Repairing the human brain after stroke: I. Mechanisms of spontaneous recovery

Common and unique structural plasticity after left and right hemisphere stroke

Strokes to the left and right hemisphere lead to distinctive behavioral profiles. Are left and right hemisphere strokes (LHS and RHS) associated with distinct or common poststroke neuroplasticity patterns? Understanding this issue would reveal hemispheric neuroplasticity mechanisms in response to brain damage. To this end, we investigated poststroke structural changes (2 weeks to 3 months post-onset) using longitudinal MRI data from 69 LHS and 55 RHS patients and 31 demographic-matched healthy control participants. Both LHS and RHS groups showed statistically common plasticity independent of the lesioned hemisphere, including 1) gray matter (GM) expansion in the ipsilesional and contralesional precuneus, and contralesional superior frontal gyrus; 2) GM shrinkage in the ipsilesional medial orbital frontal gyrus and middle cingulate cortex. On the other hand, only RHS patients had significant GM expansion in the ipsilesional medial superior and orbital frontal cortex. Importantly, these common and unique GM changes post-stroke largely overlapped with highly-connected cortical hub regions in healthy individuals. Moreover, they correlated with behavioral recovery, indicating that post-stroke GM volumetric changes in cortical hubs reflect compensatory rather than maladaptive mechanisms. These results highlight the importance of structural neuroplasticity in hub regions of the cortex, along with the hemispheric specificity, for stroke recovery.

Clinical and Neural Predictors of Treatment Response to Music Listening Intervention after Stroke

Patients with post-stroke impairments present often significant variation in response to therapeutic interventions. Recent studies have shown that daily music listening can aid post-stroke recovery of language and memory, but reliable predictors of treatment response are unknown. Utilizing data from the music intervention arms of a single-blind randomized controlled trial (RCT) on stroke patients (N = 31), we built regression models to predict the treatment response of a two-month music listening intervention on language skills and verbal memory with baseline demographic, clinical and musical data as well as fMRI data from a music listening task. Clinically, greater improvement in verbal memory and language skills after the music listening intervention were predicted by the severity of the initial deficit and educational level. Neurally, greater baseline fMRI activation during vocal music listening in the left parietal cortical and medial frontal areas predicted greater treatment-induced improvement in language skills and greater baseline engagement of the auditory network during instrumental music listening predicted improvement in both verbal memory and language skills. Our results suggest that clinical, demographic, and neuroimaging data predicts music listening treatment response. This data could be used clinically to target music-based treatments.

Dependency in Activities of Daily Living During the First Year After Stroke

Background: Dependency in personal activities of daily living (ADL) is a common short-term and long-term consequence of stroke and requires targeted rehabilitation. As the duration of hospital stay has become shorter in recent decades, early identification of patients who require rehabilitation has become vital. To our knowledge, no study has investigated whether ADL dependency in the very early stages after admission to the stroke unit can explain ADL dependency 3 and 12 months later. This knowledge would facilitate planning for very early discharge and patient-centered rehabilitation.

Objective: This study evaluated whether ADL dependency within 2 days after stroke could explain ADL dependency at 3 and 12 months after stroke.

Methods: This longitudinal cohort study included patients with stroke who were treated at a stroke unit in the Sahlgrenska University Hospital (Gothenburg, Sweden) between May 2011 and March 2016. The primary independent variable was ADL dependency at 36–48 h after admission to the stroke unit, which was assessed using a Barthel Index (BI) score of ≤90. The dependent variables were self-reported personal ADL dependency at 3 and 12 months after stroke. Binary logistic regression analyses were performed.

Results: Of 366 eligible patients (58% male; median age 71 years), a majority (76%) had mild stroke and 60% were ADL dependent 36–48 h after stroke. Univariable and multivariable logistic regression analyses showed that patients who were dependent within the first 2 days after stroke had higher odds for being dependent 3 months as well as 12 months after stroke.

Conclusion: The results indicated that dependency in personal ADL during the first 2 days can explain dependency at 3- and 12-month post-stroke. Therefore, early ADL assessments post-stroke can be used for understanding rehabilitation needs after stroke.

Acquired Brain Injury in Adults: A Review of Pathophysiology, Recovery, and Rehabilitation

Purpose

To summarize existing literature from a range of fields (i.e., neurology, neuropsychology, neuroscience, neuroimaging, rehabilitation, speech-language pathology) that is relevant to the development and/or revision of cognitive rehabilitation programs for individuals with acquired brain injury (ABI) and in particular, for young adults.

Method

This paper reviews a range of ABI-associated topics including: 1) mechanisms of injury; 2) biological, individual-specific, and behavioral drivers of recovery; and 3) current methods of cognitive rehabilitation. It then narrows focus to young adults, a frequently affected and growing population to sustain ABI. The paper concludes by providing: 1) suggestions for key components of cognitive rehabilitation for young adults with ABI; 2) an example from our own research providing intensive academically-focused cognitive rehabilitation for young adults with ABI pursuing college; and 3) recommendations for future behavioral and neuroimaging studies in this area.

Conclusions

ABI is on the rise in the United States. Young adults have been sustaining ABI at higher rates over the past several decades. These injuries occur when they would otherwise be advancing their academic and career goals, making the cognitive deficits that often accompany ABI especially devastating for this group. Review of existing literature suggests cognitive rehabilitation programs that combine aspects of restorative, comprehensive, and contextualized approaches could promote recovery for young adults with ABI. Future intervention studies may benefit from including both behavioral and neural outcomes to best understand how principles of neuroplasticity- naturally embedded within many cognitive rehabilitation approaches-could be manipulated to promote cognitive recovery and long-lasting brain reorganization in this group.

Resting motor threshold in the course of hand motor recovery after stroke: a systematic review

Background

Resting motor threshold is an objective measure of cortical excitability. Numerous studies indicate that the success of motor recovery after stroke is significantly determined by the direction and extent of cortical excitability changes. A better understanding of this topic (particularly with regard to the level of motor impairment and the contribution of either cortical hemisphere) may contribute to the development of effective therapeutical strategies in this cohort.

Objectives

This systematic review collects and analyses the available evidence on resting motor threshold and hand motor recovery in stroke patients.

Methods

PubMed was searched from its inception through to 31/10/2020 on studies investigating resting motor threshold of the affected and/or the non-affected hemisphere and motor function of the affected hand in stroke cohorts.

Results

Overall, 92 appropriate studies (including 1978 stroke patients and 377 healthy controls) were identified. The analysis of the data indicates that severe hand impairment is associated with suppressed cortical excitability within both hemispheres and with great between-hemispheric imbalance of cortical excitability. Favorable motor recovery is associated with an increase of ipsilesional motor cortex excitability and reduction of between-hemispheric imbalance. The direction of change of contralesional motor cortex excitability depends on the amount of hand motor impairment. Severely disabled patients show an increase of contralesional motor cortex excitability during motor recovery. In contrast, recovery of moderate to mild hand motor impairment is associated with a decrease of contralesional motor cortex excitability.

Conclusions

This data encourages a differential use of rehabilitation strategies to modulate cortical excitability. Facilitation of the ipsilesional hemisphere may support recovery in general, whereas facilitation and inhibition of the contralesional hemisphere may enhance recovery in severe and less severely impaired patients, respectively.

Cortical Thickness of Brain Areas Beyond Stroke Lesions and Sensory-Motor Recovery: A Systematic Review

Background: The clinical outcome of patients suffering from stroke is dependent on multiple factors. The features of the lesion itself play an important role but clinical recovery is remarkably influenced by the plasticity mechanisms triggered by the stroke and occurring at a distance from the lesion. The latter translate into functional and structural changes of which cortical thickness might be easy to quantify one of the main players. However, studies on the changes of cortical thickness in brain areas beyond stroke lesion and their relationship to sensory-motor recovery are sparse. Objectives: To evaluate the effects of cerebral stroke on cortical thickness (CT) beyond the stroke lesion and its association with sensory-motor recovery. Materials and Methods: Five electronic databases (PubMed, Embase, Web of Science, Scopus and the Cochrane Library) were searched. Methodological quality of the included studies was assessed with the Newcastle-Ottawa Scale for non-randomized controlled trials and the Risk of Bias Cochrane tool for randomized controlled trials. Results: The search strategy retrieved 821 records, 12 studies were included and risk of bias assessed. In most of the included studies, cortical thinning was seen at the ipsilesional motor area (M1). Cortical thinning can occur beyond the stroke lesion, typically in regions anatomically connected because of anterograde degeneration. Nonetheless, studies also reported cortical thickening of regions of the unaffected hemisphere, likely related to compensatory plasticity. Some studies revealed a significant correlation between changes in cortical thickness of M1 or somatosensory (S1) cortical areas and motor function recovery. Discussion and Conclusions: Following a stroke, changes in cortical thickness occur both in regions directly connected to the stroke lesion and in contralateral hemisphere areas as well as in the cerebellum. The underlying mechanisms leading to these changes in cortical thickness are still to be fully understood and further research in the field is needed. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020200539; PROSPERO 2020, identifier: CRD42020200539.

