Basic Principles & Interpretation of Nerve Conduction Study: A Short Review

Nerve conduction studies (NCS) are done to diagnose peripheral nerve diseases. These studies are extension to clinical examination and provide useful tool in the evaluation of patients who have pain, numbness, tingling, and hypo or arefelxic weakness. Proper electrophysiological approach & Technique is used to carry out the test, but more important is to interpret the result. Certain standard nerve conduction study criteria's are used to diagnose the peripheral nerve diseases. Demylinating neuropathy is recognized by moderate to severe slowing of nerve conduction velocity, prolongation of distal and F-wave latencies. A drop of more than 20% of compound motor action potential (CMAP) is strongly suggestive of conduction block provided there is no abnormal temporal dispersion. Axonapthy is recognized by normal or mildly slowed conduction velocity, reduced CMAP amplitude and sensory nerve action potential (SNAP) amplitudes, normal or mildly prolonged distal motor & F- latencies. H-reflex is measure of the arc reflex integrity; it allows evaluation of small motor fibers in proximal locations like roots and plexus.