Cappelen-Smith C, Kuwabara S, Lin C S, Mogyoros I, Burke D
Institute of Neurological Sciences, The Prince of Wales Hospital and Prince of Wales Medical Research Institute, University of South Wales, Sydney, Australia.
Ann Neurol. 2000 Dec;48(6):826-32.
Voluntary activity produces activity-dependent hyperpolarization of the active motor axons. The present study investigated whether this hyperpolarization produces conduction block in chronic inflammatory demyelinating polyneuropathy (CIDP). Studies were performed in 10 healthy control subjects, 7 patients with CIDP, and 3 patients with multifocal motor neuropathy. The compound muscle action potential (CMAP) of the abductor pollicis brevis was recorded in response to supramaximal stimuli to the median nerve at the wrist, alternating with measurements of axonal excitability. After a maximal voluntary contraction for 60 seconds, the amplitude of the maximal CMAP was significantly reduced in symptomatic CIDP patients by 40%, but there were only slight changes in the CMAPs of healthy controls, asymptomatic CIDP patients, and multifocal motor neuropathy patients. In symptomatic CIDP patients, the activity-dependent conduction block paralleled the activity-dependent hyperpolarization and was presumably precipitated by it. In these patients, the safety margin for impulse conduction was estimated to be about 12%. Activity-dependent conduction block may be clinically important in chronic demyelinating diseases and can be demonstrated electrophysiologically if testing occurs across pathological sites.
随意活动会使活跃的运动轴突产生活动依赖性超极化。本研究调查了这种超极化在慢性炎症性脱髓鞘性多发性神经病（CIDP）中是否会导致传导阻滞。对10名健康对照者、7名CIDP患者和3名多灶性运动神经病患者进行了研究。在腕部对正中神经进行超强刺激时，记录拇短展肌的复合肌肉动作电位（CMAP），并交替测量轴突兴奋性。在进行60秒的最大随意收缩后，有症状的CIDP患者最大CMAP的波幅显著降低了40%，但健康对照者、无症状CIDP患者和多灶性运动神经病患者的CMAP仅有轻微变化。在有症状的CIDP患者中，活动依赖性传导阻滞与活动依赖性超极化平行，推测是由其引发的。在这些患者中，冲动传导的安全裕度估计约为12%。活动依赖性传导阻滞在慢性脱髓鞘疾病中可能具有临床重要性，并且如果在病理部位进行检测，可以通过电生理方法予以证实。
