Brain Reorganization After Stroke

Does repetitive transcranial magnetic stimulation have a beneficial effect on improving unilateral spatial neglect caused by stroke? A meta-analysis

This review aimed to assess the effect of repetitive transcranial magnetic stimulation (rTMS) in improving post-stroke unilateral spatial neglect (USN) using a meta-analysis. Further, we aimed to identify any association between rTMS parameters, patient demographics, and treatment effect sizes using subgroup analyses and meta-regression. A literature search was conducted through four databases from inception to March 6, 2024, to retrieve all relevant controlled trials investigating the effects of rTMS on symptoms of USN in post-stroke patients. Overall, rTMS significantly improved post-stroke USN, as measured by the line bisection test (Hedges' g = - 1.301, p < 0.0001), the cancelation test (Hedge's g = - 1.512, p < 0.0001), and the Catherine Bergego Scale (Hedges'g = - 0.770, p < 0.0001), compared to sham stimulation. Subgroup analysis found that generally larger effect sizes following excitatory rTMS across several outcome measures, indicating that excitatory rTMS on the ipsilesional hemisphere may be more effective than inhibitory rTMS on the contralesional hemisphere in ameliorating neglect symptoms. Meta-regression analysis of the line bisection test showed a significant difference in the chronicity of stroke patients, suggesting that rTMS may be more effective for USN in patients at the acute stage (within 3 months since stroke) than in those at the post-acute stage (p = 0.035). In conclusion, rTMS appears to be effective in promoting recovery from post-stroke USN. Excitatory protocols and early intervention may enhance recovery outcomes for neglect behaviors in post-stroke survivors.

Corticomuscular Coupling Analysis in Stroke Rehabilitation Based on Variational Mode Decomposition-Transfer Entropy

This study aims to explore alterations in corticomuscular and cortical coupling during the rehabilitation of stroke patients. We initiated the analysis by employing variational modal decomposition (VMD) on electromyography (EMG) data, followed by the application of VDM-transfer entropy (VMD-TE) to quantify the coupling strength between electroencephalogram (EEG) and EMG signals. Subsequently, we constructed the VMD-TE connection matrix and analyzed the clustering coefficient and small-world attributes within the cortico-muscular functional network (CMFN). Finally, a random forest algorithm was employed to extract features from the VMD-TE connection matrix across different rehabilitation periods. Beta waves in EEG were emerged as the key information carrier between the cortex and muscle, and the CMFN of patients with the beta frequency band has small-world characteristics. During rehabilitation, we observed a decrease in coupling between the initially affected motor cortex and muscle, accompanied by an increase in coupling between the frontal region and muscle. Our findings suggest potential neuro-remodeling in stroke patients after rehabilitation, with CFMN serving as a valuable metric for assessing cortico-muscular coupling.

Effects of home-based telerehabilitation on dynamic alterations in regional intrinsic neural activity and degree centrality in stroke patients

Objective

To explore the effects of home-based telerehabilitation (TR) on dynamic alterations in regional intrinsic neural activity and degree centrality in stroke patients by resting-state functional MRI (fMRI) methods.

Methods

The neuroimaging data of 52 stroke patients were analyzed. Dynamic regional spontaneous neural activity (dynamic amplitude of low-frequency fluctuations, dALFF; and dynamic regional homogeneity, dReHo) and dynamic degree centrality (dDC) were compared between the TR and conventional rehabilitation (CR) groups. A flexible factorial model was employed to investigate the expected effects.

Results

The patients in the TR group showed increased dALFF in the right precuneus and bilateral precentral gyrus (PreCG) and reduced dALFF in the right inferior parietal lobule by the analysis of main effects. Significant differences between groups were detected in the right precuneus, right fusiform gyrus and left middle frontal gyrus for dReHo and in the left cingulate gyrus, right middle temporal gyrus and left precuneus for dDC. A significant correlation was found in the TR group between the changed dALFF in the left PreCG and the changed Fugl-Meyer assessment (FMA) scores from baseline to postrehabilitation.

Conclusions

This study implied that home-based TR training can alter the patterns of dynamic spontaneous brain activity and functional connectivity in certain brain regions. The identification of key brain regions by neuroimaging indicators such as dynamic regional brain activity and degree centrality in the recovery process would provide a theoretical basis for noninvasive brain stimulation technology and strategies for formulating targeted rehabilitation programs for stroke patients with motor dysfunction.

Revisiting the Rotational Field TMS Method for Neurostimulation

Transcranial magnetic stimulation (TMS) is a non-invasive technique that has shown high efficacy in the treatment of major depressive disorder (MDD) and is increasingly utilized for various neuropsychiatric disorders. However, conventional TMS is limited to activating only a small fraction of neurons that have components parallel to the induced electric field. This likely contributes to the significant variability observed in clinical outcomes. A novel method termed rotational field TMS (rfTMS or TMS 360°) enables the activation of a greater number of neurons by reducing the sensitivity to orientation. Recruitment of a larger number of neurons offers the potential to enhance efficacy and reduce variability in the treatment of clinical indications for which neuronal recruitment and organization may play a significant role, such as MDD and stroke. The potential of the method remains to be validated in clinical trials. Here, we revisit and describe in detail the rfTMS method, its principles, mode of operation, effects on the brain, and potential benefits for clinical TMS.

Relation Between the Corticospinal Tract State and Activities of Daily Living in Patients With Intracerebral Hemorrhage

Supplemental Digital Content is available in the text.

Background and Purpose:

We investigated the relation between the ipsilesional corticospinal tract (CST) state and activity of daily living independence in patients with chronic intracerebral hemorrhage.

Methods:

Fifty-six consecutive patients with unilateral intracerebral hemorrhage and 38 healthy control subjects were recruited for this study. The Motricity index and the modified Barthel index were used to evaluate motor function of the affected extremities and activity of daily living independence, respectively. The diffusion tensor imaging parameter values for fractional anisotropy (FA) and voxel number (VN) of the CST were determined. Ratios of the ipsilesional to the contralesional CST measures were calculated and are presented as the CST-ratio (FA value and VN).

Results:

The FA value and VN of the ipsilesional CST and the CST-ratio in the patient group were lower than those of the control group (P<0.05). There was a strong positive correlation between the Motricity index score of the affected extremities and the modified Barthel index score (P<0.05), while the FA value and VN of the ipsilesional CST and the CST-ratio showed moderate and strong positive correlations with the Motricity index and modified Barthel index scores, respectively (P<0.05). In addition, the VN of the ipsilesional CST showed excellent utility as a classifier, whereas the FA value of the ipsilesional CST and the FA value and VN of the CST-ratio showed good classifier utility (P<0.05).

Conclusions:

We demonstrated that impairment of activity of daily living independency was closely related to the injury severity of the ipsilesional CST in patients with chronic intracerebral hemorrhage. In addition, the injury severity of the ipsilesional CST can be used to classify the degree of activity of daily living independency.

Registration:

URL: http://www.e-irb.com/index.jsp; Unique identifier: 2021-03-014.

Neuroplasticity of Acupuncture for Stroke: An Evidence-Based Review of MRI

Acupuncture is widely recognized as a potentially effective treatment for stroke rehabilitation. Researchers in this area are actively investigating its therapeutic mechanisms. Magnetic resonance imaging (MRI), as a noninvasive, high anatomical resolution technique, has been employed to investigate neuroplasticity on acupuncture in stroke patients from a system level. However, there is no review on the mechanism of acupuncture treatment for stroke based on MRI. Therefore, we aim to summarize the current evidence about this aspect and provide useful information for future research. After searching PubMed, Web of Science, and Embase databases, 24 human and five animal studies were identified. This review focuses on the evidence on the possible mechanisms underlying mechanisms of acupuncture therapy in treating stroke by regulating brain plasticity. We found that acupuncture reorganizes not only motor-related network, including primary motor cortex (M1), premotor cortex, supplementary motor area (SMA), frontoparietal network (LFPN and RFPN), and sensorimotor network (SMN), as well as default mode network (aDMN and pDMN), but also language-related brain areas including inferior frontal gyrus frontal, temporal, parietal, and occipital lobes, as well as cognition-related brain regions. In addition, acupuncture therapy can modulate the function and structural plasticity of post-stroke, which may be linked to the mechanism effect of acupuncture.

