Issues & opinions: Single muscle fiber discharges (insertional activity, end-plate potentials, positive sharp waves, and fibrillation potentials): A unifying proposal
✍ Scribed by Daniel Dumitru
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 576 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0148-639X
No coin nor oath required. For personal study only.
✦ Synopsis
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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