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.
Risks of an NCS
The NCS is noninvasive and ordinarily results in no side effects. While patients experience various degrees of discomfort during the test itself, the electrical voltage employed during the test is very low and not damaging. Some patients with sensitive skin may have some irritation from the gel used to attach the electrodes. Typically, patients can resume normal, but not strenuous, activities immediately following the test. Some patients with sensitive skin may have some local irritation from the gel used to attach the electrodes. Individual patients with underlying medical conditions may be given speciﬁc recommendations after the examination.