COVID-19 and Aphasia

PURPOSE OF REVIEW

Aphasia is an acquired neurological language disorder after brain damages. Persons with aphasia (PWA) are more susceptible to behavioral and emotional implications due to inherent communication and/or cognitive difficulties. Currently, little is known regarding the impact of COVID-19 on PWA.

RECENT FINDINGS

There are now growing reports with evidence of neurological and dysexecutive syndromes subsequent to interference of brain functions in acute patients with COVID-19, leading to variable aphasia-like symptoms. COVID-19 affected chronic PWA more in terms of disrupted communication and daily routines, worsened psychosocial well-being, and difficulties getting aphasia services that adequately addressed their needs. Acute versus chronic PWA were disproportionately affected by COVID-19. Recognizing, examining, and managing COVID-19-related neurological and behavioral problems in PWA is not straightforward. As we passed the 1-year mark and approaching the 2-year mark of the onset of COVID-19, more research is necessary to prioritize strategies for improving current evidence-based care and rehabilitation of aphasia.

Lesion Area in the Cerebral Cortex Determines the Patterns of Axon Rewiring of Motor and Sensory Corticospinal Tracts After Stroke

The corticospinal tract (CST) is an essential neural pathway for reorganization that recovers motor functions after brain injuries such as stroke. CST comprises multiple pathways derived from different sensorimotor areas of the cerebral cortex; however, the patterns of reorganization in such complex pathways postinjury are largely unknown. Here we comprehensively examined the rewiring patterns of the CST pathways of multiple cerebral origins in a mouse stroke model that varied in size and location in the sensorimotor cortex. We found that spared contralesional motor and sensory CST axons crossed the midline and sprouted into the denervated side of the cervical spinal cord after stroke in a large cortical area. In contrast, the contralesional CST fibers did not sprout in a small stroke, whereas the ipsilesional axons from the spared motor area grew on the denervated side. We further showed that motor and sensory CST axons did not innervate the projecting areas mutually when either one was injured. The present results reveal the basic principles that generate the patterns of CST rewiring, which depend on stroke location and CST subtype. Our data indicate the importance of targeting different neural substrates to restore function among the types of injury.

Corticospinal Tract Microstructure Predicts Distal Arm Motor Improvements in Chronic Stroke

BACKGROUND AND PURPOSE

The corticospinal tract (CST) is a crucial brain pathway for distal arm and hand motor control. We aimed to determine whether a diffusion tensor imaging (DTI)-derived CST metric predicts distal upper extremity (UE) motor improvements in chronic stroke survivors.

METHODS

We analyzed clinical and neuroimaging data from a randomized controlled rehabilitation trial. Participants completed clinical assessments and neuroimaging at baseline and clinical assessments 4 months later, postintervention. Using univariate linear regression analysis, we determined the linear relationship between the DTI-derived CST fractional anisotropy asymmetry (FAasym) and the percentage of baseline change in log-transformed average Wolf Motor Function Test time for distal items (ΔlnWMFT-distal_%). The least absolute shrinkage and selection operator (LASSO) linear regressions with cross-validation and bootstrapping were used to determine the relative weighting of CST FAasym, other brain metrics, clinical outcomes, and demographics on distal motor improvement. Logistic regression analyses were performed to test whether the CST FAasym can predict clinically significant UE motor improvement.

RESULTS

lnWMFT-distal significantly improved at the group level. Baseline CST FAasym explained 26% of the variance in ΔlnWMFT-distal_%. A multivariate LASSO model including baseline CST FAasym, age, and UE Fugl-Meyer explained 39% of the variance in ΔlnWMFT-distal_%. Further, CST FAasym explained more variance in ΔlnWMFT-distal_% than the other significant predictors in the LASSO model.

DISCUSSION AND CONCLUSIONS

CST microstructure is a significant predictor of improvement in distal UE motor function in the context of an UE rehabilitation trial in chronic stroke survivors with mild-to-moderate motor impairment.Video Abstract available for more insight from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A350).

Transcranial direct current stimulation combined with robotic therapy for upper and lower limb function after stroke: a systematic review and meta-analysis of randomized control trials

BACKGROUND

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method able to modulate neuronal activity after stroke. The aim of this systematic review was to determine if tDCS combined with robotic therapy (RT) improves limb function after stroke when compared to RT alone.

METHODS

A search for randomized controlled trials (RCTs) published prior to July 15, 2021 was performed. The main outcome was function assessed with the Fugl-Meyer motor assessment for upper extremities (FM/ue) and 10-m walking test (10MWT) for the lower limbs. As secondary outcomes, strength was assessed with the Motricity Index (MI) or Medical Research Council scale (MRC), spasticity with the modified Ashworth scale (MAS), functional independence with the Barthel Index (BI), and kinematic parameters.

RESULTS

Ten studies were included for analysis (n = 368 enrolled participants). The results showed a non-significant effect for tDCS combined with RT to improve upper limb function [standardized mean difference (SMD) = - 0.12; 95% confidence interval (CI): - 0.35-0.11)]. However, a positive effect of the combined therapy was observed in the lower limb function (SMD = 0.48; 95% CI: - 0.15-1.12). Significant results favouring tDCS combined with RT were not found in strength (SMD = - 0.15; 95% CI: - 0.4-0.1), spasticity [mean difference (MD) =  - 0.15; 95% CI: - 0.8-0.5)], functional independence (MD = 2.5; 95% CI: - 1.9-6.9) or velocity of movement (SMD = 0.06; 95% CI: - 0.3-0.5) with a "moderate" or "low" recommendation level according to the GRADE guidelines.

CONCLUSIONS

Current findings suggest that tDCS combined with RT does not improve upper limb function, strength, spasticity, functional independence or velocity of movement after stroke. However, tDCS may enhance the effects of RT alone for lower limb function. tDCS parameters and the stage or type of stroke injury could be crucial factors that determine the effectiveness of this therapy.

From competition to cooperation: Visual neglect across the hemispheres

Visuospatial neglect is a frequent and disabling consequence of injuries to the right hemisphere. Patients with neglect show signs of impaired attention for left-sided events, which depends on dysfunction of fronto-parietal networks. After unilateral injury, such as stroke, these networks and their contralateral homologs can reorganize following multiple potential trajectories, which can be either adaptive or maladaptive. This article presents possible factors influencing the profile of evolution of neglect towards recovery or chronicity, and highlights potential mechanisms that may constrain these processes in time and space. The integrity of white matter pathways within and between the hemisphere appears to pose crucial connectivity constraints for compensatory brain plasticity from remote brain regions. Specifically, the availability of a sufficient degree of inter-hemispheric connectivity might be critical to shift the role of the undamaged left hemisphere in spatial neglect, from exerting maladaptive effects, to promoting compensatory activity.

Dysfunctional Tissue Correlates of Unrelated Naming Errors in Acute Left Hemisphere Stroke

Most naming error lesion-symptom mapping (LSM) studies have focused on semantic and/or phonological errors. Anomic individuals also produce unrelated word errors, which may be linked to semantic or modality-independent lexical deficits. To investigate the neural underpinnings of rarely-studied unrelated errors, we conducted LSM analyses in 100 individuals hospitalized with a left hemisphere stroke who completed imaging protocols and language assessments. We used least absolute shrinkage and selection operator regression to capture relationships between naming errors and dysfunctional brain tissue metrics (regional damage or hypoperfusion in vascular territories) in two groups: participants with and without impaired single-word auditory comprehension. Hypoperfusion-particularly within the parietal lobe-was an important error predictor, especially for the unimpaired group. In both groups, higher unrelated error proportions were associated with primarily ventral stream damage, the language route critical for processing meaning. Nonetheless, brain metrics implicated in unrelated errors were distinct from semantic error correlates.

