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Issues & opinions: Single muscle fiber discharges (insertional activity, end‐plate potentials, positive sharp waves, and fibrillation potentials): A unifying proposal
Author(s) -
Dumitru Daniel
Publication year - 1996
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(199602)19:2<221::aid-mus15>3.0.co;2-x
Subject(s) - intracellular , waveform , extracellular , muscle fibre , fiber , electrophysiology , fibrillation , electrode , chemistry , biophysics , neuroscience , spike potential , traveling wave , biomedical engineering , anatomy , voltage , physics , medicine , biology , skeletal muscle , mathematics , biochemistry , atrial fibrillation , mathematical analysis , quantum mechanics , organic chemistry , depolarization
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. © 1996 John Wiley & Sons, Inc.