Nerve Conduction Velocity Test
Alternate Names : NCV, Electroneurography, ENG, Nerve Conduction Studies, Stimulation Myelographic Study
Nerve conduction velocity testing (NCV) is used to evaluate damage or disease in peripheral nerves. In this test, electrical impulses are sent down the nerves of the arms and legs. The electrical impulse is applied to one end of a nerve. The time it takes to travel to the other end of the nerve is measured.
Who is a candidate for the test?
A nerve conduction velocity test is usually ordered to diagnose or evaluate:
nerve injury in a person who has
weakness in an extremity
nerve injury or disease, as opposed to muscular injury or disease
the severity of nerve injury
the response of a nerve disease or injury to treatment
How is the test performed?
NCV testing is done by a neurologist or physiatrist. It can done in a nerve
study clinic office or at the hospital bedside, and usually takes 15 to 30
A conducting paste is placed on patches called electrodes. A
recording electrode is placed on the skin over the particular nerve in
question. This electrode will record the activity or reaction of the nerve.
Other electrodes are placed in a particular order near the first electrode.
A special instrument is used to stimulate the nerves being studied by
delivering a small shock. The recording electrode records the time it takes for the shock to cause activity in the nerve.
The time is sent to a machine called
an oscilloscope. This machine can measure the response time of the nerve to
stimulation. A calculation is then done on the response time and the distance between the electrodes. The electrical stimulation may be slightly
uncomfortable during the test.