Longitudinal Evaluation of Resting-State fMRI After Acute Stroke With Hemiparesis

Abstract

Background. Functional magnetic resonance imaging (fMRI) of motor impairment after stroke strongly depends on patient effort and capacity to make a movement. Hence fMRI has had limited use in clinical management. Alternatively, resting-state fMRI (ie, with no task) can elucidate the brain’s functional connections by determining temporal synchrony between brain regions. Objective. The authors examined whether resting-state fMRI can elucidate the disruption of functional connections within hours of ischemic stroke as well as during recovery. Methods. A total of 51 ischemic stroke patients—31 with mild-to-moderate hand deficits (National Institutes of Health Stroke Scale [NIHSS] motor score ≥1) and 20 with NIHSS score of 0—underwent resting-state fMRI at <24 hours, 7 days, and 90 days poststroke; 15 age-matched healthy individuals participated in 1 session. Using the resting-state fMRI signal from the ipsilesional motor cortex, the strength of functional connections with the contralesional motor cortex was computed. Whole-brain maps of the resting-state motor network were also generated and compared between groups and sessions. Results. Within hours poststroke, patients with motor deficits exhibited significantly lower connectivity than controls ( P = .02) and patients with no motor impairment ( P = .03). Connectivity was reestablished after 7 days in recovered (ie, NIHSS score = 0) participants. After 90 days, recovered patients exhibited normal motor connectivity; however, reduced connectivity with subcortical regions associated with effort and cognitive processing remained. Conclusion. Resting-state fMRI within hours of ischemic stroke can demonstrate the impact of stroke on functional connections throughout the brain. This tool has the potential to help select appropriate stroke therapies in an acute imaging setting and to monitor the efficacy of rehabilitation.