Ipsilateral BDNF mRNA expression in the motor cortex positively correlates with motor function of the affected forelimb after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a subtype of stroke that causes major motor impairments. Brain-derived neurotrophic factor (BDNF) is known to have important roles in neuroplasticity and beneficially contributes to stroke recovery. This study aimed to characterize BDNF expression in the motor cortex after ICH and investigate the relationship between cortical BDNF expression and behavioral outcomes using an ICH rat model. Wistar rats were divided into two groups: a SHAM group (n = 7) and an ICH group (n = 8). ICH was induced by the injection of collagenase into the left striatum near the internal capsule. For behavioral assessments, the cylinder test and open field test were performed before surgery and 3 days, 1 week, 2 weeks, and 4 weeks after surgery. Following the behavioral assessments at 4 weeks, BDNF expression in the ipsilateral and contralateral motor cortex was assayed using RT-PCR and ELISA methods. There was no significant difference in either cortical BDNF mRNA or protein expression levels between the SHAM and ICH groups. However, the asymmetry index of BDNF mRNA expression between the ipsilateral and contralateral hemispheres shifted to the ipsilateral hemisphere after ICH. Furthermore, the ipsilateral cortical BDNF mRNA expression level positively correlated with motor function in the affected forelimb after ICH. This study describes for the first time that cortical BDNF mRNA expression is related to post-ICH motor impairment. These results highlight the importance of assessing the interhemispheric laterality of BDNF expression and could help develop novel treatment strategies for BDNF-dependent recovery after ICH.

Neuropsychiatric symptoms in a occipito-temporal infarction with remarkable long-term functional recovery

Posterior circulation infarctions (PCI) constitute 5-25% of ischemic strokes. PCI of the occipital lobe present with a panoply of symptoms including quadrantanopsia, topographical disorientation, and executive dysfunction. Long-term cognitive recovery after PCI is not well described. However, the adult brain is remarkably plastic, capable of adapting and remodeling. We describe a 43-year-old right-handed woman who complained of black spots in both eyes, headaches, photophobia, and a feeling she would faint. Initial neurological exam and a CT scan were normal; she was diagnosed with ocular migraine. A second neurological exam a week later showed left superior quadrantopsia; an MRI scan suggested right occipito-temporal infarct. In subsequent months, the patient complained of fatigue, quadrantanopsia, memory problems, and topographical disorientation. The patient participated in multi-modality treatment, and in self-directed arts projects and physical activities. Six years later, she reported noticeable improvements in cognition and daily functioning, which were documented on neurocognitive testing. Comparison between initial and subsequent MRIs using FreeSurfer 5.3 identified neuroplastic brain changes in areas serving similar functions to the areas injured from the stroke. The case illustrates the neuropsychiatric presentation after right occipito-temporal stroke, the value of formal and self-directed cognitive rehabilitation, the extended time to cognitive recovery, and the ability of the brain to undergo neuroplastic changes.

An fMRI, DTI and Neurophysiological Examination of Atypical Organization of Motor Cortex in Ipsilesional Hemisphere Following Post-Stroke Recovery

OBJECTIVES

We report a 61-year-old woman who developed left hemiparesis following a right frontal stroke. She underwent rehabilitation and regained function of the left side of her body. Three years after her first stroke, she developed a large left subdural hematoma and again presented with left hemiparesis.

MATERIALS AND METHODS

Prior to the cranioplasty, an fMRI scan involving left and right hand movement, arm movement, and foot peddling were conducted in order to determine whether the patient showed ipsilateral activation for the motor tasks, thus explaining the left hemiparesis following the left subdural hematoma. Diffusion tensor imaging (DTI) tractography was also collected to visualize the motor and sensory tracts.

RESULTS

The fMRI results revealed activation in the expected contralateral left primary motor cortex (M1) for the right-sided motor tasks, and bilateral M1 activation for the left-sided motor tasks. Intraoperative neurophysiology confirmed these findings, whereby electromyography revealed left-sided (i.e., ipsilateral) responses for four of the five electrode locations. The DTI results indicated that the corticospinal tracts and spinothalamic tracts were within normal limits and showed no displacement or disorganization.

CONCLUSIONS

These results suggest that there may have been reorganization of the M1 following her initial stroke, and that the left hemisphere may have become involved in moving the left side of the body thereby leading to left hemiparesis following the left subdural hematoma. The findings suggest that cortical reorganization may occur in stroke patients recovering from hemiparesis, and specifically, that components of motor processing subserved by M1 may be taken over by ipsilateral regions.

Potential role of exosome in post-stroke reorganization and/or neurodegeneration

Currently, stroke is a common and devastating condition, which is sometimes associated with permanent cerebral damages. Although in early time after stroke, the related treatments are mainly focused on the restoration of cerebral blood flow (CBF), at the same time, some changes are commencing that continue for a long time and need to be specially noticed. Previous studies have proposed several molecular mechanisms in these post-stroke events. Exosomes are a type of vesicle, which are formed and secreted by most cells as a mean to transfer cellular constituents such as proteins, DNA and/or RNA to distant cells. Therefore, they are considered as a novel mechanism of cellular communication. Herein, we reviewed the current knowledge on cascades, which are activated after stroke and consequently lead to the reorganization and/or continuance of tissue damage and development of other disorders such as Neurodegenerative diseases (ND). Thereafter, we summarized the latest proofs about the possible participation of exosomes in transferring some components such as proteins and micro-RNAs (miRs), from the affected areas to other parts of the brain and eventually cause the above-mentioned post-stroke events.

Therapeutic effects of acupuncture on sensory ataxia after a cerebral hemorrhage: A case report

INTRODUCTION

Sensory ataxia is a dysfunction of dynamic balance due to impairment of sensory input into the control of movement. The sequelae of stroke, such as hemiplegia, somatosensory impairment, and impaired balance may cause significant disability and may affect patients' quality of life. In addition to rehabilitation programs, acupuncture therapy has been applied to stroke patients and is recommended as a complementary therapy in stroke rehabilitation.

PATIENT CONCERNS

A 70-year-old male had a sudden onset of conscious loss. The brain computed tomography showed intracerebral hemorrhage with subdural hemorrhage and subarachnoid hemorrhage.

DIAGNOSIS

Intracerebral hemorrhagic stroke was diagnosed.

INTERVENTIONS

He received craniotomy with hematoma evacuation immediately and waked up 3 weeks with bilateral hemiparesis (right side weaker than left), impaired position sensation and tactile perception in the right lower limb. He then began to receive rehabilitation therapy and had significant improvement in muscle strength and static balance, but no improvement in tactile perception of position sense in the right lower limbs and reached plateau. Then he received acupuncture therapies to Yongquan (KI1), Tongtien (BL7) and Houxi (SI3).

OUTCOMES

The patient's walking ability recovered after receiving rehabilitation programs for 3 years, but the impairment in proprioception and dynamic balance persisted. The perception and dynamic balance had significantly improved after patient received acupuncture therapy, especially the acupuncture point of Yongquan (KI1).

CONCLUSION

The clinical effect of acupuncture in combination with conventional rehabilitation therapy for neurological impairment recovery, improving activity of daily living performance and improving post-stroke imbalance was explored. We hope that this report can facilitate further well controlled quantitative objective studies on a big size of samples.

