Health Encyclopedia - Test
Nerve conduction velocity
Nerve conduction velocity (NCV) is a test to see how fast electrical signals move through a nerve.
How the Test is Performed
How to Prepare for the Test
How the Test will Feel
Why the Test is Performed
What Abnormal Results Mean
Most often, abnormal results are due to nerve damage or destruction, including:
- Axonopathy (damage to the long portion of the nerve cell)
- Conduction block (the impulse is blocked somewhere along the nerve pathway)
- Demyelination (damage and loss of the fatty insulation surrounding the nerve cell)
The nerve damage or destruction may be due to many different conditions, including:
- Alcoholic neuropathy
- Diabetic neuropathy
- Nerve effects of uremia (from kidney failure)
- Traumatic injury to a nerve
- Guillain-Barré syndrome
- Carpal tunnel syndrome
- Brachial plexopathy
- Charcot-Marie-Tooth disease (hereditary)
- Chronic inflammatory polyneuropathy
- Common peroneal nerve dysfunction
- Distal median nerve dysfunction
- Femoral nerve dysfunction
- Friedreich's ataxia
- General paresis
- Mononeuritis multiplex
- Primary amyloidosis
- Radial nerve dysfunction
- Sciatic nerve dysfunction
- Secondary systemic amyloidosis
- Sensorimotor polyneuropathy
- Tibial nerve dysfunction
- Ulnar nerve dysfunction
Any peripheral neuropathy can cause abnormal results. Damage to the spinal cord and disk herniation (herniated nucleus pulposus) with nerve root compression can also cause abnormal results.
An NCV test shows the condition of the best surviving nerve fibers, so in some cases the results may be normal even if there is nerve damage.
Griggs RC, Jozefowicz RF, Aminoff MJ. Approach to the patient with neurologic disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 403.
Reviewed By: Luc Jasmin, MD, PhD, FRCS (C), FACS, Department of Neurosurgery at Cedars-Sinai Medical Center, Los Angeles CA; Department of Surgery at Los Robles Hospital, Thousand Oaks CA; Department of Surgery at Ashland Community Hospital, Ashland OR; Department of Surgery at Cheyenne Regional Medical Center, Cheyenne WY; Department of Anatomy at UCSF, San Francisco CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.