Plasticity-Enhancing Effects of Levodopa Treatment after Stroke

Dopaminergic treatment in combination with rehabilitative training enhances long-term recovery after stroke. However, the underlying mechanisms on structural plasticity are unknown. Here, we show an increased dopaminergic innervation of the ischemic territory during the first week after stroke induced in Wistar rats subjected to transient occlusion of the middle cerebral artery (tMCAO) for 120 min. This response was also found in rats subjected to permanent focal ischemia induced by photothrombosis (PT) and mice subjected to PT or tMCAO. Dopaminergic branches were detected in the infarct core of mice and rats in both stroke models. In addition, the Nogo A pathway was significantly downregulated in rats treated with levodopa (LD) compared to vehicle-treated animals subjected to tMCAO. Specifically, the number of Nogo A positive oligodendrocytes as well as the levels of Nogo A and the Nogo A receptor were significantly downregulated in the peri-infarct area of LD-treated animals, while the number of Oligodendrocyte transcription factor 2 positive cells increased in this region after treatment. In addition, we observed lower protein levels of Growth Associated Protein 43 in the peri-infarct area compared to sham-operated animals without treatment effect. The results provide the first evidence of the plasticity-promoting actions of dopaminergic treatment following stroke.

Remote Corticospinal Tract Degeneration After Cortical Stroke in Rats May Not Preclude Spontaneous Sensorimotor Recovery

Background. Recovery of motor function after stroke appears to be related to the integrity of axonal connections in the corticospinal tract (CST) and corpus callosum, which may both be affected after cortical stroke. Objective. In the present study, we aimed to elucidate the relationship of changes in measures of the CST and transcallosal tract integrity, with the interhemispheric functional connectivity and sensorimotor performance after experimental cortical stroke. Methods. We conducted in vivo diffusion magnetic resonance imaging (MRI), resting-state functional MRI, and behavior testing in twenty-five male Sprague Dawley rats recovering from unilateral photothrombotic stroke in the sensorimotor cortex. Twenty-three healthy rats served as controls. Results. A reduction in the number of reconstructed fibers, a lower fractional anisotropy, and higher radial diffusivity in the ipsilesional but intact CST, reflected remote white matter degeneration. In contrast, transcallosal tract integrity remained preserved. Functional connectivity between the ipsi- and contralesional forelimb regions of the primary somatosensory cortex significantly reduced at week 8 post-stroke. Comparably, usage of the stroke-affected forelimb was normal at week 28, following significant initial impairment between day 1 and week 8 post-stroke. Conclusions. Our study shows that post-stroke motor recovery is possible despite degeneration in the CST and may be supported by intact neuronal communication between hemispheres.

Current Update on the Clinical Utility of MMSE and MoCA for Stroke Patients in Asia: A Systematic Review

Objective: Primary care clinicians in Asia employed the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) to aid dementia diagnosis post-stroke. Recent studies questioned their clinical utility in stroke settings for relying on verbal abilities and education level, as well as lack of consideration for aphasia and neglect. We aimed to review the clinical utility of the MMSE and MoCA for stroke patients in Asia and provide recommendations for clinical practice. Methods: PubMed, Scopus, Web of Science, and Science Direct were searched for relevant articles. Included studies were assessed for risk of bias. RevMan 5.4 was used for data synthesis (sensitivity and specificity) and covariates were identified. Results: Among the 48 full-text articles reviewed, 11 studies were included with 3735 total subjects; of these studies, 7 (77%) were conducted in China, 3 (27%) in Singapore, and 1 (9%) in South Korea. Both the MMSE and MoCA generally showed adequate sensitivity and specificity. Education was identified as a covariate that significantly affected detection accuracy. Due to heterogeneity in cutoff scores, methodologies, and languages, it was not feasible to suggest a single cutoff score. One additional point is recommended for MoCA for patients with <6 years of education. Conclusion: Clinicians in Asia are strongly recommended to consider the education level of stroke patients when interpreting the results of the MMSE and MoCA. Further studies in other Asian countries are needed to understand their clinical value in stroke settings.

Early motor network connectivity after stroke: An interplay of general reorganization and state-specific compensation

Motor recovery after stroke relies on functional reorganization of the motor network, which is commonly assessed via functional magnetic resonance imaging (fMRI)-based resting-state functional connectivity (rsFC) or task-related effective connectivity (trEC). Measures of either connectivity mode have been shown to successfully explain motor impairment post-stroke, posing the question whether motor impairment is more closely reflected by rsFC or trEC. Moreover, highly similar changes in ipsilesional and interhemispheric motor network connectivity have been reported for both rsFC and trEC after stroke, suggesting that altered rsFC and trEC may capture similar aspects of information integration in the motor network reflecting principle, state-independent mechanisms of network reorganization rather than state-specific compensation strategies. To address this question, we conducted the first direct comparison of rsFC and trEC in a sample of early subacute stroke patients (n = 26, included on average 7.3 days post-stroke). We found that both rsFC and trEC explained motor impairment across patients, stressing the clinical potential of fMRI-based connectivity. Importantly, intrahemispheric connectivity between ipsilesional M1 and premotor areas depended on the activation state, whereas interhemispheric connectivity between homologs was state-independent. From a mechanistic perspective, our results may thus arise from two distinct aspects of motor network plasticity: task-specific compensation within the ipsilesional hemisphere and a more fundamental form of reorganization between hemispheres.

The disrupted topological properties of structural networks showed recovery in ischemic stroke patients: a longitudinal design study

Introduction

Stroke is one of the leading causes of substantial disability worldwide. Previous studies have shown brain functional and structural alterations in adults with stroke. However, few studies have examined the longitudinal reorganization in whole-brain structural networks in stroke.

Methods

Here, we applied graph theoretical analysis to investigate the longitudinal topological organization of white matter networks in 20 ischemic stroke patients with a one-month interval between two timepoints. Two sets of clinical scores, Fugl-Meyer motor assessment (FMA) and neurological deficit scores (NDS), were assessed for all patients on the day the image data were collected.

Results

The stroke patients exhibited significant increases in FMA scores and significant reductions in DNS between the two timepoints. All groups exhibited small-world organization (σ  >  1) in the brain structural network, including a high clustering coefficient (γ  >  1) and a low normalized characteristic path length (λ ≈ 1). However, compared to healthy controls, stroke patients showed significant decrease in nodal characteristics at the first timepoint, primarily in the right supplementary motor area, right middle temporal gyrus, right inferior parietal lobe, right postcentral gyrus and left posterior cingulate gyrus. Longitudinal results demonstrated that altered nodal characteristics were partially restored one month later. Additionally, significant correlations between the nodal characteristics of the right supplementary motor area and the clinical scale scores (FMA and NDS) were observed in stroke patients. Similar behavioral-neuroimaging correlations were found in the right inferior parietal lobe.

Conclusion

Altered topological properties may be an effect of stroke, which can be modulated during recovery. The longitudinal results and the neuroimaging-behavioral relationship may provide information for understanding brain recovery from stroke. Future studies should detect whether observed changes in structural topological properties can predict the recovery of daily cognitive function in stroke.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-021-00652-1.

Cellular-resolution monitoring of ischemic stroke pathologies in the rat cortex

Stroke is a leading cause of disability in the Western world. Current post-stroke rehabilitation treatments are only effective in approximately half of the patients. Therefore, there is a pressing clinical need for developing new rehabilitation approaches for enhancing the recovery process, which requires the use of appropriate animal models. Here, we demonstrate the use of nonlinear microscopy of calcium sensors in the rat brain to study the effects of ischemic stroke injury on cortical activity patterns. We longitudinally recorded from thousands of neurons labeled with a genetically-encoded calcium indicator before and after an ischemic stroke injury in the primary motor cortex. We show that this injury has an effect on the activity patterns of neurons not only in the motor and somatosensory cortices, but also in the more distant visual cortex, and that these changes include modified firing rates and kinetics of neuronal activity patterns in response to a sensory stimulus. Changes in neuronal population activity provided animal-specific, circuit-level information on the post-stroke cortical reorganization process, which may be essential for evaluating the efficacy of new approaches for enhancing the recovery process.

Coordinated increase of reliable cortical and striatal ensemble activations during recovery after stroke

Skilled movements rely on a coordinated cortical and subcortical network, but how this network supports motor recovery after stroke is unknown. Previous studies focused on the perilesional cortex (PLC), but precisely how connected subcortical areas reorganize and coordinate with PLC is unclear. The dorsolateral striatum (DLS) is of interest because it receives monosynaptic inputs from motor cortex and is important for learning and generation of fast reliable actions. Using a rat focal stroke model, we perform chronic electrophysiological recordings in motor PLC and DLS during long-term recovery of a dexterous skill. We find that recovery is associated with the simultaneous emergence of reliable movement-related single-trial ensemble spiking in both structures along with increased cross-area alignment of spiking. Our study highlights the importance of consistent neural activity patterns across brain structures during recovery and suggests that modulation of cross-area coordination can be a therapeutic target for enhancing motor function post-stroke.

