Time course of sensorimotor cortex reorganization during upper extremity task accompanying motor recovery early after stroke: An fNIRS study (original) (raw)
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Stroke, 2014
Background and Purpose-Although neuroimaging studies have revealed specific patterns of reorganization in the sensorimotor control network after stroke, their role in recovery remains unsettled. To review the existing evidence systematically, we performed activation likelihood estimation meta-analysis of functional neuroimaging studies investigating upper limb movement-related brain activity after stroke. Methods-Twenty-four studies using sensorimotor tasks in standardized coordinates were included, totaling 255 patients and 145 healthy controls. Across the entire brain, we compared task-related activity patterns in good and poor recovery and assessed the magnitude of spatial shifts in sensorimotor activity in cortical motor areas after stroke. Results-When compared with healthy controls, patients showed higher activation likelihood estimation values in contralesional primary motor soon after stroke that abated with time, but were not related to motor outcome. The observed activity changes were consistent with restoration of typical interhemispheric balance. In contrast, activation likelihood estimation values in ipsilesional medial-premotor and primary motor cortex were associated with good outcome, reorganization that may reflect vicarious processes associated with ventral activity shifts from BA4a to 4p. In the anterior cerebellum, a novel finding was the association of poor recovery with increased vermal activity, possibly reflecting behaviorally inadequate compensatory strategies engaging the fastigio-thalamo-cortical and corticoreticulospinal systems. Conclusions-Activity in ipsilesional primary motor and medial-premotor cortices in chronic stroke signals good motor recovery, whereas cerebellar vermis activity signals poor recovery. Functional MRI may be useful in identifying recovery biomarkers. (Stroke.
Early imaging correlates of subsequent motor recovery after stroke
Annals of Neurology, 2009
There is unexplained variability in the extent to which patients recover after stroke, particularly from the reference point of the first few days after onset. Among studies tracking motor impairment and recovery, only 30-50% of the variance of recovery is explained by the most commonly reported predictors --lesion volume and initial stroke severity 1 , 2. We hypothesized that functional imaging early after stroke could provide information over and above initial severity and lesion volume about the degree of subsequent recovery. Several prior functional imaging studies have reported altered brain activation patterns in patients at various stages of motor recovery after stroke3 -6. These studies describe brain activation related to concurrent recovered performance at the time of scanning that differs to varying degrees from what is seen in age-matched controls. In this study we used functional imaging to ask a specific and unique question about motor recovery after stroke: can functional imaging in the early period after stroke detect brain activation related to subsequent recovered performance? Should such activation be identified then it could serve as a physiological target for intervention (e.g. non-invasive brain stimulation) in this early time period.
Brain Function Early After Stroke in Relation to Subsequent Recovery
Journal of Cerebral Blood Flow and Metabolism, 2004
This study aimed to characterize brain activation and perfusion early after stroke within cortical regions that would later change activation during recovery. Patients were studied serially after stroke (mean t 1 , ס 16 days after stroke, t 2 ס 3.5 months later) using perfusion-weighted imaging and functional magnetic resonance imaging during finger movement. Controls (n ס 7) showed no significant change in regional activation volumes over time. Among stroke patients (n ס 8), however, recovery was accompanied by several patterns of functional magnetic resonance imaging change, with increased activation volumes over time in five patients and decreased in two. Most regions increasing activation over time were in the stroke hemisphere. Of the five patients showing increased activation over time, specific activation foci enlarged at t 2 were already activated at t 1 in four patients, and at least
No evidence for motor recovery-related cortical reorganization after stroke using resting-state fMRI
2019
Cortical reorganization has been suggested as mechanism for recovery after stroke. It has been proposed that a form of cortical reorganization (changes in functional connectivity between brain areas) can be assessed with resting-state fMRI. Here we report the largest longitudinal data-set in terms of overall sessions in 19 patients with subcortical stroke and 11 controls. Patients were imaged up to 5 times over one year. We found no evidence for post-stroke cortical reorganization despite substantial behavioral recovery. These results could be construed as questioning the value of resting-state imaging. Here we argue instead that they are consistent with other emerging reasons to challenge the idea of motor recovery-related cortical reorganization post-stroke when conceived as changes in connectivity between cortical areas.
Upper Limb Recovery After Stroke Is Associated With Ipsilesional Primary Motor Cortical Activity
Stroke, 2014
Background and Purpose— Although neuroimaging studies have revealed specific patterns of reorganization in the sensorimotor control network after stroke, their role in recovery remains unsettled. To review the existing evidence systematically, we performed activation likelihood estimation meta-analysis of functional neuroimaging studies investigating upper limb movement-related brain activity after stroke. Methods— Twenty-four studies using sensorimotor tasks in standardized coordinates were included, totaling 255 patients and 145 healthy controls. Across the entire brain, we compared task-related activity patterns in good and poor recovery and assessed the magnitude of spatial shifts in sensorimotor activity in cortical motor areas after stroke. Results— When compared with healthy controls, patients showed higher activation likelihood estimation values in contralesional primary motor soon after stroke that abated with time, but were not related to motor outcome. The observed activi...
Brain Function and Upper Limb Outcome in Stroke: A Cross-Sectional fMRI Study
PloS one, 2015
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. 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. 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...
