Functional Neuroimaging in Stroke Recovery and Neurorehabilitation: Conceptual Issues and Perspectives

Trajectory of depressive symptoms in a longitudinal stroke cohort

OBJECTIVES

Knowledge of the trajectory of post-stroke depression is important to identify high-risk patients, develop precise management programs and enhance prognosis. We aimed to characterise the course of depressive symptoms within the first year post-stroke and to evaluate associations with time.

MATERIALS AND METHODS

Depressive symptoms were measured using the Montgomery-Åsberg Depression Rating Scale (MADRS) within the first week, and at 3 and 12 months post-stroke. Scores were dichotomised into symptoms 'present' (MADRS ≥ 7) or 'absent' (MADRS < 7). The course of depressive symptoms within individuals was mapped and categorised using a trajectory diagram. The association between time and the presence of depressive symptoms was investigated using random effects logistic regression. Logistic regression was also used to assess the likelihood of participants having depressive symptoms later, given their status at earlier time points.

RESULTS

Of 142 ischaemic stroke survivors included for analysis, almost half (47.9%) experienced a change in depressive symptom status over time. Depressive symptoms were common at each timepoint (35-43%), although an association between time and frequency of depressive symptoms was not evident. Stroke survivors with depressive symptoms at 3 months were more likely to have depressive symptoms at 12 months, compared to those without symptoms at 3 months.

CONCLUSION

Our findings provide evidence for a dynamic trajectory of depressive symptoms in individuals in the first year post-stroke. The importance of repeated screening for depression is highlighted, though most necessary at 3 months post-stroke.

Quantitative EEG and prognosis for recovery in post-stroke patients: The effect of lesion laterality

OBJECTIVE

There is emerging confidence that quantitative EEG (qEEG) has the potential to inform clinical decision-making and guide individualized rehabilitation after stroke, but consensus on the best EEG biomarkers is needed for translation to clinical practice. This study investigates the spatial qEEG spectral and symmetry distribution in patients with a left/right hemispheric stroke, to evaluate their side-specific prognostic power in post-acute rehabilitation outcome.

METHODS

Resting-state 19-channel EEG recordings were collected with clinical information on admission to intensive inpatient rehabilitation (within 30 days post stroke), and six months post stroke. After preprocessing, spectral (Delta-to-Alpha Ratio, DAR) and symmetry (pairwise and hemispheric Brain Symmetry Index) features were extracted. Patients were divided into Affected Right and Left (AR/AL) groups, according to the location of their lesion. Within each group, DAR was compared between homologous electrode pairs and the pairwise difference between pairs was compared across pairs in the scalp. Then, the prognostic power of qEEG admission metrics was evaluated by performing correlations between admission metrics and discharge mBI values.

RESULTS

Fifty-two patients with hemorrhagic or ischemic stroke (20 females, 38.5 %, median age 76 years [IQR = 22]) were included in the study. DAR was significantly higher in the affected hemisphere for both AR and AL groups, and, a higher frontal (to posterior) asymmetry was found independent of the side of the lesion. DAR was found to be a prognostic marker of 6-months modified Barthel Index (mBI) only for the AL group, while hemispheric asymmetry did not correlate with follow-up outcomes in either group.

DISCUSSION

While the presence of EEG abnormalities in the affected hemisphere of a stroke is well recognized, we have shown that the extent of DAR abnormalities seen correlates with disability at 6 months post stroke, but only for left hemispheric lesions. Routine prognostic evaluation, in addition to motor and functional scales, can add information concerning neuro-prognostication and reveal neurophysiological abnormalities to be assessed during rehabilitation.

A review of combined functional neuroimaging and motion capture for motor rehabilitation

BACKGROUND

Technological advancements in functional neuroimaging and motion capture have led to the development of novel methods that facilitate the diagnosis and rehabilitation of motor deficits. These advancements allow for the synchronous acquisition and analysis of complex signal streams of neurophysiological data (e.g., EEG, fNIRS) and behavioral data (e.g., motion capture). The fusion of those data streams has the potential to provide new insights into cortical mechanisms during movement, guide the development of rehabilitation practices, and become a tool for assessment and therapy in neurorehabilitation.

RESEARCH OBJECTIVE

This paper aims to review the existing literature on the combined use of motion capture and functional neuroimaging in motor rehabilitation. The objective is to understand the diversity and maturity of technological solutions employed and explore the clinical advantages of this multimodal approach.

METHODS

This paper reviews literature related to the combined use of functional neuroimaging and motion capture for motor rehabilitation following the PRISMA guidelines. Besides study and participant characteristics, technological aspects of the used systems, signal processing methods, and the nature of multimodal feature synchronization and fusion were extracted.

RESULTS

Out of 908 publications, 19 were included in the final review. Basic or translation studies were mainly represented and based predominantly on healthy participants or stroke patients. EEG and mechanical motion capture technologies were most used for biomechanical data acquisition, and their subsequent processing is based mainly on traditional methods. The system synchronization techniques at large were underreported. The fusion of multimodal features mainly supported the identification of movement-related cortical activity, and statistical methods were occasionally employed to examine cortico-kinematic relationships.

CONCLUSION

The fusion of motion capture and functional neuroimaging might offer advantages for motor rehabilitation in the future. Besides facilitating the assessment of cognitive processes in real-world settings, it could also improve rehabilitative devices' usability in clinical environments. Further, by better understanding cortico-peripheral coupling, new neuro-rehabilitation methods can be developed, such as personalized proprioceptive training. However, further research is needed to advance our knowledge of cortical-peripheral coupling, evaluate the validity and reliability of multimodal parameters, and enhance user-friendly technologies for clinical adaptation.

Comparison of virtual reality to physical box and blocks on cortical an neuromuscualar activations in young adults

The purpose of this study was to assess the changes in neural activations when performing the box and block test (BBT) in virtual reality (VR) compared to the physical BBT. Young healthy participants performed three trials of the BBT with their left and right hands in both the VR BBT, using VR hand controllers, and physical BBT conditions. Electromyography sensors were placed on the upper extremity of both arms and functional near-infrared spectroscopy was used to measure motor cortex activations throughout each condition. While a reduction in BBT score and increased wrist extensor neuromuscular activity is exhibited during the VR condition, there is no statistical difference in motor cortex activation between the two BBT conditions. This work provides a basis for exploring cortical and neuromuscular responses to VR in patient populations.

Is cognitive reserve associated with the prevention of cognitive decline after stroke? A Systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analyses of the effect of socio-behavioral cognitive reserve (CR) proxies on cognitive decline after stroke.

METHOD

Three journal search and indexing databases (PubMed, Scopus and Web of Sciences) were crossed to examine the scientific evidence systematically. In addition, meta-analytic techniques, using mixed-effect methods, were carried out to estimate the impact (pooled effect size) of CR proxies on either dementia incidence or cognitive decline after stroke.

