David Greer, M.D. and Scott Hitchcock, D.O.
185 Chateau Dr SW Ste 301, Huntsville, AL 35801
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EMG AND NCS

Electromyography (EMG) and Nerve Conduction Studies(NCS) are ordered to learn more about the health of peripheral nerves, in other words, the nerves that travel to and from your hands and feet. These tests can establish if a nerve is working properly by measuring the speed of the nerve's conductivity and the electrical activity of the nerve. In the case of nerve injury or nerve entrapment the test can often locate the exact site. EMG NCS are often done together to provide more complete information.

EMG

The muscles are assessed by inserting a tiny Teflon coated pin electrode into the muscle with the computer then recording the muscle potential. The sensation is similar to that of an injection that goes into the muscle as the pin electrode is inserted into the muscle. (That is if sensory awareness is not a problem.) It is important for the patient to lie still to reduce interference and to achieve accurate readings.

NCS

The patient will be asked to lie on an examination table. Electrodes are placed on the skin over the nerve to be studied. These electrodes act as microphones to pick up any electrical signal that goes by them. An electrical stimulator is then placed on the skin near the electrodes and is used to create an electrical current strong enough to fully stimulate the nerve. A computer is used to record responses as various nerves are tested. This allows the physician to measure and calculate how fast the nerve is sending the impulses to the muscle.

PREPARATION:

  • Please do not wear any lotion or perfume anywhere on the body.
  • Wear loose fitting clothes that can be raised to above the knee or above the elbow, depending on the limb that will be tested.
  • Take all medications regularly, unless given other instructions by your physician.

Commonly asked questions:

1. Does it hurt?

Parts of the test are uncomfortable but not severely painful. The anxiety before the test can be more of a factor than the test itself. A majority of the time spent with the patient is setting up the studies and running the computer; a very small amount of the time involves electrical stimulation or use of the pin electrode. The electrical stimulation of the nerve conduction study could be compared to a static electricity shock from a doorknob after walking across carpet. The pin insertion could be compared to being pinched by someone's fingernails.

2. Is sedation or anesthesia used?

No, the test is well tolerated and the patient needs to be awake to follow instructions during the exam.

3. Are there any side effects?

There can be minor irritation at the pin insertion sites but otherwise, there are no lasting effects from either the NCS or the EMG.

4. Will I get results of the test that day?

The examining physician can give you an idea of any obvious abnormalities at the end of the test. However, more detailed interpretation will be done at a later time with a full report sent to the physician who referred the patient.
The results from EMG and nerve conduction studies are usually not enough on their own to diagnose a condition. They can be used along with a person's history, symptoms, physical and neurological examinations, and the results of other tests to help establish a diagnosis.

5. Why is it done?

Nerve conduction studies are done to:

  • Detect and evaluate damage to the peripheral nervous system (which includes all the nerves that lead away from the brain and spinal cord and the smaller nerves that branch out from those nerves).
  • Identify the location of abnormal sensations, such as numbness, tingling, or pain.
    Electromyography (EMG) is done to:
  • Aid in diagnosis of conditions that damage muscle tissue, nerves, or the junctions between nerve and muscle (neuromuscular junctions).
  • Evaluate the cause of weakness, paralysis, involuntary muscle twitching, or other symptoms. Problems in a muscle, the nerves supplying a muscle, the spinal cord, or the area of the brain that controls a muscle can all cause these kinds of symptoms.

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