Amino Acid Biosignature in Plasma among Ischemic Stroke Subtypes

Ischemic stroke is a neurovascular disorder caused by reduced or blockage of blood flow to the brain, which may permanently affect motor and cognitive abilities. The diagnostic of stroke is performed using imaging technologies, clinical evaluation, and neuropsychological protocols, but no blood test is available yet. In this work, we analyzed amino acid concentrations in blood plasma from poststroke patients in order to identify differences that could characterize the stroke etiology. Plasma concentrations of sixteen amino acids from patients with chronic ischemic stroke (n = 73) and the control group (n = 16) were determined using gas chromatography coupled to mass spectrometry (GC-MS). The concentration data was processed by Partial Least Squares-Discriminant Analysis (PLS-DA) to classify patients with stroke and control. The amino acid analysis generated a first model able to discriminate ischemic stroke patients from control group. Proline was the most important amino acid for classification of the stroke samples in PLS-DA, followed by lysine, phenylalanine, leucine, and glycine, and while higher levels of methionine and alanine were mostly related to the control samples. The second model was able to discriminate the stroke subtypes like atherothrombotic etiology from cardioembolic and lacunar etiologies, with lysine, leucine, and cysteine plasmatic concentrations being the most important metabolites. Our results suggest an amino acid biosignature for patients with chronic stroke in plasma samples, which can be helpful in diagnosis, prognosis, and therapeutics of these patients.

Altered functional connectivity differs in stroke survivors with impaired touch sensation following left and right hemisphere lesions

One in two survivors experience impairment in touch sensation after stroke. The nature of this impairment is likely associated with changes associated with the functional somatosensory network of the brain; however few studies have examined this. In particular, the impact of lesioned hemisphere has not been investigated. We examined resting state functional connectivity in 28 stroke survivors, 14 with left hemisphere and 14 with right hemisphere lesion, and 14 healthy controls. Contra-lesional hands showed significantly decreased touch discrimination. Whole brain functional connectivity (FC) data was extracted from four seed regions, i.e. primary (S1) and secondary (S2) somatosensory cortices in both hemispheres. Whole brain FC maps and Laterality Indices (LI) were calculated for subgroups. Inter-hemispheric FC was greater in healthy controls compared to the combined stroke cohort from the left S1 seed and bilateral S2 seeds. The left lesion subgroup showed decreased FC, relative to controls, from left ipsi-lesional S1 to contra-lesional S1 and to distributed temporal, occipital and parietal regions. In comparison, the right lesion group showed decreased connectivity from contra-lesional left S1 and bilateral S2 to ipsi-lesional parietal operculum (S2), and to occipital and temporal regions. The right lesion group also showed increased intra-hemispheric FC from ipsi-lesional right S1 to inferior parietal regions compared to controls. In comparison to the left lesion group, those with right lesion showed greater intra-hemispheric connectivity from left S1 to left parietal and occipital regions and from right S1 to right angular and parietal regions. Laterality Indices were significantly greater for stroke subgroups relative to matched controls for contra-lesional S1 (left lesion group) and contra-lesional S2 (both groups). We provide evidence of altered functional connectivity within the somatosensory network, across both hemispheres, and to other networks in stroke survivors with impaired touch sensation. Hemisphere of lesion was associated with different patterns of altered functional connectivity within the somatosensory network and with related function was associated with different patterns of altered functional connectivity within the somatosensory network and with related functional networks.

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Examined somatosensory resting functional connectivity (RSFC) in left/right lesion stroke patients and/healthy controls.

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Seed based voxel wise (SB) and laterality index (LI) analyses were used.

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Left lesion SB results showed decreased RSFC in somatosensory and attention regions vs. controls/right lesion patients.

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Right lesion patients showed increased RSFC compared to controls and left lesion patients to inferior parietal areas.

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LI results showed increased laterality in both left and right lesion groups between the somatosensory seeds.

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This suggests RSFC may differ depending on laterality of lesion damage, with altered connectivity profiles between networks.

Efficacy of mechano-acoustic vibration on strength, pain, and function in poststroke rehabilitation: a pilot study

BACKGROUND

Vibration therapy may be used to help cortical reorganization after stroke as it can cause different adaptive metabolic and mechanical effects.

OBJECTIVE

This study examined whether the application of mechano-acoustic vibration on upper limb muscles could induce changes in range of motion (ROM), function, pain, and grip strength in individuals with chronic stroke.

METHODS

Out of 52 individuals post stroke with upper limb spasticity who were eligible,16 received mechano-acoustic vibration therapy (ViSS device) 3 times weekly for 12 sessions. The frequency of vibration was set to 300 Hz for 30 minutes. The treated muscles were the extensor carpi radialis longus and brevis and triceps brachii during voluntary contraction. All participants were evaluated in both upper limbs before (T0) and at the end (T1) of treatment with a dynamometer (hand grip strength), Modified Ashworth Scale, QuickDASH, FIM score, Fugl-Meyer scale, Verbal Numerical Rating Scale of pain, and Jebsen-Taylor Hand Function Test.

RESULTS

After 4 weeks, hand grip power had improved and pain and spasticity had decreased. Improvements were recorded for all parameters and were considered statistically significant.

CONCLUSIONS

Application of vibratory stimuli to a muscle can increase the motor-evoked potential recorded from the muscle, suggesting an enhancement of corticospinal excitability. Low amplitude, high-frequency vibration treatment (300 Hz) can significantly decrease tone and pain and improve strength in upper limb of hemiplegic individuals, when applied for 30 minutes, 3 times a week over 4 weeks.

Enhancing Spinal Plasticity Amplifies the Benefits of Rehabilitative Training and Improves Recovery from Stroke

The limited recovery that occurs following stroke happens almost entirely in the first weeks postinjury. Moreover, the efficacy of rehabilitative training is limited beyond this narrow time frame. Sprouting of spared corticospinal tract axons in the contralesional spinal cord makes a significant contribution to sensorimotor recovery, but this structural plasticity is also limited to the first few weeks after stroke. Here, we tested the hypothesis that inducing plasticity in the spinal cord during chronic stroke could improve recovery from persistent sensorimotor impairment. We potentiated spinal plasticity during chronic stroke, weeks after the initial ischemic injury, in male Sprague-Dawley rats via intraspinal injections of chondroitinase ABC. Our data show that chondroitinase injections into the contralesional gray matter of the cervical spinal cord administered 28 d after stroke induced significant sprouting of corticospinal axons originating in the peri-infarct cortex. Chondroitinase ABC injection during chronic stroke without additional training resulted in moderate improvements of sensorimotor deficits. Importantly, this therapy dramatically potentiated the efficacy of rehabilitative training delivered during chronic stroke in a skilled forelimb reaching task. These novel data suggest that spinal therapy during chronic stroke can amplify the benefits of delayed rehabilitative training with the potential to reduce permanent disability in stroke survivors.SIGNIFICANCE STATEMENT The brain and spinal cord undergo adaptive rewiring ("plasticity") following stroke. This plasticity allows for partial functional recovery from stroke induced sensorimotor impairments. However, the plasticity that underlies recovery occurs predominantly in the first weeks following stroke, and most stroke survivors are left with permanent disability even after rehabilitation. Using animal models, our data show that removal of plasticity-inhibiting signals in the spinal cord (via intraspinal injections of the enzyme chondroitinase ABC) augments rewiring of circuits connecting the brain to the spinal cord, even weeks after stroke. Moreover, this plasticity can be harnessed by rehabilitative training to significantly promote sensorimotor recovery. Thus, intraspinal therapy may augment rehabilitative training and improve recovery even in individuals living with chronic disability due to stroke.

Diffusion Tensor Imaging Shows Corpus Callosum Differences between High-Grade Gliomas and Metastases

BACKGROUND AND PURPOSE

The corpus callosum (CC) has an important role in regulating interhemispheric transfer and is thought to be instrumental in contralateral brain reorganization in patients with brain tumors, as suggested by a previous study reporting callosal differences between language dominance groups through diffusion tensor imaging (DTI) characteristics. The purpose of this study was to explore the structural differences in the CC between high-grade gliomas (HGGs) and metastatic tumors (METs) using the DTI characteristics of fractional anisotropy (FA), mean diffusivity (MD), and axial diffusivity (AD).

METHODS

HGG (n = 30) and MET (n = 20) subjects with Magnetic Resonance Imaging (MRI) scans including DTI were retrospectively studied. The tumor and CC were segmented using the 3-dimensional T1-weighted scans to determine their volumes. The region of interest (ROI; mean volume of the ROI = 3,090 ± 464 mm³ ) of the body of the CC was overlaid onto the DTI parametric maps to obtain the averaged FA, MD, and AD values.

