Welcome to Winchester Orthopaedic Associates, Ltd

Patient Education:

 

What is an EMG/NCV?

 

An EMG, or electromyography is a test used to measure the electrical activity of certain skeletal muscle groups at rest and during voluntary contraction.  The EMG is performed to help diagnose neuromuscular disorders, to evaluate diseases caused by the degeneration of nerve tissue, or to distinguish between primary or secondary muscle disorders.  This test lasts approximately one hour and minimal discomfort may be felt.  The patient may be asked to restrict caffeine for two to three hours before the test takes place.  During the test the doctor inserts a needle electrode into selected muscles and measures the electrical discharge of the muscle.  The muscles electrical signal is recorded during rest and contraction.  After the test there may be mild discomfort at the injection sites and warm compresses may be applied to help with the irritation.  If there is no discomfort regular activity may be resumed as tolerated.

An NCV, or nerve conduction velocity test is usually performed in conjunction with the EMG.  The NCV allows for the detection and location of peripheral nerve injury or disease.  A mild electrical shock is given to the patient to stimulate a particular nerve.  A recording electrode that is placed a set distance from the site of the shock detects the response from the stimulated nerve.  The lag time between the shock and the response is measured.  When a peripheral nerve injury or disease is present the lag time will be abnormal.  After the test the patient may return to regular activity as tolerated.

 

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