RESULTS

Twenty-two studies were included in the systematic revision, whereas nineteen of them were eligible for the meta-analysis. The findings showed that high education is associated with a decreased rate of post-stroke dementia. Moreover, other CR proxies (e.g., occupation, bilingualism or social interaction) demonstrate a protective effect against non-dementia cognitive decline after stroke, although some inconsistencies were found in the literature. Regarding the meta-analysis, occupational attainment and education) showed a protective effect against post-stroke cognitive impairment diagnosis in comparison with a mixed category of different CR proxies. Second, a main cognitive change effect was found, pointing to greater cognitive change after stroke in those with low vs. high CR.

CONCLUSIONS

Our findings emphasize that CR may prevent cognitive decline after stroke, but this effect can be modulated by different factors such the CR proxy and individual characteristics such as age or type of lesion. The methodological divergences of the studies (i.e., follow-up intervals, cognitive outcomes) need unification to diminish external sources of variability for predicting rates of cognitive decline after stroke.

The Prognostic Utility of Electroencephalography in Stroke Recovery: A Systematic Review and Meta-Analysis

BACKGROUND

Improved ability to predict patient recovery would guide post-stroke care by helping clinicians personalize treatment and maximize outcomes. Electroencephalography (EEG) provides a direct measure of the functional neuroelectric activity in the brain that forms the basis for neuroplasticity and recovery, and thus may increase prognostic ability.

OBJECTIVE

To examine evidence for the prognostic utility of EEG in stroke recovery via systematic review/meta-analysis.

METHODS

Peer-reviewed journal articles that examined the relationship between EEG and subsequent clinical outcome(s) in stroke were searched using electronic databases. Two independent researchers extracted data for synthesis. Linear meta-regressions were performed across subsets of papers with common outcome measures to quantify the association between EEG and outcome.

RESULTS

75 papers were included. Association between EEG and clinical outcomes was seen not only early post-stroke, but more than 6 months post-stroke. The most studied prognostic potential of EEG was in predicting independence and stroke severity in the standard acute stroke care setting. The meta-analysis showed that EEG was associated with subsequent clinical outcomes measured by the Modified Rankin Scale, National Institutes of Health Stroke Scale, and Fugl-Meyer Upper Extremity Assessment (r = .72, .70, and .53 from 8, 13, and 12 papers, respectively). EEG improved prognostic abilities beyond prediction afforded by standard clinical assessments. However, the EEG variables examined were highly variable across studies and did not converge.

CONCLUSIONS

EEG shows potential to predict post-stroke recovery outcomes. However, evidence is largely explorative, primarily due to the lack of a definitive set of EEG measures to be used for prognosis.

Neuropsychological rehabilitation, neuroimaging and neuroplasticity: A clinical commentary

Initial brain imaging studies on recovery of motor functioning after stroke suggested their potential prognostic value in neurorehabilitation. However, the value of brain imaging in documenting brain changes associated with cognitive and behavioral treatment effects seem less likely. Also, neuroimaging studies at that time seem to have little, if any, value for treatment planning. Advances in neuroimaging technology are beginning to challenge these initial impressions. In this clinical commentary, we propose that advances in the field of neuroimaging have relevance for the future development of neuropsychological rehabilitation. Neuropsychological rehabilitation is entering a new era that involves collaboration with neuroimaging and associated studies on neuroplasticity. We recognize that this may seem “aspirational” rather than practical in most rehabilitation settings. However, we provide examples of how this can be achieved as illustrated by collaborative efforts of clinicians and scientists in the SARAH Network of Rehabilitation Hospitals in Brazil. We also review selective papers on neuroplasticity, spontaneous recovery and diaschisis that have relevance for research which will expand and further develop the field of neuropsychological rehabilitation.

Synchrony Between Default-Mode and Sensorimotor Networks Facilitates Motor Function in Stroke Rehabilitation: A Pilot fMRI Study

Stroke is the most common cause of complex disability in Taiwan. After stroke onset, persistent physical practice or exercise in the rehabilitation procedure reorganizes neural assembly for reducing motor deficits, known as neuroplasticity. Neuroimaging literature showed rehabilitative effects specific to the brain networks of the sensorimotor network (SMN) and default-mode network (DMN). However, whether between-network interactions facilitate the neuroplasticity after stroke rehabilitation remains a mystery. Therefore, we conducted the longitudinal assessment protocol of stroke rehabilitation, including three types of clinical evaluations and two types of functional magnetic resonance imaging (fMRI) techniques (resting state and grasp task). Twelve chronic stroke patients completed the rehabilitation protocol for at least 24 h and finished the three-time assessments: before, after rehabilitation, and 1 month after the cessation of rehabilitation. For comparison, age-matched normal controls (NC) underwent the same fMRI evaluation once without repeated measure. Increasing scores of the Fugl–Meyer assessment (FMA) and upper extremity performance test reflected the enhanced motor performances after the stroke rehabilitation process. Analysis of covariance (ANCOVA) results showed that the connections between posterior cingulate cortex (PCC) and iM1 were persistently enhanced in contrast to the pre-rehabilitation condition. The interactions between PCC and SMN were positively associated with motor performances. The enhanced cross-network connectivity facilitates the motor recovery after stroke rehabilitation, but the cross-network interaction was low before the rehabilitation process, similar to the level of NCs. Our findings suggested that cross-network connectivity plays a facilitatory role following the stroke rehabilitation, which can serve as a neurorehabilitative biomarker for future intervention evaluations.

Finding the Intersection of Neuroplasticity, Stroke Recovery, and Learning: Scope and Contributions to Stroke Rehabilitation

Aim

Neural plastic changes are experience and learning dependent, yet exploiting this knowledge to enhance clinical outcomes after stroke is in its infancy. Our aim was to search the available evidence for the core concepts of neuroplasticity, stroke recovery, and learning; identify links between these concepts; and identify and review the themes that best characterise the intersection of these three concepts.

Methods

We developed a novel approach to identify the common research topics among the three areas: neuroplasticity, stroke recovery, and learning. A concept map was created a priori, and separate searches were conducted for each concept. The methodology involved three main phases: data collection and filtering, development of a clinical vocabulary, and the development of an automatic clinical text processing engine to aid the process and identify the unique and common topics. The common themes from the intersection of the three concepts were identified. These were then reviewed, with particular reference to the top 30 articles identified as intersecting these concepts.

