Resting-State Cortico-Cerebellar Connectivity Correlates with Post-Stroke Motor Recovery - A Prospective Functional MRI Study

Cerebellar functional and structural connectivity are likely related to motor function after stroke. Less is known about motor recovery, which is defined as a gain of function between two time points, and about the involvement of the cerebellum. Fifteen patients who were hospitalized between 2018 and 2020 for a first cerebral ischemic event with persistent upper limb deficits were assessed by resting-state functional MRI (rsfMRI) and clinical motor score measurements at 3, 9 and 15 weeks after stroke. Age- and sex-matched healthy subjects (n = 15) were assessed once. The objectives were (1) to study whether the level of connectivity between the contralesional cerebellum (lobules IV-V-VI and lobule VIII) and the ipsilesional motor regions on rsfMRI is predictive of motor recovery and (2) to compare these connectivities with those of healthy subjects. Upper limb motor recovery was positively correlated with functional connectivity between contralesional cerebellar lobule VIII and the ipsilesional supplementary motor area (SMA). The greater the connectivity between these regions, the better the motor recovery. In patients, the corticocerebellar network between lobule IV-V-VI and the ipsilesional M1 and SMA showed weaker synchronization at rest than in healthy subjects. Cortico-cortical connectivity was not associated with recovery. Resting-state functional connectivity, including contralesional cerebellar lobule VIII, could be a tool for studying and predicting recovery in stroke patients. Our study highlights the role of the cerebellum in motor recovery after stroke, enabling us to consider new therapeutic targets in neuromodulation.