title: Assessing motor deficits in compressive neuropathy using quantitative electromyography.
abstract: BACKGROUND
  Studying the changes that occur in motor unit potential trains (MUPTs) may provide insight into the extent of motor unit loss and neural re-organization resulting from nerve compression injury. The purpose of this study was to determine the feasibility of using decomposition-based quantitative electromyography (DQEMG) to study the pathophysiological changes associated with compression neuropathy.
  
  
  METHODS
  The model used to examine compression neuropathy was carpal tunnel syndrome (CTS) due to its high prevalence and ease of diagnosis. Surface and concentric needle electromyography data were acquired simultaneously from the abductor pollicis brevis muscle in six individuals with severe CTS, eight individuals with mild CTS and nine healthy control subjects. DQEMG was used to detect intramuscular MUPTs during constant-intensity contractions and to estimate parameters associated with the surface- and needle-detected motor unit potentials (SMUPs and MUPs, respectively). MUP morphology and stability, SMUP morphology and motor unit number estimates (MUNEs) were compared among the groups using Kruskal-Wallis tests.
  
  
  RESULTS
  The severe CTS group had larger amplitude and longer duration MUPs and smaller MUNEs than the mild CTS and control groups, suggesting that the individuals with severe CTS had motor unit loss with subsequent collateral reinnervation, and that DQEMG using a constant-intensity protocol was sensitive to these changes. SMUP morphology and MUP complexity and stability did not significantly differ among the groups.
  
  
  CONCLUSIONS
  These results provide evidence that MUP amplitude parameters and MUNEs obtained using DQEMG, may be a valuable tool to investigate pathophysiological changes in muscles affected by compressive motor neuropathy to augment information obtained from nerve conduction studies. Although there were trends in many of these measures, in this study, MUP complexity and stability and SMUP parameters were, of limited value.
authors.affiliation: School of Rehabilitation Therapy, Queen's University, Kingston, Ontario, Canada.
authors.forename: Joseph
authors.initials: J
authors.lastname: Nashed
authors.forename: Andrew
authors.initials: A
authors.lastname: Hamilton-Wright
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Stashuk
authors.forename: Matthew
authors.initials: M
authors.lastname: Faris
authors.forename: Linda
authors.initials: L
authors.lastname: McLean
mesh_terms: D000328:Adult; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis* / Q000503:physiopathology*; D016022:Case-Control Studies; D003627:Data Interpretation, Statistical; D004576:Electromyography / Q000379:methods*; D019054:Evoked Potentials, Motor; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009431:Neural Conduction; D012720:Severity of Illness Index; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors