Ridding M C, Sheean G, Rothwell J C, Inzelberg R, Kujirai T
MRC Human Movement and Balance Unit, Institute of Neurology, London, UK.
J Neurol Neurosurg Psychiatry. 1995 Nov;59(5):493-8. doi: 10.1136/jnnp.59.5.493.
Transcranial magnetic stimulation has been used in a double pulse paradigm to investigate the excitability of intrinsic motor cortical circuits in 15 patients with focal task specific dystonia of the right hand and a group of eight age matched controls. The left hemisphere was examined in five patients; in the remainder, both hemispheres were tested. There was no significant difference in stimulation threshold between patients and controls nor between the left and right hemispheres in the patients. There was a significant decrease in early corticocortical suppression when comparing stimulation of the left hemisphere in the patients and controls at interstimulus intervals of 1-15 ms (P < 0.01). There was no difference in the amount of suppression in the right and left hemispheres of the patients. It is concluded that in focal task specific dystonia there is shift in the balance between excitation and inhibition in local circuits of the motor cortex which leads to a net decrease in the amount of short latency suppression. These changes reflect disturbed basal ganglia input to the motor cortex. Reduced excitability of cortical inhibitory circuits may be one factor which contributes to the excessive and inappropriate muscle contraction which occurs during fine motor tasks in patients with focal dystonia.
经颅磁刺激已被用于双脉冲范式，以研究15例右手局灶性任务特异性肌张力障碍患者和一组8名年龄匹配的对照组的固有运动皮质回路的兴奋性。对5例患者的左半球进行了检查；其余患者双侧半球均进行了测试。患者与对照组之间以及患者的左右半球之间，刺激阈值均无显著差异。当在1-15毫秒的刺激间隔比较患者和对照组左半球的刺激时，早期皮质皮质抑制有显著降低（P<0.01）。患者左右半球的抑制量没有差异。结论是，在局灶性任务特异性肌张力障碍中，运动皮质局部回路中兴奋与抑制之间的平衡发生了改变，导致短潜伏期抑制量的净减少。这些变化反映了基底神经节对运动皮质的输入紊乱。皮质抑制回路兴奋性降低可能是导致局灶性肌张力障碍患者在精细运动任务中出现过度和不适当肌肉收缩的一个因素。
