Functional reorganization associated with outcome in hand function after stroke revealed by regional homogeneity

Previous studies of task-based functional neuroimaging have shown that various patterns of functional reorganization underlie motor recovery following stroke. However, the mechanisms underlying functional reorganization that contribute to outcome differences in hand function after stroke have not been completely characterized. We, for the first time, investigate subgroups of stroke patients with different outcomes in hand function using a resting-state fMRI approach. We selected 24 patients with subcortical stroke and divided them into two subgroups: completely paralyzed hands (CPH, 12 patients) and partially paralyzed hands (PPH, 12 patients). Twenty-four healthy controls (HCs) matched for age and handedness were also recruited. We used regional homogeneity (ReHo) method to map regional spontaneous activity across the whole brain and performed a two-sample t test between each pair of the three diagnostic groups. Compared to HCs, we found increased ReHo in the ipsilesional hemisphere in PPH and, conversely, increased ReHo in the contralesional hemisphere in CPH. Moreover, we detected decreased ReHo in the ipsilesional primary sensorimotor cortex and superior temporal gyrus, in addition to increased ReHo in the contralesional premotor cortex and ipsilesional medial frontal gyrus in CPH compared to PPH. Additionally, the ReHo index of these regions significantly correlated with the Fugl-Meyer assessment scores (hand + wrist) across all stroke patients. Our study offers a new insight into relationships between functional reorganization and outcomes in hand function after subcortical stroke, and the ReHo method can provide an effective tool for evaluating the efficiency of rehabilitative therapies following stroke.