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Brain Function and Upper Limb Outcome in Stroke: A Cross-Sectional fMRI Study.

Buma FE, Raemaekers M, Kwakkel G, Ramsey NF - PLoS ONE (2015)

Bottom Line: Finally, no significant relationship between brain activation and hand function was found in patients.The absence of significant differences in brain activity even in patients with a residual impairment may suggest that infarcts do not necessarily induce reorganization of motor function.While brain activity could be abnormal with higher task demands, this may also introduce performance confounds.

View Article: PubMed Central - PubMed

Affiliation: Centre of Knowledge, Rehabilitation Centre 'De Hoogstraat', Utrecht, The Netherlands; Dept. Rehabilitation & Sports Medicine, Brain Center Rudolf Magnus, UMCU, Utrecht, The Netherlands.

ABSTRACT

Objective: The nature of changes in brain activation related to good recovery of arm function after stroke is still unclear. While the notion that this is a reflection of neuronal plasticity has gained much support, confounding by compensatory strategies cannot be ruled out. We address this issue by comparing brain activity in recovered patients 6 months after stroke with healthy controls.

Methods: We included 20 patients with upper limb paresis due to ischemic stroke and 15 controls. We measured brain activation during a finger flexion-extension task with functional MRI, and the relationship between brain activation and hand function. Patients exhibited various levels of recovery, but all were able to perform the task.

Results: Comparison between patients and controls with voxel-wise whole-brain analysis failed to reveal significant differences in brain activation. Equally, a region of interest analysis constrained to the motor network to optimize statistical power, failed to yield any differences. Finally, no significant relationship between brain activation and hand function was found in patients. Patients and controls performed scanner task equally well.

Conclusion: Brain activation and behavioral performance during finger flexion-extensions in (moderately) well recovered patients seems normal. The absence of significant differences in brain activity even in patients with a residual impairment may suggest that infarcts do not necessarily induce reorganization of motor function. While brain activity could be abnormal with higher task demands, this may also introduce performance confounds. It is thus still uncertain to what extent capacity for true neuronal repair after stroke exists.

No MeSH data available.


Related in: MedlinePlus

Mean results for Laterality Index for Amplitude and Force tasks for the unaffected and affected hand for patients and controls.Mean LI per ROI (±1 SD) cerebellum, PM, SMA, postcentral gyrus, precentral gyrus and insula.
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pone.0139746.g005: Mean results for Laterality Index for Amplitude and Force tasks for the unaffected and affected hand for patients and controls.Mean LI per ROI (±1 SD) cerebellum, PM, SMA, postcentral gyrus, precentral gyrus and insula.

Mentions: In addition, there was no difference in ipsi- or contralesional ROI activity between the affected and unaffected hand neither for patients nor for controls. The laterality index did not show a significant effect for group (Table 4, Fig 5), and did not show a difference between affected and unaffected hands for patients or for controls. There was no interaction effect for group with task, ROI, or hemisphere. To see if significant results were absent due to heterogeneity in lesion location, we repeated the ROI analysis with inclusion of only patients with lesions in the basal ganglia, the largest subgroup. However, still none of the tasks showed a significant effect regarding activity levels (betas) or laterality indices. In addition, we repeated the analysis within patients (affected vs. unaffected) while including time post stroke as covariate, to ify potential within group variance as a result of different levels of functional reorganization as a consequence of between subject differences in time post stroke. Again this did not produce significant effects for any of the tasks.


Brain Function and Upper Limb Outcome in Stroke: A Cross-Sectional fMRI Study.

Buma FE, Raemaekers M, Kwakkel G, Ramsey NF - PLoS ONE (2015)

Mean results for Laterality Index for Amplitude and Force tasks for the unaffected and affected hand for patients and controls.Mean LI per ROI (±1 SD) cerebellum, PM, SMA, postcentral gyrus, precentral gyrus and insula.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595281&req=5

pone.0139746.g005: Mean results for Laterality Index for Amplitude and Force tasks for the unaffected and affected hand for patients and controls.Mean LI per ROI (±1 SD) cerebellum, PM, SMA, postcentral gyrus, precentral gyrus and insula.
Mentions: In addition, there was no difference in ipsi- or contralesional ROI activity between the affected and unaffected hand neither for patients nor for controls. The laterality index did not show a significant effect for group (Table 4, Fig 5), and did not show a difference between affected and unaffected hands for patients or for controls. There was no interaction effect for group with task, ROI, or hemisphere. To see if significant results were absent due to heterogeneity in lesion location, we repeated the ROI analysis with inclusion of only patients with lesions in the basal ganglia, the largest subgroup. However, still none of the tasks showed a significant effect regarding activity levels (betas) or laterality indices. In addition, we repeated the analysis within patients (affected vs. unaffected) while including time post stroke as covariate, to ify potential within group variance as a result of different levels of functional reorganization as a consequence of between subject differences in time post stroke. Again this did not produce significant effects for any of the tasks.

Bottom Line: Finally, no significant relationship between brain activation and hand function was found in patients.The absence of significant differences in brain activity even in patients with a residual impairment may suggest that infarcts do not necessarily induce reorganization of motor function.While brain activity could be abnormal with higher task demands, this may also introduce performance confounds.

View Article: PubMed Central - PubMed

Affiliation: Centre of Knowledge, Rehabilitation Centre 'De Hoogstraat', Utrecht, The Netherlands; Dept. Rehabilitation & Sports Medicine, Brain Center Rudolf Magnus, UMCU, Utrecht, The Netherlands.

ABSTRACT

Objective: The nature of changes in brain activation related to good recovery of arm function after stroke is still unclear. While the notion that this is a reflection of neuronal plasticity has gained much support, confounding by compensatory strategies cannot be ruled out. We address this issue by comparing brain activity in recovered patients 6 months after stroke with healthy controls.

Methods: We included 20 patients with upper limb paresis due to ischemic stroke and 15 controls. We measured brain activation during a finger flexion-extension task with functional MRI, and the relationship between brain activation and hand function. Patients exhibited various levels of recovery, but all were able to perform the task.

Results: Comparison between patients and controls with voxel-wise whole-brain analysis failed to reveal significant differences in brain activation. Equally, a region of interest analysis constrained to the motor network to optimize statistical power, failed to yield any differences. Finally, no significant relationship between brain activation and hand function was found in patients. Patients and controls performed scanner task equally well.

Conclusion: Brain activation and behavioral performance during finger flexion-extensions in (moderately) well recovered patients seems normal. The absence of significant differences in brain activity even in patients with a residual impairment may suggest that infarcts do not necessarily induce reorganization of motor function. While brain activity could be abnormal with higher task demands, this may also introduce performance confounds. It is thus still uncertain to what extent capacity for true neuronal repair after stroke exists.

No MeSH data available.


Related in: MedlinePlus