A Massive Right Hemisphere Infarction After Autologous Fat Grafting for Facial Filling

ABSTRACT

Cerebral fat embolism following facial autologous fat injection is a rare and serious complication. There are limited long-term follow-up data on the motion, cognitive and mental outcomes of surviving patients with cerebral fat embolism following facial autologous fat injection. In this study, the authors reported a patient with a 22-year-old woman with a massive right hemisphere infarction following facial autologous fat injection had normal cognitive function, independent living ability, and social function at 5 years follow-up visit, even though computed tomography showed her entire right cerebral hemisphere had atrophied with softening lesions.

Combined real-time fMRI and real time fNIRS brain computer interface (BCI): Training of volitional wrist extension after stroke, a case series pilot study

OBJECTIVE

Pilot testing of real time functional magnetic resonance imaging (rt-fMRI) and real time functional near infrared spectroscopy (rt-fNIRS) as brain computer interface (BCI) neural feedback systems combined with motor learning for motor recovery in chronic severely impaired stroke survivors.

APPROACH

We enrolled a four-case series and administered three sequential rt-fMRI and ten rt-fNIRS neural feedback sessions interleaved with motor learning sessions. Measures were: Arm Motor Assessment Tool, functional domain (AMAT-F; 13 complex functional tasks), Fugl-Meyer arm coordination scale (FM); active wrist extension range of motion (ROM); volume of activation (fMRI); and fNIRS HbO concentration. Performance during neural feedback was assessed, in part, using percent successful brain modulations during rt-fNIRS.

MAIN RESULTS

Pre-/post-treatment mean clinically significant improvement in AMAT-F (.49 ± 0.22) and FM (10.0 ± 3.3); active wrist ROM improvement ranged from 20° to 50°. Baseline to follow-up change in brain signal was as follows: fMRI volume of activation was reduced in almost all ROIs for three subjects, and for one subject there was an increase or no change; fNIRS HbO was within normal range, except for one subject who increased beyond normal at post-treatment. During rt-fNIRS neural feedback training, there was successful brain signal modulation (42%-78%).

SIGNIFICANCE

Severely impaired stroke survivors successfully engaged in spatially focused BCI systems, rt-fMRI and rt-fNIRS, to clinically significantly improve motor function. At the least, equivalency in motor recovery was demonstrated with prior long-duration motor learning studies (without neural feedback), indicating that no loss of motor improvement resulted from substituting neural feedback sessions for motor learning sessions. Given that the current neural feedback protocol did not prevent the motor improvements observed in other long duration studies, even in the presence of fewer sessions of motor learning in the current work, the results support further study of neural feedback and its potential for recovery of motor function in stroke survivors. In future work, expanding the sophistication of either or both rt-fMRI and rt-fNIRS could hold the potential for further reducing the number of hours of training needed and/or the degree of recovery. ClinicalTrials.gov ID: NCT02856035.

Effects of aerobic cycling training on mobility and functionality of acute stroke subjects: A randomized clinical trial

BACKGROUND

Studies demonstrate the benefits of aerobic cycling training in subacute and chronic stroke subjects, but there is a lack in the literature about its effects on the acute phase.

OBJECTIVE

Verify the effects of aerobic cycling training on lower limbs muscle strength, gait speed, balance, mobility and functionality of acute stroke subjects.

METHODS

Control group (CG) performed conventional physiotherapy twice a day and the intervention group (IG) performed a conventional physiotherapy and a cycle ergometer session, for five consecutive days. Subjects were assessed for muscle strength by a digital dynamometer, gait speed by the 10-meter-walk-test, balance by the Berg Balance Scale, mobility by the ICU-Mobility-Scale and functionality by the Perme Score.

RESULTS

Twenty subjects were enrolled in the study, 10 in the CG and 10 in the IG. Lower limbs muscle strength, the main endpoint, was better in the IG compared to the CG. The same was found in the secondary endpoints. The intragroup analysis was also positive for the CG in the mobility and functionality.

CONCLUSIONS

Conventional physiotherapy combined with cycling exercise showed better results in the improvement of muscle strength of lower limbs, mobility and functionality of subjects who suffered from acute stroke.

The Effectiveness of Verbal-Gestural Treatment on Verb Naming in Acute Inpatient Rehabilitation

Purpose The purpose of this study was to investigate the effectiveness of verbal-gestural treatment on verb production in patients with acute aphasia. Method Treatment was delivered during inpatient stay to four participants using a single-subject design. Results All patients demonstrated improvements in verbal expression. Some patients' improvements generalized to untrained verbs and nouns. Conclusions This study indicates verbal-gestural treatment can be an effective treatment model for acute aphasia in a hospital environment. Concurrent deficits resulting from stroke may impact the success with verbal-gestural treatment at this acute phase of recovery.

HoMEcare aRm rehabiLItatioN (MERLIN): telerehabilitation using an unactuated device based on serious games improves the upper limb function in chronic stroke

BACKGROUND

HoMEcare aRm rehabiLItatioN (MERLIN) is an unactuated version of the robotic device ArmAssist combined with a telecare platform. Stroke patients are able to train the upper limb function using serious games at home. The aim of this study is to investigate the effect of MERLIN training on the upper limb function of patients with unilateral upper limb paresis in the chronic phase of stroke (> 6 months post stroke).

METHODS

Patients trained task specific serious games for three hours per week during six weeks using an unactuated version of a robotic device. Progress was monitored and game settings were tailored through telerehabilitation. Measurements were performed six weeks pre-intervention (T0), at the start (T1), end (T2) and six weeks post-intervention (T3). Primary outcome was the Wolf Motor Function Test (WMFT). Secondary outcomes were other arm function tests, quality of life, user satisfaction and motivation.

RESULTS

Twelve patients were included, ten completed the training. From start of the intervention to six weeks follow up, WMFT improved significantly with 3.8 points (p = .006), which is also clinically relevant. No significant changes in quality of life were observed. Patients were overall satisfied with the usability of the device. Comfort and the robustness of the system need further improvements.

CONCLUSION

Patients in the chronic phase of stroke significantly improved their upper limb function with the MERLIN training at home. Trial registration This study is registered at the Netherlands Trial Register (NL7535). Registered 18-02-2019, https://www.trialregister.nl/trial/7535 .

Evaluating telehealth delivery of a compensatory memory rehabilitation programme following stroke: A single-case experimental design

Rehabilitation of memory remains an unmet need for many stroke survivors. Telehealth methods may provide a solution, however evidence supporting the efficacy of remotely-delivered therapy is needed. A non-concurrent multiple baseline design was used with randomized onset of intervention across five individuals with chronic stroke-related memory complaints. A six-week compensatory memory skills programme was delivered individually via internet videoconferencing. Target behaviours of frequencies of self-reported lapses of everyday and prospective memory were measured weekly across baseline, intervention, and follow-up phases. A secondary outcome of functional goal attainment was measured once per phase, with participants setting two personal rehabilitation goals. Data were analysed visually and statistically. Improvements in memory functioning were statistically significant on at least one measure of target behaviour for four out of five participants at intervention or follow-up. Visual evidence of level change indicated at least modest improvements for all participants by follow-up. All participants attained at least one functional goal by follow-up. High rates of treatment adherence and participant satisfaction were observed. Technological issues were minimal and did not impact content delivery or engagement. These results provide preliminary support for the efficacy of a telehealth-delivered rehabilitation programme in improving memory function and achieving memory-related goals for stroke survivors.

Interaction between cognitive reserve and age moderates effect of lesion load on stroke outcome

The concepts of brain reserve and cognitive reserve were recently suggested as valuable predictors of stroke outcome. To test this hypothesis, we used age, years of education and lesion size as clinically feasible coarse proxies of brain reserve, cognitive reserve, and the extent of stroke pathology correspondingly. Linear and logistic regression models were used to predict cognitive outcome (Montreal Cognitive Assessment) and stroke-induced impairment and disability (NIH Stroke Scale; modified Rankin Score) in a sample of 104 chronic stroke patients carefully controlled for potential confounds. Results revealed 46% of explained variance for cognitive outcome (p < 0.001) and yielded a significant three-way interaction: Larger lesions did not lead to cognitive impairment in younger patients with higher education, but did so in younger patients with lower education. Conversely, even small lesions led to poor cognitive outcome in older patients with lower education, but didn’t in older patients with higher education. We observed comparable three-way interactions for clinical scores of stroke-induced impairment and disability both in the acute and chronic stroke phase. In line with the hypothesis, years of education conjointly with age moderated effects of lesion on stroke outcome. This non-additive effect of cognitive reserve suggests its post-stroke protective impact on stroke outcome.

