Electromyography: Testing Your Muscle And Nerve Function

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Electromyography (EMG) and nerve conduction studies (NCS) are tests that measure muscle and nerve function. In most cases, both tests are performed. NSC is most often done first.

What Are These Tests?

During NSC, mild electrical currents are applied to the skin on some parts of your body. This is done to see how quickly impulses travel between nerves. EMG assesses muscle function. To do this, a fine needle is placed under your skin into the muscle being tested. This is repeated on other muscles. The needle allows the electrical activity in your muscles to be measured. No electrical currents are applied with the needle.

During each test, wavy lines (waveforms) appear on a screen or on paper. These lines show how well your nerves and muscles work. These waveforms help to determine your test results.

Before Your Test

Prepare for your test as instructed. Shower or bathe, but don’t use powder, oil, or lotion. Your skin should be clean and free of excess oil. Wear loose clothes. Be aware that you may be asked to change into a hospital gown. The entire test will take about 1 hour. Be sure to allow extra time to check-in.

During Your Test

You will be asked to lie on an exam table with a blanket over you. You may have one or both of the following:

Nerve Conduction Study (NCS)

Small metal disks (electrodes) will be attached to your skin on the area of your body being tested. This will be done using water-based gel or paste. A doctor or technologist will apply mild electrical currents to your skin. Your muscles will twitch. But the test won’t harm you. Currents may again be applied to the same area. Or, the test may continue on other parts of your body.

Electromyography (EMG)

Most of the electrodes will be removed for EMG. The doctor will clean the area being tested with alcohol. A fine needle will be inserted into the muscles in this region. When he needle is inserted, you may feel as if your skin is being pinched. Try to relax and do as instructed.

After Your Test

Before you leave, all electrodes will be removed. You can then get right back into your normal routine. If you feel tired or have some discomfort, take it easy. If you were told to stop taking any medications for your test, ask when you can start taking them again. Your doctor will let you know when your test results are ready.

Make the safety and success of your test a priority. Contact us or schedule an appointment if you have any questions regarding electromyography.

Sleep Apnea and the Brain

Obstructive sleep apnea, which has been linked to cognitive problems, is treatable.

Living Well, NeurologyNow, February/March 2012

Obstructive sleep apnea, which has been linked to cognitive problems, is treatable. Obstructive sleep apnea (OSA) usually produces the type of loud snoring exaggerated for comic effect by cartoon characters and comedians. Homer Simpson snores operatically. So does Curly of the Three Stooges. But there’s nothing funny about OSA. This common form of “sleep-disordered breathing” results when the tongue and soft palate in the back of the throat relax during sleep and block the windpipe, leaving the sleeper gasping and struggling for air (for more Neurology Now coverage of OSA). Although these episodes don’t always wake up the sleeper, they often rouse a person dozens of times during the night. In either case, the person may fail to get the deep, restful sleep that restores the body and the mind. As a result of these episodes of sleep-disordered breathing, people with OSA often experience head-aches, irritability, forgetfulness, and daytime sleepiness that can be severe. People with OSA are up to five times more likely to be involved in a serious traffic accident. Sleep-disordered breathing, such as the kind caused by OSA, has also been associated with hypertension, heart disease, diabetes, mild cognitive impairment, and dementia.

Less Oxygen To the Brain

A recent study suggests how OSA might contribute to dementia, including Alzheimer’s disease, and to its precursor, mild cognitive impairment (MCI), defined by the U.S. National Library of Medicine as “the stage between normal forgetfulness due to aging and the development of dementia.” People with MCI generally recognize they’re having memory problems, but the lapses do not interfere significantly with everyday activities, and not everyone with MCI develops dementia.Kristine Yaffe, M.D., member of the American Academy of Neurology (AAN) and professor of psychiatry, neurology, and epidemiology and biostatistics, and Roy and Marie Scola Endowed Chair in Psychiatry at the University of California, San Francisco, led a study that began with 298 older women who were free of cognitive problems. An overnight sleep study showed that 35 percent of them stopped breathing in their sleep 15 or more times per night. During the next five years, 44 percent of these women developed mild cognitive impairment or dementia, compared to only 31 percent of the women with normal nighttime breathing.


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Sleep Medicine with Dr. Gary Polk

Dr. Polk is a member of the Amarillo Diagnostic Clinic, P.A.