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Updated: May 7, 2026

Simultaneous Intracellular Recording of a Lumbar Motoneuron and the Force Produced by its Motor Unit in the Adult Mouse In vivo
13:07

Simultaneous Intracellular Recording of a Lumbar Motoneuron and the Force Produced by its Motor Unit in the Adult Mouse In vivo

Published on: December 5, 2012

Motor unit potential induced repetitive discharges (MIRDs): description of an unusual iterative discharge

Noel F So1, Devon I Rubin, Lyell K Jones

  • 1Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, Minnesota, USA.

Muscle & Nerve
|September 17, 2013
PubMed
Abstract

Insights

Motor unit potential induced repetitive discharges (MIRDs) are rare, iterative discharges time-locked to voluntary motor unit potentials. Their presence may suggest a chronic neurogenic disorder, though their exact cause remains unclear.

Area of Science:

  • Neurophysiology
  • Clinical Electrophysiology

Background:

  • Repetitive discharges are typically seen during nerve conduction studies or at rest during needle electromyography.
  • Repetitive discharges synchronized with voluntary motor unit potentials (MUPs) during activation have not been previously documented.

Purpose of the Study:

  • To describe motor unit potential induced repetitive discharges (MIRDs), a novel electrophysiological finding.
  • To analyze the characteristics and clinical associations of MIRDs.

Main Methods:

  • Retrospective review of identified MIRDs in an EMG laboratory.
  • Analysis of MIRD characteristics, patient demographics, co-occurring EMG findings, and electrophysiological diagnoses.

Main Results:

  • MIRDs were identified in 15 patients, exhibiting variable morphology, spike counts, and durations.
  • These discharges occurred at frequencies ranging from 50-200 Hz.
  • The majority of patients (13/15) displayed EMG evidence of a chronic neurogenic disorder.

Conclusions:

  • Motor unit potential induced repetitive discharges (MIRDs) are rare, iterative discharges synchronized with voluntary MUPs.
  • The underlying pathophysiology of MIRDs is currently unknown.
  • The presence of MIRDs may serve as an indicator of an underlying chronic neurogenic process.
Keywords:
complex repetitive dischargeelectromyographyiterative dischargemyokymiarepetitive discharge

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