A Virtual, Randomized, Control Trial of a Digital Therapeutic for Speech, Language, and Cognitive Intervention in Post-stroke Persons With Aphasia

Background: Post-stroke aphasia is a chronic condition that impacts people's daily functioning and communication for many years after a stroke. Even though these individuals require sustained rehabilitation, they face extra burdens to access care due to shortages in qualified clinicians, insurance limitations and geographic access. There is a need to research alternative means to access intervention remotely, such as in the case of this study using a digital therapeutic.

Objective: To assess the feasibility and clinical efficacy of a virtual speech, language, and cognitive digital therapeutic for individuals with post-stroke aphasia relative to standard of care.

Methods: Thirty two participants completed the study (experimental: average age 59.8 years, 7 female, 10 male, average education: 15.8 years, time post-stroke: 53 months, 15 right handed, 2 left handed; control: average age 64.2 years, 7 female, 8 male, average education: 15.3 years, time post-stroke: 36.1 months, 14 right handed, 1 left handed). Patients in the experimental group received 10 weeks of treatment using a digital therapeutic, Constant Therapy-Research (CT-R), for speech, language, and cognitive therapy, which provides evidence-based, targeted therapy with immediate feedback for users that adjusts therapy difficulty based on their performance. Patients in the control group completed standard of care (SOC) speech-language pathology workbook pages.

Results: This study provides Class II evidence that with the starting baseline WAB-AQ score, adjusted by −0.69 for every year of age, and by 0.122 for every month since stroke, participants in the CT-R group had WAB-AQ scores 6.43 higher than the workbook group at the end of treatment. Additionally, secondary outcome measures included the WAB-Language Quotient, WAB-Cognitive Quotient, Brief Test of Adult Cognition by Telephone (BTACT), and Stroke and Aphasia Quality of Life Scale 39 (SAQOL-39), with significant changes in BTACT verbal fluency subtest and the SAQOL-39 communication and energy scores for both groups.

Conclusions: Overall, this study demonstrates the feasibility of a fully virtual trial for patients with post-stroke aphasia, especially given the ongoing COVID19 pandemic, as well as a safe, tolerable, and efficacious digital therapeutic for language/cognitive rehabilitation.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT04488029.

Neuroprotection by cattle encephalon glycoside and ignotin beyond the time window of thrombolysis in ischemic stroke

Cattle encephalon glycoside and ignotin (CEGI) injection is known as a multi-target neuroprotective drug that contains numerous liposoluble molecules, such as polypeptides, monosialotetrahexosyl ganglioside (GM-1), free amino acids, hypoxanthine and carnosine. CEGI has been approved by the Chinese State Food and Drug Administration and widely used in the treatments of various diseases, such as stroke and Alzheimer's disease. However, the neuroprotective effects of CEGI beyond the time window of thrombolysis (within 4.5 hours) on acute ischemic stroke remain unclear. This study constructed a rat middle cerebral artery occlusion model by suture-occluded method to simulate ischemic stroke. The first daily dose was intraperitoneally injected at 8 hours post-surgery and the CEGI treatments continued for 14 days. Results of the modified five-point Bederson scale, beam balance test and rotameric test showed the neurological function of ischemic stroke rats treated with 4 mL/kg/d CEGI improved significantly, but the mortality within 14 days did not change significantly. Brain MRI and 2,3,5-triphenyltetrazolium chloride staining confirmed that the infarct size in the 4 mL/kg/d CEGI-treated rats was significantly reduced compared with ischemic insult only. The results of transmission electron microscopy and double immunofluorescence staining showed that the hippocampal neuronal necrosis in the ischemic penumbra decreased whereas the immunopositivity of new neuronal-specific protein doublecortin and the percentage of Ki67/doublecortin positive cells increased in CEGI-treated rats compared with untreated rats. Our results suggest that CEGI has an effective neuroprotective effect on ischemic stroke when administered after the time window of thrombolysis. The study was approved by the Animal Ethics Committee of The Third Military Medical University, China.

Neurotrophin-3 upregulation associated with intravenous transplantation of bone marrow mononuclear cells induces axonal sprouting and motor functional recovery in the long term after neocortical ischaemia

Bone marrow mononuclear cells (BMMCs) have been identified as a relevant therapeutic strategy for the treatment of several chronic diseases of the central nervous system. The aim of this work was to evaluate whether intravenous treatment with BMMCs facilitates the reconnection of lesioned cortico-cortical and cortico-striatal pathways, together with motor recovery, in injured adult Wistar rats using an experimental model of unilateral focal neocortical ischaemia. Animals with cerebral cortex ischaemia underwent neural tract tracing for axonal fibre analysis, differential expression analysis of genes involved in apoptosis and neuroplasticity by RT-qPCR, and motor performance assessment by the cylinder test. Quantitative and qualitative analyses of axonal fibres labelled by an anterograde neural tract tracer were performed. Ischaemic animals treated with BMMCs showed a significant increase in axonal sprouting in the ipsilateral neocortex and in the striatum contralateral to the injured cortical areas compared to untreated rodents. In BMMC-treated animals, there was a trend towards upregulation of the Neurotrophin-3 gene compared to the other genes, as well as modulation of apoptosis by BMMCs. On the 56th day after ischaemia, BMMC-treated animals showed significant improvement in motor performance compared to untreated rats. These results suggest that in the acute phase of ischaemia, Neurotrophin-3 is upregulated in response to the lesion itself. In the long run, therapy with BMMCs causes axonal sprouting, reconnection of damaged neuronal circuitry and a significant increase in motor performance.

Distinction of High- and Low-Frequency Repetitive Transcranial Magnetic Stimulation on the Functional Reorganization of the Motor Network in Stroke Patients

Objective

To investigate the functional reorganization of the motor network after repetitive transcranial magnetic stimulation (rTMS) in stroke patients with motor dysfunction and the distinction between high-frequency rTMS (HF-rTMS) and low-frequency rTMS (LF-rTMS).

Methods

Thirty-three subcortical stroke patients were enrolled and assigned to the HF-rTMS group, LF-rTMS group, and sham group. Each patient of rTMS groups received either 10.0 Hz rTMS over the ipsilesional primary motor cortex (M1) or 1.0 Hz rTMS over the contralesional M1 for 10 consecutive days. A resting-state functional magnetic resonance imaging (fMRI) scan and neurological examinations were performed at baseline and after rTMS. The motor network and functional connectivities intramotor network with the core brain regions including the bilateral M1, premotor area (PMA), and supplementary motor area (SMA) were calculated. Comparisons of functional connectivities and Pearson correlation analysis between functional connectivity changes and behavioral improvement were calculated.

Results

Significant motor improvement was found after rTMS in all groups which was larger in two rTMS groups than in the sham group. The functional connectivities of the motor network were significantly increased in bilateral M1, SMA, and contralesional PMA after real rTMS. These changes were only detected in the regions of the ipsilesional hemisphere in the HF-rTMS group and in the regions of the contralesional hemisphere in the LF-rTMS group. Significantly changed functional connectivities of the intramotor network were found between the ipsilesional M1 and SMA and contralesional PMA, between contralesional M1 and contralesional SMA, between contralesional SMA and ipsilesional SMA and contralesional PMA in the HF-rTMS group in which the changed connectivity between ipsilesional M1 and contralesional PMA was obviously correlated with the motor improvement. In addition, the functional connectivity of the intramotor network between ipsilesional M1 and contralesional PMA was significantly higher in the HF-rTMS group than in the LF-rTMS group.

Conclusion

Both HF-rTMS and LF-rTMS have a positive effect on motor recovery in patients with subcortical stroke and could promote the reorganization of the motor network. HF-rTMS may contribute more to the functional connectivity reorganization of the ipsilesional motor network and realize greater benefit to the motor recovery.

Neuro-Clinical Signatures of Language Impairments after Acute Stroke: A VBQ Analysis of Quantitative Native CT Scans

OBJECTIVES

Ischemic stroke affects language production and/or comprehension and leads to devastating long-term consequences for patients and their families. Previous studies have shown that neuroimaging can increase our knowledge of the basic mechanisms of language recovery. Currently, models for predicting patients' outcomes have limited use in the clinic for the evaluation and optimization of rehabilitative strategies mostly because that are often based on high-resolution magnetic resonance imaging (MRI) data, which are not always possible to carry out in the clinical routine. Here, we investigate the use of Voxel-Based Morphometry (VBM), multivariate modelling and native Computed Tomography (nCT) scans routinely acquired in the acute stage of stroke for identifying biological signatures that explicate the relationships between brain anatomy and types of impairments.

