Inhibition versus facilitation of contralesional motor cortices in stroke: Deriving a model to tailor brain stimulation.
Inhibition versus facilitation of contralesional motor cortices in stroke: Deriving a model to tailor brain stimulation.
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DOI：
10.1016/j.clinph.2017.03.030
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发表时间：
2017-06
期刊：
影响因子：
--
通讯作者：
Plow EB
中科院分区：
文献类型：
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作者：
Sankarasubramanian V;Machado AG;Conforto AB;Potter-Baker KA;Cunningham DA;Varnerin NM;Wang X;Sakaie K;Plow EB
卒中脑刺激的标准方法是基于同侧M1 （iM1）对麻痹上肢的运动功能很重要的前提，而对侧皮层与iM1竞争。因此，该方法通常提倡促进iM1和/或抑制对侧M1 （cM1）。但是，这种方法不能引起严重影响患者的很大改善，这些患者由于同侧病变通路的广泛损伤，不能依赖于iM1。这些患者被认为依赖于未受损的皮质，特别是对侧背侧运动前皮质（cPMd）来支持瘫肢体的功能。在这里，我们首次测试了cPMd的促进是否可以改善严重影响患者的双亲肢体功能，以及是否可以确定一个临界值来区分cPMd的应答者和标准刺激方法的应答者。在一项随机、假对照交叉研究中，15名患者接受了标准的刺激方法，包括抑制cM1和一种新的刺激方法，包括使用重复经颅磁刺激（rTMS）促进cPMd。患者还接受了rTMS控制区域。在基线时，测量损伤[上肢Fugl-Meyer (UEFMPROXIMAL, max =36)]和通路损伤[分数各向异性（FA）]。我们测量了近端麻痹肢体到达时间的变化，以及使用经颅磁刺激的神经生理学。与FA（0.5）和UEFMPROXIMAL（26-28）的临界值相比，cPMd的促进对严重感染患者产生了更大的改善。相反，标准方法在轻度影响的患者中产生了更多的改善。cPMd的应答者表现出对iM1施加的半球间竞争的减轻，而标准方法的应答者表现出与改善相关的同侧兴奋性的增加。一个初步的严重程度临界值区分了标准方法和cPMd促进的应答者。这里确定的截断值可以帮助在未来的研究中选择适合的刺激候选人，因此所有严重程度的患者都可能在麻痹的上肢功能方面获得最大的益处。
The standard approach to brain stimulation in stroke is based on the premise that ipsilesional M1 (iM1) is important for motor function of the paretic upper limb, while contralesional cortices compete with iM1. Therefore, the approach typically advocates facilitating iM1 and/or inhibiting contralesional M1 (cM1). But, this approach fails to elicit much improvement in severely affected patients, who on account of extensive damage to ipsilesional pathways, cannot rely on iM1. These patients are believed to instead rely on the undamaged cortices, especially the contralesional dorsal premotor cortex (cPMd), for support of function of the paretic limb. Here, we tested for the first time whether facilitation of cPMd could improve paretic limb function in severely affected patients, and if a cut-off could be identified to separate responders to cPMd from responders to the standard approach to stimulation. In a randomized, sham-controlled crossover study, fifteen patients received the standard approach of stimulation involving inhibition of cM1 and a new approach involving facilitation of cPMd using repetitive transcranial magnetic stimulation (rTMS). Patients also received rTMS to control areas. At baseline, impairment [Upper Extremity Fugl-Meyer (UEFMPROXIMAL, max =36)] and damage to pathways [fractional anisotropy (FA)] was measured. We measured changes in time to perform proximal paretic limb reaching, and neurophysiology using TMS. Facilitation of cPMd generated more improvement in severely affected patients, who had experienced greater damage and impairment than a cut-off value of FA (0.5) and UEFMPROXIMAL (26–28). The standard approach instead generated more improvement in mildly affected patients. Responders to cPMd showed alleviation of interhemispheric competition imposed on iM1, while responders to the standard approach showed gains in ipsilesional excitability in association with improvement. A preliminary cut-off level of severity separated responders for standard approach vs. facilitation of cPMd. Cut-offs identified here could help select candidates for tailored stimulation in future studies so patients in all ranges of severity could potentially achieve maximum benefit in function of the paretic upper limb.