A Longitudinal Study Of Brain Motor Function During Stroke Recovery Using Multi-stage BOLD-fMRI

Stroke recovery involves a battery of plastic changes in the brain, which may result in a serial of damage to motor function. Blood oxygen level dependent(BOLD) functional magnetic resonance imaging(f MRI) technology provides brain activation information with exquisite spatial and temporal resolution as a powerful tool for investigating changes in brain plasticity.In this dissertation, we performed a longitudinal task related study examining plasticity of functional activation by BOLD-f MRI following stroke. Data were collected from 19 patients with corticospinal tract(CST) damage, in which 11 subjects had lesion at basal ganglia. We obtained the data at three stages of recovery, i.e., acute stage(<2wks), early stage(1mon-3mons) and chronic stage(>3mons) post stroke. The cortical activations for both affected and unaffected hand motion tasks were studied. Quantitative activation measurements including the effective size, sum of t values and weighted lateral index(w LI) were calculated and the correlations of these values with Fugl-Meyer index were analyzed across all stages. We got the following results:(1) For all stoke patients with CST damage, they showed a shift from bilateral activation in acute and early stage to ipsilesional activation at chronic stage when performing the affected hand movement task, which suggests a compensation effect from the contralesional hemisphere during the recovery. At the chronic stage, there is a significantly positive correlation between w LI in primary motor cortex for affected hand task and behavior score. Also, significant correlation between sum of t within M1 at acute stage and Fugl-Meyer index at early stage was found. In early stage, w LI and activated volume in cerebellum were negatively correlated with the index difference between early and chronic stages. There are positive correlations between the sum of t or volume within bilateral cingulated cortex with the index difference between early and chronic stages.(2) For patients with stroke in basal ganglia, they showed similar activation areas with CST damage patients. The correlation analysis exhibited significant correlations within contralesional cingulate cortex and ipsilesional thalamus in aspects of both effective size and sum of t values. There is also a significantly negative correlation with w LI in cerebellum at early stage as well. And a significantly negative correlation between the w LI at early stage and the Fugl-Meyer index difference between chronic stage and early stage in cingulate cortex was found,indicating its prognostic value.These results suggest that: the brain functional activations showed compensation effect from contralesional to ipsilesional hemisphere during recovery stages after stroke. Significant correlations were found between activation volume, sum of t or w LI in several motion related brain regions with behavior score, i.e., Fugl-Meyer Index, at different recovery stages, suggesting the influence on motor recovery. Particularly, the predictive correlation between activation parameters and FuglMeyer Index in later stage is of important clinical significance.