Nerve conduction velocity test is an important aspect of nerve conduction studies. It is the speed at which an electrochemical impulse propagates down a neural pathway. Conduction velocities are affected by a wide array of factors, including age, sex, and various medical conditions. Studies allow for better diagnoses of various neuropathies, especially demyelinating conditions as these conditions result in reduced or non-existent conduction velocities.
Normal Conduction Velocities
Ultimately, conduction velocities are specific to each individual and depend largely on an axon’s diameter and the degree to which that axon is myelinated, but the majority of ‘normal’ individuals fall within defined ranges.
Nerve impulses are extremely fast, with some myelinated neurons conducting at speeds up to 120 m/s (432 km/h)
Nerve Conduction Velocity is just one of many measurements commonly made during a nerve conduction study (NCS). The purpose of these studies is to determine whether nerve damage is present and how severe that damage may be.
Nerve conduction studies are performed as follows:
->Two electrodes are attached to the subject’s skin over the nerve being tested.
->Electrical impulses are sent through one electrode to stimulate the nerve.
->The second electrode records the impulse sent through the nerve as a result of stimulation.
->The time difference between stimulation from the first electrode and pick-up by the downstream electrode is known as latency.Nerve conduction latencies are typically on the order of milliseconds.