EMG Test: What to Expect, What It’s Like…
An EMG test will determine if you have a deadly neurological disease as well as many benign conditions.
But exactly is involved during an EMG test?
And what IS an EMG test?
“A peripheral nerve test often has two parts to the nerve conduction study which tells about the function of the nerve as the signal travels to the spinal cord and back,” says Mitzi J. Williams, MD, clinical neurologist with Morehouse School of Medicine and clinical advisor for the Multiple Sclerosis Foundation.
“The actual EMG part involves a needle being inserted into the muscle, and the wave forms generated are compared to baseline normal values — and the muscle is activated or contracted to see if the activity is normal when the muscle contracts,” continues Dr. Williams.
What I Witnessed at the EMG Test
I sat in on an EMG test that was done on my mother, and it’s actually a very fascinating invention of medical technology.
The EMG test took about an hour, but some of that time was spent by the neurologist pausing to explain things related to her suspected condition (pronator syndrome or carpal tunnel syndrome).
The doctor will place very small sticker-like patches on the patient’s body, at the location of the symptoms.
He’ll then attach recording electrodes nearby these stickers. The electrodes are attached to a computer that’s a little bulkier than a laptop.
Preceding the actual testing, the doctor will type a lot of things into the computer.
To measure nerve conductivity, the doctor must provide an electric shock to the patient with a two-pronged device about the size of a cell phone.
When he delivers the shock, the result appears on the computer screen as a jagged horizontal line with a plus sign.
Moments later two more images (jagged horizontal lines or sine waves) will appear, one reflecting the muscle activity and one reflecting nerve activity.
The computer also shows the number of milliseconds it took for the nerve impulse to be conducted.
The neurologist at one point said that four milliseconds was normal, and 10 milliseconds was abnormal; that 50 meters per second was normal, and 42 meters per second was slow.
The patient may not be able to see the computer when all this is happening; my mother was lying on her back while the doctor conducted the EMG test on her right arm first.
He was heavily favoring pronator teres (a forearm muscle) syndrome as the diagnosis, though he concentrated the initial testing at the wrist and fingers.
Then he said, “It’s carpal tunnel.” This was a 100 percent positive diagnosis, because the EMG test can determine:
1) if nerves are firing normally, and
2) if numbness, tingling and strength loss are caused by a healthy nerve signal merely being blocked from arriving at its destination, as in my mother’s case of carpal tunnel syndrome.
Delivering the Electric Shocks
The EMG test involves the doctor moving around the various stickers and recording-electrodes, then administering a shock at various points higher up from where the recording devices are.
In my mother’s case, many of the shocks were delivered to her forearm.
In between the adjustments with the stickers and electrodes, he placed a tape measure to her skin to measure the length of the nerves.
The patient, if lying down and unable to see what the doctor is doing, will feel the doctor moving around the stickers and attaching the recording electrodes, then running a tape measure along the skin, and then the electric shock.
The voltage of the shock can be adjusted, and it can be very unpleasant, though it lasts a second.
The other thing that the patient will feel is pin pricks. The needle is a little thicker than an acupuncture needle, and the doctor will place a needle at varying locations as part of the EMG exam.
In the case of my mother, it appeared at one point that he embedded the needle a quarter of an inch into her palm.
The “poke” he did there hurt to high heaven based on my mother’s reaction, but again, it was only for a fraction of a second.
The neurologist also had her press her arm against resistance a few times.
Since all he needed was her arms, she was able to maintain any leg position she was comfortable with. An EMG test does not require the patient to be sedated.
So now you know what’s involved in an EMG test.
If you’re scheduled for an EMG exam, there’s nothing to be afraid of as far as how the procedure feels on your body.
If the idea of electric shocks and pin pricks has you unnerved (no pun intended), remember, this test is a godsend for doctors, and it has to be done to provide a diagnosis for your condition (or to rule out an imagined condition).
Dr. Williams is author of “MS Made Simple: The Essential Guide to Understanding Your Multiple Sclerosis Diagnosis,” available on Amazon. She is a member of the American Academy of Neurology.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.