Toward the validation of a new method (MUNIX) for motor unit number assessment.

Introduction: This prospectively designed study analyzed the correlation of a new, non-invasive neurophysiological method (Motor Unit Number Index - MUNIX) with two established Motor Unit Number Estimation (MUNE) methods.

Methods: MUNIX and incremental stimulation MUNE (IS-MUNE) were done in the abductor digiti minimi muscle (ADM), while MUNIX and spike-triggered averaging MUNE (STA-MUNE) were tested in the trapezius muscle. Twenty healthy subjects and 17 patients with amyotrophic lateral sclerosis (ALS) were examined.