Neurodiagnostic Testing (EMG/ NCV)

A nerve conduction velocity (NCV) test — also called a nerve conduction study (NCS) — measures 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.

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.

Electromyography (EMG) is an electrodiagnostic medicine technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyograph detects the electric potential generated by muscle cells when these cells are electrically or neurologically activated. The signals can be analyzed to detect medical abnormalities, activation level, or recruitment order, or to analyze the biomechanics of human or animal movement.

Your doctor may perform an EMG if you’re experiencing symptoms that may indicate a muscle or nerve disorder. Some symptoms that may call for an EMG include:

  • tingling

  • numbness

  • muscle weakness

  • muscle pain or cramping

  • paralysis

  • involuntary muscle twitching (or tics)

The results of an EMG can help your doctor determine the underlying cause of these symptoms. Possible causes could include:

  • muscle disorders, such as muscular dystrophy

  • disorders that affect the ability of the motor neuron to send electrical signals to the muscle, such as myasthenia gravis

  • radiculopathies

  • peripheral nerve disorders that affect the nerves outside the spinal cord, such as carpal tunnel syndrome

  • nerve disorders, such as amyotrophic lateral sclerosis (ALS)

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Pacific Care Medical Group, Inc.

6800 Lincoln Ave., Ste-203B Buena Park, CA 90620

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