Results

The search of the three concepts separately yielded 405,636 publications. Publications were filtered to include only human studies, generating 263,751 publications related to the concepts of neuroplasticity (n = 6,498), stroke recovery (n = 79,060), and learning (n = 178,193). A cluster concept map (network graph) was generated from the results; indicating the concept nodes, strength of link between nodes, and the intersection between all three concepts. We identified 23 common themes (topics) and the top 30 articles that best represent the intersecting themes. A time-linked pattern emerged.

Discussion and Conclusions

Our novel approach developed for this review allowed the identification of the common themes/topics that intersect the concepts of neuroplasticity, stroke recovery, and learning. These may be synthesised to advance a neuroscience-informed approach to stroke rehabilitation. We also identified gaps in available literature using this approach. These may help guide future targeted research.

White Matter Biomarkers Associated with Motor Change in Individuals with Stroke: A Continuous Theta Burst Stimulation Study

Continuous theta burst stimulation (cTBS) is a form of noninvasive repetitive brain stimulation that, when delivered over the contralesional hemisphere, can influence the excitability of the ipsilesional hemisphere in individuals with stroke. cTBS applied prior to skilled motor practice interventions may augment motor learning; however, there is a high degree of variability in individual response to this intervention. The main objective of the present study was to assess white matter biomarkers of response to cTBS paired with skilled motor practice in individuals with chronic stroke. We tested the effects of stimulation of the contralesional hemisphere at the site of the primary motor cortex (M1c) or primary somatosensory cortex (S1c) and a third group who received sham stimulation. Within each stimulation group, individuals were categorized into responders or nonresponders based on their capacity for motor skill change. Baseline diffusion tensor imaging (DTI) indexed the underlying white matter microstructure of a previously known motor learning network, named the constrained motor connectome (CMC), as well as the corticospinal tract (CST) of lesioned and nonlesioned hemispheres. Across practice, there were no differential group effects. However, when categorized as responders vs. nonresponders using change in motor behaviour, we demonstrated a significant difference in CMC microstructural properties (as measured by fractional anisotropy (FA)) for individuals in M1c and S1c groups. There were no significant differences between responders and nonresponders in clinical baseline measures or microstructural properties (FA) in the CST. The present study identifies a white matter biomarker, which extends beyond the CST, advancing our understanding of the importance of white matter networks for motor after stroke.

Brain-machine interface of upper limb recovery in stroke patients rehabilitation: A systematic review

BACKGROUND

Technologies such as brain-computer interfaces are able to guide mental practice, in particular motor imagery performance, to promote recovery in stroke patients, as a combined approach to conventional therapy.

OBJECTIVE

The aim of this systematic review was to provide a status report regarding advances in brain-computer interface, focusing in particular in upper limb motor recovery.

METHODS

The databases PubMed, Scopus, and PEDro were systematically searched for articles published between January 2010 and December 2017. The selected studies were randomized controlled trials involving brain-computer interface interventions in stroke patients, with upper limb assessment as primary outcome measures. Reviewers independently extracted data and assessed the methodological quality of the trials, using the PEDro methodologic rating scale.

RESULTS

From 309 titles, we included nine studies with high quality (PEDro ≥ 6). We found that the most common interface used was non-invasive electroencephalography, and the main neurofeedback, in stroke rehabilitation, was usually visual abstract or a combination with the control of an orthosis/robotic limb. Moreover, the Fugl-Meyer Assessment Scale was a major outcome measure in eight out of nine studies. In addition, the benefits of functional electric stimulation associated to an interface were found in three studies.

CONCLUSIONS

Neurofeedback training with brain-computer interface systems seem to promote clinical and neurophysiologic changes in stroke patients, in particular those with long-term efficacy.

Sensorimotor integration in chronic stroke: Baseline differences and response to sensory training

BACKGROUND

The integration of somatosensory information from the environment into the motor cortex to inform movement is essential for motor function. As motor deficits commonly persist into the chronic phase of stroke recovery, it is important to understand potential contributing factors to these deficits, as well as their relationship with motor function. To date the impact of chronic stroke on sensorimotor integration has not been thoroughly investigated.

OBJECTIVES

The current study aimed to comprehensively examine the influence of chronic stroke on sensorimotor integration, and determine whether sensorimotor integration can be modified with an intervention. Further, it determined the relationship between neurophysiological measures of sensorimotor integration and motor deficits post-stroke.

METHODS

Fourteen individuals with chronic stroke and twelve older healthy controls participated. Motor impairment and function were quantified in individuals with chronic stroke. Baseline neurophysiology was assessed using nerve-based measures (short- and long-latency afferent inhibition, afferent facilitation) and vibration-based measures of sensorimotor integration, which paired vibration with single and paired-pulse TMS techniques. Neurophysiological assessment was performed before and after a vibration-based sensory training paradigm to assess changes within these circuits.

RESULTS

Vibration-based, but not nerve-based measures of sensorimotor integration were different in individuals with chronic stroke, as compared to older healthy controls, suggesting that stroke differentially impacts integration of specific types of somatosensory information. Sensorimotor integration was behaviourally relevant in that it related to both motor function and impairment post-stroke. Finally, sensory training modulated sensorimotor integration in individuals with chronic stroke and controls.

CONCLUSION

Sensorimotor integration is differentially impacted by chronic stroke based on the type of afferent feedback. However, both nerve-based and vibration-based measures relate to motor impairment and function in individuals with chronic stroke.

Efficacy of ICT-Based Neurocognitive Rehabilitation Programs for Acquired Brain Injury

Abstract. This systematic review aims to analyze the methods used in the assessment of the efficacy of Neurocognitive Rehabilitation Programs (NRP) based on Information and Communication Technologies in patients with Acquired Brain Injury, namely platforms and online rehabilitation programs. Studies with the main purpose of evaluating the efficacy of those programs were retrieved from multiple literature databases, accordingly to inclusion and exclusion criteria. The inclusion and analysis of the studies followed preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) and Cochrane Collaboration Guidelines. Thirty-one studies were included in this review. Results showed that most studies used a pre-post methodological design, with few studies performing assessment moments during intervention or follow-up. Attention, memory, and executive functions were the cognitive variables considered by a larger number of studies at the assessment of NRP efficacy. Despite that, there is a growing evidence on the inclusion of variables related to everyday functioning in this process, increasing its ecological validity. Concerning the instruments used, the studies presented a large heterogeneity of the instruments and methods used, even for the same assessment purpose, highlighting a lack of consensus regarding assessment protocol. Psychophysiological and neuroimaging techniques are seldom used on this field. This review identifies the main characteristics of the methodology used at the assessment of NRP and potential limitations, providing useful information to guide the practice of the health care professionals in rehabilitation of Acquired Brain Injury. It also suggests new directions for future studies.

