Difference in intracortical inhibition of the motor cortex between cortical myoclonus and focal hand dystonia
Difference in intracortical inhibition of the motor cortex between cortical myoclonus and focal hand dystonia
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DOI：
10.1016/j.clinph.2008.02.009
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发表时间：
2008-06-01
影响因子：
4.7
通讯作者：
Ugawa, Y.
中科院分区：
文献类型：
--
作者：
Hanajima, R.;Okabe, S.;Ugawa, Y.
目的：在皮质性肌阵挛和局灶性手肌张力障碍中，运动皮质（M1）的短时间期皮质内抑制（SICI）降低。这种减少归因于运动皮质内gaba能系统的功能障碍。然而，在这两种疾病中，减少的确切机制可能并不完全相同，可能是由于M1的原发病理参与或继发于M1以外的功能改变。本研究的目的是阐明这两种疾病在皮质内抑制方面可能存在的差异。方法：选取良性肌阵挛性癫痫11例，局灶性手肌张力障碍7例，正常人11例。我们使用脑前-后（AP）定向和后-前（PA）定向诱导电流研究SICI。结果：在这两种疾病中，与先前报道的一样，pa定向电流降低了SICI。相比之下，在局灶性手肌张力障碍患者中，AP电流研究的SICI是正常的，但在皮质肌阵挛患者中则有所降低。结论：两种疾病的差异可能反映了潜在的病理差异。在皮质肌阵挛中，运动皮层的抑制性中间神经元受到影响，而在肌张力障碍中，相同的中间神经元是完整的。在肌张力障碍中，AP和PA定向电流引起的SICI的差异可能由以下可能性来解释：促进肌电图产生的i波组成的差异以及通过自主收缩调节神经元间活动的差异。这些变化可能继发于肌张力障碍中基底神经节或相关皮层对运动皮质的失调。意义：使用AP定向电流的SICI与使用PA定向电流的传统SICI能够显示肌阵挛和局灶性手肌张力障碍之间M1的内在电路存在一定差异。与先前报道的方法相比，使用AP定向电流的SICI可以提供关于运动皮层兴奋性变化的额外信息。(c) 2008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: The short interval intracortical inhibition (SICI) of the motor cortex (M1) is reduced in both cortical myoclonus and focal hand dystonia. This reduction has been attributed to the dysfunction of GABAergic system within the motor cortex. However, the precise mechanisms underlying the reduction may not be entirely identical in these two disorders, being due to primary pathological involvement in M1 or secondary to functional changes outside M1. The aim of this study was to elucidate possible differences in intracortical inhibition between these two disorders.Methods: Subjects were 11 patients with benign myoclonus epilepsy, 7 with focal hand dystonia, and 11 normal volunteers. We studied SICI using anterior-posterior (AP) directed and posterior-anterior (PA) directed induced currents in the brain.Results: In both disorders, SICI with PA-directed currents was reduced as reported previously. In contrast, SICI studied with AP currents was normal in patients with focal hand dystonia, but reduced in patients with cortical myoclonus.Conclusions: The difference between the two disorders might reflect the underlying pathological difference. In cortical myoclonus, the inhibitory interneurons of the motor cortex are affected, whereas the same interneurons are intact in dystonia. The difference in SICI induced by AP and PA directed currents in dystonia may be explained by the following possibilities: the difference in composition of I-waves contributing to EMG generation and the difference in modulation of the interneuronal activity by voluntary contraction. These changes may be secondary to dysregulation of the motor cortex by the basal ganglia or related cortices in dystonia.Significance: The SICI using AP directed currents together with the conventional SICI using PA directed currents was able to demonstrate some difference in the intrinsic circuits of M1 between myoclonus and focal hand dystonia. SICI using AP directed currents can provide additional information about the motor cortical excitability changes over those obtained by the previously reported methods. (c) 2008 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.