RESULTS

There were significant differences in the distributions of FA and MD values between the two patient groups (mean FA for HGG/MET = .691/.646, P < .05; mean MD for HGG/MET = .894×10-3 mm 2/ second /.992×10-3 mm² /second, P < .01), while there was no correlation between the DTI parameters and the anatomical volumes.

CONCLUSION

These results suggest that there is more contralateral brain reorganization in HGG patients than MET patients and that neither the tumor nor callosal volume impact the degree of contralateral brain reorganization.

Reorganized neural activation in motor cortex following subdural fluid collection: an fMRI and DTI study

We report a patient with a cavernous malformation involving the right lentiform nucleus. Pre-surgical planning included fMRI localization of language, motor, and sensory processing, and DTI of white matter tracts. fMRI results revealed no activation near the planned resection zone. However, post-surgery the patient developed a subdural fluid collection, which applied pressure to the primary motor cortex (M1). Follow-up scans revealed that motor activation had shifted due to pressure, and then shifted to a new location after the fluid collection subsided. This case report suggests that long-term neural reorganization can occur in response to short term compression in the cortex.

Slower EEG alpha generation, synchronization and "flow"-possible biomarkers of cognitive impairment and neuropathology of minor stroke

Background

We investigated EEG rhythms, particularly alpha activity, and their relationship to post-stroke neuropathology and cognitive functions in the subacute and chronic stages of minor strokes.

Methods

We included 10 patients with right middle cerebral artery (MCA) ischemic strokes and 11 healthy controls. All the assessments of stroke patients were done both in the subacute and chronic stages. Neurological impairment was measured using the National Institute of Health Stroke Scale (NIHSS), whereas cognitive functions were assessed using the Montreal Cognitive Assessment (MoCA) and MoCA memory index (MoCA-MIS). The EEG was recorded using a 19 channel EEG system with standard EEG electrode placement. In particular, we analyzed the EEGs derived from the four lateral frontal (F3, F7, F4, F8), and corresponding lateral posterior (P3, P4, T5, T6) electrodes. Quantitative EEG analysis included: the group FFT spectra, the weighted average of alpha frequency (αAVG), the group probability density distributions of all conventional EEG frequency band relative amplitudes (EEG microstructure), the inter- and intra-hemispheric coherences, and the topographic distribution of alpha carrier frequency phase potentials (PPs). Statistical analysis was done using a Kruskal–Wallis ANOVA with a post-hoc Mann–Whitney U two-tailed test, and Spearman’s correlation.

Results

We demonstrated transient cognitive impairment alongside a slower alpha frequency (αAVG) in the subacute right MCA stroke patients vs. the controls. This slower alpha frequency showed no amplitude change, but was highly synchronized intra-hemispherically, overlying the ipsi-lesional hemisphere, and inter-hemispherically, overlying the frontal cortex. In addition, the disturbances in EEG alpha activity in subacute stroke patients were expressed as a decrease in alpha PPs over the frontal cortex and an altered “alpha flow”, indicating the sustained augmentation of inter-hemispheric interactions. Although the stroke induced slower alpha was a transient phenomenon, the increased alpha intra-hemispheric synchronization, overlying the ipsi-lesional hemisphere, the increased alpha F3–F4 inter-hemispheric synchronization, the delayed alpha waves, and the newly established inter-hemispheric “alpha flow” within the frontal cortex, remained as a permanent consequence of the minor stroke. This newly established frontal inter-hemispheric “alpha flow” represented a permanent consequence of the “hidden” stroke neuropathology, despite the fact that cognitive impairment has been returned to the control values. All the detected permanent changes at the EEG level with no cognitive impairment after a minor stroke could be a way for the brain to compensate for the lesion and restore the lost function.

Discussion

Our study indicates slower EEG alpha generation, synchronization and “flow” as potential biomarkers of cognitive impairment onset and/or compensatory post-stroke re-organizational processes.

Somatosensory deficits after stroke: a scoping review

In the past years, there have been increasing research activities focusing on somatosensory symptoms following stroke. However, as compared to the large number of clinical and neuroimaging studies on motor symptoms, the number of studies tracing somatosensory symptoms after stroke and their recovery is rather small. It is an ongoing discussion, to which extent somatosensory deficits after stroke influence patient's long-term outcome in motor and sensory performance and functional independence in activities of daily living. Modern brain imaging techniques allow for studying the impact of stroke lesion localization and size on acute and persisting clinical impairment. Here, we review the literature on somatosensory symptoms after stroke. We summarize epidemiological information on frequency and characteristics of somatosensory symptoms affecting all parts of the body in the acute and chronic stage of stroke. We further give an overview of brain imaging studies of stroke affecting the somatosensory system. Finally, we identify open questions which need to be addressed in future research and summarize the implications for clinical practice.

Early Fiber Number Ratio Is a Surrogate of Corticospinal Tract Integrity and Predicts Motor Recovery After Stroke

BACKGROUND AND PURPOSE

The contribution of imaging metrics to predict poststroke motor recovery needs to be clarified. We tested the added value of early diffusion tensor imaging (DTI) of the corticospinal tract toward predicting long-term motor recovery.

METHODS

One hundred seventeen patients were prospectively assessed at 24 to 72 hours and 1 year after ischemic stroke with diffusion tensor imaging and motor scores (Fugl-Meyer). The initial fiber number ratio (iFNr) and final fiber number ratio were computed as the number of streamlines along the affected corticospinal tract normalized to the unaffected side and were compared with each other. The prediction of motor recovery (ΔFugl-Meyer) was first modeled using initial Fugl-Meyer and iFNr. Multivariate ordinal logistic regression models were also used to study the association of iFNr, initial Fugl-Meyer, age, and stroke volume with Fugl-Meyer at 1 year.

RESULTS

The iFNr correlated with the final fiber number ratio at 1 year (r=0.70; P<0.0001). The initial Fugl-Meyer strongly predicted motor recovery (≈73% of initial impairment) for all patients except those with initial severe stroke (Fugl-Meyer<50). For these severe patients (n=26), initial Fugl-Meyer was not correlated with motor recovery (R(2)=0.13; p=ns), whereas iFNr showed strong correlation (R(2)=0.56; P<0.0001). In multivariate analysis, the iFNr was an independent predictor of motor outcome (β=2.601; 95% confidence interval=0.304-5.110; P=0.031), improving prediction compared with using only initial Fugl-Meyer, age, and stroke volume (P=0.026).

CONCLUSIONS

Early measurement of FNr at 24 to 72 hours poststroke is a surrogate marker of corticospinal tract integrity and provides independent prediction of motor outcome at 1 year especially for patients with severe initial impairment.

Real-Time Control of a Neuroprosthetic Hand by Magnetoencephalographic Signals from Paralysed Patients

Neuroprosthetic arms might potentially restore motor functions for severely paralysed patients. Invasive measurements of cortical currents using electrocorticography have been widely used for neuroprosthetic control. Moreover, magnetoencephalography (MEG) exhibits characteristic brain signals similar to those of invasively measured signals. However, it remains unclear whether non-invasively measured signals convey enough motor information to control a neuroprosthetic hand, especially for severely paralysed patients whose sensorimotor cortex might be reorganized. We tested an MEG-based neuroprosthetic system to evaluate the accuracy of using cortical currents in the sensorimotor cortex of severely paralysed patients to control a prosthetic hand. The patients attempted to grasp with or open their paralysed hand while the slow components of MEG signals (slow movement fields; SMFs) were recorded. Even without actual movements, the SMFs of all patients indicated characteristic spatiotemporal patterns similar to actual movements, and the SMFs were successfully used to control a neuroprosthetic hand in a closed-loop condition. These results demonstrate that the slow components of MEG signals carry sufficient information to classify movement types. Successful control by paralysed patients suggests the feasibility of using an MEG-based neuroprosthetic hand to predict a patient's ability to control an invasive neuroprosthesis via the same signal sources as the non-invasive method.

