Abstract：
OBJECTIVE: Strength-duration time constant (SDTC) may now be determined for cortical motor neurones, with activity mediated by transient Na+ conductances. The present study determined whether cortical SDTC is abnormal and linked to the pathogenesis of amyotrophic lateral sclerosis.
METHODS: Cortical SDTC and rheobase were estimated from 17 ALS patients using a controllable pulse parameter transcranial magnetic stimulation (cTMS) device. Resting motor thresholds (RMTs) were determined at pulse widths (PW) of 30, 45, 60, 90 and 120 µs and M-ratio of 0.1, using a figure-of-eight coil applied to the primary motor cortex.
RESULTS: SDTC was significantly reduced in ALS patients (150.58 ± 9.98 µs; controls 205.94 ± 13.7 µs, P < 0.01). The reduced SDTC correlated with a rate of disease progression (Rho = -0.440, P < 0.05), ALS functional rating score (ALSFRS-R) score (Rho = 0.446, P < 0.05), and disease duration (R = 0.428, P < 0.05). The degree of change in SDTC was greater in patients with cognitive abnormalities as manifested by an abnormal total Edinburgh Cognitive ALS Screen score (140.5 ± 28.7 µs, P < 0.001) and ALS-specific subscore (141.7 ± 33.2 µs, P = 0.003).
CONCLUSIONS: Cortical SDTC reduction was associated with a more aggressive ALS phenotype, or with more prominent cognitive impairment.
CONCLUSIONS: An increase in transient Na+ conductances may account for the reduction in SDTC, linked to the pathogenesis of ALS.
METHODS: Cortical SDTC and rheobase were estimated from 17 ALS patients using a controllable pulse parameter transcranial magnetic stimulation (cTMS) device. Resting motor thresholds (RMTs) were determined at pulse widths (PW) of 30, 45, 60, 90 and 120 µs and M-ratio of 0.1, using a figure-of-eight coil applied to the primary motor cortex.
RESULTS: SDTC was significantly reduced in ALS patients (150.58 ± 9.98 µs; controls 205.94 ± 13.7 µs, P < 0.01). The reduced SDTC correlated with a rate of disease progression (Rho = -0.440, P < 0.05), ALS functional rating score (ALSFRS-R) score (Rho = 0.446, P < 0.05), and disease duration (R = 0.428, P < 0.05). The degree of change in SDTC was greater in patients with cognitive abnormalities as manifested by an abnormal total Edinburgh Cognitive ALS Screen score (140.5 ± 28.7 µs, P < 0.001) and ALS-specific subscore (141.7 ± 33.2 µs, P = 0.003).
CONCLUSIONS: Cortical SDTC reduction was associated with a more aggressive ALS phenotype, or with more prominent cognitive impairment.
CONCLUSIONS: An increase in transient Na+ conductances may account for the reduction in SDTC, linked to the pathogenesis of ALS.
摘要：
目的：现在可以确定皮质运动神经元的强度持续时间常数（SDTC），具有由瞬时Na电导介导的活性。本研究确定皮质SDTC是否异常，并与肌萎缩侧索硬化症的发病机理有关。
方法：使用可控的脉冲参数经颅磁刺激（cTMS）装置从17名ALS患者中估算皮质SDTC和流变酶。在30、45、60、90和120µs的脉冲宽度（PW）和0.1的M比率下，使用应用于初级运动皮层的8字形线圈确定静息运动阈值（RMT）。
结果：ALS患者的SDTC显着降低（150.58±9.98µs；对照组205.94±13.7µs，P<0.01)。SDTC降低与疾病进展率相关(Rho=-0.440,P<0.05),ALS功能评分(ALSFRS-R)评分(Rho=0.446,P<0.05),病程(R=0.428,P<0.05)。在患有认知异常的患者中，SDTC的变化程度更大，表现为总爱丁堡认知ALSScreen评分异常（140.5±28.7µs，P<0.001）和ALS特异性子评分（141.7±33.2µs，P=0.003)。
结论：皮质SDTC降低与更具侵袭性的ALS表型相关，或更明显的认知障碍。
结论：瞬时Na+电导的增加可能是SDTC降低的原因，与ALS的发病机制有关。
方法：使用可控的脉冲参数经颅磁刺激（cTMS）装置从17名ALS患者中估算皮质SDTC和流变酶。在30、45、60、90和120µs的脉冲宽度（PW）和0.1的M比率下，使用应用于初级运动皮层的8字形线圈确定静息运动阈值（RMT）。
结果：ALS患者的SDTC显着降低（150.58±9.98µs；对照组205.94±13.7µs，P<0.01)。SDTC降低与疾病进展率相关(Rho=-0.440,P<0.05),ALS功能评分(ALSFRS-R)评分(Rho=0.446,P<0.05),病程(R=0.428,P<0.05)。在患有认知异常的患者中，SDTC的变化程度更大，表现为总爱丁堡认知ALSScreen评分异常（140.5±28.7µs，P<0.001）和ALS特异性子评分（141.7±33.2µs，P=0.003)。
结论：皮质SDTC降低与更具侵袭性的ALS表型相关，或更明显的认知障碍。
结论：瞬时Na+电导的增加可能是SDTC降低的原因，与ALS的发病机制有关。