METHODS

80 stroke patients and 30 controls were included. nCT-scans were acquired in the acute ischemia stage and bedside clinical assessment from board-certified neurologist based on the NIH stroke scale. We use a multivariate Principal Component Analyses (PCA) to identify the brain signatures group the patients according to the presence or absence of impairment and identify the association between local Grey Matter (GM) and White Matter (WM) nCT values with the presence or absence of the impairment.

RESULTS

Individual patient's nCT scans were compared to a group of controls' with no radiological signs of stroke to provide an automated delineation of the lesion. Consistently across the whole group the regions that presented significant difference GM and WM values overlap with known areas that support language processing.

CONCLUSION

In summary, the method applied to nCT scans performed in the acute stage of stroke provided robust and accurate information about brain lesions' location and size, as well as quantitative values. We found that nCT and VBQ analyses are effective for identifying neural signatures of concomitant language impairments at the individual level, and neuroanatomical maps of aphasia at the population level. The signatures explicate the neurophysiological mechanisms underlying aetiology of the stroke. Ultimately, similar analyses with larger cohorts could lead to a more integrated multimodal model of behaviour and brain anatomy in the early stage of ischemic stroke.

Encouraging an excitable brain state: mechanisms of brain repair in stroke

Stroke induces a plastic state in the brain. This period of enhanced plasticity leads to the sprouting of new axons, the formation of new synapses and the remapping of sensory-motor functions, and is associated with motor recovery. This is a remarkable process in the adult brain, which is normally constrained in its levels of neuronal plasticity and connectional change. Recent evidence indicates that these changes are driven by molecular systems that underlie learning and memory, such as changes in cellular excitability during memory formation. This Review examines circuit changes after stroke, the shared mechanisms between memory formation and brain repair, the changes in neuronal excitability that underlie stroke recovery, and the molecular and pharmacological interventions that follow from these findings to promote motor recovery in animal models. From these findings, a framework emerges for understanding recovery after stroke, central to which is the concept of neuronal allocation to damaged circuits. The translation of the concepts discussed here to recovery in humans is underway in clinical trials for stroke recovery drugs.

Recovery After Stroke

PURPOSE OF REVIEW

This article describes restorative therapies to improve patient outcomes after stroke. These therapies contrast with acute stroke treatments such as recombinant tissue plasminogen activator (rtPA) and thrombectomy that target clots, aim to salvage threatened brain tissue to limit injury, and have a time window measured in hours. Restorative therapies target the brain, aim to promote plasticity within surviving brain tissue, and have a time window measured in days to weeks or longer.

RECENT FINDINGS

A number of drugs are under study. Preclinical studies are providing attractive therapeutic candidates for translation, such as the C-C chemokine receptor 5 inhibitor maraviroc. Some drug studies have used a pragmatic approach, which is premature for the nascent field of neural repair. Substantial data support the utility of activity-dependent therapies, including constraint-induced movement therapy, with recent studies supporting the need for very high doses to generate the best functional gains. While stem cell therapies are at an early stage, mounting preclinical evidence supports the efficacy of mesenchymal stem cells; some initial human studies are supportive. Several types of brain stimulation have been examined, and in some cases initial studies are promising.

SUMMARY

Improved insights into stroke recovery and its treatment have the potential to reduce disability in a large segment of stroke survivors.

Stroke core revealed by tissue scattering using spatial frequency domain imaging

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We present OCT and SFDI as methods to measure the spatial extent of stroke in mice.

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OCT was a reliable predictor of the stroke core in a photothrombosis stroke model.

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SFDI scattering coefficient spatially overlaps with OCT attenuation after stroke.

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Scattering increases following stroke reliably predict ischemic injury.

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SFDI provides a wide-field optical approach to map the stroke core.

Ischemic stroke leads to a reduction or complete loss of blood supply causing injury to brain tissue, which ultimately leads to behavioral impairment. Optical techniques are widely used to study the structural and functional changes that result as a consequence of ischemic stroke both in the acute and chronic phases of stroke recovery. It is currently a challenge to accurately estimate the spatial extent of the infarct without the use of histological parameters however, and in order to follow recovery mechanisms longitudinally at the mesoscopic scale it is essential to know the spatial extent of the stroke core. In this paper we first establish optical coherence tomography (OCT) as a reliable indicator of the stroke core by analyzing signal attenuation and spatially correlating it with the infarct, determined by staining with triphenyl-tetrazolium chloride (TTC). We then introduce spatial frequency domain imaging (SFDI) as a mesoscopic optical technique that can be used to accurately measure the infarct spatial extent by exploiting changes in optical scattering that occur as a consequence of ischemic stroke. Additionally, we follow the progression of ischemia through the acute and sub-acute phases of stroke recovery using both OCT and SFDI and show a consistently high spatial overlap in estimating infarct location. The use of SFDI in assessing infarct location will allow longitudinal studies targeted at following functional recovery mechanisms on a mesoscopic level without having to sacrifice the mouse acutely.

Cerebellar Transcranial Direct Current Stimulation for Motor Learning in People with Chronic Stroke: A Pilot Randomized Controlled Trial

Cerebellar transcranial direct current stimulation (ctDCS) is a non-invasive brain stimulation technique that alters neural plasticity through weak, continuous, direct currents delivered to the cerebellum. This study aimed to evaluate the feasibility of conducting a randomized controlled trial (RCT) delivering three consecutive days of ctDCS during split-belt treadmill training (SBTT) in people with chronic stroke. Using a double-blinded, parallel-group RCT design, eligible participants were randomly allocated to receive either active anodal ctDCS or sham ctDCS combined with SBTT on three consecutive days. Outcomes were assessed at one-week follow-up, using step length symmetry as a measure of motor learning and comfortable over-ground walking speed as a measure of walking capacity. The feasibility of the RCT protocol was evaluated based on recruitment, retention, protocol deviations and data completeness. The feasibility of the intervention was assessed based on safety, adherence and intervention fidelity. Of the 26 potential participants identified over four months, only four were enrolled in the study (active anodal ctDCS n = 1, sham ctDCS n = 3). Both the inclusion criteria and the fidelity of the SBTT relied upon the accurate estimation of step length asymmetry. The method used to determine the side of the step length asymmetry was unreliable and led to deviations in the protocol. The ctDCS intervention was well adhered to, safe, and delivered as per the planned protocol. Motor learning outcomes for individual participants revealed that treadmill step length symmetry remained unchanged for three participants but improved for one participant (sham ctDCS). Comfortable over-ground walking speed improved for two participants (sham ctDCS). The feasibility of the planned protocol and intervention was limited by intra-individual variability in the magnitude and side of the step length asymmetry. This limited the sample and compromised the fidelity of the SBTT intervention. To feasibly conduct a full RCT investigating the effect of ctDCS on locomotor adaptation, a reliable method of identifying and defining step length asymmetry in people with stroke is required. Future ctDCS research should either optimize the methods for SBTT delivery or utilize an alternative motor adaptation task.

Angiogenesis and Blood-Brain Barrier Permeability in Vascular Remodeling after Stroke

Angiogenesis, the growth of new blood vessels, is a natural defense mechanism helping to restore oxygen and nutrient supply to the affected brain tissue following an ischemic stroke. By stimulating vessel growth, angiogenesis may stabilize brain perfusion, thereby promoting neuronal survival, brain plasticity, and neurologic recovery. However, therapeutic angiogenesis after stroke faces challenges: new angiogenesis-induced vessels have a higher than normal permeability, and treatment to promote angiogenesis may exacerbate outcomes in stroke patients. The development of therapies requires elucidation of the precise cellular and molecular basis of the disease. Microenvironment homeostasis of the central nervous system is essential for its normal function and is maintained by the blood-brain barrier (BBB). Tight junction proteins (TJP) form the tight junction (TJ) between vascular endothelial cells (ECs) and play a key role in regulating the BBB permeability. We demonstrated that after stroke, new angiogenesis-induced vessels in peri-infarct areas have abnormally high BBB permeability due to a lack of major TJPs in ECs. Therefore, promoting TJ formation and BBB integrity in the new vessels coupled with speedy angiogenesis will provide a promising and safer treatment strategy for improving recovery from stroke. Pericyte is a central neurovascular unite component in vascular barriergenesis and are vital to BBB integrity. We found that pericytes also play a key role in stroke-induced angiogenesis and TJ formation in the newly formed vessels. Based on these findings, in this article, we focus on regulation aspects of the BBB functions and describe cellular and molecular special features of TJ formation with an emphasis on role of pericytes in BBB integrity during angiogenesis after stroke.

