A related procedure that is performed with the Electromyelogram is the nerve conduction study (NCS) or nerve conduction velocity (NCV). NCS is a measurement of the amount and speed of conduction of an electrical impulse through a nerve. NCS can determine whether there is nerve damage and destruction. Both procedures help to detect the presence, location, and extent of diseases that damage the nerves and muscles.
NCTs measure how fast an electrical impulse moves through your nerve. NCV can identify nerve damage.
During the test, your nerve is stimulated, usually with electrode patches attached to your skin. Two electrodes are placed on the skin over your nerve. One electrode stimulates your nerve with a very mild electrical impulse. The other electrode records it. The resulting electrical activity is recorded by another electrode. This is repeated for each nerve being tested.
The speed is then calculated by measuring the distance between electrodes and the time it takes for electrical impulses to travel between electrodes.
NCV detects a problem with the nerve, whereas an EMG detects whether the muscle is working properly in response to the nerve’s stimulus.
Diseases or conditions that may be checked with NCV include:
- Guillain-Barré syndrome. A condition in which the body’s immune system attacks part of the peripheral nervous system. The first symptoms may include weakness or a tingling sensation in the legs.
- Carpal tunnel syndrome. A condition in which the median nerve, which runs from the forearm into the hand, becomes pressed or squeezed at the wrist by enlarged tendons or ligaments. This causes pain and numbness in the fingers.
- Charcot-Marie-Tooth disease. An inherited neurological condition that affects both the motor and sensory nerves. It causes weakness of the foot and lower leg muscles.
- Herniated disk disease. This condition occurs when the fibrous cartilage that surrounds the disks of your vertebrae breaks down. The center of each disk, which contains a gelatinous substance, is forced outward. This places pressure on a spinal nerve and causes pain and damage to the nerve.
- Chronic inflammatory polyneuropathy and neuropathy. These are conditions resulting from diabetes or alcoholism. Symptoms may include numbness or tingling in a single nerve or many nerves at the same time.
- Sciatic nerve problems. There are many causes of sciatic nerve problems. The most common is a bulging or ruptured spinal disk that presses against the roots of the nerve leading to the sciatic nerve. Pain, tingling, or numbness often result.
Nerve conduction studies may also be done to find the cause of symptoms, such as numbness, tingling, and continuous pain. Consult with a pain management doctor if you are experiencing any of these symptoms.