Physiotherapy based on problem-solving in upper limb function and neuroplasticity in chronic stroke patients: A case series

RATIONALE, AIMS, AND OBJECTIVES

Upper limb recovery is one of the main concerns of stroke neurorehabilitation. Neuroplasticity might underlie such recovery, particularly in the chronic phase. The purpose of this study was to assess the effect of physiotherapy based on problem-solving in recovering arm function in chronic stroke patients and explore its neuroplastic changes.

METHODS

A small sample research design with a n of 3 using a pre-post test design was carried out. Neuroplasticity and function were assessed by using functional magnetic resonance imaging (during motor imagery and performance), action research arm test, motor assessment scale, and Fugl-Meyer assessment scale, at 3 sequential time periods: baseline(m0-before a 4-week period without physiotherapy), pre-treatment(m1), and post-treatment(m2). Minimal clinical important differences and a recovery score were assessed. Assessors were blinded to moment assignment. Patients¹ underwent physiotherapy sessions, 50 minutes, 5 days/week for 4 weeks. Four control subjects served as a reference for functional magnetic resonance imaging changes.

RESULTS

All patients recovered more than 20% after intervention. Stroke patients had similar increased areas as healthy subjects during motor execution but not during imagination at baseline. Consequently, all patients increased activity in the contralateral precentral area after intervention.

CONCLUSIONS

This study indicates that 4 weeks of physiotherapy promoted the recovery of arm function and neuroplasticity in all chronic stroke patients. Future research is recommended to determine the efficacy of this therapy.

Prediction of Walking and Arm Recovery after Stroke: A Critical Review

Clinicians often base their predictions of walking and arm recovery on multiple predictors. Multivariate prediction models may assist clinicians to make accurate predictions. Several reviews have been published on the prediction of motor recovery after stroke, but none have critically appraised development and validation studies of models for predicting walking and arm recovery. In this review, we highlight some common methodological limitations of models that have been developed and validated. Notable models include the proportional recovery model and the PREP algorithm. We also identify five other models based on clinical predictors that might be ready for further validation. It has been suggested that neurophysiological and neuroimaging data may be used to predict arm recovery. Current evidence suggests, but does not show conclusively, that the addition of neurophysiological and neuroimaging data to models containing clinical predictors yields clinically important increases in predictive accuracy.

Neural correlates of motor recovery after robot-assisted stroke rehabilitation: a case series study

Robot-assisted bilateral arm therapy (RBAT) has shown promising results in stroke rehabilitation; however, connectivity mapping of the sensorimotor networks after RBAT remains unclear. We used fMRI before and after RBAT and a dose-matched control intervention (DMCI) to explore the connectivity changes in 6 subacute stroke patients. Sensorimotor functions improved in the RBAT and DMCI groups after treatment. Enhanced activation changes were observed in bilateral primary motor cortex (M1) and bilateral supplementary motor area (SMA) after RBAT. Dynamic causal model analysis revealed that interhemispheric connections were enhanced in RBAT patients. These preliminary findings suggest that intracortical and intercortical coupling might underlie poststroke RBAT.

Same Intervention-Different Reorganization: The Impact of Lesion Location on Training-Facilitated Somatosensory Recovery After Stroke

BACKGROUND

The brain may reorganize to optimize stroke recovery. Yet relatively little is known about neural correlates of training-facilitated recovery, particularly after loss of body sensations.

OBJECTIVE

Our aim was to characterize changes in brain activation following clinically effective touch discrimination training in stroke patients with somatosensory loss after lesions of primary/secondary somatosensory cortices or thalamic/capsular somatosensory regions using functional magnetic resonance imaging (fMRI).

METHODS

Eleven stroke patients with somatosensory loss, 7 with lesions involving primary (S1) and/or secondary (S2) somatosensory cortex (4 male, 58.7 ± 13.3 years) and 4 with lesions primarily involving somatosensory thalamus and/or capsular/white matter regions (2 male, 58 ± 8.6 years) were studied. Clinical and MRI testing occurred at 6 months poststroke (preintervention), and following 15 sessions of clinically effective touch discrimination training (postintervention).

RESULTS

Improved touch discrimination of a magnitude similar to previous clinical studies and approaching normal range was found. Patients with thalamic/capsular somatosensory lesions activated preintervention in left ipsilesional supramarginal gyrus, and postintervention in ipsilesional insula and supramarginal gyrus. In contrast, those with S1/S2 lesions did not show common activation preintervention, only deactivation in contralesional superior parietal lobe, including S1, and cingulate cortex postintervention. The S1/S2 group did, however, show significant change over time involving ipsilesional precuneus. This change was greater than for the thalamic/capsular group (P = .012; d = -2.43; CI = -0.67 to -3.76).

CONCLUSION

Different patterns of change in activation are evident following touch discrimination training with thalamic/capsular lesions compared with S1/S2 cortical somatosensory lesions, despite common training and similar improvement.

Changes of the corticospinal tract in the unaffected hemisphere in stroke patients: A diffusion tensor imaging study

We investigated changes of the corticospinal tract (CST) in the unaffected hemisphere according to severity of the CST injury, using diffusion tensor imaging (DTI). According to the severity of the CST injury in the affected hemisphere, the stroke patients showed different aspects of fiber volume increment of the CST in the unaffected hemisphere; the fiber volume was increased in the early phase in patients with mild injury of CST and later phase in patients with severe injury of CST.

Recovery Potential After Acute Stroke

In acute stroke, the major factor for recovery is the early use of thrombolysis aimed at arterial recanalization and reperfusion of ischemic brain tissue. Subsequently, neurorehabilitative training critically improves clinical recovery due to augmention of postlesional plasticity. Neuroimaging and electrophysiology studies have revealed that the location and volume of the stroke lesion, the affection of nerve fiber tracts, as well as functional and structural changes in the perilesional tissue and in large-scale bihemispheric networks are relevant biomarkers of post-stroke recovery. However, associated disorders, such as mood disorders, epilepsy, and neurodegenerative diseases, may induce secondary cerebral changes or aggravate the functional deficits and, thereby, compromise the potential for recovery.

Visual search training in occupational therapy – an example of expert practice in community-based stroke rehabilitation

Introduction

Visual searching is an essential component of many everyday activities. Search training is practised as part of occupational therapy to improve performance skills both in people with hemianopia and those with spatial inattention post stroke. Evaluation of the effectiveness of such training first requires a systematic and detailed description of the intervention. To this end, this study describes the practice of a specialist occupational therapist.

Method

Single sessions of intervention delivered by the occupational therapist to five participants with visual search disorders post stroke were video recorded. The recordings were analysed for content using a framework approach.

Results

The occupational therapist educated participants about the impact of their visual impairment on everyday activities. She used instructions, spatial cueing, placement of objects and verbal feedback to train increased amplitudes of eye and head movements, to direct attention into the blind field or neglected space and to encourage systematic searching during occupations and activities. Activities were graded by manipulating the area for attention and complexity in the environment.

