Effect of small motor unit potentials on the motor unit number estimate

J.P. Dijk, M.J. Zwarts, H.J. Schelhaas, D.F. Stegeman

    Research output: Contribution to JournalArticleAcademicpeer-review


    Small surface motor unit potentials (S-MUPs) may have a negative influence on the variability of the motor unit number estimate (MUNE). According to published consensus criteria S-MUPs with a negative peak amplitude smaller than 10 μV should be omitted. The effect of omitting small S-MUPs on the MUNE was evaluated using a simulation model. The model incorporated a healthy and amyotrophic lateral sclerosis (ALS) distribution formed with real S-MUPs. Using a random drawing process the MUNE was calculated with and without small S-MUPs. In the healthy population 27% of all S-MUPs were small. MUNE determined without these S-MUPs was marginally less variable. However, MUNE values dropped about 24% at a sample size of 20. In ALS, only 12% of the total population of 130 S-MUPs were small. MUNE dropped about 12% without the small S-MUPs. By omitting small S-MUPs the differences between the healthy and ALS distributions become smaller. Therefore, incorporating small S-MUPs in the estimate is suggested. © 2008 Wiley Periodicals, Inc.
    Original languageEnglish
    Pages (from-to)887-892
    JournalMuscle and Nerve
    Issue number1
    Publication statusPublished - 2008


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