Brain, 2006
Clinical recovery after stroke can be significant and has been attributed to plastic reorganization and recruitment of novel areas previously not engaged in a given task. As equivocal results have been reported in studies using single imaging or electrophysiological methods, here we applied an integrative multimodal approach to a group of well-recovered chronic stroke patients (n = 11; aged 50-81 years) with left capsular lesions. Focal activation during recovered hand movements was assessed with EEG spectral analysis and H 2 15 O-PET with EMG monitoring, cortico-cortical connectivity with EEG coherence analysis (cortico-cortical coherence) and corticospinal connectivity with transcranial magnetic stimulation (TMS). As seen from comparisons with agematched controls, our patients showed enhanced recruitment of the lateral premotor cortex of the lesioned hemisphere [Brodmann area (BA) 6], lateral premotor and to a lesser extent primary sensorimotor and parietal cortex of the contralesional hemisphere (CON-H; BA 4 and superior parietal lobule) and left cerebellum (patients versus controls, Z > 3.09). EEG coherence analysis showed that after stroke cortico-cortical connections were reduced in the stroke hemisphere but relatively increased in the CON-H (ANOVA, contrast analysis, P < 0.05), suggesting a shift of functional connectivity towards the CON-H. Nevertheless, fast conducting corticospinal transmission originated exclusively from the lesioned hemisphere. No direct ipsilateral motor evoked potentials (MEPs) could be elicited with TMS over the contralesional primary motor cortex (iM1) in stroke patients. We conclude that (i) effective recovery is based on enhanced utilization of ipsi-and contralesional resources, (ii) basic corticospinal commands arise from the lesioned hemisphere without recruitment of ('latent') uncrossed corticospinal tract fibres and (iii) increased contralesional activity probably facilitates control of recovered motor function by operating at a higher-order processing level, similar to but not identical with the extended network concerned with complex movements in healthy subjects.
Longitudinal Evaluation of Resting-State fMRI After Acute Stroke With Hemiparesis
Neurorehabilitation and Neural Repair, 2013
Background. Functional magnetic resonance imaging (fMRI) of motor impairment after stroke strongly depends on patient effort and capacity to make a movement. Hence fMRI has had limited use in clinical management. Alternatively, restingstate fMRI (ie, with no task) can elucidate the brain's functional connections by determining temporal synchrony between brain regions. Objective. The authors examined whether resting-state fMRI can elucidate the disruption of functional connections within hours of ischemic stroke as well as during recovery. Methods. A total of 51 ischemic stroke patients-31 with mild-to-moderate hand deficits (National Institutes of Health Stroke Scale [NIHSS] motor score ≥1) and 20 with NIHSS score of 0-underwent resting-state fMRI at <24 hours, 7 days, and 90 days poststroke; 15 age-matched healthy individuals participated in 1 session. Using the resting-state fMRI signal from the ipsilesional motor cortex, the strength of functional connections with the contralesional motor cortex was computed. Whole-brain maps of the resting-state motor network were also generated and compared between groups and sessions. Results. Within hours poststroke, patients with motor deficits exhibited significantly lower connectivity than controls (P = .02) and patients with no motor impairment (P = .03). Connectivity was reestablished after 7 days in recovered (ie, NIHSS score = 0) participants. After 90 days, recovered patients exhibited normal motor connectivity; however, reduced connectivity with subcortical regions associated with effort and cognitive processing remained. Conclusion. Resting-state fMRI within hours of ischemic stroke can demonstrate the impact of stroke on functional connections throughout the brain. This tool has the potential to help select appropriate stroke therapies in an acute imaging setting and to monitor the efficacy of rehabilitation.
NeuroImage, 2007
We studied motor representation in well-recovered stroke patients. Eighteen right-handed stroke patients and eleven age-matched control subjects underwent functional Magnetic Resonance Imaging (fMRI) while performing unimanual index finger (abductionadduction) and wrist movements (flexion-extension) using their recovered and non-affected hand. A subset of these patients underwent Transcranial Magnetic Stimulation (TMS) to elicit motor evoked potentials (MEP) in the first dorsal interosseous muscle of both hands. Imaging results suggest that good recovery utilizes both ipsi-and contralesional resources, although results differ for wrist and index finger movements. Wrist movements of the recovered arm resulted in significantly greater activation of the contralateral (lesional) and ipsilateral (contralesional) primary sensorimotor cortex (SM1), while comparing patients to control subjects performing the same task. In contrast, recovered index finger movements recruited a larger motor network, including the contralateral SM1, Supplementary Motor Area (SMA) and cerebellum when patients were compared to control subjects. TMS of the lesional hemisphere but not of the contralesional hemisphere induced MEPs in the recovered hand. TMS parameters also revealed greater transcallosal inhibition, from the contralesional to the lesional hemisphere than in the reverse direction. Disinhibition of the contralesional hemisphere observed in a subgroup of our patients suggests persistent alterations in intracortical and transcallosal (interhemispheric) interactions, despite complete functional recovery.
International Journal of Stroke, 2007
Background In stroke, functional neuroimaging has become a potent diagnostic tool; opened new insights into the pathophysiology of ischaemic damage in the human brain; and made possible the assessment of functional-structural relationships in postlesion recovery. Summary of review Here, we give a critical account on the potential and limitation of functional neuroimaging and discuss concepts related to the use of neuroimaging for exploring the neurobiological and neuroanatomical mechanisms of poststroke recovery and neurorehabilitation. We identify and provide evidence for five hypotheses that functional neuroimaging can provide new insights into: 1. adaptation occurs at the level of functional brain systems; 2. the brain-behaviour relationship varies with recovery and over time; 3. functional neuroimaging can improve our ability to predict recovery and select individuals for rehabilitation; 4. mechanisms of recovery reflect different pathophysiological phases; and 5. brain adaptation may be modulated by experience and specific rehabilitation. The significance and application of this new evidence is discussed, and recommendations made for investigations in the field. Conclusion Functional neuroimaging is an important tool to explore the mechanisms underlying brain plasticity and, thereby, to guide clinical research in neurorehabilitation.