Nerve Conduction Study (NCS) evaluates the ability of electrical conduction of the motor and sensory nerves. It is performed by placing electrodes on the skin over certain muscles and recording the response when they are artificially activated through a mild electrical impulse applied to the responsible nerve. The test typically takes approximately 30-60 minutes to complete. The procedure is entirely safe, even in patients who have pacemakers or other electrical devices. There is a mild degree of discomfort with due to the electrical stimuli mostly a brief tingling sensation. The stimuli are not dangerous to anyone and are usually well tolerated without the need for medication beforehand. There are no lasting effects from the electrical stimulation. A disturbance of the nerve conduction velocity occurs because of a trapped nerve or in polyneuropathy.