Hello lady67,
A nerve conduction study is a test commonly used to evaluate the function, especially the ability of electrical conduction, of the motor and sensory nerves of the human body.
Nerve conduction velocity is a common measurement made during this test.
In nerve conduction studies, the nerve on one side of the carpal tunnel is activated by a small shock to the skin. An oscilloscope measures how long it takes for the resulting nerve-impulse to arrive on the other side of the carpal tunnel. When the median nerve is pinched, the nerve-impulse is delayed or blocked.
Nerve conduction studies not only show whether or not the median nerve is impaired at the wrist, but also provide precise data concerning how bad the impairment is. In addition, these studies survey the function of other nerves in the arm and hand.
Refer http://www.ergonomictimes.com/carpal_tunnel_syndrome_symptom.php
Best