Abstract TP93: Increased Contralesional Activation during Reach is Associated with Recovery of Chronic Arm Motor Deficits

Abstract

Background: In chronic stroke, recovery of coordinated reaching is critical to arm function and quality of life. Improvement of motor function can be achieved with intensive rehabilitation even years after stroke, but current methods fall short of restoring normal movement for many stroke survivors. Little is known regarding the change in brain function that is required to improve shoulder/elbow reach function. Therefore, the aim of this study was to characterize the change in brain activity of bilateral motor-sensory brain regions, which may drive recovery of functional reach. Methods: 22 stroke subjects (>6 months post-stroke) with arm motor deficits were enrolled and treated with intensive arm rehabilitation (5 hours/day, 5 days/week for 12 weeks). Outcome measures were: 1) functional magnetic resonance imaging (fMRI) during a shoulder/elbow reach task (paretic arm), 2) skilled motor function (Arm Motor Assessment Test (AMAT)). fMRI activation (voxel count) was calculated for bilateral sensory-motor control regions. Multiple linear regression analysis was conducted to determine the relationship between the change in brain function and recovery of functional reach. Co-variates included pre-treatment AMAT, age and time-since-stroke. Results: Subject characteristics were: age, 56.3 (±12.8years); 41%, female; and 1.8 (±1.1) years post-stroke. AMAT improved from 1636.63 (±668.41) to 1213.67 (±6643.79) seconds (p<.0001). Regression analyses demonstrated that greater improvement of AMAT score was associated with increase in activation in the ipsilesional primary motor(p=.02), and in the contralesional regions as follows: primary motor(p=0.02), primary sensory(p=0.03), secondary sensory(p=0.03), premotor(p=0.009), supplementary motor(p=0.05), thalamus(p=0.02), putamen(p=0.03) and cerebellum( p=0.009). Conclusions: In chronic stroke, important gain in functional reach is associated with increased activation, not only in the ipsilesional primary motor region, but also in the contralesional motor-sensory regions, which occurred in response to intensive neurorehabilitation. Arm neurorehabilitation methods should be based on principles that engage this brain plasticity, which may drive recovery of arm function.