Chuang Wen-Li, Huang Ying-Zu, Lu Chin-Song, Chen Rou-Shayn
Movement Disorder Section, Department of Neurology, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan; Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan.
Mov Disord. 2014 Apr;29(4):501-7. doi: 10.1002/mds.25809. Epub 2014 Jan 21.
Essential tremor (ET) is the most common movement disorder among adults. Cerebellar dysfunction is thought to be involved in the pathogenesis of ET; however, imaging, electrophysiological studies, and clinical observations have suggested that the cerebral cortex also may participate. We sought to investigate the possible motor cortical contribution to ET by assessing response to continuous theta-burst stimulation (cTBS), a recognized tool that can produce transient plastic changes, in the primary motor and premotor cortex of patients with ET. We compared parameters, including motor-evoked potential amplitude, cortical silent period, and short-interval intracortical inhibition, before and after applying cTBS in healthy controls and patients with ET. We found that, although cTBS applied to either the motor or premotor cortex was capable of producing a suppressive effect on motor cortical excitability in ET patients, the effects lasted for a significantly shorter time compared with the effect produced in healthy individuals. The change seen in measures of intracortical inhibition after motor cortical or premotor cTBS in healthy controls was reduced or absent in the ET patients. Tremor amplitude was decreased significantly after applying cTBS over either the motor or premotor cortex, but the tremor frequency remained unchanged. These findings suggest that inhibitory circuits within the motor cortex are aberrant and less modifiable in ET patients. The reduced plasticity in response to motor and premotor TBS supports the theory of abnormal gamma-aminobutyric acid (GABA) modulation in ET.
特发性震颤（ET）是成年人中最常见的运动障碍。小脑功能障碍被认为参与了ET的发病机制；然而，影像学、电生理研究及临床观察表明大脑皮层也可能参与其中。我们试图通过评估ET患者初级运动皮层和运动前区皮层对连续theta爆发刺激（cTBS）（一种可产生短暂可塑性变化的公认工具）的反应，来研究运动皮层对ET可能的贡献。我们比较了在健康对照者和ET患者中应用cTBS前后的参数，包括运动诱发电位幅度、皮层静息期和短间隔皮层内抑制。我们发现，尽管将cTBS应用于运动皮层或运动前区皮层均能对ET患者的运动皮层兴奋性产生抑制作用，但与健康个体相比，这种作用持续的时间明显更短。健康对照者在运动皮层或运动前区cTBS后皮层内抑制测量值的变化在ET患者中减少或不存在。在运动皮层或运动前区皮层应用cTBS后，震颤幅度显著降低，但震颤频率保持不变。这些发现表明，ET患者运动皮层内的抑制性回路异常且可塑性较低。对运动和运动前区TBS反应的可塑性降低支持了ET中γ-氨基丁酸（GABA）调节异常的理论。
