Electromyography (EMG):
What Is It, and Does It Hurt?


Gary E Cordingley, MD, PhD
What do an EMG and a Stephen King novel have in common? And
what does either have to do with your brother-in-law?  Read on...
Medical tests are the pits. Not only do you have to worry about the meaning of the symptoms that earned you the
test in the first place, but you also have to worry about the test itself.  Will it be painful? Will it be difficult? Will the
person who does it be cruel?

Suspense can be valuable if you're Stephen King and writing horror fiction.  Mr. King takes advantage of the fact
that your own imagination can conjure up scarier things than he can put on the page. That's why he makes you
wait page after page to discover what scary thing is around the next corner. When he finally tells you about the
giant, blue monster, it's not nearly as bad as what you had already imagined. If his monster was scarier than what
you could imagine, do you think he would have made you wait so long? Of course not! Mr. King is no dummy. Just
look at his sales record.

But when it comes to medical tests, suspense is no good. You don't need to worry about the test you're going to
have in addition to the medical problem that got your referred for it in the first place.

What about electromyography, also known as EMG? You should definitely not listen to what your brother-in-law
has to say about it. If he had the test already, do you think he's going to make himself sound like: (1) the bravest
guy in existence, or (2) a total wimp? Well, you know your brother-in-law better than I do, but my money is on
number one.

So if you listen to your brother-in-law, he'll tell you what a terrible, awful, painful test it was, and how he was
brave, valiant, and just about the most courageous guy who ever had it. So now he's got you quaking in your
boots. Or at least worried.

Relax. It's not that big a deal. Have you been to a dentist? Probably not as bad. Have you ever given blood?
Probably not as bad. Have you ever had a baby? Definitely, nowhere near as bad! (I'm a male, but my wife
assures me on this one.)

So let's get down to the particulars. An electromyography test involves needles. The needles do puncture the
skin. Moreover, they enter muscle tissue. But the testing is done with just one needle at a time and just one
muscle at a time. Although the needles used in this test are larger than those tiny, hair-like items used for
acupuncture, they are much skinnier than those used for blood-drawing.

You do feel them when they are inserted, but the electromyographer (doctor doing the test) gives you advance
warning in each case, and the doctor tries to get the maximum diagnostic information out of each needle-insertion
while simultaneously minimizing the pain. The goal is to obtain information, not to hurt you.

Why would this be inflicted upon you in the first place? Usually it's because your own doctor thinks you might
have a nerve or muscle condition and wants to narrow down the possibilities, seek confirmation, or eliminate a
particular diagnosis.

Electromyography is a term meaning "electrical muscle recording."  Because muscle is an electrical tissue, the
needle electrode in the muscle, when connected to an amplifier and an oscilloscope screen, can show the
muscle's electrical activity as a series of voltage-fluctuations. Moreover, the signal is also fed through a speaker,
so you and the electromyographer can listen to what the muscle has to say. Each muscle is analyzed while you
tense it, and again while you relax it.

Normal muscles display typical patterns to the eye and ear through the oscilloscope and speaker. Abnormal
muscles show altered patterns.  Sometimes the abnormality is more evident on the oscilloscope, and sometimes
more evident on the speaker.  Muscles that are themselves sick (myopathy) show one pattern, while muscles that
are connected to sick nerves (neuropathy) or spinal roots (radiculopathy) can show yet another pattern.

Electromyography is often paired with nerve conduction studies performed at the same testing session by the
same doctor and with the same equipment. Each test—EMG and nerve conduction studies—has its own story to
tell, as well as its own strengths and weaknesses in its ability to show signs of disease. The results of the
electromyography and nerve conduction studies are considered together to come up with a more complete,
combined test-outcome and report.

The time required for testing can depend on the nature of the problem. Also, the electromyographer might add or
subtract additional testing depending on how the initial components turn out. Overall, a typical session might last
between 45 and 90 minutes. That doesn't mean that the patient is subjected to unpleasantries during that whole
period of time. Actually, much of the time is devoted to getting all the little pieces and parts of equipment
organized and in place for each "mini-test" comprising the overall testing session.

So when your doctor refers you for electromyography, don't listen to your brother-in-law. What does he know
anyway? (Wait a minute, I'm somebody's brother-in-law, too! But you get the idea.) As an adventure, EMG is less
than it's cracked up to be. As a diagnostic test, it can be very useful.


(C) 2005 by Gary Cordingley