Conclusion

This investigation provides a detailed description of a specialist occupational therapist’s community-based intervention for improving visual search post stroke.

Improvement in Touch Sensation after Stroke is Associated with Resting Functional Connectivity Changes

Background

Distributed brain networks are known to be involved in facilitating behavioral improvement after stroke, yet few, if any, studies have investigated the relationship between improved touch sensation after stroke and changes in functional brain connectivity.

Objective

We aimed to identify how recovery of somatosensory function in the first 6 months after stroke was associated with functional network changes as measured using resting-state connectivity analysis of functional magnetic resonance imaging (fMRI) data.

Methods

Ten stroke survivors underwent clinical testing and resting-state fMRI scans at 1 and 6 months post-stroke. Ten age-matched healthy participants were included as controls.

Results

Patients demonstrated a wide range of severity of touch impairment 1 month post-stroke, followed by variable improvement over time. In the stroke group, significantly stronger interhemispheric functional correlations between regions of the somatosensory system, and with visual and frontal areas, were found at 6 months than at 1 month post-stroke. Clinical improvement in touch discrimination was associated with stronger correlations at 6 months between contralesional secondary somatosensory cortex (SII) and inferior parietal cortex and middle temporal gyrus, and between contralesional thalamus and cerebellum.

Conclusion

The strength of connectivity between somatosensory regions and distributed brain networks, including vision and attention networks, may change over time in stroke survivors with impaired touch discrimination. Connectivity changes from contralesional SII and contralesional thalamus are associated with improved touch sensation at 6 months post-stroke. These functional connectivity changes could represent future targets for therapy.

Neural substrates underlying motor skill learning in chronic hemiparetic stroke patients

Motor skill learning is critical in post-stroke motor recovery, but little is known about its underlying neural substrates. Recently, using a new visuomotor skill learning paradigm involving a speed/accuracy trade-off in healthy individuals we identified three subpopulations based on their behavioral trajectories: fitters (in whom improvement in speed or accuracy coincided with deterioration in the other parameter), shifters (in whom speed and/or accuracy improved without degradation of the other parameter), and non-learners. We aimed to identify the neural substrates underlying the first stages of motor skill learning in chronic hemiparetic stroke patients and to determine whether specific neural substrates were recruited in shifters versus fitters. During functional magnetic resonance imaging (fMRI), 23 patients learned the visuomotor skill with their paretic upper limb. In the whole-group analysis, correlation between activation and motor skill learning was restricted to the dorsal prefrontal cortex of the damaged hemisphere (DLPFC_damh: r = −0.82) and the dorsal premotor cortex (PMd_damh: r = 0.70); the correlations was much lesser (−0.16 < r > 0.25) in the other regions of interest. In a subgroup analysis, significant activation was restricted to bilateral posterior parietal cortices of the fitters and did not correlate with motor skill learning. Conversely, in shifters significant activation occurred in the primary sensorimotor cortex_damh and supplementary motor area_damh and in bilateral PMd where activation changes correlated significantly with motor skill learning (r = 0.91). Finally, resting-state activity acquired before learning showed a higher functional connectivity in the salience network of shifters compared with fitters (qFDR < 0.05). These data suggest a neuroplastic compensatory reorganization of brain activity underlying the first stages of motor skill learning with the paretic upper limb in chronic hemiparetic stroke patients, with a key role of bilateral PMd.

A Randomized Controlled Trial of the Effect of Early Upper-Limb Training on Stroke Recovery and Brain Activation

Background. Upper-limb (UL) dysfunction is experienced by up to 75% of patients poststroke. The greatest potential for functional improvement is in the first month. Following reperfusion, evidence indicates that neuroplasticity is the mechanism that supports this recovery. Objective. This preliminary study hypothesized increased activation of putative motor areas in those receiving intensive, task-specific UL training in the first month poststroke compared with those receiving standard care. Methods. This was a single-blinded, longitudinal, randomized controlled trial in adult patients with an acute, first-ever ischemic stroke; 23 participants were randomized to standard care (n = 12) or an additional 30 hours of task-specific UL training in the first month poststroke beginning week 1. Patients were assessed at 1 week, 1 month, and 3 months poststroke. The primary outcome was change in brain activation as measured by functional magnetic resonance imaging. Results. When compared with the standard-care group, the intensive-training group had increased brain activation in the anterior cingulate and ipsilesional supplementary motor areas and a greater reduction in the extent of activation ( P = .02) in the contralesional cerebellum. Intensive training was associated with a smaller deviation from mean recovery at 1 month (Pr>F0 = 0.017) and 3 months (Pr>F = 0.006), indicating more consistent and predictable improvement in motor outcomes. Conclusion. Early, more-intensive, UL training was associated with greater changes in activation in putative motor (supplementary motor area and cerebellum) and attention (anterior cingulate) regions, providing support for the role of these regions and functions in early recovery poststroke.

Pontine infarction: diffusion-tensor imaging of motor pathways-a longitudinal study

PURPOSE

To investigate the dynamic evolution of diffusion indexes in the corticospinal tract (CST) distal to a pontine infarct by using diffusion-tensor imaging, to determine the relationship of these indexes with clinical prognosis, and to explore the structural changes in the motor pathway during recovery.

MATERIALS AND METHODS

This study was approved by the institutional ethics committee, and written informed consent was obtained from each participant. Seventeen patients with pontine infarct underwent five diffusion-tensor imaging examinations during a period of 6 months (within 7 days of onset, 14, 30, 90, and 180 after onset). Fractional anisotropic values were measured in the medulla, cerebral peduncle, internal capsule, and centrum semiovale. Fractional anisotropic values of the CST in the ipsilateral side of the infarct were compared with those in the contralateral sides and those in control subjects by using the Student t test and one-way analysis of variance, and their relationships with clinical scores were analyzed by using Pearson correlation analysis. Reconstructions of the CST were performed. Structural changes of the damaged CST were followed up.

RESULTS

Fractional anisotropic ratios in the CST above the pons decreased significantly compared with those in the contralateral side and those in control subjects within 7 days, on day 14, and on day 30 after onset (P < .001). Fractional anisotropic ratios above the pons on day 14 correlated positively with Fugl-Meyer scores on day 90 (r = 0.771, P < .001) and day 180 (r = 0.730, P = .001). Follow-up diffusion-tensor tractographic images showed regeneration and reorganization of the motor pathways.

CONCLUSION

Secondary degeneration of the CST can be detected at diffusion-tensor imaging in the early stages after pontine infarction, which could help predict the motor outcomes. Diffusion-tensor tractography can allow detection of regeneration and reorganization of the motor pathways during recovery.

