Data_Sheet_1_Case Report: True Motor Recovery of Upper Limb Beyond 5 Years Post-stroke.pdf

Most of motor recovery usually occurs within the first 3 months after stroke. Herein is reported a remarkable late recovery of the right upper-limb motor function after a left middle cerebral artery stroke. This recovery happened progressively, from two to 12 years post-stroke onset, and along a proximo-distal gradient, including dissociated finger movements after 5 years. Standardized clinical assessment and quantified analysis of the reach-to-grasp movement were repeated over time to characterize the recovery. Twelve years after stroke onset, diffusion tensor imaging (DTI), functional magnetic resonance imaging (fMRI), and transcranial magnetic stimulation (TMS) analyses of the corticospinal tracts were carried out to investigate the plasticity mechanisms and efferent pathways underlying motor control of the paretic hand. Clinical evaluations and quantified movement analysis argue for a true neurological recovery rather than a compensation mechanism. DTI showed a significant decrease of fractional anisotropy, associated with a severe atrophy, only in the upper part of the left corticospinal tract (CST), suggesting an alteration of the CST at the level of the infarction that is not propagated downstream. The finger opposition movement of the right paretic hand was associated with fMRI activations of a broad network including predominantly the contralateral sensorimotor areas. Motor evoked potentials were normal and the selective stimulation of the right hemisphere did not elicit any response of the ipsilateral upper limb. These findings support the idea that the motor control of the paretic hand is mediated mainly by the contralateral sensorimotor cortex and the corresponding CST, but also by a plasticity of motor-related areas in both hemispheres. To our knowledge, this is the first report of a high quality upper-limb recovery occurring more than 2 years after stroke with a genuine insight of brain plasticity mechanisms.

脑卒中后运动功能恢复大多发生于发病后前3个月内。本文报告1例左侧大脑中动脉脑卒中患者，其右侧上肢运动功能出现显著延迟恢复。该恢复进程呈渐进性，始于脑卒中发病后2年，持续至发病后12年，且遵循近端至远端的恢复梯度，患者于发病5年后可完成分离式手指运动。研究通过多次标准化临床评估与伸手抓握运动量化分析，对该恢复过程进行了特征刻画。

在患者脑卒中发病后12年时，研究团队对其皮质脊髓束（corticospinal tracts, CST）开展了扩散张量成像（diffusion tensor imaging, DTI）、功能磁共振成像（functional magnetic resonance imaging, fMRI）及经颅磁刺激（transcranial magnetic stimulation, TMS）分析，以探究瘫痪侧手部运动控制背后的神经可塑性机制与传出通路。

临床评估与量化运动分析结果均支持该现象为真正的神经功能恢复，而非代偿机制。DTI结果显示，仅左侧皮质脊髓束（CST）上段出现各向异性分数（fractional anisotropy, FA）显著降低，并伴随严重萎缩，提示梗死部位的CST发生改变且未向远端扩散。右侧瘫痪手的手指对掌运动与广泛脑网络的fMRI激活相关，该网络主要激活对侧感觉运动皮层。运动诱发电位检测结果正常，且对右侧半球的选择性刺激未引发同侧上肢的任何反应。

上述研究结果支持以下结论：瘫痪侧手部的运动控制主要由对侧感觉运动皮层及其对应的CST介导，同时也依赖双侧大脑运动相关脑区的可塑性。据我们所知，本研究首次报道了脑卒中发病2年后仍出现高质量上肢功能恢复，并对脑可塑性机制进行了深入阐释。