NCV is often used along with an EMG to tell the difference between a nerve disorder and a muscle disorder. 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.

Other conditions may prompt your healthcare provider to recommend NCV.