Nerve conduction study (NCS), also known as a nerve conduction velocity (NCV) test, enables the diagnosis of possible nerve damage by measuring the speed with which an electrical impulse travels through a nerve. This test, often performed in conjunction with electromyography (EMG), allows the doctor to differentiate nervous system issues from musculoskeletal ones, and is invaluable in helping to establish the source of nerve damage, information that can be vital to effective treatment. Nerve conduction studies may be used to diagnose specific causes of nerve damages, including: substance abuse, nerve compression or various types of neuropathy.
Candidates for an NCS
Nerve conduction studies may be administered to patients with symptoms such of chronic pain, numbness or tingling in various parts of the body. Physicians may recommend an NSC study to either rule out or confirm a diagnosis of one of the following conditions:
- Myasthenia gravis
- Amyotrophic lateral sclerosis (Lou Gehrig's disease)
- Alcoholic or diabetic neuropathy
- Traumatic nerve injury
- Guillain-Barre syndrome
- Certain hereditary diseases
- Spinal nerve compression
It is important that the doctor administering the NCS be aware of any medications the patient is taking and of any underlying medical conditions. The patient's temperature needs to be taken because a low body temperature will result in slower nerve conduction.
The NCS Study Procedure
During the outpatient NCS study, the nerves presumed to be affected are targeted. Electrodes are placed at various points on the skin, their adherence aided by a sticky gel. Each electrode is placed at a precise distance from its partner, a recording electrode.
As the nerve is stimulated by a mild, brief electrical charge, the exact time the impulse takes to reach the receptive device is recorded. This response time is displayed on a monitor for the doctor to observe and evaluate. Patients usually experience some discomfort from the mild shocks administered during the NCS study, but this is short-lived. After the procedure, patients may experience some muscle soreness.
What do nerve conduction studies diagnose?
Nerve conduction studies are done to find and evaluate damage to all the nerves that lead away from the brain and spinal cord to the smaller nerves that branch out from them. They help diagnose nerve disorders, such as carpal tunnel syndrome, cubital tunnel syndrome, peripheral neuropathies, and radiculopathies (to name a few).
What is the difference between a nerve conduction study and an EMG?
An electromyogram (EMG) measures the electrical activity of your muscles when you are not using them (at rest) and when you tighten them (muscle contraction). Nerve conduction studies (NCS) measure how well and how fast the nerves can send electrical signals. EMG and nerve conduction studies are often done together.
What is the most common symptom of nerve damage?
The most common symptoms of a nerve condition include: A feeling of numbness, pain, tingling, or burning in your limbs or extremities, Unexplained weakness, loss of muscle strength, or paralysis.
What should I avoid before having a nerve conduction studies performed?
Avoid putting cream, lotion or perfume on your skin. Creams and lotions can affect the test's accuracy. Tell the provider performing the study if you have a pacemaker or any other electrical medical device.
Will a nerve conduction test show neuropathy?
The results of nerve conduction studies and EMGs can help in the diagnosis of various neuropathies (disease of the nerve), myopathies (disease of the muscle), and neuromuscular junction disorders (disease of transmission between the nerve and muscle).
