中風後執行上肢近端與遠端功能性動作任務之大腦活化情形： 近紅外光頻譜儀研究

Abstract

肢體動作受損為常見的中風後遺症之一，其嚴重影響個案之自主生活功能及社會參與度。先前影像實驗使用功能性磁振造影或正子斷層造影探討肢體動作時之腦部活化情形；研究結果指出，患側大腦活化程度低下與上肢動作表現嚴重度呈現正相關性。然而，因造影儀器對於個案之姿勢限制，相關文章僅探討上肢遠端動作時之功能性腦部活化，尚未釐清上肢近端功能性動作與腦部活化之相關性。因此，本實驗為一橫斷面研究，使用較無姿勢限制之穿戴式近紅外光頻譜儀，探討中風患者在執行遠端及近端上肢功能性動作時之大腦皮質活化情形，並與健康成年人之腦部活化情形比較。本實驗共收取31位中風患者及9位健康受試者，請受試者執行右側及左側上肢的近端與遠端動作，包含近端之前伸任務（手臂往前伸碰到前方物品），及遠端之抓握任務（手抓握再放開）動作。上肢有嚴重癱瘓或無力情形之中風受試者則以動作心像 (motor imagery) 模式進行此實驗。執行任務中同時使用近紅外光頻譜儀探討大腦雙側前運動皮質區(premotor cortex, PMC)、主要動作皮質 (primary motor cortex, M1) 及主要感覺皮質區 (primary sensory cortex, S1) 執行各項動作任務時之活化情形。本研究使用二因子變異數分析與重複量數 (Two-way ANOVA with repeated measures) 搭配Tukey事後檢定，探討大腦活化皮質區域執行前伸任務及抓握任務時族群與任務之間是否有顯著相互作用 (p < 0.05)；此外，使用皮爾森相關分析法 (Pearson’s correlation)，探討腦部活化與中風後動作損傷之關係。研究結果顯示，與健康受試者相比，中風受試者執行上肢功能性任務時的大腦活化程度整體較高。動作恢復較差之中風受試者（動作心像）相較於動作恢復較好之中風受試者(實際執行)及健康受試者在執行患側遠端動作時，其健側大腦之PMC及M1活化更高。此外，近端和遠端上肢任務之大腦活化沒有顯著差異，但執行近端與遠端任務時，大腦活化皆呈現顯著的側化現象。最後，本研究也發現執行近遠端上肢功能性動作時之腦部活化與中風後動作恢復呈現顯著相關性。

Background and Purpose: Impairment of upper limb function is a significant cause of disability following stroke. Studies revealed that brain reorganization post-stroke shows increased overactivation of the contralesional cortex, which was associated with poor upper limb motor recovery. Previous investigations under functional magnetic resonance imaging and positron emission tomography have sought to characterize the differences in cortical activity between stroke and healthy individuals during upper limb movement, but cortical activity during distal movements were mainly assessed, and little is known about the cortical activity associated with proximal upper limb movements following stroke. The purpose of this cross-sectional study was to investigate the cortical activation patterns in stroke individuals during functional tasks of the proximal and distal upper limb and compare activation of stroke survivors with that of healthy individuals. Methods: Thirty-one participants with stroke and 9 healthy individuals were recruited for this cross-sectional study. After initial screening for eligibility, all participants were instructed to perform four upper limb functional tasks: forward reaching of the non-affected/right arm, forward reaching of the affected/left arm, grasping of the non-affected/right hand, and grasping of the affected/left hand. Stroke participants with severe paralysis or weakness performed motor imagery in place of actual movement execution. Functional near-infrared spectroscopy (fNIRS) was used to record brain activation patterns in the bilateral premotor cortices (PMC), primary motor cortices (M1), and primary somatosensory cortices (S1). Two-way analysis of variance (ANOVA) with Tukey post hoc test was used to assess significant differences in cortical activation between groups (healthy, stroke motor execution, and stroke motor imagery) and the tasks. Pearson’s correlation analysis was used to assess the relationship between cortical activation of each channel and stroke characteristics. Results: Significant differences in cortical activation were found between groups and between tasks. Overall, greater brain activation was seen in the stroke participants compared to healthy participants. Stroke participants with poorer motor recovery, when engaging in motor imagery, exhibit higher activation in the non-affected hemisphere''s PMC and M1compared to stroke participants with better motor recovery (actual execution) and healthy participants during the execution of affected-side distal movements. No significant activation pattern differences were found between proximal and distal upper limb tasks, but rather, significant differences were observed between tasks of the non-affected and affected limbs. Stroke individuals in the motor execution group showed lateralization index patterns similar to that of the healthy participants. In other words, Stroke individuals in the motor imagery group tend to exhibit ipsilateral activation. Significant correlation was also found between cortical activation during the upper limb tasks and upper limb motor outcome and stroke characteristics. Conclusion: Cortical activation patterns differ between subacute stroke participants depending on their stage of recovery. Significantly higher, bilateral cortical activation was observed in subacute stroke as compared to healthy participants, and stroke participants using motor imagery showed greater contra-lesional activation patterns as compared to stroke participants using motor execution. Cortical activation during proximal and distal upper limb tasks was significantly correlated with upper limb motor outcomes and stroke characteristics, thus making it an important marker for movement recovery.