Correlation of Motor-Task Related Brain Activation Changes With Motor Performance Changes Induced by Constraint-Induced Therapy After Stroke.
George F Wittenberg, Xiaoyan Leng, Andrew J Butler and 1 others
Arm function improved with CIMT, as expected from the parent trial, but brain activation for a controlled finger task did not significantly change in any group.
The one significant link: more functional gain went with preserved affected-hemisphere M1 activation.
Key findings
1No group showed a statistically significant change in motor task-related brain activation over time, whether or not they received CIMT, at either the 1 Hz or 70% maximum-rate task.
2Across all groups, greater improvement in Wolf Motor Function Test time was associated with preserved or increased affected-hemisphere M1 activation for the 70% effort task (r² = 0.271, P = .0076); no other region showed a significant correlation.
3In both the subacute treated and subacute delayed groups, improved grip strength between the first and second scans was associated with decreased contralesional superior parietal activation.
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What it does not show
Only 46 participants entered, 10 withdrew and 1 declined before final evaluations, and the chronic delayed group (2 people) was dropped, leaving three small groups. The fMRI was acquired on 1.5 Tesla scanners and the authors themselves note that older fMRI methods may lack sensitivity to detect real activation changes. The analysis was completed close to the original trial and was not re-run with current software; the authors acknowledge that more recent methods could have produced different results. The paper was 'mothballed for several years' and completed from a draft about 10 years old; some exact statistical procedures for certain analyses have been lost. The correlation between WMFT change and M1 activation is small (r² = 0.271) and was found across all groups combined, not within a single treatment arm. The finger flexion/extension task is a simple, well-controlled movement; it may not reflect the more complex, variable movements a patient uses in daily life.
Declared interests
Funded by USPHS award NICHD R01 HD-40984 (National Center for Medical Rehabilitation Research). The authors declared no potential conflicts of interest.
The easy way to misread this
Do not read the null brain-activation result as evidence that CIMT does not work. The functional outcome (WMFT) improved significantly, consistent with the parent EXCITE trial. The null is specifically about group-level change in cortical activation for a simple, well-paced finger task. Conversely, do not read the small correlation (r² = 0.271) between functional gain and M1 activation as a proven mechanism or a treatment target; it is a modest association in a small, heterogeneous sample, and the authors themselves call the results exploratory.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →