Neuromuscular remodeling and neuromuscular junction instability in human diabetic neuropathy (1168.1)

Diabetic polyneuropathy (DPN) is a progressive axonopathy marked by loss of motor fibers, compensatory collateral reinnervation and reduced stability of neuromuscular transmission. Our objective was to assess the degree of reinnervation and motor unit instability in patients with DPN using decomposition‐based quantitative electromyography (DQEMG). Additionally, relationships between motor unit stability and muscle function were examined. The tibialis anterior (TA) muscle was tested in twelve patients with DPN (65 ± 15 yrs) and 12 age‐matched controls (63 ± 15 yrs). DQEMG was used to analyze surface and intramuscular EMG signals recorded from the TA during moderate voluntary dorsiflexion contractions. Individual motor unit action potential (MUP) trains were identified and analyzed for: MUP size (peak to peak amplitude, area), complexity (turns, fiber dispersion) and stability (near fiber jiggle). DPN patients featured larger (+45% MUP area), more complex (+40% fiber dispersion), and less stable (+30% near fiber jiggle) MUPs (p<0.05). No significant relationships were found between MUP stability and muscular denervation, or strength. MUP complexity and instability were positively related in DPN patients (r=0.46; p<0.05) and controls (r=0.37; p<0.05). DPN is associated with neuromuscular remodeling which leads to increasingly impaired neuromuscular transmission that is detectable using DQEMG. Grant Funding Source : NSERC