Reorganizing therapy: changing the clinical approach to upper limb recovery post-stroke

Stroke is the leading cause of adult disability, and as a consequence, most therapists will provide health care to patients with stroke during their professional careers. An increasing number of studies are investigating the association between upper limb recovery and changes in brain activation patterns following stroke. In this review, we explore the translational implications of this research for health professionals working in stroke recovery. We argue that in light of the most recent evidence, therapists should consider how best to take full advantage of the brain's natural ability to reorganize, when prescribing and applying interventions to those with a stroke-affected upper limb. The authors propose that stroke is a brain-based problem that needs a brain-based solution. This review addresses two topics, anticipating recovery and maximizing recovery. It proposes five practice-ready recommendations that are based on the evidence reviewed. The over-riding aim of this review and discussion is to challenge therapists to reconsider the health care they prescribe and apply to people with a stroke-affected upper limb.

Imaging brain plasticity after trauma

The brain is highly plastic after stroke or epilepsy; however, there is a paucity of brain plasticity investigation after traumatic brain injury (TBI). This mini review summarizes the most recent evidence of brain plasticity in human TBI patients from the perspective of advanced magnetic resonance imaging. Similar to other forms of acquired brain injury, TBI patients also demonstrated both structural reorganization as well as functional compensation by the recruitment of other brain regions. However, the large scale brain network alterations after TBI are still unknown, and the field is still short of proper means on how to guide the choice of TBI rehabilitation or treatment plan to promote brain plasticity. The authors also point out the new direction of brain plasticity investigation.

Upper limb recovery after stroke is associated with ipsilesional primary motor cortical activity: a meta-analysis

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.

Beyond the lesion: neuroimaging foundations for post-stroke recovery

A shift is emerging in the way in which we view post-stroke recovery. This shift, supported by evidence from neuroimaging studies, encourages us to look beyond the lesion and to identify viable brain networks with capacity for plasticity. In this article, the authors review current advances in neuroimaging techniques and the new insights that they have contributed. The ability to quantify salvageable tissue, evidence of changes in remote networks, changes of functional and structural connectivity, and alterations in cortical thickness are reviewed in the context of their impact on post-stroke recovery. The value of monitoring spared structural connections and functional connectivity of brain networks within and across hemispheres is highlighted.

Diffusion tensor and volumetric magnetic resonance imaging using an MR-compatible hand-induced robotic device suggests training-induced neuroplasticity in patients with chronic stroke

Stroke is the third leading cause of mortality and a frequent cause of long-term adult impairment. Improved strategies to enhance motor function in individuals with chronic disability from stroke are thus required. Post-stroke therapy may improve rehabilitation and reduce long-term disability; however, objective methods for evaluating the specific impact of rehabilitation are rare. Brain imaging studies on patients with chronic stroke have shown evidence for reorganization of areas showing functional plasticity after a stroke. In this study, we hypothesized that brain mapping using a novel magnetic resonance (MR)-compatible hand device in conjunction with state-of-the-art magnetic resonance imaging (MRI) can serve as a novel biomarker for brain plasticity induced by rehabilitative motor training in patients with chronic stroke. This hypothesis is based on the premises that robotic devices, by stimulating brain plasticity, can assist in restoring movement compromised by stroke-induced pathological changes in the brain and that these changes can then be monitored by advanced MRI. We serially examined 15 healthy controls and 4 patients with chronic stroke. We employed a combination of diffusion tensor imaging (DTI) and volumetric MRI using a 3-tesla (3T) MRI system using a 12-channel Siemens Tim coil and a novel MR-compatible hand-induced robotic device. DTI data revealed that the number of fibers and the average tract length significantly increased after 8 weeks of hand training by 110% and 64%, respectively (p<0.001). New corticospinal tract (CST) fibers projecting progressively closer to the motor cortex appeared during training. Volumetric data analysis showed a statistically significant increase in the cortical thickness of the ventral postcentral gyrus areas of patients after training relative to pre-training cortical thickness (p<0.001). We suggest that rehabilitation is possible for a longer period of time after stroke than previously thought, showing that structural plasticity is possible even after 6 months due to retained neuroplasticity. Our study is an example of personalized medicine using advanced neuroimaging methods in conjunction with robotics in the molecular medicine era.

Motor recovery of the ipsilesional upper limb in subacute stroke

OBJECTIVE

To investigate the time-related changes in motor performance of the ipsilesional upper limb in subacute poststroke patients by using clinical and kinematic assessments.

DESIGN

Observational, longitudinal, prospective, monocentric study.

SETTING

Physical medicine and rehabilitation department.

PARTICIPANTS

Stroke patients (n=19; mean age, 62.9y) were included less than 30 days after a first unilateral ischemic/hemorrhagic stroke. The control group was composed of age-matched, healthy volunteers (n=9; mean age, 63.1y).

INTERVENTIONS

Clinical and kinematic assessments were conducted once a week during 6 weeks and 3 months after inclusion. Clinical measures consisted of Fugl-Meyer Assessment, Box and Block Test (BBT), Nine-Hole Peg Test (9HPT), and Barthel Index. We used a 3-dimensional motion recording system during a reach-to-grasp task to analyze movement smoothness, movement time, and peak velocity of the hand. Healthy controls performed both clinical (BBT and 9HPT) and kinematic evaluation within a single session.

MAIN OUTCOME MEASURES

BBT and 9HPT.

RESULTS

Recovery of ipsilesional upper arm capacities increased over time and leveled off after a 6-week period of rehabilitation, corresponding to 9 weeks poststroke. At study discharge, patients demonstrated similar ipsilesional clinical scores to controls but exhibited less smooth reaching movements. We found no effect of the hemispheric side of the lesion on ipsilesional motor deficits.

CONCLUSIONS

Our findings provide evidence that ipsilesional motor capacities remain impaired at least 3 months after stroke, even if clinical tests fail to detect the impairment. Focusing on this lasting ipsilesional impairment through a more detailed kinematic analysis could be of interest to understand the specific neural network underlying ipsilesional upper-limb impairment.

A program for solving the brain ischemia problem

Our recently described nonlinear dynamical model of cell injury is here applied to the problems of brain ischemia and neuroprotection. We discuss measurement of global brain ischemia injury dynamics by time course analysis. Solutions to proposed experiments are simulated using hypothetical values for the model parameters. The solutions solve the global brain ischemia problem in terms of "master bifurcation diagrams" that show all possible outcomes for arbitrary durations of all lethal cerebral blood flow (CBF) decrements. The global ischemia master bifurcation diagrams: (1) can map to a single focal ischemia insult, and (2) reveal all CBF decrements susceptible to neuroprotection. We simulate measuring a neuroprotectant by time course analysis, which revealed emergent nonlinear effects that set dynamical limits on neuroprotection. Using over-simplified stroke geometry, we calculate a theoretical maximum protection of approximately 50% recovery. We also calculate what is likely to be obtained in practice and obtain 38% recovery; a number close to that often reported in the literature. The hypothetical examples studied here illustrate the use of the nonlinear cell injury model as a fresh avenue of approach that has the potential, not only to solve the brain ischemia problem, but also to advance the technology of neuroprotection.