Funktionserholung nach Schlaganfall und die therapeutische Rolle der nicht-invasiven Hirnstimulation

Im Bereich der non-invasiven Hirnstimulation stellen die transkranielle Magnetstimulation (engl. transcranial magnetic stimulation, TMS) sowie die transkranielle Gleichstromstimulation (engl. transcranial direct current stimulation, tDCS) bis heute die wichtigsten Techniken zur Modulation kortikaler Erregbarkeit dar. Beide Verfahren induzieren Nacheffekte, welche die Zeit der reinen Stimulation überdauern, und ebnen damit den Weg für ihren therapeutischen Einsatz beim Schlaganfall. In diesem Übersichtsartikel diskutieren wir die aktuelle Datenlage TMS- und tDCS-vermittelter Therapien für die häufigsten schlaganfallbedingten Defizite wie Hemiparese, Aphasie und Neglect. Darüber hinaus adressieren wir mögliche Einschränkungen der gegenwärtigen Ansätze und zeigen Ansatzpunkte auf, um Neuromodulation nach Schlaganfall effektiver zu gestalten und damit das Outcome der Patienten zu verbessern.

BDNF (rs6265) Val < Met polymorphism can buffer cognitive functions against post stroke CT/MRI pathological findings

Brain lesions following stroke have been shown prevalently in CT/MRI, and it was confirmed that lesions usually are accompanied by cognitive deficits. Although previous studies have emphasized that BDNF Val66Met polymorphism had a substantial role in neurogenesis and synaptic plasticity, it remains unclear to what extent an interaction may be appeared between neuroimaging findings and Val66Met variants on different cognitive functions following stroke. In a case-control study the carriers of at least one Val allele (n = 56), were compared with the carriers of Met/Met homozygotes (n = 156) in order to find possible neuroimaging factors in relation to cognitive functions in a sample from the north of Iran. The third edition of Addenbrooke's Cognitive Examination (ACE-III) was used to determine the cognitive functions. There were interactive effects among Val66Met genotypes with dominant hemisphere lesions [F = 6.97, ή² = 0.03, p = 0.009], cerebral atrophy [F = 5.43, ή² = 0.03, p = 0.011] and number of lesions [F = 4.32, ή² = 0.04, p = 0.014], for visuospatial skills, memory, and attention functions respectively; implying that the effect of dominant hemisphere lesions, cerebral atrophy, and multiple lesions on cognitive functions have been modulated by Met/Met homozygosity. The destructive effect of Val/Met homozygosity on cognitive functions was shown to be exacerbated by dominant hemispheric lesions, cerebral atrophy, and multiple lesions following stroke. The findings of present research support our hypothesis that interaction of Val66Met variants with cerebral lesions is associated with cognitive dysfunctions in post stroke conditions; particularly through Met/Met homozygosity which act as a buffer mechanism against some CT/MRI pathological findings.

Sensorimotor cortex beta oscillations reflect motor skill learning ability after stroke

Recovery of skilled movement after stroke is assumed to depend on motor learning. However, the capacity for motor learning and factors that influence motor learning after stroke have received little attention. In this study, we first compared motor skill acquisition and retention between well-recovered stroke patients and age- and performance-matched healthy controls. We then tested whether beta oscillations (15–30 Hz) from sensorimotor cortices contribute to predicting training-related motor performance. Eighteen well-recovered chronic stroke survivors (mean age 64 ± 8 years, range: 50–74 years) and 20 age- and sex-matched healthy controls were trained on a continuous tracking task and subsequently retested after initial training (45–60 min and 24 h later). Scalp electroencephalography was recorded during the performance of a simple motor task before each training and retest session. Stroke patients demonstrated capacity for motor skill learning, but it was diminished compared to age- and performance-matched healthy controls. Furthermore, although the properties of beta oscillations prior to training were comparable between stroke patients and healthy controls, stroke patients did show less change in beta measures with motor learning. Lastly, although beta oscillations did not help to predict motor performance immediately after training, contralateral (ipsilesional) sensorimotor cortex post-movement beta rebound measured after training helped predict future motor performance, 24 h after training. This finding suggests that neurophysiological measures such as beta oscillations can help predict response to motor training in chronic stroke patients and may offer novel targets for therapeutic interventions.

Predicting clinically significant motor function improvement after contemporary task-oriented interventions using machine learning approaches

BACKGROUND

Accurate prediction of motor recovery after stroke is critical for treatment decisions and planning. Machine learning has been proposed to be a promising technique for outcome prediction because of its high accuracy and ability to process large volumes of data. It has been used to predict acute stroke recovery; however, whether machine learning would be effective for predicting rehabilitation outcomes in chronic stroke patients for common contemporary task-oriented interventions remains largely unexplored. This study aimed to determine the accuracy and performance of machine learning to predict clinically significant motor function improvements after contemporary task-oriented intervention in chronic stroke patients and identify important predictors for building machine learning prediction models.

METHODS

This study was a secondary analysis of data using two common machine learning approaches, which were the k-nearest neighbor (KNN) and artificial neural network (ANN). Chronic stroke patients (N = 239) that received 30 h of task-oriented training including the constraint-induced movement therapy, bilateral arm training, robot-assisted therapy and mirror therapy were included. The Fugl-Meyer assessment scale (FMA) was the main outcome. Potential predictors include age, gender, side of lesion, time since stroke, baseline functional status, motor function and quality of life. We divided the data set into a training set and a test set and used the cross-validation procedure to construct machine learning models based on the training set. After the models were built, we used the test data set to evaluate the accuracy and prediction performance of the models.

RESULTS

Three important predictors were identified, which were time since stroke, baseline functional independence measure (FIM) and baseline FMA scores. Models for predicting motor function improvements were accurate. The prediction accuracy of the KNN model was 85.42% and area under the receiver operating characteristic curve (AUC-ROC) was 0.89. The prediction accuracy of the ANN model was 81.25% and the AUC-ROC was 0.77.

CONCLUSIONS

Incorporating machine learning into clinical outcome prediction using three key predictors including time since stroke, baseline functional and motor ability may help clinicians/therapists to identify patients that are most likely to benefit from contemporary task-oriented interventions. The KNN and ANN models may be potentially useful for predicting clinically significant motor recovery in chronic stroke.

Conditions requiring hospitalisations, more than general anaesthesia itself, are associated with diagnosis of learning disorders in children

BACKGROUND

Anaesthesia is neurotoxic in developing primates. Retrospective clinical studies show a correlation between exposure to anaesthesia during infancy and the occurrence of learning disorders (LD). Prospective studies failed to detect any influence of a single exposure to anaesthesia on neurodevelopment. We hypothesised that some specific populations of children were electively sensitive to anaesthesia-related neurotoxicity.

METHODS

Using a case-control design, we analysed the medical histories of children with LD, compared to those of their normally reading siblings. Interviews were conducted and medical records were reviewed. The numbers of hospitalisations and anaesthesia exposures before the age of five years were determined.

RESULTS

Four hundred fourteen dyslexic children were screened over a one-year period. Two hundred and seventy patients were excluded due to confounding variables (single child, all siblings showing LD or any condition placing the neurological prognosis at risk (N = 107/414 for the latter)) or inability to accurately collect evaluation criteria. In the 144 case-control pairs studied, the mean number of hospitalisations was significantly different (N = 1.097 ± 0 .135/case versus 0.667 ± 0.097/control, p = 0.0052), as was the proportion of hospitalised patients (54.2% versus 38.9%, p = 0.0031). The mean number of anaesthesia exposures per individual was not statistically different (N = 0.958 ± 0.183/case versus 0.569 ± 0.107/control, p =  0.0732), but the proportion of children anaesthetised at least once was (43.8% (cases) versus 33.3% (controls), p =  0.0301).

DISCUSSION

One or more hospitalisation(s) may reflect a health status and/or have an iatrogenic effect disrupting the normal setting up of learning abilities. Anaesthesia may play a role, but a correlation between LD and anaesthesia is of a lower magnitude than between LD and hospitalisation.

