walking.  They also carry the signals from your skin back to your spinal cord and ultimately your brain to tell you if you are touching something hot, cold, soft, rough, etc.  These nerves can malfunction and send the signal to your brain that you are being poked by pins and needles, being stung by bees, have cold or hot water running down your leg, or any number of strange sensations that are not really there.  The NCS/EMG is the study that helps us figure out how well those nerves are working and specific pattern of the nerves that are damaged.  From here, we are better able to determine a specific diagnosis and treatment options.

Some helpful tips about preparing for your NCS/EMG study.

Wear loose clothing

Do not apply lotion the day of the exam

Expect the study to take 30-90 minutes depending on the extent of the exam ordered

If the study is on the hands, minimize jewelry on the day of your exam

Common conditions evaluated by NCS/EMG

Carpal tunnel syndrome

Ulnar neuropathy

Peripheral neuropathy

Radiculopathy (pinched nerve in the neck or back)

More complex nerve and muscle diseases

Is the study painful?

During the study you will have small stickers (electrodes) applied to your skin which in turn are connected to a computer.  The examiner will then send a small electrical current through your nerves, one at a time.  These are very short, less than a fraction of a second.  Some people report these stimulations as mildly uncomfortable, but nearly everyone states it was much more tolerable than expected.

The EMG portion of the study involves a tiny electrode which will be placed under the skin while recording the electrical activity of the muscle.  This has been compared to acupuncture by many patients.  Again, most people report this as much more tolerable than expected.

Why can’t I just have the MRI?

Many patients question why they can’t have an MRI and skip the EMG.  The two studies give us different information.  An MRI tells us what your anatomy LOOKS like.  It can show a pinched nerve which may or may not be causing some of the issues at hand.  However, an NCS/EMG tells us how the nerve and muscle are FUNCTIONING.  The two studies work together to give your physician more information about the right therapy to benefit you.

The physician will be happy to answer any questions you have about the exam at the time of the study.

Jonathan Moravek, M.D.