Sleutjes Boudewijn T H M, Ruisch Janna, Nassi Thijs E, Buitenweg Jan R, van Schelven Leonard J, van den Berg Leonard H, Franssen Hessel, Stephan Goedee H
Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, the Netherlands.
Biomedical Signals and Systems, Technical Medical Centre, University of Twente, Enschede, the Netherlands.
Clin Neurophysiol. 2021 Feb;132(2):323-331. doi: 10.1016/j.clinph.2020.10.026. Epub 2020 Dec 2.
To investigate the impact of stimulus duration on motor unit (MU) thresholds and alternation within compound muscle action potential (CMAP) scans.
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.
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).
The stimulus duration significantly affects MU threshold distribution and alternation within CMAP scans.
Stimulation settings can be further optimized and their standardization is preferred when using CMAP scans for monitoring neuromuscular diseases.
研究刺激持续时间对复合肌肉动作电位（CMAP）扫描中运动单位（MU）阈值及交替现象的影响。
系统改变14名健康受试者小鱼际肌CMAP扫描及单个运动单位的刺激持续时间（0.1、0.2、0.6和1.0毫秒）。我们通过相对离散度（RS）量化单个运动单位阈值的变异性，通过引发最大CMAP的5%（S5）、50%（S50）和95%（S95）的目标CMAP所需的刺激电流来确定运动单位阈值，并通过100×[S95 - S5]/S50计算相对范围（RR）。我们还进一步评估了强度 - 持续时间时间常数（SDTC）。随后对实验观察结果进行模拟以量化交替现象。
RS不受刺激持续时间影响，所有记录的平均RS为1.65%。RR随刺激持续时间延长而增加（每毫秒增加11.4%，p < 0.001）。SDTC随目标CMAP升高而缩短（每10% CMAP缩短0.007毫秒，p < 0.001）。实验和模拟结果支持这可能是RR增加的原因。与长刺激持续时间相比，短刺激持续时间在S50时相对募集更多运动单位（交替更多），而在两端（交替更少）。
刺激持续时间显著影响CMAP扫描中运动单位阈值分布及交替现象。
在使用CMAP扫描监测神经肌肉疾病时，刺激设置可进一步优化，且标准化更佳。
