Introduction
Electrodiagnostic studies (EMG/NCV) are used to evaluate how well your nerves and muscles are working. An electrodiagnostic study consists of two parts.

The nerve conduction velocity test (NCV) is an electrical test that is designed to study how well your nerves and muscles are working.

The other test is called an electromyogram, or EMG. The purpose of the EMG is to look for disease or abnormalities in the nerves and/or muscles.

Both parts of the test combined give the most information.

Nerve Conduction Velocity Test

NCV (Nerve Conduction Velocity) tests record the responses of sensory and motor (muscle) nerves in the extremities(arms and legs) to electrical stimulation. These studies are used to identify and aid in the diagnosis of entrapment syndromes (pressure on the nerves), peripheral nerve lesions and neuropathies (diseases of the nerves).

This test also helps identify muscle problems. The nerve is given an electrical stimulation, and the speed of the impulse is measured, recorded and evaluated. Nerves are stimulated with a small amount of electricity and the responses are recorded using small electrodes. Some of the electrodes are small metal discs and some are wires that slip around the fingers.

When testing a leg, the nerves are usually stimulated at the ankle and knee.

When testing the arms, the nerves are usually stimulated at the wrist and elbow. Other sites on the arm may be stimulated such as the palm of the hand and the shoulder.

Electrical stimulus applied is not painful but does feel a little "weird" since it will sometimes make the fingers or toes "twitch."

Electromyography

EMG (electromyography) is a diagnostic study in which specific muscles are stimulated to look for abnormal electrical signals in the muscles. If the muscles are not working properly, it can be assumed that the nerves are being irritated, pinched, functioning abnormally, or are damaged. EMGs provide information about the presence of nerve injury and extent of the patient's problem. EMGs can differentiate an old injury from a new injury.

How Is It Done?

Upper Extremity (Arm) EMG:
(Jewelry must be removed from the hands and wrists)

• The patient may be sitting, or lying down.
• Using very fine needle electrodes, the physician tests specific muscles of the limb.
• A ground electrode is placed on the limb that is being studied.
• The electrical impulses are traced on the EMG machine.

Lower Extremity (leg) EMG:

• The patient is usually supine (face up) on the exam table.
• Electrodes are taped at specific locations on the feet and calves.
• Using very fine needle electrodes, the physician assesses specific muscles of the feet, lower legs and low back.
• The impulses are traced on the screen and may be transferred to a printout for evaluation.

What Will I Feel?

There may be some discomfort when the needles are inserted into the muscles. The needles are very fine and may have a Teflon coating so that they can be inserted as painlessly as possible.

There may be muscle spasms when the electrical impulses are transmitted, this lasts only a short time. If you relax during the procedure, the discomfort will be minimal.

How Long Does It Take?

The procedure usually lasts thirty to ninety minutes depending on which nerves are being tested.

Preparation

You should not wear lotion on your hands, arms, feet or legs. There is no other preparation necessary.

Results

The test data will be evaluated by the physician performing the electrodiagnostic tests.

The results will be sent to your physician for correlation with your clinical examination.