NCS (Nerve Conduction Studies)


What is it?

A Nerve Conduction Study (NCS), also called a Nerve Conduction Velocity (NCV) test - is a measurement of the speed of conduction of an electrical impulse through a nerve. NCS can determine nerve damage and destruction.

During the test, the nerve is stimulated, usually with surface electrode patches attached to the skin. Two electrodes are placed on the skin over the nerve. One electrode stimulates the nerve with a very mild electrical impulse and the other electrode records it. The resulting electrical activity is recorded by another electrode. This is repeated for each nerve being tested.

The nerve conduction velocity (speed) is then calculated by measuring the distance between electrodes and the time it takes for electrical impulses to travel between electrodes.

Why it is done?

The nerve conduction test provides physicians with information about the functioning of the peripheral nerves including both the type of dysfunction and the likely location of its cause.

Nerve conduction studies are used for a wide variety of reasons including:

  • To assess nerve damage following an injury.
  • To check for damage to nerves, caused by conditions such asdiabetes.
  • To test for conditions affecting the nervous system.
  • To check for 'trapped' nerves - conditions such as carpal tunnel syndrome.
  • Guillain-Barr syndrome.
  • Tarsal tunnel syndrome.
  • Charcot-Marie-Tooth disease
  • Chronic inflammatory polyneuropathy and neuropathy
  • Sciatic nerve problems
  • Peripheral nerve injury
How it is done?

The NCS is performed by a Neurologist (a doctor who specializes in brain and nerve disorders), although a Neurotechnologist may also perform some portions of the test.

Generally, a NCS procedure follows this process:

  • You will be asked to remove any clothing, jewelry, hairpins, eyeglasses, hearing aids, or other metal objects that may interfere with the procedure.
  • If you are asked to remove clothing, you will be given a gown to wear.
  • You will be asked to sit or lie down for the test.
  • A neurologist/technologist will locate the nerve(s) to be studied.
  • A recording electrode will be attached to the skin over the nerve with a special paste and a stimulating electrode will be placed at a known distance away from the recording electrode.
  • The nerve will be stimulated by a mild and brief electrical shock given through the stimulating electrode.
  • You may experience minor discomfort for a few seconds.
  • The stimulation of the nerve and the detected response will be displayed on a monitor (electrical activity in the form of waves).
How long will it take?

Nerve conduction tests may take from 15 minutes to 1 hour or more, depending on how many nerves and muscles are studied.

After the procedure

The paste used to attach the electrodes will be removed from your skin. After the test, you may return to your previous activities, unless your doctor advises you differently.