Narirutin-rich fraction from grape fruit peel protects against transient cerebral ischemia reperfusion injury in rats

Objective: Ischemic stroke is one of the leading causes of disability in adults worldwide. The present study was aimed to evaluate the efficacy of Narirutin-rich fraction (NRF), obtained from grape fruit peel, on cerebral ischemia/reperfusion injury in rats.Methods: Male Wistar rats (180-200 g) were subjected to bilateral carotid artery occlusion for 30 min followed by reperfusion for 24 h to induce cerebral ischemia/reperfusion injury. NRF (150, 300 mg/kg, oral) was administered for 7 days continuously before animals were subjected to ischemia/reperfusion injury. Various behavioral tests (for measurement of motor coordination, locomotor activity, and spatial memory), biochemical parameters (lipid peroxidation, superoxide dismutase, and catalase activity), and histopathological alterations were assessed.Results: Seven-day NRF (150 and 300 mg/kg) pretreatment significantly improved neurobehavioral alterations and histological findings as compared to the disease control group. Further NRF treatment significantly reduced oxidative damage as indicated by improved lipid peroxidation, superoxide dismutase, and catalase activity as compared to disease control animals.Conclusion: The present study demonstrated the protective effect of NRF against cerebral ischemia/reperfusion injury in rats. The results suggest that NRF can be a potential pretreatment option against cerebral ischemia/reperfusion injury.

Impact of malnutrition on post-stroke cognitive impairment in convalescent rehabilitation ward inpatients

PURPOSE

To investigate the relationship between malnutrition risk on admission and improvement in post-stroke cognitive impairment (PSCI).

METHODS

This retrospective cohort study included 90 patients with PSCI with a Mini-Mental State Examination (MMSE) score ≤ 23, who were admitted to a rehabilitation hospital between July 2013 and December 2015. We assessed the malnutrition risk using the Mini Nutritional Assessment-Short Form (MNA-SF) and cognitive improvement using the Functional Independence Measure cognitive subscale (cognitive FIM) gain. Participants were classified into the malnourished (MNA-SF score ≤ 7) and adequately nourished groups (≥ 8). The patients' age, modified Rankin Scale score, time to hospitalization, and length of stay were recorded. The relationship between nutritional status and cognitive FIM was determined using a multivariate regression model.

RESULTS

The study included 47 men and 43 women, with a mean age of 75.0 (standard deviation: 8.7) years. The number of patients in the malnourished and adequately nourished groups were 68 (75.6%) and 22 (24.4%), respectively. The median MMSE score was 19 (interquartile range 15-22), and the median cognitive FIM score at admission was 17 (interquartile range 11-21.8). Univariate analysis showed no significant difference in cognitive FIM gain between the malnourished and adequately nourished groups (P = 0.781). Multivariate regression analysis showed that the MNA-SF score (beta = 0.84, P = 0.009) and cognitive FIM at admission (beta = - 0.347, P < 0.001) were independently related to cognitive FIM gain.

CONCLUSION

Most patients with PSCI were malnourished; malnutrition on admission for rehabilitation was associated with poor improvement after PSCI.

Relationship between first mobilization following the onset of stroke and clinical outcomes in patients with ischemic stroke in the general ward of a hospital: A cohort study

OBJECTIVE

The purpose of this study was to compare the effects of first mobilization following a stroke with independently performing the activities of daily living at discharge in acute phase ischemic stroke patients in a general ward of a hospital.

METHODS

A total of 158 patients with ischemic strokes were admitted to a general ward from June 1, 2014 to March 31, 2015. Of the 158 patients, 53 met the study's eligibility criteria. First mobilization was defined as the transfer of a patient from the bed to a wheelchair by a rehabilitation therapist. A favorable primary outcome at discharge was defined as a modified Rankin Scale score of < 3. The outcome was analyzed using the proportional hazards analysis and receiver operating characteristic curves.

RESULTS

The age of the participants was 78.2 ± 11.7 years, stroke severity evaluated by the National Institutes of Health Stroke Scale scores on admission was 14.3 ± 10.6 points, and first mobilization of this population was 6.4 ± 5.2 days. Thirteen [25%] patients had a favorable outcome. Hazards analysis showed a favorable outcome due to first mobilization (adjusted hazards ratio 0.80, 95% confidence interval 0.65-0.98; p < 0.05). The cutoff point for first mobilization to produce a favorable outcome was 6.5 days after the stroke onset (area under the curve 0.729; p < 0.05).

CONCLUSION

As seen in stroke units, early first mobilization is associated with improved clinical outcomes in ischemic stroke patients admitted to a general ward.

Delayed (21 Days) Post Stroke Treatment With RPh201, a Botany-Derived Compound, Improves Neurological Functional Recovery in a Rat Model of Embolic Stroke

Background

Despite the recent advances in the acute stroke care, treatment options for long-term disability are limited. RPh201 is a botany-derived bioactive compound that has been shown to exert beneficial effects in various experimental models of neural injury. The present study evaluated the effect of delayed RPh201 treatment on long term functional recovery after stroke.

Methods

Adult male Wistar rats subjected to embolic middle cerebral artery occlusion (MCAO) were randomized into the following experimental groups (n = 20/group): (1) RPh201 treatment, and (2) Vehicle (cottonseed oil). RPh201 (20 μl) or Vehicle were subcutaneously administered twice a week for 16 consecutive weeks starting at 21 days after MCAO. An array of behavioral tests was performed up to120 days after MCAO.

Results

Ischemic rats treated with RPh201 exhibited significant (p < 0.05) improvement of neurological function measured by adhesive removal test, foot-fault test, and modified neurological severity score at 90 and 120 days after MCAO. Immunohistochemistry analysis showed that RPh201 treatment robustly increased neurofilament heavy chain positive axons and myelin basic protein densities in the peri-infarct area by 61% and 31%, respectively, when compared to the Vehicle treatment, which were further confirmed by Western blot analysis. The RPh201 treatment did not reduce infarct volume.

Conclusion

Our data demonstrated that RPh201 has a therapeutic effect on improvement of functional recovery in male ischemic rats even when the treatment was initiated 21 days post stroke. Enhanced axonal and myelination densities by RPh201 in ischemic brain may contribute to improved stroke recovery.

The Efficiency, Efficacy, and Retention of Task Practice in Chronic Stroke

In motor skill learning, larger doses of practice lead to greater efficacy of practice, lower efficiency of practice, and better long-term retention. Whether such learning principles apply to motor practice after stroke is unclear. Here, we developed novel mixed-effects models of the change in the perceived quality of arm movements during and following task practice. The models were fitted to data from a recent randomized controlled trial of the effect of dose of task practice in chronic stroke. Analysis of the models' learning and retention rates demonstrated an increase in efficacy of practice with greater doses, a decrease in efficiency of practice with both additional dosages and additional bouts of training, and fast initial decay following practice. Two additional effects modulated retention: a positive "self-practice" effect, and a negative effect of dose. Our results further suggest that for patients with sufficient arm use post-practice, self-practice will further improve use.

Test-Retest Reliability of Kinematic Assessments for Upper Limb Robotic Rehabilitation

Robot-measured kinematic variables are increasingly used in neurorehabilitation to characterize motor recovery following stroke. However, few studies have evaluated the reliability of these kinematic variables. This study aimed at evaluating the test-retest reliability of typically-used robot-measured kinematic variables in healthy subjects (HS) and patients with stroke (SP). Sixty-one participants (40 HS, 21 SP) carried out a planar robot-pointing task on two consecutive days. Nine robot-measured kinematic variables were computed: movement time (T), mean velocity (mV), maximal velocity (MV), smoothness error (SE), number of velocity peaks (nP), mean arrest period ratio (MAPR), normalized path length (NPL), root mean square error (RMS) from a straight line and the orthogonal projection of the last point of movement (LP). Intraclass Correlation Coefficients (ICC), percentage of the Standard Error of Measurement (SEM measured as a percentage of the mean value of the variable (%SEM)) and percentage of the Minimum Detectable Difference (MDD measured as a percentage of the mean value of the variable (%MDD)) were used to analyze the test-retest reliability of the kinematic variables. ICC scores for all kinematic variables were above 0.75 in both groups. %SEM values were below 10% except for MAPR (13.4%) in HS and nP, MAPR and RMS in SP (13.0%, 11.7% and 15.2% respectively). %MDD values were higher for RMS in SP (42.1%) and MAPR in HS (37.1%) and lower for LP (1.6% in HS and 8.1% in SP). The nine robot-measured kinematic variables all demonstrated good reliability, with high ICC values (>0.75) and an acceptable level of measurement error (%SEM< 16%). However, 3/9 robot-measured kinematic variables, did not appear to be sufficiently sensitive to change (%MDD>30%) to be considered useful in patients with stroke.