Immediate and Long-Term Changes in Corticomotor Output in Response to Rehabilitation: Correlation with Functional Improvements in Chronic Stroke

TMS assessment of corticospinal tract integrity after stroke: broadening the concept to inform neurorehabilitation prescription

Upper limb actions require intersegmental coordination of the scapula, shoulders, elbows, forearms, wrists, and hand muscles. Stroke hemiparesis, presenting as an impairment of an intersegmentally coordinated voluntary movement, is associated with altered integrity of corticospinal tract (CST) transmission from the motor cortex (M1) to muscles. Motor evoked potentials (MEPs) elicited by M1 transcranial magnetic stimulation (TMS) of "at rest" muscles, or as a backup, during muscle contraction have been used to identify CST integrity and predict the outcome after hemiparesis, under the implicit assumption that MEPs present in only one or two muscles are manifest surrogates of CST integrity for other muscles of the upper limbs. This study presents a method for applying TMS during motor tasks that involve proximal and distal muscles. It focuses on evaluating multi-muscle electromyography (EMG) and MEPs across all task-relevant limb segments. Protocols are presented for assessing voluntary motor behavior in individuals with hemiparetic stroke using isometric, unimanual, bimanual, and "REST" conditions that broaden the concept of the degree of CST integrity in order to inform clinical prescription for neurorehabilitation and distinguish its potential as a prognostic tool. Data describing the recordings of multi-muscle transcranial magnetic stimulation induced motor evoked potentials (TMS-MEP) will be presented in a case of subacute hemiparetic stroke to elucidate our perspective.

The impact of fine motor activities like playing musical instruments on the thickness and strength of the flexor digitorum muscle

BACKGROUND

This study aimed to explore the impact of occupational activities involving extensive finger movement on the muscular characteristics of the forearms. In particular, the flexor digitorum (FD) muscular thickness and strength asymmetry between right and left hand were compared between musicians and non-musicians.

METHODS

Ultrasonography was employed to measure the thickness of the FD in each hand, while a validated custom-made device was used to assess the strength of the flexor and extensor digitorum (ED). Initially, muscle differences were estimated by computing the asymmetry index between dominant and non-dominant hands. To assess potential occupational disparities, comparisons of the asymmetry index were conducted between 25 right-handed instrumental musicians and 25 right-handed non-musicians.

RESULTS

Musicians exhibited lower asymmetry between dominant and non-dominant hands in both FD thickness and ED strength when compared to non-musicians. This effect was particularly pronounced in musicians playing instruments that extensively use the left-hand fingers (e.g., violinists).

CONCLUSIONS

Occupational activities, such as playing a musical instrument, can alter forearm muscle mass and strength distribution between dominant and non-dominant hands. This underscores the importance of considering occupational parameters in clinical or experimental interventions and musculoskeletal assessments.

M2M-InvNet: Human Motor Cortex Mapping From Multi-Muscle Response Using TMS and Generative 3D Convolutional Network

Transcranial magnetic stimulation (TMS) is often applied to the motor cortex to stimulate a collection of motor evoked potentials (MEPs) in groups of peripheral muscles. The causal interface between TMS and MEP is the selective activation of neurons in the motor cortex; moving around the TMS 'spot' over the motor cortex causes different MEP responses. A question of interest is whether a collection of MEP responses can be used to identify the stimulated locations on the cortex, which could potentially be used to then place the TMS coil to produce chosen sets of MEPs. In this work we leverage our previous report on a 3D convolutional neural network (CNN) architecture that predicted MEPs from the induced electric field, to tackle an inverse imaging task in which we start with the MEPs and estimate the stimulated regions on the motor cortex. We present and evaluate five different inverse imaging CNN architectures, both conventional and generative, in terms of several measures of reconstruction accuracy. We found that one architecture, which we propose as M2M-InvNet, consistently achieved the best performance.

