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Updated: Jan 3, 2026
Electrophysiological Motor Unit Number Estimation MUNE Measuring Compound Muscle Action Potential CMAP in Mouse Hindlimb Muscles
Published on: September 25, 2015
Motor unit number of the first dorsal interosseous muscle estimated from CMAP scan with different pulse widths and
Ya Zong1,2,3, Zhiyuan Lu1, Lining Zhang1,4
1Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, TIRR Memorial Hermann Research Center, Houston, TX, United States of America.
Objective:
A compound muscle action potential (CMAP) scan has different settings such as stimulus frequency, duration (or pulse width), and the number of stimuli (or steps). This study aims to evaluate the influence of different stimulation protocols on MScanFit, a recently developed approach to motor unit number estimation (MUNE) from CMAP scan.
Approach:
CMAP scans of the first dorsal interosseous (FDI) muscle were performed using four protocols with different pulse widths (0.1 ms, 0.2 ms) and steps (500, 1000) in twelve neurologically intact subjects. For each CMAP scan, the MUNE was derived using MScanFit.
Main Results:
Across all subjects, a significantly higher MUNE was obtained using stimulus pulse width of 0.1 ms (500 steps: 107. 7 ± 21.3; 1000 steps: 94.9 ± 22.07) than that using pulse width of 0.2 ms (500 steps: 81.8 ± 9.9; 1000 steps: 77.8 ± 16.1) (p < 0.001). However, no significant difference in MUNE was observed using 500 and 1000 steps (p > 0.1). No cross effect of pulse width and steps was found between four different protocols (p > 0.1).
Significance:
Given these results, a stimulation protocol of 0.1 ms pulse width and 500 steps is recommended for CMAP scan recording of the FDI muscle toward estimating motor unit number using MScanFit.
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