Kanai Kazuaki, Shibuya Kazumoto, Kuwabara Satoshi
Department of Neurology, Graduate School of Medicine, Chiba University.
Rinsho Shinkeigaku. 2011 Nov;51(11):1118-9. doi: 10.5692/clinicalneurol.51.1118.
Fasciculation is a characteristic feature of ALS. Nerve excitability studies have shown increased persistent sodium currents and reduced potassium currents in motor axons of ALS patients, both of which lead to axonal hyperexcitability and thereby generation of fasciculations. The present study was undertaken to investigate whether abnormal axonal excitability indices are correlated with survival in ALS patients. A total of 112 consecutive patients with sporadic ALS were followed-up until endpoint (death or tracheostomy). Univariate analyses revealed longer strength-duration time constant (SDTC) was associated with a shorter survival. In multivariate analyses using the Cox proportional hazard model, onset age>60 years and longer SDTC were strong predictors of shorter survival. Assuming that SDTC depends on nodal persistent sodium conductances, our results showed that an increased persistent sodium current is strong and independent predictor for short survival of ALS patients. These findings support the hypothesis that membrane hyperexcitability would contribute to motor neuronal death in ALS.
肌束震颤是肌萎缩侧索硬化症（ALS）的一个特征性表现。神经兴奋性研究表明，ALS患者运动轴突中的持续钠电流增加，钾电流减少，这两者都会导致轴突兴奋性过高，从而产生肌束震颤。本研究旨在调查异常的轴突兴奋性指标是否与ALS患者的生存率相关。总共112例连续性散发性ALS患者被随访至终点（死亡或气管切开）。单因素分析显示，较长的强度-时间常数（SDTC）与较短的生存期相关。在使用Cox比例风险模型的多因素分析中，发病年龄>60岁和较长的SDTC是生存期较短的有力预测因素。假设SDTC取决于节点持续钠电导，我们的结果表明，持续钠电流增加是ALS患者生存期短的有力且独立的预测因素。这些发现支持了膜兴奋性过高会导致ALS患者运动神经元死亡的假说。
