Nerve Conduction Velocity or NCV tests the peripheral nervous system to the arms, legs, and face. This test checks both sensory and motor nerve fibers. NCV studies diagnose different entrapment neuropathies, such as carpal tunnel syndrome, as well as ulnar, radial, peroneal, femoral, posterior tibial, and peripheral neuropathies. The test checks axonal loss, demyelination of the peripheral nerves, and conduction blocks. It is useful in diagnosing anterior horn cell diseases, as seen in amyotrophic lateral sclerosis, and neuromuscular junction problems, such as myasthenia gravis. The NCV test differentiates inherited neuropathies such as Charcot-Marie-Tooth and Dejerine-Sottas entrapment neuropathies (avoiding multiple unnecessary surgeries).