Correlation of Motor-Task Related Brain Activation Changes With Motor Performance Changes Induced by Constraint-Induced Therapy After Stroke.

BACKGROUND

Steven Wolf made an exceptional effort to design, organize, and conduct a study of the biology of constraint induced movement therapy (CIMT) but only the transcranial magnetic stimulation results have been published previously.

OBJECTIVE

To evaluate changes in motor-task related brain activation and their relationship to functional recovery in participants with stroke undergoing CIMT during the subacute and chronic periods.

METHODS

Participants with hemiparetic stroke (n = 42) underwent fMRI of a hand task at baseline, immediately after a 2-week intervention or waiting period, and 4 months later, with effort or rate controlled at each timepoint. Functional outcome was assessed via the Wolf Motor Function Test (WMFT). Functional images were analyzed at the individual and group level.

RESULTS

Significant improvement in WMFT occurred in the intervention groups. Group-level changes in task-related activation over time were not significant. However, across all participants, increased WMFT task speed correlated significantly with increased ipsilesional M1 activation. No significant difference between activation changes were noted between any groups.

CONCLUSIONS

Despite meaningful functional gains, longitudinal changes in cortical activation were limited when controlled for rate or effort, yet individual recovery was significantly associated with preserved or increased activation in the affected primary motor cortex. These results suggest that post-stroke motor recovery may reflect changes in how effort to move activates the stroke-affected motor cortex and more distal changes in response to motor cortical activation. Multi-site fMRI in stroke rehabilitation trials remains challenging, with strong control and monitoring of task performance needed.