A nerve conduction study is a set of four diagnostic procedures used to determine whether nerves are functioning properly. It is often ordered when the patient has peripheral neuropathy that cannot be explained.
The test consists of four components:
- Motor NCS - an electrical current is applied to a nerve and a reading is taken from the muscle that is served by the nerve to determine the time interval between the stimulation and reaction.
- Sensory NCS - an electrical current is applied to a peripheral nerve and a recording is made from another periperal nerve with many nerve endings, such as a finger.
- F-wave study - an electrical current is applied to a major motor nerve and the reaction of the muscle is measured. This measures the time it takes for an impulse to reach the spine and return to the site of stimulation.
- H-reflex study - a nerve is stimulated and the reflex action of the muscle is measured.