title: Length dependent loss of motor axons and altered motor unit properties in human diabetic polyneuropathy.
abstract: OBJECTIVE
  To assess the number and properties of motor units in an upper and lower limb muscle (tibialis anterior [TA] and first dorsal interosseous [FDI]) in human diabetic polyneuropathy (DPN) using decomposition-based quantitative electromyography (DQEMG).
  
  
  METHODS
  DQEMG protocols were performed in the TA and FDI of 12 patients with confirmed diabetes mellitus and associated DPN, as well as 12 age-matched control participants. Maximal dorsiflexion strength was also assessed using a dynamometer.
  
  
  RESULTS
  In both muscles, patients with DPN had significantly reduced motor unit number estimates (MUNEs) (ΔTA ∼45%; ΔFDI ∼30%), compound muscle action potentials (CMAPs) (ΔTA ∼30%; ΔFDI ∼20%), and mean firing rates were reduced (ΔTA ∼15%; ΔFDI ∼15%) compared to controls (p<0.05). For the TA, patients with DPN had larger mean surface motor unit potentials (SMUPs) (ΔTA ∼40%; p<0.05), whereas in the FDI no differences were found (p>0.05).
  
  
  CONCLUSIONS
  DPN may result in motor unit loss, remodeling, and altered firing rate patterns. The magnitude of changes in the neuromuscular properties of DPN patients are muscle dependent and reflect a length-dependent disease progression.
  
  
  CONCLUSIONS
  DQEMG may be a clinically useful technique in identifying the presence and severity of neuromuscular pathophysiology and tracking disease progression in DPN.
authors.affiliation: School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada. Electronic address: mallen9@uwo.ca.
authors.forename: Matti D
authors.initials: MD
authors.lastname: Allen
authors.affiliation: Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada.
authors.forename: Kurt
authors.initials: K
authors.lastname: Kimpinski
authors.affiliation: School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada; Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada; Department of Physical Medicine and Rehabilitation, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Doherty
authors.affiliation: School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Rice
mesh_terms: D000328:Adult; D000368:Aged; D001369:Axons / Q000473:pathology* / Q000502:physiology; D003929:Diabetic Neuropathies / Q000473:pathology* / Q000503:physiopathology; D018450:Disease Progression; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000473:pathology* / Q000502:physiology; D018482:Muscle, Skeletal / Q000473:pathology* / Q000502:physiology
keywords: Diabetes mellitus; Diabetic neuropathy; Motor neuron; Motor unit; Weakness