Electrodiagnostic Testing

Nerves carry electrical signals along pathways between the brain, spinal cord, muscles, and skin.  These signals transmit information needed for our sense of touch, pain and temperature, balance, and enable us to move our muscles.  Abnormalities at any point along these pathways may result in symptoms of numbness, tingling, weakness, imbalance, and/or radiating pain.

Electromyogram (EMG) and nerve conduction study (NCS) are two distinct components of electrodiagnostic testing.   Performed together, these tests provide valuable information about the nerves and muscles in patients who have numbness, tingling, weakness, or radiating pain.

EMG/NCS is often used as an important tool to correctly diagnose and confirm where an abnormality may exist along the pathway of transmission; between the tips of the fingers and toes, and the spinal cord.  Without EMG/NCS, distinguishing the location of a nerve problem is often difficult or impossible to confirm. 

EMG/NCS may also help determine if a problem is acute (new) or chronic (old).  The test can help track the progression of pathology by showing evidence for the condition worsening or signs of healing with nerve regeneration.  This information is helpful to determine the prognosis, that is, the future outlook for the condition.

The physicians at The Centers for Advanced Orthopaedics - Robinwood Division, who carry out this important test are board certified in Physical Medicine and Rehabilitation and have decades of combined experience performing EMG/NCS. The test is performed personally by the physician with meticulous attention to the unique details of the patient. 

Here are some commonly asked questions answered:

Can you tell me more about EMG?

An electromyogram (EMG) is a test that is used to record the electrical activity of nerves and muscles.  When muscles are active, they produce an electrical current.  This current is usually proportional to the level of the muscle activity.  The electrical signals are traced on a computer screen and can also be heard through a speaker.  This information is interpreted by the physician.

Why is an EMG test done?

An EMG is most often performed when patients have unexplained muscle weakness, numbness, or tingling.  The EMG helps to distinguish between conditions affecting the muscle, and muscle weakness due to nerve disorders. 

What problems can EMG help diagnose?

The test is done to evaluate how your nerves and muscles are functioning.  EMGs can be used to detect abnormal muscle electrical activity  that can occur in many diseases and conditions, including muscular dystrophy, inflammation of muscles, pinched nerves, peripheral nerve damage (damage to nerves in the arms and legs), amyotrophic lateral sclerosis (ALS) (also known as Lou Gehrig disease), myasthenia gravis, sciatica, and others.

Are there any risks or side effects associated with this test?

There are no commonly associated risks or side effects. There may be some mild temporary soreness, but this should be minimal. 

How do I prepare for the test?

No preparation is necessary.  You may eat before the test.  You may continue to take medications as usual.

How is the EMG/NCS performed?

There is usually a brief physical exam before the test.  The test takes about an hour to completes.

There are two parts to the test.  Electromyopraghy (EMG) and nerve conduction study (NCS). 

The NCS is performed by small electrical stimuli administered to different nerves and measuring the response on a computer.  The computer tracing is interpreted by the physician.  The nerve conduction velocity, amplitude, and shape of the response provide important information that is used to make a diagnosis.

EMG is used to test muscle function.  A very thin disposable needle (an electrode) is inserted into muscles, and electrical activity is recorded.  These are tiny needles similar to the ones used in acupuncture.  The electrical activity is recorded on the computer screen and heard over a speaker.  This data is analyzed by the doctor and interpreted. 

What will I feel?

The electrical stimulation feels like tiny electrical shocks.  Although it may cause minimal discomfort, it is easy to tolerate.  You may experience some very mild discomfort when the needle is inserted into each of the muscles to be tested.  This is also well tolerated, like acupuncture.

Will I be sedated for the test?

No this procedure is done with your participation, there are no medication used to put you to sleep.  You will be fully awake throughout the test.

Can I go to work the same day?

Yes, you should be able to immediately return to work.

Who should not have this test done?

Patients should inform the physician if they have a tape allergy, latex allergy, pacemaker, defibrillator, bleeding disorder.

Will I be able to drive myself home following this test?

Yes. 

Is anything injected into my body?

No. Nothing is injected into your body.

How will I receive the results of my test?

The doctor who ordered your test will explain the results at your follow up visit in the clinic. (please allow a few days for the results)