NCV is related to the diameter of the nerve and the degree of myelination (the presence of a myelin sheath on the axon) of the nerve. Newborn infants have values that are approximately half that of adults, and adult values are normally reached by age 3 or 4.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Most often, abnormal results are due to some sort of 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-Barre syndrome
• Diphtheria
• 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, as can damage to the spinal cord and disk herniation (herniated nucleus pulposus) with nerve root compression.