Sleutjes Boudewijn T H M, Wijngaarde Camiel A, Wadman Renske I, Otto Louise A M, Asselman Fay-Lynn, Cuppen Inge, van den Berg Leonard H, van der Pol W Ludo, Goedee H Stephan
Department of Neurology, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, the Netherlands.
Department of Neurology, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, the Netherlands.
Clin Neurophysiol. 2020 Jun;131(6):1280-1286. doi: 10.1016/j.clinph.2020.01.018. Epub 2020 Feb 13.
To assess motor unit (MU) changes in patients with spinal muscular atrophy (SMA) using compound muscle action potential (CMAP) scans.
We performed CMAP scan recordings in median nerves of 24 treatment-naïve patients (median age 39; range 12-75 years) with SMA types 2-4. From each scan, we determined maximum CMAP amplitude (CMAP), a motor unit number estimate (MUNE), and D50 which quantifies the largest discontinuities within CMAP scans.
Median CMAP was 8.1 mV (range 0.9-14.6 mV), MUNE was 29 (range 6-131), and D50 was 25 (range 2-57). We found a reduced D50 (<25) in patients with normal CMAP (n = 12), indicating MU loss and enlarged MUs due to reinnervation. Lower D50 values were associated with decreased MUNE (P < 0.001, r = 0.68, n = 43). CMAP, MUNE and D50 values differed between SMA types (P < 0.001). Lower motor function scores were related to patients with lower CMAP, MUNE and D50 values (P < 0.001).
The CMAP scan is an easily applicable technique that is superior to routine assessment of CMAP in SMA.
The detection of pathological MU changes across the spectrum of SMA may provide important biomarkers for evaluating disease course and monitoring treatment efficacy.
使用复合肌肉动作电位（CMAP）扫描评估脊髓性肌萎缩症（SMA）患者的运动单位（MU）变化。
我们对24例未经治疗的2 - 4型SMA患者（中位年龄39岁；范围12 - 75岁）的正中神经进行了CMAP扫描记录。从每次扫描中，我们确定了最大CMAP波幅（CMAP）、运动单位数量估计值（MUNE）以及量化CMAP扫描中最大间断点的D50。
CMAP中位数为8.1 mV（范围0.9 - 14.6 mV），MUNE为29（范围6 - 131），D50为25（范围2 - 57）。我们发现CMAP正常的患者（n = 12）中D50降低（<25），表明存在运动单位丢失以及由于神经再支配导致运动单位增大。较低的D50值与MUNE降低相关（P < 0.001，r = 0.68，n = 43）。CMAP、MUNE和D50值在不同SMA类型之间存在差异（P < 0.001）。较低的运动功能评分与CMAP、MUNE和D50值较低的患者相关（P < 0.001）。
CMAP扫描是一种易于应用的技术，在SMA中优于常规的CMAP评估。
检测SMA全谱中的病理性运动单位变化可能为评估疾病进程和监测治疗效果提供重要的生物标志物。
