Simulation and analysis of the electromyographic interference pattern in normal muscle. Part II: Activity, upper centile amplitude, and number of small segments.

Journal Article

We have defined three new features of the electromyographic (EMG) interference pattern (IP): activity, upper centile amplitude (UCA), and number of small segments (NSS). These parameters were measured in simulated IPs constructed by adding together motor unit action potentials (MUAPs) recorded with a concentric needle EMG electrode. The activity increases linearly with the number of MUAP discharges to approximately 80% of its theoretical maximum value. The UCA correlates strongly with the peak-to-peak amplitude of the largest MUAP in the IP and the mean segment amplitude and does not depend on the discharge rate of the largest MUAPs. We infer that the UCA defines the upper limit of the peak-to-peak amplitude of the MUAPs contained in the IP. The NSS increases with the number of MUAP discharges, but reaches a constant value at higher MUAP discharge rates, probably because small amplitude MUAPs are masked by the large amplitude MUAPs. The potential value of these parameters in automated IP analysis is discussed.

Full Text

Duke Authors

Cited Authors

  • Nandedkar, SD; Sanders, DB; Stålberg, EV

Published Date

  • July 1, 1986

Published In

Volume / Issue

  • 9 / 6

Start / End Page

  • 486 - 490

PubMed ID

  • 3736582

International Standard Serial Number (ISSN)

  • 0148-639X

Digital Object Identifier (DOI)

  • 10.1002/mus.880090603

Language

  • eng

Conference Location

  • United States