Acupuncture for ischemic stroke: cerebellar activation may be a central mechanism following Deqi

The needling sensation of Deqi during acupuncture is a key factor of influencing acupuncture outcome. Recent studies have mainly focused on the brain function effects of Deqi in a physiological state. Functional magnetic resonance imaging (fMRI) on the effects of acupuncture at Waiguan (SJ5) in pathological and physiological states is controversial. In this study, 12 patients with ischemic stroke received acupuncture at Waiguan (SJ5) and simultaneously underwent fMRI scanning of the brain, with imaging data of the activated areas obtained. Based on the patient's sensation, imaging data were allocated to either the Deqi group or non-Deqi group. In the Deqi group, the activated/deactivated areas were the left superior temporal gyrus (BA39)/right anterior lobe of the cerebellum and left thalamus. In the non-Deqi group, the activated areas included the medial frontal gyrus of the right frontal lobe (BA11), right limbic lobe (BA30, 35), and left frontal lobe (BA47), while the only deactivated area was the right parietal lobe (BA40). Compared with the non-Deqi group, the Deqi group exhibited marked activation of the right anterior lobe of the cerebellum and right limbic lobe (BA30). These findings confirm that the clinical effect of Deqi during acupuncture is based on brain functional changes. Cerebellar activation may be one of the central mechanisms of acupuncture in the treatment of ischemic stroke.

The effects of very early mirror therapy on functional improvement of the upper extremity in acute stroke patients

[Purpose] The aim of the study was to evaluate the effects of a very early mirror therapy program on functional improvement of the upper extremity in acute stroke patients. [Subjects] Eight stroke patients who were treated in an acute neurology unit were included in the study. [Methods] The patients were assigned alternatively to either the mirror therapy group receiving mirror therapy and neurodevelopmental treatment or the neurodevelopmental treatment only group. The primary outcome measures were the upper extremity motor subscale of the Fugl-Meyer Assessment, Motricity Index upper extremity score, and the Stroke Upper Limb Capacity Scale. Somatosensory assessment with the Ayres Southern California Sensory Integration Test, and the Barthel Index were used as secondary outcome measures. [Results] No statistically significant improvements were found for any measures in either group after the treatment. In terms of minimally clinically important differences, there were improvements in Fugl-Meyer Assessment and Barthel Index in both mirror therapy and neurodevelopmental treatment groups. [Conclusion] The results of this pilot study revealed that very early mirror therapy has no additional effect on functional improvement of upper extremity function in acute stroke patients. Multicenter trials are needed to determine the results of early application of mirror therapy in stroke rehabilitation.

Models of care for late-life depression of the medically ill: examples from chronic obstructive pulmonary disease and stroke

Depression worsens most treatment outcomes in medically ill older adults. Chronic medical illnesses weaken and demoralize patients and compromise their ability to adhere to treatments requiring consistency and effort. Acute medical illnesses create a psychosocial storm that finds patients and their ecosystem unprepared. We describe two intervention models that can be used to target and personalize treatment in depressed, chronically, or acutely medically ill older adults. The Personalized Adherence Intervention for Depression and COPD (PID-C) is a model intervention for depressed patients with chronic medical illnesses. It targets patient-specific barriers to treatment engagement and aims to shift the balance in favor of treatment participation. PID-C led to higher remission rates of depression, reduction in depressive symptoms, and reduction in dyspnea-related disability. The addition of problem-solving training enables patients to use resources available to them and hopefully improve their outcomes. Ecosystem-focused therapy (EFT) is a model intervention for depression developing in the context of an acute medical event. It was developed for patients with poststroke depression (PSD) and targets five areas, part of the "psychosocial storm" originating from the patient's sudden disability and the resulting change in the patient's needs and family's life. A preliminary study suggests that EFT is feasible and efficacious in reducing depressive symptoms and signs and disability in PSD.

Laterality of Motor Control Revisited: Directionality of Callosal Traffic and Its Rehabilitative Implications

Based on evidence derived from personal data and a comprehensive review of the literature, this article provides a perspective of laterality of motor control in humans. The evidence supports existence of directionality in callosal traffic, codified in handedness. However, it is the neural handedness that definitively reveals the directionality of signal traffic between the executive and the minor hemisphere; the minor hemisphere is devoted to the affairs occurring on or toward the nondominant side of the body. Thus, moving the nondominant side of the body (and sensing from it) are bi-hemispherical events that require callosal participation. Time-resolved data are provided that indicate the absence of any ipsilateral corticospinal tract innervation in humans. The rehabilitative aspects of the new circuitry (i.e., one-way callosal traffic scheme) is reviewed, establishing that previously described plasticity or reorganization of cortical structure was a reflection of the newly described anatomy underpinning handedness. The distinction between neural and behavioral handedness is emphasized, suggesting simple and robust ways to establish a person's handedness without resorting to invasive and inconclusive tests currently in vogue. In the past, lack of knowledge of directionality in callosal traffic has resulted in surgical removal of healthy hemispheres (including the major hemisphere) in futile attempts to stop epilepsy in those with an intractable condition. Evidence is provided for lack of any motor communication from the minor to the major hemisphere, which makes the minor hemisphere incapable of initiating and propagating seizures.

Plasticity and Reorganization of the Brain Post Stroke

Reorganization of the cortex post stroke is dependent not only on the lesion site but also on remote brain areas that have structural connections with the area damaged by the stroke. Motor recovery is largely dependent on the intact cortex adjacent to the infarct, which points out the importance of preserving the penumbral areas. There appears to be a priority setting with contralateral and ipsilateral motor pathways, with ipsilateral (unaffected hemisphere) pathways only becoming prominent after more severe strokes where functional contralateral (affected hemisphere) pathways are unable to recover. Ipsilateral or unaffected hemisphere motor pathway activation is therefore associated with a worse prognosis.

Training and Stimulation in Post Stroke Recovery Brain Reorganization

In both animal and clinical studies, training or rehabilitation increases cortical representation with subsequent functional recovery, whereas a lack of rehabilitation or training decreases cortical representation and delays recovery. Animals exposed to enriched environments post stroke have improved functional outcomes compared with animals exposed to nonenriched environments. In humans, stroke units may be the closest approximation there is to an enriched environment. However, studies indicate that patients spend the majority of time being inactive and alone while on a stroke unit. Given the animal evidence (which emphasizes increased stimulation and increased activity), there is clearly an opportunity for improving the stroke rehabilitation experience to maximize post stroke recovery.

A combined therapeutic approach in stroke rehabilitation: A review on non-invasive brain stimulation plus pharmacotherapy

Stroke is a leading cause of disability in the United States. Available treatments for stroke have only a modest effect on motor rehabilitation and about 50-60% of stroke patients remain with some degree of motor impairment after standard treatment. Non-invasive brain stimulation (NIBS) techniques have been proposed as adjuvant treatments to physical therapy for motor recovery after stroke. High frequency rTMS and anodal tDCS can be delivered over the affected motor cortex in order to increase cortical excitability and induce brain plasticity with the intention to enhance motor learning and achieve functional goals in stroke patients. Similarly, low frequency rTMS and cathodal tDCS can be delivered to the unaffected motor cortex to reduce interhemispheric inhibition and hinder maladaptive plasticity. The use of several drugs such as amphetamines, selective serotonin reuptake inhibitors (SSRIs), levodopa and cholinergic agents have been also proposed to enhance the motor function. Given that both NIBS and pharmacotherapy might provide some treatment effect independently for motor rehabilitation in stroke and with the rationale that they could work in a synergistic fashion, we believe that a combined therapy- NIBS plus pharmacotherapy- canlead to better outcomes than one or the other alone. In this paper we review the literature that support the potential use of a combined approach in stroke recovery and present the studies that have already investigated this idea.

Practice effects and test-re-test reliability of the Five Digit Test in patients with stroke over four serial assessments

OBJECTIVES

To investigate practice effect and test-re-test reliability of the Five Digit Test (FDT) over four serial assessments in patients with stroke.

DESIGN

Single-group repeated measures design.