The effects of rTMS on motor recovery after stroke: a systematic review of fMRI studies

Repetitive transcranial magnetic stimulation (rTMS) has been widely used in motor rehabilitation after stroke, and functional magnetic resonance imaging (fMRI) has been used to investigate the neural mechanisms of motor recovery during stroke therapy. However, there is no review on the mechanism of rTMS intervention for motor recovery after stroke based on fMRI explicitly. We aim to reveal and summarize the neural mechanism of the effects of rTMS on motor function after stroke as measured by fMRI. We carefully performed a literature search using PubMed, EMBASE, Web of Science, and Cochrane Library databases from their respective inceptions to November 2022 to identify any relevant randomized controlled trials. Researchers independently screened the literature, extracted data, and qualitatively described the included studies. Eleven studies with a total of 420 poststroke patients were finally included in this systematic review. A total of 338 of those participants received fMRI examinations before and after rTMS intervention. Five studies reported the effects of rTMS on activation of brain regions, and four studies reported results related to brain functional connectivity (FC). Additionally, five studies analyzed the correlation between fMRI and motor evaluation. The neural mechanism of rTMS in improving motor function after stroke may be the activation and FCs of motor-related brain areas, including enhancement of the activation of motor-related brain areas in the affected hemisphere, inhibition of the activation of motor-related brain areas in the unaffected hemisphere, and changing the FCs of intra-hemispheric and inter-hemispheric motor networks.

Repetitive peripheral magnetic stimulation combined with transcranial magnetic stimulation in rehabilitation of upper extremity hemiparesis following stroke: a pilot study

OBJECTIVE

To investigate the effect of combined repetitive peripheral magnetic stimulation and transcranial magnetic stimulation on upper extremity function in subacute stroke patients.

DESIGN

Pilot study.

SUBJECTS

Subacute stroke patients.

METHODS

Included patients were randomized into 3 groups: a central-associated peripheral stimulation (CPS) group, a central-stimulation-only (CS) group, and a control (C) group. The CPS group underwent a new paired associative stimulation (combined repetitive peripheral magnetic stimulation and transcranial magnetic stimulation), the CS group underwent repetitive transcranial magnetic stimulation, and the C group underwent sham stimulation. All 3 groups received physiotherapy after the stimulation or sham stimulation. The treatment comprised 20 once-daily sessions. Primary outcome was the Fugl-Meyer Assessment Upper Extremity (FMA-UE) score, and secondary outcomes were the Barthel Index and Comprehensive Functional Assessment scores, and neurophysiological assessments were mainly short-interval intracortical inhibition. A 3-group (CPS, CS, C) × 2-time (before, after intervention) repeated measures analysis of variance was conducted to determine whether changes in scores were significantly different between the 3 groups.

RESULTS

A total of 45 patients were included in the analysis. Between-group comparisons on the FMA-UE demonstrated a significant improvement (group × time interaction, F2,42 = 4.86; p = 0.013; C vs CS, p = 0.020; C vs CPS, p = 0.016; CS vs CPS, p = 0.955). Correlation analysis did not find any substantial positive correlation between changes in FMA-UE and short-interval intracortical inhibition variables (C, r = -0.196, p = 0.483; CS, r = -0.169, p = 0.546; CPS, r = -0.424, p = 0.115).

CONCLUSION

This study suggests that the real-stimulus (CS and CPS) groups had better outcomes than the control (C) group. In addition, the CPS group showed a better trend in clinical and neurophysiological assessments compared with the CS group.

Similarity of hand muscle synergies elicited by transcranial magnetic stimulation and those found during voluntary movement

Converging evidence in human and animal models suggests that exogenous stimulation of the motor cortex (M1) elicits responses in the hand with similar modular structure to that found during voluntary grasping movements. The aim of this study was to establish the extent to which modularity in muscle responses to transcranial magnetic stimulation (TMS) to M1 resembles modularity in muscle activation during voluntary hand movements involving finger fractionation. Electromyography (EMG) was recorded from eight hand-forearm muscles in eight healthy individuals. Modularity was defined using non-negative matrix factorization to identify low-rank approximations (spatial muscle synergies) of the complex activation patterns of EMG data recorded during high-density TMS mapping of M1 and voluntary formation of gestures in the American Sign Language alphabet. Analysis of synergies revealed greater than chance similarity between those derived from TMS and those derived from voluntary movement. Both data sets included synergies dominated by single intrinsic hand muscles presumably to meet the demand for highly fractionated finger movement. These results suggest that corticospinal connectivity to individual intrinsic hand muscles may be combined with modular multimuscle activation via synergies in the formation of hand postures.NEW & NOTEWORTHY This is the first work to examine the similarity of modularity in hand muscle responses to transcranial magnetic stimulation (TMS) of the motor cortex and that derived from voluntary hand movement. We show that TMS-elicited muscle synergies of the hand, measured at rest, reflect those found in voluntary behavior involving finger fractionation. This work provides a basis for future work using TMS to investigate muscle activation modularity in the human motor system.

