Increased intrinsic connectivity for structural atrophy and functional maintenance after acute ischemic stroke.

BACKGROUND: Significant clinical recovery has been commonly observed in ischemic stroke patients with irreversible brain structural damage. However, brain mechanisms that help to maintain clinical function remain unclear.

METHODS: Sixty-two patients with acute ischemic stroke underwent longitudinal clinical assessments and MRI scanning. We evaluated clinical recovery trajectory using Hierarchical Linear Model and analysed intrinsic connectivity with a seed-based approach to examine its changing pattern based on the regional volume changes calculated using voxel-wise analysis.

RESULTS: We observed that clinical outcome measures improved mainly in the short-term period (baseline vs. 3 weeks) and then remained stable. Gray matter volume was reduced significantly in bilateral caudate over the entire 3-year long-term period. Significant intrinsic connectivity increases in caudate-middle cingulum over the short-term period and in caudate-precuneus and caudate-calcarine over the long-term period were observed. Finally, we found that increased caudate-calcarine connectivity was associated with reduced right caudate volume, and a positive correlation was found between increased caudate-middle cingulum connectivity and the amount of the modified Rankin score changes.

CONCLUSIONS: Increased intrinsic connectivity found in this study tends to be a compensatory mechanism for post-stroke structural damage, associated with clinical recovery. This study helped in understanding the significance of enhanced intrinsic connectivity in post-stroke long-term assessment and rehabilitation. This article is protected by copyright. All rights reserved.