title: Improving the reproducibility of motor unit number index.
abstract: Reproducibility is an important aspect of any method intended to be a marker of disease progression. In this study we investigated approaches for improving motor unit number index (MUNIX) reproducibility.
  
  
  
  We used the intraclass correlation coefficient (ICC) and the coefficient of variation (CV) to study reproducibility in healthy subjects. We tested reproducibility between test and retest of a single MUNIX from 3 different muscles (S-MUNIX) and also of the mean of a set of 3 measurements from these same muscles (M-MUNIX).
  
  
  
  M-MUNIX was more reproducible than S-MUNIX. The CV showed a greater improvement than the ICC in all 3 muscles.
  
  
  
  M-MUNIX may be a valuable approach for following motor unit loss, because it is more replicable than MUNIX. This may be especially relevant in amyotrophic lateral sclerosis patients, in whom MUNIX variability is higher than in healthy individuals. Muscle Nerve, 2016 Muscle Nerve 55: 635-638, 2017.
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: Marcio Luiz
authors.initials: ML
authors.lastname: Escorcio-Bezerra
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: Acary Souza Bulle
authors.initials: ASB
authors.lastname: Oliveira
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: Nadia Iandoli
authors.initials: NI
authors.lastname: De Oliveira Braga
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: Gilberto Mastrocola
authors.initials: GM
authors.lastname: Manzano
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology; D018450:Disease Progression; D004576:Electromyography / Q000379:methods; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011999:Recruitment, Neurophysiological / Q000502:physiology; D015203:Reproducibility of Results
keywords: ALS; MUNIX; coefficient of variation; intraclass correlation coefficient; motor unit; reproducibility