Motor Impairment and Recovery in the Upper Limb After Stroke

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Abstract
Background and Purpose— Motor recovery after stroke is associated with cerebral reorganization. However, few studies have investigated the relationship directly, and findings are equivocal. We therefore aimed to characterize the relationship between motor impairment, motor recovery, and task-related changes in regional cerebral blood flow (ΔrCBF) longitudinally. Methods— We obtained a profile of motor impairment and recovery in the upper limb and conducted positron emission tomography motor activation studies using a simple finger-tapping task in 9 stroke patients 2 to 7 weeks after stroke and 6 months later. For correlation analysis, mean images of task-related ΔrCBF for each individual were linearly regressed with motor impairment scores. Motor recovery was correlated with longitudinal ΔrCBF images. Results— Patients (7 males; 72.0±9.8 years) demonstrated a wide range of impairment severity and variable recovery. Upper-limb motor function was linearly correlated with task-related ΔrCBF. Importantly, sites of correlated ΔrCBF differed over time. Subacutely correlated ΔrCBF was observed in supplementary motor area (SMA), bilateral cingulate, and contralesional insula with a small area in ipsilesional primary sensorimotor cortex (SM1). Conversely, at the 6-month study, correlated ΔrCBF was primarily in ipsilesional SM1, extending to the cingulate gyrus. Better motor recovery was correlated with reduction in contralesional activity and increase in ipsilesional SM1. Conclusions— Upper-limb motor function and recovery are correlated with ΔrCBF in SMA, cingulate, insula, and SM1, highlighting the role of these areas in the recovery process. The dynamic nature of the relationship suggests ongoing adaptation within motor networks.