EMGs: What You Need To Know

An EMG, otherwise known as electromyogram, is a test used to measure the electrical activity in muscles. It's typically done alongside a nerve conduction velocity test (NCV), which measures nerves ability to send signals.

The tests are usually performed by an electromyographer, who is typically a Psychiatrist or Neurologist. In some cases, the NCV test is performed by a trained technician. This is a procedure that can be done in-office and doesn't require hospitalization. The average EMG takes between 30 minutes and 2 hours, depending on how extensive the testing is. In most cases, it doesn't require any preparation and can be done at any time of the day.

What Happens During These Tests

At the time of the test, you'll be in a room with one or more EMG machines. They look like a regular laptop or desktop computer and aren't as intimidating as they sound. The test usually consists of two parts, and you'll be laying comfortably on an examination table while they are performed.

The first test, the NCV, the doctor will attach some small electrodes to the surface of your skin and then touch you in another area with electrodes to produce a small electric shock. This is to determine how well your nerves conduct the current - an indication of how healthy they are. You may feel a slight tingling sensation during this test, but the electrical current is always at a safe level. This procedure is normally repeated a few times to ensure all nerves in the area are tested.

The second part of the test is known as a needle examination. In this test, the doctor will insert very thin needles into relaxed muscles and gently moved around to record the muscle activity. The needle insertion itself may cause a little pain, but once inserted you should only feel a little pressure or discomfort.

Why an EMG is Performed

EMG tests are most often performed when a patient has symptoms that might indicate a muscle or nerve disorder. These symptoms can include, numbness, tingling, muscle pain, weakness or cramping and some types of limb pain. Also, a patient experiencing difficulty walking, handling objects or buttoning clothes may need an EMG.

Disorders EMG Tests can Diagnose

The results of EMG tests can be used to rule out or diagnose many conditions including muscle disorders like polymyositis and muscular dystrophy.

Results may also help in the diagnosis of nerve disorders such as a pinched nerve, peripheral neuropathies and carpel tunnel syndrome and disorders that affect the root of the nerve like a herniated disk or sciatica.

EMG test results are also used to diagnose disorders that affect motor neurons in the spinal cord or brain like polio and amyotrophic lateral sclerosis, otherwise known as Lou Gehrig's Disease.

The EMG test is a relatively new procedure, with electrodes and the cables necessary to produce signals being mass produced in the mid-1980s, and is one of the fairly recent medical testing advances that can detect and diagnose conditions and save lives. 

This is a blog post by Nancy Evans.