• carpal tunnel syndrome;
  • nerve conduction study;
  • neurophysiological severity;
  • premotor potential;
  • second lumbrical–interosseous comparison study


Introduction: Premotor potentials (PMPs) precede compound muscle action potentials evoked from the second lumbrical muscle after median nerve stimulation. Although PMP has been identified as a median sensory nerve action potential, few reports have documented the significance of PMP parameters for diagnosing carpal tunnel syndrome (CTS). Methods: We investigated the relationships between PMP parameters and results of 6 standard median nerve conduction studies in 74 CTS hands. Results: Significant correlations were noted in all comparisons. PMP conduction velocity was strongly correlated with the sensory conduction velocity between wrist and digit 2 (r2 = 0.91). Moreover, PMP parameters were significantly correlated with neurophysiological severity of CTS. Conclusion: Measuring PMP parameters with a second lumbrical–interosseous study may be useful for diagnosing CTS. Muscle Nerve, 2012