Functional recovery after stroke is believed to be associated with brain plasticity, but the exact relationship is far from well understood.
Objective The present study was designed to investigate brain reorganization after acute ischemic stroke using functional magnetic resonance imaging (fMRI).
Materials and Methods Six patients with unilateral acute subcortical infarction and six normal subjects were scanned during passive index finger movement within 14 days after stroke. Brain activations were compared between normal and patient subjects. The patients were also evaluated individually. Lateral index(LI)for each activated region was calculated and the correlation between the volume of each ROI and motor performance was examined.
Results In the normal subjects, activation in the contralateral sensorimotor cortex (SMC), posterior parietal cortex (PPC) and bilateral supplementary area (SMA) was observed during passive movements. In the patients, while similar result was recorded during unaffected hand movement, the movements of the paretic hand activated ipsilateral PPC in all six patients, and bilateral SMC, SMA and premotor cortex (PMC) in only three patients. LI further confirmed that movment of the affected hand mainly elicited activation in the ipsilateral hemisphere, and there was a marginal significant positive correlation between activation volume of ipsilateral PPC and motor function.
Conclusions To our knowledge, this is the first study that investigated neural correlates of motor recovery in acute ischemic stroke using fMRI through prolonged constant passive stimulation. Our study showed significant difference in brain activation pattern between normal subjects and patients, and provided direct evidence for brain reorganization from acute stroke. This study also offered novel neuroimaging evidence for the role of PPC in unaffected hemisphere in motor recovery following acute stroke.
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