Longitudinal Resting-State fMRI Study: A Seed-Based Connectivity Analysis in Patients with Ischemic Stroke and Intracerebral Hemorrhage

Abstract The primary aim of the research was to compare the impact of post-ischemic and hemorrhagic stroke on brain connectivity and recovery using resting-state functional magnetic resonance imaging (rsfMRI). We serially imaged 20 stroke patients, ten with ischemic (IS) and 10 with intracerebral hemorrhage (ICH), at 1, 3, and 12 months after ictus. Data from ten healthy volunteers were obtained from a publically available imaging dataset. All functional and structural images underwent standard processing for brain extraction, realignment, serial registration, unwrapping, and de-noising using SPM12. A seed-based group analysis using CONN software was used to evaluate the Default Mode (DMN) and the Sensorimotor Network (SMN) connections by applying bivariate correlation and hemodynamic response function (hrf) weighting. In comparison to healthy controls (HC), both IS and ICH exhibited disrupted interactions (decreased connectivity) between these two networks at 1M. Interactions then increased by 12M in each group. Temporally, each group exhibited a minimal increase in connectivity at 3M as compared to 12M. Overall, the ICH patients exhibited a greater magnitude of connectivity disruption compared to IS patients, despite a significant intra-subject reduction in hematoma volume. We did not observe any significant correlation between change in connectivity and recovery as measured on the National Institute Stroke Scale (NIHSS) at any time point. These finding demonstrate that largest changes in functional connectivity occur earlier (3M) rather than later (12M) and show subtle differences between IS and ICH during recovery and should be explored further in larger samples.