Effect of a tailored upper extremity strength training intervention combined with direct current stimulation in chronic stroke survivors: A Randomized Controlled Trial

Strengthening exercises are recommended for managing persisting upper limb (UL) weakness following a stroke. Yet, strengthening exercises often lead to variable gains because of their generic nature. For this randomized controlled trial (RCT), we aimed to determine whether tailoring strengthening exercises using a biomarker of corticospinal integrity, as reflected in the amplitude of motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS), could optimize training effects in the affected UL. A secondary aim was to determine whether applying anodal transcranial direct current stimulation (tDCS) could enhance exercise-induced training effects. For this multisite RCT, 90 adults at the chronic stage after stroke (>6 months) were recruited. Before training, participants underwent TMS to detect the presence of MEPs in the affected hand. The MEP amplitude was used to stratify participants into three training groups: (1) low-intensity, MEP <50 μV, (2) moderate-intensity, 50 μV < MEP < 120 μV, and (3) high-intensity, MEP>120 μV. Each group trained at a specific intensity based on the one-repetition maximum (1 RM): low-intensity, 35–50% 1RM; moderate-intensity, 50–65% 1RM; high-intensity, 70–85% 1RM. The strength training targeted the affected UL and was delivered 3X/week for four consecutive weeks. In each training group, participants were randomly assigned to receive either real or sham anodal tDCS (2 mA, 20 min) over the primary motor area of the affected hemisphere. Pre-/post-intervention, participants underwent a clinical evaluation of their UL to evaluate motor impairments (Fugl-Meyer Assessment), manual dexterity (Box and Blocks test) and grip strength. Post-intervention, all groups exhibited similar gains in terms of reduced impairments, improved dexterity, and grip strength, which was confirmed by multivariate and univariate analyses. However, no effect of interaction was found for tDCS or training group, indicating that tDCS had no significant impact on outcomes post-intervention. Collectively, these results indicate that adjusting training intensity based on the size of MEPs in the affected extremity provides a useful approach to optimize responses to strengthening exercises in chronic stroke survivors. Also, the lack of add-on effects of tDCS applied to the lesioned hemisphere on exercise-induced improvements in the affected UL raises questions about the relevance of combining such interventions in stroke.

The effects of repetitive transcranial magnetic stimulation on standing balance and walking in older adults with age-related neurological disorders: a systematic review and meta-analysis

BACKGROUND

Considerable evidence showed that repetitive transcranial magnetic stimulation (rTMS) can improve standing balance and walking performance in older adults with age-related neurological disorders. We here thus completed a systematic review and meta-analysis to quantitatively examine such benefits of rTMS.

METHODS

A search strategy based on the PICOS principle was used to obtain the literature in four databases. The screening and assessments of quality and risk of bias in the included studies were independently completed by two researchers. Outcomes included scales related to standing balance, Timed Up and Go (TUG) time, and walking speed/time/distance.

RESULTS

Twenty-three studies consisting of 532 participants were included, and the meta-analysis was completed on 21 of these studies. The study quality was good. Compared to control, rTMS induced both short-term (≤3 days after last intervention session) and long-term (≥1 month following last intervention session) significant improvements in balance scales (e.g., Berg Balance Scale), TUG time, and walking speed/time/distance (short-term: standardized mean difference [SMD]=0.26~0.34, 95% confidence interval [CI]=0.05~0.62; long-term: SMD=0.40~0.44, 95% CI=0.04~0.79) for both PD and stroke cohorts. Subgroup analyses suggested that greater than nine sessions of high-frequency rTMS targeting primary motor cortex with greater than 3000 pulses per week can maximize such benefits. Only few mild-to-moderate adverse events/side effects were reported, which were similar between rTMS and control group.

CONCLUSION

The results suggest that rTMS holds promise to improve balance and walking performance in older adults with age-related neurological disorders. Future studies with more rigorous design are needed to confirm the observations in this work.

