Kubis Nathalie
Service de Physiologie Clinique, AP-HP, Hôpital LariboisièreParis, France; Université Paris Diderot, Sorbonne Paris Cité, CART, INSERM U965Paris, France.
Front Neural Circuits. 2016 Jul 27;10:56. doi: 10.3389/fncir.2016.00056. eCollection 2016.
Brain plasticity after stroke remains poorly understood. Patients may improve spontaneously within the first 3 months and then more slowly in the coming year. The first day, decreased edema and reperfusion of the ischemic penumbra may possibly account for these phenomena, but the improvement during the next weeks suggests plasticity phenomena and cortical reorganization of the brain ischemic areas and of more remote areas. Indeed, the injured ischemic motor cortex has a reduced cortical excitability at the acute phase and a suspension of the topographic representation of affected muscles, whereas the contralateral motor cortex has an increased excitability and an enlarged somatomotor representation; furthermore, contralateral cortex exerts a transcallosal interhemispheric inhibition on the ischemic cortex. This results from the imbalance of the physiological reciprocal interhemispheric inhibition of each hemisphere on the other, contributing to worsening of neurological deficit. Cortical excitability is measurable through transcranial magnetic stimulation (TMS) and prognosis has been established according to the presence of motor evoked potentials (MEP) at the acute phase of stroke, which is predictive of better recovery. Conversely, the lack of response to early stimulation is associated with a poor functional outcome. Non-invasive stimulation techniques such as repetitive TMS (rTMS) or transcranial direct current stimulation (tDCS) have the potential to modulate brain cortical excitability with long lasting effects. In the setting of cerebrovascular disease, around 1000 stroke subjects have been included in placebo-controlled trials so far, most often with an objective of promoting motor recovery of the upper limb. High frequency repetitive stimulation (>3 Hz) rTMS, aiming to increase excitability of the ischemic cortex, or low frequency repetitive stimulation (≤1 Hz), aiming to reduce excitability of the contralateral homonymous cortex, or combined therapies, have shown various effects on the functional disability score and neurological scales of treated patients and on the duration of the treatment. We review here the patients' characteristics and parameters of stimulation that could predict a good response, as well as safety issues. At last, we review what we have learnt from experimental studies and discuss potential directions to conduct future studies.
中风后脑可塑性仍未得到充分理解。患者可能在头3个月内自发改善，随后的一年中改善速度则较慢。第一天，缺血半暗带水肿减轻和再灌注可能是这些现象的原因，但接下来几周的改善提示了可塑性现象以及脑缺血区域和更远区域的皮质重组。实际上，受损的缺血性运动皮质在急性期皮质兴奋性降低，受影响肌肉的地形表征暂停，而对侧运动皮质兴奋性增加，躯体运动表征扩大；此外，对侧皮质对缺血皮质施加胼胝体间半球抑制。这是由于每个半球对另一个半球的生理性相互半球抑制失衡，导致神经功能缺损恶化。皮质兴奋性可通过经颅磁刺激（TMS）测量，并且根据中风急性期运动诱发电位（MEP）的存在已确定了预后，MEP可预测更好的恢复。相反，对早期刺激无反应与功能预后不良相关。重复TMS（rTMS）或经颅直流电刺激（tDCS）等非侵入性刺激技术有潜力调节脑皮质兴奋性并产生持久影响。在脑血管疾病背景下，迄今为止约1000名中风患者被纳入安慰剂对照试验，最常见的目的是促进上肢运动恢复。旨在增加缺血皮质兴奋性的高频重复刺激（>3 Hz）rTMS，或旨在降低对侧同名皮质兴奋性的低频重复刺激（≤1 Hz），或联合治疗，已在治疗患者的功能残疾评分和神经学量表以及治疗持续时间方面显示出各种效果。我们在此回顾可预测良好反应的患者特征和刺激参数以及安全性问题。最后，我们回顾从实验研究中学到的内容并讨论进行未来研究的潜在方向。
