Single muscle fiber discharges (Insertional activity, end-plate potentials, positive sharp waves, and fibrillation potentials): A unifying proposal

Daniel Dumitru

Research output: Contribution to journalReview articlepeer-review

20 Scopus citations

Abstract

The exact origin and precise morphologic explanation of positive sharp waves (PSWs) are presently lacking. Observing normal needle electromyographic insertional activity reveals two types of waveforms: (1) biphasic negative/positive spikes, and (2) positive spikes followed by a small negative phase. In the end-plate region, it is possible to occasionally observe a biphasic end-plate spike transform into a monophasic positive end-plate waveform. It is postulated that this waveform is simply a form of intracellular recording for the biphasic end-plate spike or a form of extracellularly recorded but blocked single muscle fiber discharge. Similarly, the observed monophasic positive insertional activity may be an intracellularly recorded single muscle fiber discharge or a blocked extracellular discharge originating about the needle electrode. Applying this reasoning to PSWs suggests that they may also be an intracellular recording of a fibrillation potential, or needle-induced extracellular blocked local single muscle fiber discharge. This unifying concept is applied to various clinical situations purported to demonstrate "different" types of PSWs.

Original languageEnglish (US)
Pages (from-to)221-226
Number of pages6
JournalMuscle and Nerve
Volume19
Issue number2
StatePublished - Feb 1 1996

Keywords

  • Fibrillation potentials
  • Insertional activity
  • Intracellular recordings
  • Positive sharp waves
  • Single muscle fiber discharge

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)

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