Nerve Motor Fiber Characteristics in Chronic Ischemia

MOTOR nerve conduction velocity, as usually determined in clinical practice, gives information about the fastest conducting fibers of a peripheral nerve. Conduction velocity in the smaller and more slowly conducting fibers cannot be measured because the time of onset of their muscle action potential is hidden by the discharge of the faster units. With the available technique, therefore, conduction velocity of a peripheral nerve may, not infrequently, be within normal limits in the presence of clinical evidence of neuropathy, as long as some of the remaining fibers are of the fastest conducting type. A method of estimating the conduction velocity of the slowest as well as the fastest motor fibers has recently been described by Hopf.1Differences of 4 to 7 meters per second were reported between the fast and slow fibers of the ulnar nerve in normal subjects. The method may provide a better insight into the motor