The origin of the premotor potential recorded from the second lumbrical muscle in normal man

Antidromic vs orthodromic sensory median nerve conduction studies

Objective

Median sensory nerve conduction studies are arguably the most often performed electrodiagnostic tests worldwide. Routine tests in clinical practice are done using either antidromic or orthodromic techniques type of stimulation, with no universal agreement on the use of one or the other technique.

Methods

We review the advantages and drawbacks of antidromic and orthodromic as well as their particularities for clinical application and research.

Results

The two techniques differ on how physical and physiological changes affect the action potential. Near-nerve recording is better suited for the orthodromic than for the antidromic technique, while studies of nerve excitability are better suited for the antidromic than for the orthodromic technique.

Conclusion

Both techniques are equally suitable for routine tests but research studies may specifically demand one or the other.

Premotor potential study in carpal tunnel syndrome

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 (r(2) = 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.