TY - JOUR
T1 - Impact of stimulus duration on motor unit thresholds and alternation in compound muscle action potential scans
AU - Sleutjes, Boudewijn T.h.m.
AU - Ruisch, Janna
AU - Nassi, Thijs E.
AU - Buitenweg, Jan R.
AU - Van Schelven, Leonard J.
AU - Van Den Berg, Leonard H.
AU - Franssen, Hessel
AU - Stephan Goedee, H.
N1 - Elsevier deal
PY - 2021/2/1
Y1 - 2021/2/1
N2 - Objective: To investigate the impact of stimulus duration on motor unit (MU) thresholds and alternation within compound muscle action potential (CMAP) scans. Methods: The stimulus duration (0.1, 0.2, 0.6, and 1.0 ms) in thenar CMAP scans and individual MUs of 14 healthy subjects was systematically varied. We quantified variability of individual MU's thresholds by relative spread (RS), MU thresholds by stimulus currents required to elicit target CMAPs of 5% (S5), 50% (S50) and 95% (S95) of the maximum CMAP, and relative range (RR) by 100*[S95-S5]/S50. We further assessed the strength-duration time constant (SDTC). Experimental observations were subsequently simulated to quantify alternation. Results: RS, unaffected by stimulus duration, was 1.65% averaged over all recordings. RR increased for longer stimulus duration (11.4% per ms, p < 0.001). SDTC shortened with higher target CMAPs (0.007 ms per 10% CMAP, p < 0.001). Experiments and simulations supported that this may underlie the increased RR. A short compared to long stimulus duration recruited relative more MUs at S50 (more alternation) than at the tails (less alternation). Conclusions: The stimulus duration significantly affects MU threshold distribution and alternation within CMAP scans. Significance: Stimulation settings can be further optimized and their standardization is preferred when using CMAP scans for monitoring neuromuscular diseases.
AB - Objective: To investigate the impact of stimulus duration on motor unit (MU) thresholds and alternation within compound muscle action potential (CMAP) scans. Methods: The stimulus duration (0.1, 0.2, 0.6, and 1.0 ms) in thenar CMAP scans and individual MUs of 14 healthy subjects was systematically varied. We quantified variability of individual MU's thresholds by relative spread (RS), MU thresholds by stimulus currents required to elicit target CMAPs of 5% (S5), 50% (S50) and 95% (S95) of the maximum CMAP, and relative range (RR) by 100*[S95-S5]/S50. We further assessed the strength-duration time constant (SDTC). Experimental observations were subsequently simulated to quantify alternation. Results: RS, unaffected by stimulus duration, was 1.65% averaged over all recordings. RR increased for longer stimulus duration (11.4% per ms, p < 0.001). SDTC shortened with higher target CMAPs (0.007 ms per 10% CMAP, p < 0.001). Experiments and simulations supported that this may underlie the increased RR. A short compared to long stimulus duration recruited relative more MUs at S50 (more alternation) than at the tails (less alternation). Conclusions: The stimulus duration significantly affects MU threshold distribution and alternation within CMAP scans. Significance: Stimulation settings can be further optimized and their standardization is preferred when using CMAP scans for monitoring neuromuscular diseases.
KW - UT-Hybrid-D
U2 - 10.1016/j.clinph.2020.10.026
DO - 10.1016/j.clinph.2020.10.026
M3 - Article
SN - 1388-2457
VL - 132
SP - 323
EP - 331
JO - Clinical neurophysiology
JF - Clinical neurophysiology
IS - 2
ER -