Effectiveness and Success Factors of Bilateral Arm Training After Stroke: A Systematic Review and Meta-Analysis

Bilateral arm training (BAT) presents as a promising approach in upper extremity (UE) rehabilitation after a stroke as it may facilitate neuroplasticity. However, the effectiveness of BAT is inconclusive, and no systematic reviews and meta-analyses have investigated the impact of different factors on the outcomes of BAT. This systematic review and meta-analysis aimed to (1) compare the effects of bilateral arm training (BAT) with unilateral arm training (UAT) and conventional therapy (CT) on the upper limb (UL) motor impairments and functional performance post-stroke, and (2) investigate the different contributing factors that may influence the success of BAT. A comprehensive literature search was performed in five databases. Randomized control trials (RCTs) that met inclusion criteria were selected and assessed for methodological qualities. Data relating to outcome measures, characteristics of participants (stroke chronicity and severity), and features of intervention (type of BAT and dose) were extracted for meta-analysis. With 25 RCTs meeting the inclusion criteria, BAT demonstrated significantly greater improvements in motor impairments as measured by Fugl-Meyer Assessment of Upper Extremity (FMA-UE) than CT (MD = 3.94, p = < 0.001), but not in functional performance as measured by the pooled outcomes of Action Research Arm Test (ARAT), Box and Block Test (BBT), and the time component of Motor Function Test (WMFT-time) (SMD = 0.28, p = 0.313). The superior motor impairment effects of BAT were associated with recruiting mildly impaired individuals in the chronic phase of stroke (MD = 6.71, p < 0.001), and applying a higher dose of intervention (MD = 6.52, p < 0.001). Subgroup analysis showed that bilateral functional task training (BFTT) improves both motor impairments (MD = 7.84, p < 0.001) and functional performance (SMD = 1.02, p = 0.049). No significant differences were detected between BAT and UAT for motor impairment (MD = -0.90, p = 0.681) or functional performance (SMD = -0.09, p = 0.457). Thus, our meta-analysis indicates that BAT may be more beneficial than CT in addressing post-stroke UL motor impairment, particularly in the chronic phase with mild UL paresis. The success of BAT may be dose-dependent, and higher doses of intervention may be required. BFTT appears to be a valuable form of BAT that could be integrated into stroke rehabilitation programs. BAT and UAT are generally equivalent in improving UL motor impairments and functional performance.

The Immediate Carryover Effects of Peroneal Functional Electrical Stimulation Differ between People with and without Chronic Ankle Instability

Chronic ankle instability (CAI) is a common condition that may develop after an ankle sprain. Compared with healthy individuals, those with CAI demonstrate excessive ankle inversion and increased peroneal electromyography (EMG) activity throughout the stance phase of gait, which may put them at greater risk for re-injury. Functional electrical stimulation (FES) of targeted muscles may provide benefits as a treatment modality to stimulate immediate adaptation of the neuromuscular system. The present study investigated the effect of a single, 10 min peroneal FES session on ankle kinematics and peroneal EMG activity in individuals with (n = 24) or without (n = 24) CAI. There were no significant differences in ankle kinematics between the groups before the intervention. However, after the intervention, healthy controls demonstrated significantly less ankle inversion between 0-9% (p = 0.009) and 82-87% (p = 0.011) of the stance phase. Furthermore, a significant within-group difference was observed only in the control group, demonstrating increased ankle eversion between 0-7% (p = 0.011) and 67-81% (p = 0.006) of the stance phase after the intervention. Peroneal EMG activity did not differ between groups or measurements. These findings, which demonstrate that peroneal FES can induce ankle kinematics adaptations during gait, can help to develop future interventions for people with CAI.

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.

Efficient TMS-Based Motor Cortex Mapping Using Gaussian Process Active Learning

Transcranial Magnetic Stimulation (TMS) can be used to map cortical motor topography by spatially sampling the sensorimotor cortex while recording Motor Evoked Potentials (MEP) with surface electromyography (EMG). Traditional sampling strategies are time-consuming and inefficient, as they ignore the fact that responsive sites are typically sparse and highly spatially correlated. An alternative approach, commonly employed when TMS mapping is used for presurgical planning, is to leverage the expertise of the coil operator to use MEPs elicited by previous stimuli as feedback to decide which loci to stimulate next. In this paper, we propose to automatically infer optimal future stimulus loci using active learning Gaussian Process-based sampling in place of user expertise. We first compare the user-guided (USRG) method to the traditional grid selection method and randomized sampling to verify that the USRG approach has superior performance. We then compare several novel active Gaussian Process (GP) strategies with the USRG approach. Experimental results using real data show that, as expected, the USRG method is superior to the grid and random approach in both time efficiency and MEP map accuracy. We also found that an active warped GP entropy and a GP random-based strategy performed equally as well as, or even better than, the USRG method. These methods were completely automatic, and succeeded in efficiently sampling the regions in which the MEP response variations are largely confined. This work provides the foundation for highly efficient, fully automatized TMS mapping, especially when considered in the context of advances in robotic coil operation.

