Selectively disrupted sensorimotor circuits in chronic stroke with hand dysfunction

Aim To investigate the directional and selective disconnection of the sensorimotor cortex (SMC) subregions in chronic stroke patients with hand dysfunction. Methods We mapped the resting‐state fMRI effective connectivity (EC) patterns for seven SMC subregions in each hemisphere of 65 chronic stroke patients and 40 healthy participants and correlated these patterns with paretic hand performance. Results Compared with controls, patients demonstrated disrupted EC in the ipsilesional primary motor cortex_4p, ipsilesional primary somatosensory cortex_2 (PSC_2), and contralesional PSC_3a. Moreover, we found that EC values of the contralesional PSC_1 to contralesional precuneus, the ipsilesional inferior temporal gyrus to ipsilesional PSC_1, and the ipsilesional PSC_1 to contralesional postcentral gyrus were correlated with paretic hand performance across all patients. We further divided patients into partially (PPH) and completely (CPH) paretic hand subgroups. Compared with CPH patients, PPH patients demonstrated decreased EC in the ipsilesional premotor_6 and ipsilesional PSC_1. Interestingly, we found that paretic hand performance was positively correlated with seven sensorimotor circuits in PPH patients, while it was negatively correlated with five sensorimotor circuits in CPH patients. Conclusion SMC neurocircuitry was selectively disrupted after chronic stroke and associated with diverse hand outcomes, which deepens the understanding of SMC reorganization. Stroke remains the primary reason for adult disability, and hand function recovery is vital for survivors to regain quality of life. Here, we found two functional reorganization patterns in chronic stroke patients with different hand outcomes. For stroke patients with a partially paretic hand (PPH), all motor‐related sensorimotor circuits were positive, while for stroke patients with a completely paretic hand (CPH), this relationship was reversed. Meanwhile, the effective couplings among the PSC_1, inferior temporal gyrus, precuneus, and postcentral gyrus were correlated with hand performance in all stroke patients. PMC, primary motor cortex; PSC, primary somatosensory cortex.