Split-hand phenomenon in amyotrophic lateral sclerosis: A motor unit number index study

Muscle Nerve. 2016 Jun;53(6):885-8. doi: 10.1002/mus.24958. Epub 2016 Mar 1.

Abstract

Introduction: The split-hand phenomenon refers to preferential wasting of the thenar muscles with relative sparing of the hypothenar muscles in amyotrophic lateral sclerosis (ALS).

Methods: We compared the split-hand index (SI) calculated from the compound muscle action potential (CMAP; SICMAP ) with that calculated from the motor unit number index (MUNIX; SIMUNIX ). We performed MUNIX on the abductor policis brevis (APB), first dorsal interosseous (FDI), and abductor digiti minimi (ADM) muscles of 39 ALS patients and 40 age-matched, healthy controls. SI is derived by multiplying the CMAP (or MUNIX) recorded over the APB and FDI and dividing by the CMAP (or MUNIX) recorded over the ADM.

Results: Receiver-operating characteristic curve analysis revealed good diagnostic accuracy for both indices, but better performance of SIMUNIX than SICMAP .

Conclusion: SIMUNIX and SICMAP were useful in differentiating ALS patients from healthy controls. SIMUNIX appears to be a better electrophysiological marker than SICMAP for the split-hand sign of ALS. Muscle Nerve 53: 885-888, 2016.

Keywords: MUNIX; amyotrophic lateral sclerosis; compound muscle action potential; motor unit number index; split hand; split index.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Amyotrophic Lateral Sclerosis / complications*
  • Amyotrophic Lateral Sclerosis / pathology*
  • Case-Control Studies
  • Electromyography
  • Evoked Potentials, Motor / physiology*
  • Female
  • Hand / innervation
  • Hand / physiopathology*
  • Humans
  • Male
  • Middle Aged
  • Muscle, Skeletal / pathology
  • Muscle, Skeletal / physiopathology*
  • ROC Curve