Using the endocannabinoid system as a neuroprotective strategy in perinatal hypoxic-ischemic brain injury

One of the most important causes of brain injury in the neonatal period is a perinatal hypoxic-ischemic event. This devastating condition can lead to long-term neurological deficits or even death. After hypoxic-ischemic brain injury, a variety of specific cellular mechanisms are set in motion, triggering cell damage and finally producing cell death. Effective therapeutic treatments against this phenomenon are still unavailable because of complex molecular mechanisms underlying hypoxic-ischemic brain injury. After a thorough understanding of the mechanism underlying neural plasticity following hypoxic-ischemic brain injury, various neuroprotective therapies have been developed for alleviating brain injury and improving long-term outcomes. Among them, the endocannabinoid system emerges as a natural system of neuroprotection. The endocannabinoid system modulates a wide range of physiological processes in mammals and has demonstrated neuroprotective effects in different paradigms of acute brain injury, acting as a natural neuroprotectant. The aim of this review is to study the use of different therapies to induce long-term therapeutic effects after hypoxic-ischemic brain injury, and analyze the important role of the endocannabinoid system as a new neuroprotective strategy against perinatal hypoxic-ischemic brain injury.

Changes in bimanual coordination during the first 6 weeks after moderate hemiparetic stroke

BACKGROUND

Better understanding of how bimanual coordination changes over the first weeks of recovery after stroke is required to address the potential utility for bimanual rehabilitation. Three-dimensional kinematic analysis can provide quantitative assessment of unimanual and bimanual movements.

OBJECTIVE

To assess the natural evolution of reaching kinematics during standard poststroke rehabilitation, focusing on bimanual coordination.

METHODS

A total of 12 hemiparetic, moderately impaired patients were included within 30 days after a first unilateral ischemic/hemorrhagic stroke; 7 kinematic assessments were performed once a week for 6 weeks and at 3 months after inclusion. The reach-to-grasp task was performed in 3 different conditions: unimanual with the healthy limb (UN), unimanual with the paretic limb (UP), and bimanual (BN/BP).

RESULTS

For the paretic limb, movement fluency (number of movement units and total movement time) was lower for bimanual reaching compared with unimanual reaching. For bimanual reaching, (1) movement kinematics were similar for both limbs, (2) recovery patterns of both limbs followed a similar profile with a plateau phase at 6 weeks poststroke, and (3) intertrial variability of between-hands synchronization decreased over sessions, although the mean delays remained the same.

CONCLUSIONS

Bimanual coordination started to become efficient 6 weeks after onset of stroke, so for patients such as those we tested, this time could be most opportune to start bimanual-oriented rehabilitation. The challenge in future research includes determining the characteristics of patients who may best benefit from bimanual therapy.

Neuroimaging Assessment of Spasticity Developed after Acquired Brain Injuries and Multiple Sclerosis

This study evaluated whether different imaging techniques correlate with specific variables routinely used to grade the types and complexities of patient conditions in neurorehabilitation services and their clinical outcomes, and if there are radiological patterns, topography or distribution of the lesions correlated to spasticity. The cohort studied included 75 patients, 38 patients with multiple sclerosis (MS) and 37 patients with acquired brain injuries (ABI) referred to the neurorehabilitation department from April 2009 to March 2010. Data included age, gender, diagnoses, complications, spasticity, length of stay, Rehabilitation Complexity Scale (RCS) and Northwick Park Dependency (NPDS) scores on admission and discharge. Forward stepwise multiple regressions were performed considering Spasticity as dependent and considering NPDS, RCS on admission and discharge, age, gender and length of stay as independent variables. Standardized intra-axial lesions in those with spasticity were fused with standardized axial DTIs from normal controls obtained under 3 T and 1.5 T MRI scanners. Spasticity was present in 36 patients. Regression was found between spasticity and all the other variables with r = 0.42, r2 = 0.17, adjr2 = 0.12r, F(4,66) = 3.53, p < 0.01. Residuals were acceptable. If the same is calculated excluding MS patients the results are higher with: r = 0.59, r2 = 0.35, adjr2 = 0.30, F(2,27) = 7.1885, p < 0.003. In MS subjects, spasticity appeared if lesions affected pyramidal tracts, callosal radiations extensively or brainstem. Those with ABI did develop spasticity if the lesion involved the internal capsules, pericommissural areas, optochiasmatic cistern or brainstem. Findings suggest that NPDSa and discharge and RCSd are higher in those developing spasticity. No obvious correlation between spasticity and RCSa was found. Subjects with MS are more likely to develop spasticity especially if the lesions are numerous and affect the corticospinal tracts, callosal radiations extensively or brainstem. In patients with ABI lesions affecting pyramidal tracts, pericommissural areas and optochiasmatic cisterns seem more likely to develop spasticity.

Rehabilitation for children after acquired brain injury: current and emerging approaches

Evidence is emerging of diverse, chronic, cumulative disabilities experienced by children in the months and years after acquired brain injury. The long-held assumption that younger children recover better from brain injury than older children or adults has been challenged by recent studies. Populations with acquired brain injury include children with traumatic brain injury and stroke, and a proportion of children with cerebral palsy. Although characteristics of brain injury in children vary, subgroups of this population offer the potential to inform our understanding of developing brain structure-function relationships in response to intervention. Limited evidence and few controlled rehabilitation trials exist regarding children with neurologic conditions. A number of rehabilitation approaches produced benefits in adult stroke, and cerebral palsy populations may be applied to children with other acquired brain injuries. Rehabilitation approaches that have been applied to children with acquired brain injuries, or hold promise for future applications, are reviewed.

Neural Plasticity as a Basis for Motor Learning and Neurorehabilitation

Skilled action is the end-product of learning processes that can improve several aspects of motor control such as strategic movement organisation, perceptual–motor associations, or muscle commands for basic components of sequentially evolving, complex movements. Experimental studies in healthy participants using functional imaging and transcranial magnetic stimulation have identified separable processes that form cortical motor representations and that assist this formation of representations. These processes capitalise on use-dependent plasticity and changes in cortical excitability before and after practice. In terms of neural circuits, motor learning manifests measurably via structures that support transient phenomena, such as attentive error monitoring, or through continued activation of brain structures that support control processes still adapting. Specifically, movement guidance engages the dorsal premotor and parietal cortex along the intraparietal sulcus in addition to the supplementary motor area and the anterior cerebellum. Movement conception based on explicit experience of the movement task involves the inferior premotor cortex. Evidence in patients recovering from brain lesions such as stroke, suggests that similar principles hold for neurorehabilitation as well. The challenging issue is to what degree altered motor strategies afford improvement in function through relearning and neural plasticity.