METHODS

Twenty-five patients with stroke were administered the FDT in four consecutive assessments every 2 weeks. The FDT contains four parts with five indices: 'basic measures of attention and processing speed', 'selective attention', 'alternating attention', 'ability of inhibition' and 'ability of switching'.

RESULTS

The five indices of the FDT showed trivial-to-small practice effects (Cohen's d = 0.03-0.47) and moderate-to-excellent test-re-test reliability (intra-class correlation coefficient = 0.59-0.97). Practice effects of the five indices all appeared cumulative, but one index, 'basic measures of attention and processing speed', reached a plateau after the second assessment. The minimum and maximum values of the 90% confidence interval (CI) of reliable change index modified for practice (RCIp) for this index were [-17.6, 11.2].

CONCLUSIONS

One of five indices of the FDT reached a plateau, whose minimum and maximum values of the 90% CI RCIp are useful to determine whether the change in an individual's score is real. However, clinicians and researchers should be cautious when interpreting the test results of these four indices over repeated assessments.

Randomized trial of a robotic assistive device for the upper extremity during early inpatient stroke rehabilitation

BACKGROUND

A recent Cochrane Review showed that early robotic training of the upper limb in stroke survivors can be more effective than other interventions when improving activities of daily living involving the arm function is the aim of therapy.

OBJECTIVE

We tested for efficacy of the study a protocol which involved the use of the NeReBot therapy in partial substitution of standard upper limb rehabilitation in post-acute stroke patients.

METHODS

In this dose-matched, randomized controlled clinical trial, 34 hemiparetic participants with movement against gravity in shoulder, elbow, and wrist muscle groups were enrolled within 15 days of the onset of stroke. All participants received a total daily rehabilitation treatment for 120 minutes, 5 days per week for 5 weeks. The control group received standard therapy for the upper limb. The experimental group received standard therapy (65% of exercise time) associated with robotic training (35% of exercise time). Muscle tone (Modified Ashworth Scale), strength (Medical Research Council), and synergism (Fugl-Meyer motor scores) were measured at impairment level, whereas dexterity (Box and Block Test and Frenchay Arm Test) and activities of daily living (Functional Independence Measure) were measured at activity level. All assessments were performed at baseline, at the end of therapy (time T1), at 3 months (time T2), and at 7 months (time T3) after entry. All between-group analyses were tested using nonparametric test with Bonferroni's adjustments for multiple testing.

RESULTS

No significant between-group differences were found with respect to demographic characteristics, motor, dexterity, and ADLs at baseline, postintervention (T1) and at follow-up (T2 and T3).

CONCLUSIONS

The robot therapy by NeReBot did not lead to better outcomes compared with conventional inpatient rehabilitation.

Design of Wrist Gimbal: a forearm and wrist exoskeleton for stroke rehabilitation

In this paper, we present design, implementation and specifications of the Wrist Gimbal, a three degree-of-freedom (DOF) exoskeleton developed for forearm and wrist rehabilitation. Wrist Gimbal has three active DOF, corresponding to pronation/supination, flexion/extension and adduction/abduction joints. We mainly focused on a robust, safe and practical device design to facilitate clinical implementation, testing and acceptance. Robustness and mechanical rigidity was achieved by implementing two bearing supports for each of the pronation/supination and adduction/abduction axes. Rubber hard stops for each axis, an emergency stop button and software measures ensured safe operation. An arm rest with padding and straps, a handle with adjustable distal distance and height and a large inner volume contribute to ease of use, of patient attachment and to comfort. We present the specifications of Wrist Gimbal in comparison with similar devices in the literature and example data collected from a healthy subject.

Bone-marrow mononuclear cells reduce neurodegeneration in hippocampal CA1 layer after transient global ischemia in rats

Global cerebral ischemia (GCI) results in death of the pyramidal neurons in the CA1 layer of the hippocampus. In this study we used the four-vessel occlusion (4VO) model of GCI to investigate a potential neuroprotective role of bone-marrow mononuclear cells (BMMCs) transplantation. BMMCs (3×10(7)) were injected through the carotid artery, 1 or 3 days after ischemia (DAI), and the number of cells undergoing degeneration was investigated in brains at 7 DAI. A significant decrease in the number of dying cells was observed in the treated group, compared to animals treated with saline. Biodistribution of the injected cells (1 or 3 DAI) was investigated by (99m)Technetium labeling of the BMMCs and subsequent image analysis 2h after transplantation. In addition, the presence of CellTrace(™)-labeled BMMCs was investigated in tissue sections of the hippocampal area of these transplanted animals. BMMCs treatment significantly reduced the number of FJ-C positive cells in the hippocampal CA1 layer at 7 DAI. We also observed a decrease in the number of activated microglia/macrophage (ED1-positive cells) in the BMMCs-treated group compared with the untreated group. Our data show that BMMCs are able to modulate the microglial response and reduce neurodegeneration in the CA1 layer.

Prognostic factors of motor recovery after stereotactic evacuation of intracerebral hematoma

Spontaneous intracerebral hemorrhage represents 20 to 30% of all stroke patients in Japan. However, the treatment strategy of intracerebral hematoma remains controversial. Stereotactic hematoma evacuation is minimally invasive surgery and is beneficial for clot removal with limited tissue damage. The purpose of this study was to investigate the factors affecting motor recovery after stereotactic hematoma evacuation. This retrospective analysis included 30 patients with spontaneous thalamic or putaminal hemorrhage who underwent stereotactic hematoma evacuation. We compared age, presurgical muscle strength, hematoma volume and removal rate between the patients who showed improvement of motor function (improved group) and the patients associated with no motor improvement (unchanged group). Twenty-one patients were classified into the improved group and nine patients into the unchanged group. Statistical analysis revealed that age in the improved group was significantly younger than in the unchanged group (p < 0.01), whereas there was no significant difference in presurgical muscle strength, hematoma volume and removal rate between the two groups. The present results revealed that stereotactic hematoma evacuation is attributable to the improvement of motor function, especially in the younger population, indicating the importance of cortical reorganization during post-surgical rehabilitation. In addition, this procedure could provide functional improvement in severely disabled patients. Proper patient selection to receive this therapy would be beneficial for further advances of this technique. The present result might be useful in elucidating the mechanism of motor recovery and proper patient selection for this technique.

Detection of self-paced reaching movement intention from EEG signals

Future neuroprosthetic devices, in particular upper limb, will require decoding and executing not only the user's intended movement type, but also when the user intends to execute the movement. This work investigates the potential use of brain signals recorded non-invasively for detecting the time before a self-paced reaching movement is initiated which could contribute to the design of practical upper limb neuroprosthetics. In particular, we show the detection of self-paced reaching movement intention in single trials using the readiness potential, an electroencephalography (EEG) slow cortical potential (SCP) computed in a narrow frequency range (0.1–1 Hz). Our experiments with 12 human volunteers, two of them stroke subjects, yield high detection rates prior to the movement onset and low detection rates during the non-movement intention period. With the proposed approach, movement intention was detected around 500 ms before actual onset, which clearly matches previous literature on readiness potentials. Interestingly, the result obtained with one of the stroke subjects is coherent with those achieved in healthy subjects, with single-trial performance of up to 92% for the paretic arm. These results suggest that, apart from contributing to our understanding of voluntary motor control for designing more advanced neuroprostheses, our work could also have a direct impact on advancing robot-assisted neurorehabilitation.

Recovery from ischemia in the middle-aged brain: a nonhuman primate model

Studies of recovery from stroke mainly utilize rodent models and focus primarily on young subjects despite the increased prevalence of stroke with age and the fact that recovery of function is more limited in the aged brain. In the present study, a nonhuman primate model of cortical ischemia was developed to allow the comparison of impairments in young and middle-aged monkeys. Animals were pretrained on a fine motor task of the hand and digits and then underwent a surgical procedure to map and lesion the hand-digit representation in the dominant motor cortex. Animals were retested until performance returned to preoperative levels. To assess the recovery of grasp patterns, performance was videotaped and rated using a scale adapted from human occupational therapy. Results demonstrated that the impaired hand recovers to baseline in young animals in 65-80 days and in middle-aged animals in 130-150 days. However, analysis of grasp patterns revealed that neither group recover preoperative finger thumb grasp patterns, rather they develop compensatory movements.

