Repeater F waves

Abstract
Thirty-five thousand six hundred supramaximal shocks were applied to 209 healthy and 147 entrapped median nerves (carpal tunnel syndrome—CTS) to characterize the backfiring behavior of the alpha motor neuron pool of abductor pollicis brevis in health and the modifying effect of a compressive neuropathy. A contraction of the normal subpopula-tion of active F-wave generators was found in CTS, while active neurons backfired at higher than normal frequencies (p < 0.001). These modifications in spinal behavior are reflected in the % Repeater F-wave value, whose sensitivity in the detection of CTS approaches that of sensory wrist-to-palm latency estimation. This technique offers an alternative to latency measurement in the diagnosis of CTS. An economical strategy for the electrodiagnosis of CTS is proposed.