Introduction: The objective of this study was to evaluate a recently developed motor unit number estimation (MUNE) method, MScanFit MUNE (MScan), as a measure of disease progression in amyotrophic lateral sclerosis (ALS) compared with compound muscle action potential (CMAP) amplitude and 2 traditional MUNE methods.
Methods: ALS patients were evaluated clinically using the ALS Functional Rating Scale-Revised (ALSFRS-R). MScan, multiple-point stimulation MUNE (MPS), and motor unit number index (MUNIX) were performed in the abductor pollicis brevis (APB) muscle at baseline (27 patients), 4 months (23 patients), and 8 months (16 patients).
Results: Of the 5 measures, MScan registered the largest decline (8.7% per month), compared with MPS (3.4%), MUNIX (4.8%), CMAP amplitude (2.0%), and ALSFRS-R (1.9%). Only MScan and ALSFRS-R registered significant decrements over 4 and 8 months.
Discussion: MScan may be useful as a sensitive, objective tool for quantifying motor unit loss in ALS. Muscle Nerve 59:82-87, 2019.
Keywords: ALS Functional Rating Scale; MScan, motor unit loss; MUNE, motor unit number estimation; MUNIX, multiple-point stimulation; amyotrophic lateral sclerosis; follow-up study.
© 2018 Wiley Periodicals, Inc.