title: CMAP scan discontinuities: automated detection and relation to motor unit loss.
abstract: Objective To evaluate an automated method that extracts motor unit (MU) information from the CMAP scan, a high-detail stimulus-response curve recorded with surface EMG. Discontinuities in the CMAP scan are hypothesized to result from MU loss and reinnervation.
  
  
  METHODS
  We introduce the parameter D50 to quantify CMAP scan discontinuities. D50 was compared with a previously developed manual score in 253 CMAP scans and with a simultaneously obtained motor unit number estimate (MUNE) in 173 CMAP scans. The effect of MU loss on D50 was determined with a simulation model.
  
  
  RESULTS
  We found a high agreement (sensitivity=86.8%, specificity=96.6%) between D50 and the manual score. D50 and MUNE were significantly correlated below 80 MUs (r=0.65, n=68, p<0.001), but not when MUNE was larger than 120 MUs (r=0.23, n=59, p=0.08).
  
  
  CONCLUSIONS
  Discontinuities in the CMAP scan as expressed by a decreased D50 are related to significant MU loss. The determination of D50 is objective, quantitative, and less time-consuming than both manual scoring and many existing MUNE methods.
  
  
  CONCLUSIONS
  D50 is potentially useful to monitor neurogenic disorders and moderate to severe MU loss.
authors.affiliation: Department of Clinical Neurophysiology, Erasmus MC, University Medical Centre Rotterdam, The Netherlands. Electronic address: b.sleutjes@erasmusmc.nl.
authors.forename: B T H M
authors.initials: BT
authors.lastname: Sleutjes
authors.affiliation: Department of Clinical Neurophysiology, Erasmus MC, University Medical Centre Rotterdam, The Netherlands.
authors.forename: I
authors.initials: I
authors.lastname: Montfoort
authors.affiliation: Department of Clinical Neurophysiology, Erasmus MC, University Medical Centre Rotterdam, The Netherlands.
authors.forename: E M
authors.initials: EM
authors.lastname: Maathuis
authors.affiliation: Department of Clinical Neurophysiology, Erasmus MC, University Medical Centre Rotterdam, The Netherlands; Department of Neurology, Erasmus MC, University Medical Centre Rotterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Drenthen
authors.affiliation: Department of Neurology, Erasmus MC, University Medical Centre Rotterdam, The Netherlands.
authors.forename: P A
authors.initials: PA
authors.lastname: van Doorn
authors.affiliation: Department of Clinical Neurophysiology, Erasmus MC, University Medical Centre Rotterdam, The Netherlands; Department of Clinical Neurophysiology, SEIN Heemstede, The Netherlands.
authors.forename: G H
authors.initials: GH
authors.lastname: Visser
authors.affiliation: Department of Clinical Neurophysiology, Erasmus MC, University Medical Centre Rotterdam, The Netherlands; Department of Clinical Physics, Reinier de Graaf Groep Delft, The Netherlands.
authors.forename: J H
authors.initials: JH
authors.lastname: Blok
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D003198:Computer Simulation; D004576:Electromyography / Q000379:methods*; D006801:Humans; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology* / Q000503:physiopathology; D009468:Neuromuscular Diseases / Q000175:diagnosis* / Q000503:physiopathology; D012680:Sensitivity and Specificity
keywords: CMAP scan; Motor unit; Neurogenic disorders; Surface EMG