Electromyography and Nerve Conduction Velocity Studies studies are ordered to evaluate for injury or disease of your muscle, nerve roots, and peripheral nerves. They test the condition of the nerves from the spine, face, and extremities, including the foot and hand.
- The electromyogram (EMG) is to look for disease or abnormalities in your nerves and/or muscles.
- The nerve conduction velocity studies (NCS) is an electrical test that is designed to study how well your nerves and muscles are working.
These studies are normally done together and are usually performed as a workup for complaints of pain, weakness, numbness, or tingling.
Common problems tested include:
- Carpal tunnel syndrome
- Cervical & lumbar radiculopathy
- Ulnar neuropathy (cubital tunnel)
- Peripheral neuropathy (diabetes, alcohol)
- Trauma (facial nerve injury, brachioplexopathy, radial nerve injury from humeral fracture, peroneal neuropathy)
- Guillain-Barre Syndrome
- Nerve injuries after an accident
- Effects of diabetes
Your health insurance carrier may require electrodiagnostic testing to confirm a diagnosis before authorizing medical or surgical treatment.
An EMG records and analyzes the electrical activity in your muscles to determine if there's a nerve injury and the extent of any injury. If the muscles are not working properly, it can be assumed that the nerves are being irritated, pinched, functioning abnormally or are damaged. An EMG can differentiate an old injury from a new injury.
What to expect
During an EMG, small, thin needle electrodes are placed in the muscle to record the electrical activity. When the needles are inserted, you may feel some pain and discomfort.
Your physicians will ask you to relax the muscle and to tense it slightly while they listen and watch a TV-like screen that broadcasts the electrical signals. You will also be able to hear the signal sounds as you move the muscle.
If you relax during the procedure, the discomfort will be minimal. When the needles are removed, you may experience some soreness and bruising, but this will disappear in a few days. There are no long-term side effects.
Nerve conduction studies
NCS record the responses of sensory and motor (muscle) nerves in your 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 finger. As the current travels down the nerve pathway, the electrodes placed along the way capture the signal and time how fast the signal is traveling.
Although you may initially be startled by the suddenness of the stimulation, it is not painful and most people are comfortable during the testing procedure. It may feel a little strange since the test will sometimes make the fingers or toes twitch.