Abstract
Previous studies have shown that motor recovery of stroke can be assessed by the cortical activity and the structural integrity of the corticospinal tract (CST), but little is known about the relation between the cortical activity and the structural integrity during motor recovery. In the present study, we investigated the changes in brain activities evoked by twenty days’ functional electrical stimulation (FES) training in twelve sub-acute stroke patients with unilateral upper-limb disability. We compared cortex activity evoked by wrist movement of eleven stroke patients to that of eleven age-matched healthy subjects to figure out how cortex activity changed after stroke. We also measured the structural integrity represented by the fractional anisotropy (FA) asymmetry of the posterior limb of the internal capsule (PLIC) to find the relationship between the brain activity and the structure integrity. In our study, we found that patients with sub-acute stroke have shown greater activity in the contralesional primary motor cortex (M1) during the affected hand’s movement compared with healthy group, while the activity in ipsilesional M1 was decreased after the therapy compared to that before therapy, and the contralesional non-primary motor cortex showed greater activity after therapy. At the baseline we found that the positive correlation between the FA asymmetry of PLIC and the contralesional non-primary motor cortex activity showed that the greater damaged CST, the greater contralesional non-primary motor cortex recruited. While the negative correlation between them after the FES training indicates that after recovery the non-primary motor cortex plays different role in different stroke phases. Our study demonstrates that functional organization of a residual distributed motor system is related to the degree of disruption to the CST, and the non-primary motor areas plays an important role in motor recovery.
Highlights
Stroke is a major cause of long-term disability in adults throughout the world, and the majority of post-stroke people endure motor impairment, especially a paretic hand
We considered the changes of fractional anisotropy asymmetric in posterior limb of the internal capsule (PLIC) before and after therapy as an index to study the relationship of changes of structural integrity [24] and cortical activity
We found a decreased activity in ipsilesional M1 in the patients after recovery compared to healthy group and the patients before therapy, and suggested that the improvement of motor performance in stroke patients may be induced by the contralesional M1 and other motor-related brain areas after the functional electrical stimulation (FES) training
Summary
Stroke is a major cause of long-term disability in adults throughout the world, and the majority of post-stroke people endure motor impairment, especially a paretic hand. Recent studies on the recovery from stroke have demonstrated that the adult brain is capable of regeneration and compensation for motor deficits [1]. Given such plasticity of the brain, many rehabilitative procedures have been applied to improve the motor function in people with stroke [2]. Among these compensatory strategies, functional electrical stimulation (FES) is one of the effective and practical methods. It is still unknown how the brain functionally and anatomically changes resulting from training of FES for the patient with motor deficits
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