Reproducibility of motor unit number index and multiple point stimulation motor unit number estimation in controls.

INTRODUCTION

Reproducibility of the multiple point stimulation motor unit number estimation (MPS-MUNE) technique was compared with the recently developed motor unit number index (MUNIX) technique.

METHODS

MPS-MUNE and MUNIX were performed on 15 healthy subjects at 3 different time-points by the same examiner. Reproducibility was analyzed using intraclass correlation coefficient (ICC) and coefficient of variation (CV).

RESULTS

ICC values for MUNIX and MPS-MUNE were excellent across 3 tests (0.80 and 0.77, respectively), although CV values were significantly lower for MUNIX than MPS-MUNE (P < 0.01). In addition, test-retest reproducibility was better for MUNIX, a finding largely attributable to poor reproducibility of the single motor unit action potential area. MUNIX (R = -0.48, P < 0.05) and MPS-MUNE (R = -0.53, P < 0.05) were significantly correlated with age.

DISCUSSION: MUNIX demonstrated better intrarater reproducibility and may be a more reliable neurophysiological biomarker than MPS-MUNE. Muscle Nerve 58: 660-664, 2018.