Stroke Rehabilitation

The need for stroke rehabilitation will lessen if stroke incidence declines and acute stroke medical and surgical treatment improves. The burden of stroke will also lessen as effective rehabilitation services (stroke rehabilitation units) and interventions are widely implemented. Despite the considerable amount of evidence available, implementation has been slow. Improvement in stroke rehabilitation will require continued professional advocacy, supported by local and national audit and future focused research.

The SWIFT Cast trial protocol: a randomized controlled evaluation of the efficacy of an ankle-foot cast on walking recovery early after stroke and the neural-biomechanical correlates of response

RATIONALE

An ankle-foot cast may enable people to repeatedly practice walking with a more normal movement pattern early after stroke.

AIMS

To evaluate the clinical efficacy of using an ankle-foot cast [soft scotch ankle-foot (SWIFT) Cast] to enhance walking recovery and to find whether site of stroke lesion and/or baseline biomechanical characteristics predict response to a SWIFT Cast.

DESIGN

Randomized, controlled, observer-blind trial.

STUDY

Participants (n = 120), 3-42 days after stroke with walking difficulty. All will receive conventional physical therapy. Those allocated to the experimental group will also receive a SWIFT Cast for up to six-weeks. During therapy sessions, the SWIFT Cast will be worn for retraining of walking as clinically appropriate. Outside therapy sessions, participants will initially wear the SWIFT Cast for the whole of their waking day, and this will be adjusted as clinically appropriate.

OUTCOMES

Measures will be undertaken before randomization, six-weeks thereafter and six-months after stroke. Primary outcome will be walking speed. Secondary outcomes will include the Functional Ambulation Category and efficiency of gait (e.g. step-time symmetry). Structural brain imaging using magnetic resonance imaging (standard fluid attenuated inversion recovery and T1-weighted high-resolution 'volume' spoiled gradient) will be undertaken at baseline. The clinical efficacy analysis will use analysis of covariance. The relationship between clinical response to therapy and biomechanical data will use correlation and multivariate regression techniques as required. For neuroimaging data, the relationship to clinical response to therapy will be computed using voxel-based lesion-symptom mapping. An interaction test across groups will identify which voxels are associated with different mean levels of treatment efficacy.

Relationship between touch impairment and brain activation after lesions of subcortical and cortical somatosensory regions

BACKGROUND

The neural basis underlying somatosensory impairment and recovery poststroke is virtually unexplored.

OBJECTIVE

To investigate the relationship between touch discrimination impairment and task-related brain activation in stroke survivors with somatosensory impairment following subcortical or cortical lesions.

METHODS

A total of 19 stroke survivors with touch impairment were investigated using fMRI and a touch discrimination paradigm 1-month poststroke; 11 had subcortical and 8 cortical sensory lesions; 12 age-matched healthy controls were also studied. Mean task-related contrast images were regressed with sensory impairment using random effects analysis for each subgroup and the total group.

RESULTS

There was no significant difference in touch impairment between stroke subgroups. Touch discrimination of the affected hand correlated negatively with task-related activation in the ipsilesional primary somatosensory cortex (SI; adjacent to the SI hand area activated in healthy controls); ipsilesional secondary somatosensory cortex (SII); contralesional thalamus; and attention-related frontal and occipital regions in the subcortical group. In contrast, the cortical group did not show significant correlated activity. Yet there was no significant between-group difference in a priori somatosensory regions: only in the superior medial frontal gyrus. A negative correlation was observed in the contralesional thalamus for the total group, irrespective of lesion type.

CONCLUSION

The findings provide novel evidence of neural correlates of poststroke touch impairment involving a distributed network of ipsilesional SI and SII, the contralesional thalamus, and frontal attention regions, particularly following subcortical lesions. Further systematic investigation of a modulatory role for ipsilesional SI, the thalamus, and frontal attention regions in sensory processing and recovery is warranted, particularly given implications for rehabilitation.

Effect of repetitive arm cycling following botulinum toxin injection for poststroke spasticity: evidence from FMRI

BACKGROUND AND OBJECTIVE

Investigations were performed to establish if repetitive arm cycling training enhances the antispastic effect of intramuscular botulinum toxin (BTX) injections in postischemic spastic hemiparesis. Effects on cerebral activation were evaluated by functional magnetic resonance imaging (fMRI).

METHODS

Eight chronic spastic hemisyndrome patients (49 ± 10 years) after middle cerebral artery infarction (5.5 ± 2.7 years) were investigated. BTX was injected into the affected arm twice, 6 months apart. Spasticity was assessed using the Ashworth Scale and range of motion before and 3 months after BTX injections. Images were analyzed using Brain Voyager QX 1.8, and fMRI signal changes were corrected for multiple comparisons.

RESULTS

During passive movements of affected and nonaffected hands, fMRI activity was increased bilaterally in the sensorimotor cortex (MISI), secondary somatosensory areas (SII), and supplementary motor area predominantly in the contralesional hemisphere, compared with the rest. Following repetitive arm cycling, fMRI activity increased further in MISI of the lesioned hemisphere and SII of the contralesional hemisphere. For patients with residual motor activity, treatment-related fMRI activity increases were associated with reduced spasticity; in completely plegic patients, there was no fMRI activity change in SII but increased spasticity after training.

CONCLUSION

Increased activity in SII of the contralesional hemisphere and in MISI of the lesioned hemisphere reflect a treatment-induced effect in the paretic arm. It is hypothesized that the increased BOLD activity results from increased afferent information related to the antispastic BTX effect reinforced by training.

Use of magnetic resonance imaging to predict outcome after stroke: a review of experimental and clinical evidence

Despite promising results in preclinical stroke research, translation of experimental data into clinical therapy has been difficult. One reason is the heterogeneity of the disease with outcomes ranging from complete recovery to continued decline. A successful treatment in one situation may be ineffective, or even harmful, in another. To overcome this, treatment must be tailored according to the individual based on identification of the risk of damage and estimation of potential recovery. Neuroimaging, particularly magnetic resonance imaging (MRI), could be the tool for a rapid comprehensive assessment in acute stroke with the potential to guide treatment decisions for a better clinical outcome. This review describes current MRI techniques used to characterize stroke in a preclinical research setting, as well as in the clinic. Furthermore, we will discuss current developments and the future potential of neuroimaging for stroke outcome prediction.