Influence of needle electrode depth on DE-STA motor unit number estimation

Authors

  • Colleen T. Ives PhD,

    1. Department of Clinical Neurological Sciences, Western University, London, Ontario, Canada
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  • Timothy J. Doherty MD, PhD

    Corresponding author
    1. Department of Clinical Neurological Sciences, Western University, London, Ontario, Canada
    2. Department of Physical Medicine and Rehabilitation, Western University, London, Ontario, Canada
    • Correspondence to: T.J. Doherty, University Hospital, London Health Sciences Centre, 339 Windermere Road, London, Ontario, Canada N6A 5A5; e-mail: tim.doherty@lhsc.on.ca

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  • Supported in part by an NSERC Canada Graduate Scholarship and a Queen Elizabeth II Graduate Scholarship in Science and Technology

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

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