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Nerve Conduction Velocity (NCV) Testing

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Nerve Conduction Velocity (NCV) and Electromyography (EMG) are tests your doctor may order to measure nerve conduction and muscle action potential. These tests are performed to determine if symptoms (e.g. sciatica, weakness) are caused by a nerve or muscle disorder. Both tests may be performed.

A NCV assesses how well a specific nerve conducts impulses by evaluating the speed of an impulse as it travels along a nerve. This test can help determine if there is nerve damage, the extent of the damage and if nerves have been destroyed.

Test Preparation and Performance
The patient may lie down or sit during the test. Normal body temperature is important. Low or high body temperature affects normal nerve conduction.

Patch-like electrodes, similar to those used during an electrocardiogram, are affixed on the skin at various nerve locations. A probe held against the skin emits a very low electrical impulse to stimulate the nerve. The electrodes measure the speed of the impulse as it travels from point A to B. Nerve activity is recorded on a CRT screen.

Discomfort and Risks
It is extremely unusual to experience significant pain or discomfort from this test. There are no risks.

Updated on: 02/06/10
Rick C. Sasso, MD
These tests may help your doctor determine if your problem is due to a nerve abnormality. They must, however, be viewed in association with imaging studies such as an MRI and a complete physical examination. A compressed nerve root in the neck or back may be a source of pain but these tests could still be normal. These tests are also normal when the problem is due to a spinal cord abnormality.
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