What is an NCS?
NCS may be performed on either sensory or motor nerves. From the skin surface, a brief electrical stimulus is applied to the nerve of interest, and the evoked electrical signal is recorded distally from another point in the nerve in the case of a sensory nerve or from the innervated muscle in the case of a motor nerve; the evoked responses are known as SNAP or CMAP, respectively. Characteristics of the evoked action potentials such as amplitude, onset and/or peak latency, and conduction velocity provide information about axon and myelin components of the tested nerve.
