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Keywords:

  • Decomposition-based quantitative electromyography (DQEMG);
  • decomposition-enhanced spike-triggered averaging (DE-STA);
  • motor unit number estimation (MUNE);
  • trapezius muscle;
  • needle electrode depth

ABSTRACT

Introduction: To assess a potential source of technique-associated error, we evaluated the influence of needle electrode depth on decomposition-enhanced spike-triggered averaging (DE-STA) motor unit number estimation (MUNE) and quantitative motor unit analysis in the upper trapezius (UT). Methods: The DE-STA MUNE protocol was performed at superficial, intermediate, and deep needle electrode depths in 18 control subjects. Results: Mean surface-detected motor unit potential amplitudes were significantly smaller for intermediate versus superficial (P < 0.05), deep versus superficial (P < 0.001), and deep versus intermediate (P < 0.05). MUNE was significantly larger for deep versus superficial (P < 0.001), with statistical trends toward larger MUNE values at greater depths for the remaining comparisons. No significant differences were found among needle electrode depths for quantitative motor unit potential parameters. Conclusions: These results demonstrate the important influence of needle electrode depth on DE-STA MUNE in the UT. Suggestions are made for improved standardization of the protocol. Muscle Nerve 50: 587–592, 2014