Distal excitability changes in motor axons in amyotrophic lateral sclerosis
Distal excitability changes in motor axons in amyotrophic lateral sclerosis
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DOI：
10.1016/j.clinph.2006.04.005
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发表时间：
2006-07-01
影响因子：
4.7
通讯作者：
Bostock, Hugh
中科院分区：
文献类型：
--
作者：
Nakata, Miho;Kuwabara, Satoshi;Bostock, Hugh
目的：以往对肌萎缩侧索硬化症(ALS)轴突兴奋性的研究表明，钾通道功能受损可能是肌束形成的原因，但异位活动主要来自运动神经末梢。本研究验证了钾通道功能障碍在轴突远端更为明显的假说。方法：采用阈值电紧张仪比较22例ALS患者和19例正常人拇短展肌运动点和正中神经腕部的调节能力。结果：与正常人相比，ALS患者对运动点和腕部去极化条件电流的阈值变化较大，提示钾电流的调节作用较弱。结论：ALS患者轴突远端的轴索钾通道受损较神经干明显，这与神经束主要来自神经末梢的证据一致。意义：运动点的兴奋性测试为ALS的病理生理学提供了补充信息。(C)2006年国际临床神经生理学联合会。爱思唯尔爱尔兰有限公司出版。版权所有。
Objective: Previous axonal excitability studies in amyotrophic lateral sclerosis (ALS) have suggested that impaired potassium channel function could be responsible for the generation of fasciculations, but the ectopic activity arises predominantly from the motor nerve terminals. This study tested the hypothesis that dysfunction of potassium channels is more pronounced in the more distal parts of axons.Methods: Threshold electrotonus was used to compare accommodation at the motor point of abductor pollicis brevis, and at the wrist portion of the median nerve, between 22 patients with ALS and 19 normal subjects. As target responses for motor point stimulation, movement-related potentials were recorded using an accelerometer.Results: Compared to normal subjects, ALS patients showed greater threshold changes to depolarizing conditioning currents at both the motor point and wrist, suggesting less accommodation by potassium currents. Differences in the threshold electrotonus curves between the normal and ALS groups were much more prominent at the motor point than at the wrist.Conclusions: In ALS, axonal potassium channels are impaired more prominently in distal portions of axons than at the nerve trunk, and this is consistent with evidence that fasciculations mostly arise from the nerve terminals.Significance: Excitability testing at the motor point provides additional information about the pathophysiology of ALS. (c) 2006 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.