Altered Dynamic Resting State Functional Connectivity Associated With Somatosensory Impairments in the Upper Limb in the Early Sub-Acute Phase Post-Stroke.

Abstract

Background.: Altered dynamic functional connectivity has been associated with motor impairments in the acute phase post-stroke. Its association with somatosensory impairments in the early sub-acute phase remains unexplored.

Objective.: To investigate altered dynamic functional connectivity associated with somatosensory impairments in the early sub-acute phase post-stroke.

Methods.: We collected resting state magnetic resonance imaging and clinical somatosensory function of the upper limb of 20 subacute stroke patients and 16 healthy controls (HC). A sliding-window approach was used to identify 3 connectivity states based on the estimated dynamic functional connectivity of sensorimotor related networks. Network components were subdivided into 3 domains: cortical and subcortical sensorimotor, as well as cognitive control network. Between-group differences were investigated using independent t-tests and Mann-Whitney-U tests. Analyzes were performed with correction for age, head motion and time post-stroke and corrected for multiple comparisons.

Results.: Stroke patients spent significantly less time in a weakly connected network state (state 3; dwell time: p_state3 = 0.003, mean_stroke = 53.02, SD_stroke = 53.13; mean_HC = 118.92, SD_HC = 72.84), and stayed shorter but more time intervals in a highly connected intra-domain network state (state 1; fraction time: p_{state 1} < 0.001, mean_stroke = 0.46, SD_stroke = 0.26; mean_HC = 0.26, SD_HC = 0.21) compared to HC. After 8 weeks of therapy, improvements in wrist proprioception were moderately associated with decreases in dwell and fraction times toward a more normalized pattern.

Conclusion.: Changes in temporal properties of large-scale network interactions are present in the early rehabilitation phase post-stroke and could indicate enhanced neural plasticity. These findings could augment the understanding of cerebral reorganization after loss of neural tissue specialized in somatosensory functions.