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Nerve Conduction

Nerves use electrical impulses to coordinate muscle movement in our bodies. Diseases affecting the muscles and nerves can result in abnormal electrical activity.

Nerve conduction studies are diagnostic tests used to detect nerve and muscle disorders and to evaluate the functioning of your nerves and muscles. Nerve conduction studies measure the conductivity of the nerves.

Indications

Nerve Conduction Studies (NCS) are used to detect damage or injury to the peripheral nervous system (PNS), which consists of the extracranial nerves and spinal cord. This test can be used to diagnose neurological disorders, such as carpal tunnel syndrome or Guillain-Barré syndrome.

Before the procedure

Certain medications that act on the nervous system can cause abnormal test results. Therefore, your physician may advise you to stop these medicines 3 to 6 days prior to your procedure. If you are on blood thinners, your doctor may ask you to stop taking them, before the test. Also, inform your doctor if you have a pacemaker implanted. You will be instructed not to smoke, eat or drink foods that contain caffeine for 3 hours before the test.

Procedure

Nerve conduction studies: A nerve conduction study usually takes about 15 to 60 minutes depending on the number of areas to be studied. Often, nerve conduction studies are done before an electromyography (EMG). This test is usually done with several flat metal disc electrodes that are placed on the skin with a paste or tape. Your doctor places a shock-emitting electrode directly over the nerve to be studied and a recording electrode over the muscles supplied by that nerve. Small and brief electrical impulses are generated to stimulate the nerves. The time taken for the muscle to contract in response to the pulse is then recorded. The speed of transmission of the impulse is called nerve conduction velocity. To compare the conduction velocity, the corresponding nerves on the other side of the body may be studied. After the test, the electrodes are removed.

Risks

In a nerve conduction study, the chance of any risks or complications is minimal as the amount of electricity that is transmitted is very small. You may experience a brief, burning pain, a tingling sensation and a twitching of the muscle during the transmission of the electrical impulses.

Certain factors or conditions may interfere with the test results. These tests are usually avoided in individuals with swelling, bleeding, or obesity and those taking medications, such as skeletal muscle relaxants and anticholinergics.

Other In–Office Diagnostic Testing List

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