National Stroke Research Institute, Florey Neuroscience Institutes, Melbourne, Victoria, Australia.
Neurorehabil Neural Repair. 2011 Jun;25(5):443-57. doi: 10.1177/1545968310395777. Epub 2011 Mar 7.
The neural basis underlying somatosensory impairment and recovery poststroke is virtually unexplored.
To investigate the relationship between touch discrimination impairment and task-related brain activation in stroke survivors with somatosensory impairment following subcortical or cortical lesions.
A total of 19 stroke survivors with touch impairment were investigated using fMRI and a touch discrimination paradigm 1-month poststroke; 11 had subcortical and 8 cortical sensory lesions; 12 age-matched healthy controls were also studied. Mean task-related contrast images were regressed with sensory impairment using random effects analysis for each subgroup and the total group.
There was no significant difference in touch impairment between stroke subgroups. Touch discrimination of the affected hand correlated negatively with task-related activation in the ipsilesional primary somatosensory cortex (SI; adjacent to the SI hand area activated in healthy controls); ipsilesional secondary somatosensory cortex (SII); contralesional thalamus; and attention-related frontal and occipital regions in the subcortical group. In contrast, the cortical group did not show significant correlated activity. Yet there was no significant between-group difference in a priori somatosensory regions: only in the superior medial frontal gyrus. A negative correlation was observed in the contralesional thalamus for the total group, irrespective of lesion type.
The findings provide novel evidence of neural correlates of poststroke touch impairment involving a distributed network of ipsilesional SI and SII, the contralesional thalamus, and frontal attention regions, particularly following subcortical lesions. Further systematic investigation of a modulatory role for ipsilesional SI, the thalamus, and frontal attention regions in sensory processing and recovery is warranted, particularly given implications for rehabilitation.
脑卒中后体感障碍及其恢复的神经基础尚不清楚。
研究皮质下或皮质感觉损伤后脑卒中幸存者体感障碍患者的触诊辨别障碍与任务相关脑激活之间的关系。
19 名脑卒中后触诊障碍患者在脑卒中后 1 个月接受 fMRI 和触诊辨别范式检查；11 名患者有皮质下感觉损伤，8 名患者有皮质感觉损伤；还研究了 12 名年龄匹配的健康对照者。使用随机效应分析对每个亚组和总组进行了体感障碍与任务相关对比图像的均值回归。
亚组间触诊障碍无显著差异。患手触诊辨别与皮质下组患侧初级体感皮层（SI；与健康对照组激活的 SI 手区相邻）、对侧次级体感皮层（SII）、对侧丘脑、与注意力相关的额顶叶区域的任务相关激活呈负相关；而皮质组未显示出显著相关的活动。然而，在皮质下组中，在预先设定的体感区域内，也未发现组间差异有统计学意义：只有在额上回。总的来说，无论病变类型如何，在对侧丘脑都观察到负相关。
这些发现为脑卒中后触诊障碍的神经相关性提供了新的证据，涉及到同侧 SI 和 SII、对侧丘脑和额叶注意力区域的分布式网络，尤其是皮质下损伤后。需要进一步系统地研究同侧 SI、丘脑和额叶注意力区域在感觉处理和恢复中的调节作用，特别是考虑到对康复的影响。