Electrocorticographic control of a prosthetic arm in paralyzed patients

OBJECTIVE

Paralyzed patients may benefit from restoration of movement afforded by prosthetics controlled by electrocorticography (ECoG). Although ECoG shows promising results in human volunteers, it is unclear whether ECoG signals recorded from chronically paralyzed patients provide sufficient motor information, and if they do, whether they can be applied to control a prosthetic.

METHODS

We recorded ECoG signals from sensorimotor cortices of 12 patients while they executed or attempted to execute 3 to 5 simple hand and elbow movements. Sensorimotor function was severely impaired in 3 patients due to peripheral nervous system lesion or amputation, moderately impaired due to central nervous system lesions sparing the cortex in 4 patients, and normal in 5 patients. Time frequency and decoding analyses were performed with the patients' ECoG signals.

RESULTS

In all patients, the high gamma power (80-150 Hz) of the ECoG signals during movements was clearly responsive to movement types and provided the best information for classifying different movement types. The classification performance was significantly better than chance in all patients, although differences between ECoG power modulations during different movement types were significantly less in patients with severely impaired motor function. In the impaired patients, cortical representations tended to overlap each other. Finally, using the classification method in real time, a moderately impaired patient and 3 nonparalyzed patients successfully controlled a prosthetic arm.

INTERPRETATION

ECoG signals appear useful for prosthetic arm control and may provide clinically feasible motor restoration for patients with paralysis but no injury of the sensorimotor cortex.

Rhythmic exercises in rehabilitation of TBI patients: a case report

SUMMARY

Patients who have sustained traumatic brain injury (TBI) often present with a multiplicity of dysfunctions making rehabilitation challenging. Patients who have taken part in studies of rehabilitation exercises that incorporated monotonous timed auditory cues (using a metronome) following cerebrovascular events demonstrated improvement in gait and motor functions. The purpose of this case report is to describe the efficacy of Rhythmic Exercises with Auditory Cues (REAC) to improve functions in a patient, years after their traumatic brain injury.

METHODS

A single case report of a 24-year-old female patient, nine years post hemispherectomy following TBI that resulted in right hemiparesis. The patient was taught to perform REAC exercises at home. These exercises were designed to activate the body while Alternating hands and feet Bilaterally with Cross-midline movements for a short Duration while synchronizing the movements with a metronome as a Rhythm regulator. Outcome measurements included gait and functional assessment and cognitive and psychological instrument scores that were compared pre and post treatment. Clinical improvement was observed in the patient's gait pattern with reduced hip hiking motion and increased cadence. There was a decrease in spasticity in the right arm and leg with some isolated volitional movements of the hand and fingers returning. She also regained sensation in her right arm and leg. Cognitive improvement was demonstrated by increased IQ scores from 78 to 94.

TAT-mediated protein transduction of Nogo extracellular peptide 1-40 and its biological activity

AIM

Nogo extracellular peptide 1-40 (NEP1-40), a Nogo-66 antagonistic peptide, is one of the potential candidates for therapeutic intervention after central nervous system injury. This study is focused on the generation of TAT-NEP1-40 fusion protein and its transducible effects and biological activity.

METHODS

TAT-NEP1-40 fusion protein was expressed in vitro. Transducible effects of TAT-NEP1-40 were analyzed by using immunofluorescence staining or Western blot in vitro and in vivo. The biological activity of TAT-NEP1-40 was assessed by its effects against oxygen and glucose deprivation (OGD)-induced PC12 cell damages.

RESULTS

Our results showed that the TAT-NEP1-40 fusion protein was successfully expressed, purified, and refolded. Western blot analysis and immunofluorescence staining confirmed the delivery of TAT-NEP1-40 protein into PC12 cells and rat brains. OGD caused cell apoptosis or death, decreased cell viability, increased lactate dehydrogenase release in medium and the Bax/Bcl-2 ratio, all of which were prevented by the TAT-NEP1-40 fusion proteins when added exogenously to culture medium. In addition, TAT-NEP1-40 promoted neurite outgrowth of PC12 cells exposed to OGD.

CONCLUSION

These results demonstrate that the TAT-NEP1-40 can be successfully generated and efficiently transduced into PC12 cells and rat brains. The TAT-NEP1-40 can protect PC12 cells against OGD and promote neurite outgrowth. This finding suggests that the transducible TAT-NEP1-40 fusion protein offers a possibility of the development of novel therapy for cerebral injuries via delivery of the biologically active TAT-NEP1-40 fusion protein into injured sites.

Magnetic resonance imaging in cerebral ischemia: focus on neonates

Magnetic resonance imaging (MRI) has dramatically changed our ability to diagnose and treat stroke as well as follow its evolution and response to treatment. Early stroke and ischemia can be visualized using diffusion-weighted imaging (DWI), which utilizes proton diffusion within tissues as a reporter for evolving neuropathology that reflects cytotoxic edema, particularly during the first several days after injury. Historically, T2-weighted imaging (T2WI) has been used for evaluation of vasogenic edema and also is a reliable indicator of injured tissue late after injury. While visual analysis of MR data can provide information about the evolution of injury, quantitative analyses allow definitive and objective evaluations of injury size and location and the effectiveness of novel therapeutic strategies. We review the clinical basis of imaging for stroke and ischemia diagnosis and the methods for post-processing of MR data that could provide novel insights into the evolution and pathophysiology of stroke in the newborn.

Establishing an effective quantity of physiotherapy after stroke: A discussion

Physiotherapy is a well-established part of stroke rehabilitation and the UK National Clinical Guidelines for Stroke recommend that patients should have as much therapy as is appropriate to their needs. However there is no conclusive evidence of a definitive amount of treatment that is effective.

This discussion paper seeks to explore four trends that appear to be emerging from current research on intensity of physiotherapy treatment, namely quantity of treatment, type of interventions used, influence of levels of impairment and lastly, responsiveness of different body parts for recovery.

The authors suggest that further research is needed to investigate some key issues. First of all, research should investigate whether the amount of traditional physiotherapy alone should be increased or if additional treatment should be focused on functional tasks and repetition, as advocated within neuroplasticity literature. Further investigation could also explore whether more intensive treatment is beneficial to all patients or only those with specific types of impairment and activity limitation. To reflect this concept, the possibility of establishing more careful matching of patients to treatments should be explored. Finally, it should be determined whether particular contributions to recovery, e.g. lower limb function, are more responsive to intensive treatment than others, e.g hand function.

Reorganisation of the somatosensory system after early brain damage

OBJECTIVE

To examine the reorganisation of the somatosensory system after early brain lesions.

METHODS

We studied 12 young patients with congenital hemiplegia. Causative lesions were brain malformations, periventricular injuries and cortico-subcortical lesions. We explored the somatosensory system using evoked potentials, fMRI during sensory stimulation and clinical assessment of sensory function. To correlate sensory and motor function, we also performed transcranial magnetic stimulation, fMRI of hand movement and assessment of motor function by means of Melbourne test.

RESULTS

Eleven patients showed a perilesional reorganisation of primary somatosensory function, as expressed by short latency potentials following stimulation of the paretic hand; in a remaining patient, delayed latency responses (N27.1) were only elicited over the ipsilateral undamaged hemisphere. Five of the eleven patients with perilesional somatosensory representation of the affected hand showed contralesional shifting of motor function, thus exhibiting sensory-motor dissociation. Significant correlation was found between sensory deficit and fMRI activation during sensory stimulation.

CONCLUSIONS

In subjects with early brain lesions, somato-sensory function is generally reorganised within the affected hemisphere. A contralesional shifting is uncommon and poorly efficient in function restoration.

SIGNIFICANCE

This study confirms and further explores the difference in reorganisation capabilities of the motor and sensory system following early brain injury of different etiologies and timing.

