THE REFRACTORY PERIOD OF TRANSMISSION IN PATIENTS WITH CARPAL-TUNNEL SYNDROME

In patients with the carpal tunnel syndrome (CTS) and in control subjects, pairs of shocks at intervals of 0.8 msec and 1.0 msec were used to stimulate the median nerve just above the wrist. Nerve action potentials were recorded at the elbow and from the index or middle finger. In patients but not in controls, recordings from the finger frequently showed loss of the second action potential of the pair, although a second action potential was present at the elbow. In these cases it seemed likely that impulse transmission through the carpal tunnel had failed because the damaged nerve at the level of the lesion had an increased refractory period of transmission (RPT) compared with its refractory period under the stimulating cathode. The possible diagnostic use of RPT measurement in CTS patients is discussed. Copyright © 1990 John Wiley & Sons, Inc.