Dynamic Structural and Functional Reorganizations Following Motor Stroke.

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• The interplay between corticospinal tract (CST) reorganization and interhemispheric functional connectivity (FC) in motor recovery post-stroke is not fully understood.
• Investigating these combined effects is crucial for understanding upper and lower limb motor function restoration after stroke.

Purpose of the Study:

• To examine the dynamic changes in bilateral CST structural reorganization and SMN interhemispheric FC after stroke.
• To determine the relationship between these structural and functional changes and motor recovery in patients.

Main Methods:

• Utilized magnetic resonance imaging (MRI), including diffusion tensor imaging (DTI) for CST fractional anisotropy (FA) and resting-state fMRI (rs-fMRI) for interhemispheric FC.
• Recruited 34 stroke patients assessed at 1, 4, and 12 weeks post-stroke, and 34 healthy controls.
• Employed multiple linear regression to correlate FA and FC with motor recovery outcomes.

Main Results:

• Interhemispheric FC restoration was largely observed within 4 weeks post-stroke.
• Fractional anisotropy (FA) in the ipsilesional CST remained elevated throughout the 12-week study period.
• Both increased interhemispheric FC and ipsilesional CST-FA correlated with motor recovery from weeks 1-4; however, only increased ipsilesional CST-FA significantly predicted recovery from weeks 4-12.

Conclusions:

• Stroke induces dynamic structural and functional brain reorganizations.
• Structural reorganization of the ipsilesional CST appears more critical for motor recovery in the later subacute phase compared to interhemispheric FC.
• Findings may inform the development of targeted neurological rehabilitation strategies.