Progress in clinical neurosciences: stroke recovery and rehabilitation

BACKGROUND

Recent literature has provided new insights into the role of rehabilitation in neurological recovery post-stroke. The present review combines results of animal and clinical research to provide a summary of published information regarding the mechanisms of neural recovery and impact of rehabilitation.

METHODS

Plasticity of the uninjured and post-stroke brain is examined to provide a background for the examination of brain reorganization and recovery following stroke.

SUMMARY AND CONCLUSIONS

Recent research has confirmed many of the basic underpinnings of rehabilitation and provided new insight into the role of rehabilitation in neurological recovery. Recovery post stroke is dependent upon cortical reorganization, and therefore, upon the presence of intact cortex, especially in areas adjacent to the infarct. Exposure to stimulating and complex environments and involvement in tasks or activities that are meaningful to the individual with stroke serves to increase cortical reorganization and enhance functional recovery. Additional factors associated with neurological recovery include size of stroke lesion, and the timing and intensity of therapy.

Evidence for early activation of primary motor cortex and SMA after electrical lower limb stimulation using EEG source reconstruction

Compared to median nerve somatosensory evoked potentials (SEP), less is known about activity evoked by nerve stimulation of the lower limb. To understand the mechanisms and the physiology of sensor- and motor control it is useful to investigate the sensorimotor functions as revealed by a standardized functional status. Therefore, we investigated SEPs of the lower limb in 6 healthy male volunteers. For each side, tibial and peroneal nerves were stimulated transcutaneously at the fossa poplitea. The tibial nerves were also stimulated further distally at the ankle joint. Source localization was applied to 64-EEG-channel data of the SEPs. In contrast to somatosensory areas, which are activated after median nerve stimulation, we found dipoles adjacent to motor areas near Brodmann area 4 (BA 4) for SEP components P 32/40 and P 54/60 and near the supplementary motor area (SMA) for the N 75/83 component. These sources could reliably be distinguished for each individual subject as well as for the grand mean data set. Our data show that afferent projections from the lower limb mainly reach primary motor areas (BA 4) and only subsequently, with a delay of 40 ms, higher order motor areas such as SMA. We conclude that a focused view on SEP of the lower limb could be a useful tool to investigate pathological states in motor control or peripheral deafferentiation.

Ideal timing to transfer from an acute care hospital to an interdisciplinary inpatient rehabilitation program following a stroke: an exploratory study

BACKGROUND

Timely accessibility to organized inpatient stroke rehabilitation services may become compromised since the demand for rehabilitation services following stroke is rapidly growing with no promise of additional resources. This often leads to prolonged lengths of stays in acute care facilities for individuals surviving a stroke. It is believed that this delay spent in acute care facilities may inhibit the crucial motor recovery process taking place shortly after a stroke. It is important to document the ideal timing to initiate intensive inpatient stroke rehabilitation after the neurological event. Therefore, the objective of this study was to examine the specific influence of short, moderate and long onset-admission intervals (OAI) on rehabilitation outcomes across homogeneous subgroups of patients who were admitted to a standardized interdisciplinary inpatient stroke rehabilitation program.

METHODS

A total of 418 patients discharged from the inpatient neurological rehabilitation program at the Montreal Rehabilitation Hospital Network after a first stroke (79% of all cases reviewed) were included in this retrospective study. After conducting a matching procedure across these patients based on the degree of disability, gender, and age, a total of 40 homogeneous triads (n = 120) were formed according to the three OAI subgroups: short (less than 20 days), moderate (between 20 and 40 days) or long (over 40 days; maximum of 70 days) OAI subgroups. The rehabilitation outcomes (admission and discharge Functional Independence Measure scores (FIM), absolute and relative FIM gain scores, rehabilitation length of stay, efficiency scores) were evaluated to test for differences between the three OAI subgroups.

RESULTS

Analysis revealed that the three OAI subgroups were comparable for all rehabilitation outcomes studied. No statistical difference was found for admission (P = 0.305-0.972) and discharge (P = 0.083-0.367) FIM scores, absolute (P = 0.533-0.647) and relative (P = 0.496-0.812) FIM gain scores, rehabilitation length of stay (P = 0.096), and efficiency scores (P = 0.103-0.674).

CONCLUSION

OAI does not seem to affect significantly inpatient stroke rehabilitation outcomes of patients referred from acute care facilities where rehabilitation services are rapidly initiated after the onset of the stroke and offered throughout their stay. However, other studies considering factors such as the type and intensity of the rehabilitation are required to support those results.

Feedback and Cognition in Arm Motor Skill Reacquisition After Stroke

Background and Purpose— A debated subject in stroke rehabilitation relates to the best type of training approach for motor recovery. First, we analyzed the effects of repetitive movement practice in 2 feedback conditions (knowledge of results [KR]; knowledge of performance, [KP]) on reacquisition of reaching. Second, we evaluated the impact of cognitive impairment on motor relearning ability.

Methods— A randomized controlled clinical trial was conducted in Montreal-area rehabilitation centers between 1998 and 2003 with 37 patients with chronic hemiparesis. Patients were randomly assigned to 3 groups: (1) KR (n=14) practiced a reaching task involving 75 repetitions per day, 5 days per week for 2 weeks, with 20% KR about movement precision; (2) KP (n=14) trained on the same task and schedule as KR but with faded KP about joint motions; and (3) control (C; n=9) practiced a nonreaching task. Physical (motor impairment, function) and kinematic (movement time, precision, segmentation, variability) variables were assessed before and after (immediately, 1 month) practice. Cognitive functions (memory, attention, mental flexibility, planning) were also evaluated.

Results— Kinematic gains in KR (precision) and KP (time, variability) exceeded those in C and depended on memory and mental flexibility deficits. In KP, more severely impaired patients made the most clinical gains (>2×C), which were related to memory and planning abilities.

Conclusions— Use of KP during repetitive movement practice resulted in better motor outcomes. Stroke severity together with cognitive impairments are important factors for choosing motor rehabilitation interventions after stroke.

Intrinsic factors influencing post stroke brain reorganization

Reorganization of the brain, specifically the motor cortex surrounding the stroke, accounts for much of the observed neurological recovery following stroke. Not surprisingly, size of the stroke lesion has the greatest impact on neurological recovery in both animal and clinical research studies. Spontaneous recovery of lost function is possible after a cortical lesion, particularly if the lesion is small. Age correlates negatively with recovery; older individuals generally demonstrate slower and less complete recovery. However, age by itself is a poor predictor of functional recovery.

Measurements of BOLD/CBV ratio show altered fMRI hemodynamics during stroke recovery in rats

Brain responses to external stimuli after permanent and transient ischemic insults have been documented using cerebral blood volume weighted (CBVw) functional magnetic resonance imaging (fMRI) in correlation with tissue damage and neurological recovery. Here, we extend our previous studies of stroke recovery in rat models of focal cerebral ischemia by comparing blood oxygen level-dependent (BOLD) and cerebral blood volume (CBV) changes. Responses to forepaw stimulation were measured in normal rats (n=5) and stroke rats subjected to 2 h of middle cerebral artery occlusion (n=6). Functional magnetic resonance imaging was performed 2 weeks after stroke to evaluate the recovery process. After stroke, animals showed variable degrees of fMRI activation in ipsilesional cortex, the extent of which did not correlate with structural damages as measured using apparent diffusion coefficient, fractional anisotropy, blood volume, and vessel size index. While the contralesional cortex showed good overlap between BOLD and CBV-activated regions, the ipsilesional cortex showed low covariance between significantly activated voxels by BOLD and CBVw techniques. In particular, the relative activation during contralateral stimuli in the ipsilesional somatosensory cortex was significantly higher for CBVw responses than BOLD, which might be due to stroke-related alterations in fMRI hemodynamic coupling. Aberrant subcortical activations were also observed. When unaffected forelimbs were stimulated, strong bilateral responses were observed. However, little thalamic responses accompanied stimulation of affected forelimbs despite significant activation in the ipsilesional somatosensory cortex. These results suggest that stroke affects not only local hemodynamics and coupling but also other factors including neural connectivity.