Central Post-Stroke Pain: An Integrative Review of Somatotopic Damage, Clinical Symptoms, and Neurophysiological Measures

Introduction: The physiopathology of central post-stroke pain (CPSP) is poorly understood, which may contribute to the limitations of diagnostic and therapeutic advancements. Thus, the current systematic review was conducted to examine, from an integrated perspective, the cortical neurophysiological changes observed via transcranial magnetic stimulation (TMS), focusing on the structural damage, and clinical symptoms in patients with CPSP. Methods: The literature review included the databases EMBASE, PubMed, and ScienceDirect using the following search terms by MeSH or Entree descriptors: [("Cerebral Stroke") AND ("Pain" OR "Transcranial Magnetic Stimulation") AND ("Transcranial Magnetic Stimulation")] (through September 29, 2020). A total of 297 articles related to CPSP were identified. Of these, only four quantitatively recorded cortical measurements. Results: We found four studies with different methodologies and results of the TMS measures. According to the National Institutes of Health (NIH) guidelines, two studies had low methodological quality and the other two studies had satisfactory methodological quality. The four studies compared the motor threshold (MT) of the stroke-affected hemisphere with the unaffected hemisphere or with healthy controls. Two studies assessed other cortical excitability measures, such as cortical silent period (CSP), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF). The main limitations in the interpretation of the results were the heterogeneity in parameter measurements, unknown cortical excitability measures as potential prognostic markers, the lack of a control group without pain, and the absence of consistent and validated diagnosis criteria. Conclusion: Despite the limited number of studies that prevented us from conducting a meta-analysis, the dataset of this systematic review provides evidence to improve the understanding of CPSP physiopathology. Additionally, these studies support the construction of a framework for diagnosis and will help improve the methodological quality of future research in somatosensory sequelae following stroke. Furthermore, they offer a way to integrate dysfunctional neuroplasticity markers that are indirectly assessed by neurophysiological measures with their correlated clinical symptoms.

Developmental and Interventional Plasticity of Motor Maps after Perinatal Stroke

Within the perinatal stroke field, there is a need to establish preclinical models where putative biomarkers for motor function can be examined. In a mouse model of perinatal stroke, we evaluated motor map size and movement latency following optogenetic cortical stimulation against three factors of post-stroke biomarker utility: (1) correlation to chronic impairment on a behavioral test battery; (2) amenability to change using a skilled motor training paradigm; and (3) ability to distinguish individuals with potential to respond well to training. Thy1-ChR2-YFP mice received a photothrombotic stroke at postnatal day 7 and were evaluated on a battery of motor tests between days 59 and 70. Following a cranial window implant, mice underwent longitudinal optogenetic motor mapping both before and after 3 weeks of skilled forelimb training. Map size and movement latency of both hemispheres were positively correlated with impaired spontaneous forelimb use, whereas only ipsilesional hemisphere map size was correlated with performance in skilled reaching. Map size and movement latency did not show groupwise changes with training; however, mice with the smallest pretraining map sizes and worst impairments demonstrated the greatest expansion of map size in response to skilled forelimb training. Overall, motor map size showed utility as a potential biomarker for impairment and training-induced modulation in specific individuals. Future assessment of the predictive capacity of post-stroke motor representations for behavioral outcome in animal models opens the possibility of dissecting how plasticity mechanisms contribute to recovery following perinatal stroke.SIGNIFICANCE STATEMENT We investigated the utility of two cortical motor representation measures (motor map size and movement onset latency) as potential biomarkers for post-stroke motor recovery in a mouse model of perinatal stroke. Both motor map size and movement latency were associated with functional recovery after perinatal stroke, with map size showing an additional association between training responsiveness and severity of impairment. Overall, both motor map size and movement onset latency show potential as neurophysiological correlates of recovery. As such, future studies of perinatal stroke rehabilitation and neuromodulation should include these measures to help explain neurophysiological changes that might be occurring in response to treatment.

A Case Report: Effect of Robotic Exoskeleton Based Therapy on Neurological and Functional Recovery of a Patient With Chronic Stroke

Background: In this study, a novel electromechanical robotic exoskeleton was developed for the rehabilitation of distal joints. The objective was to explore the functional MRI and the neurophysiological changes in cortical-excitability in response to exoskeleton training for a 9-year chronic stroke patient. Case-Report: The study involved a 52-year old female patient with a 9-year chronic stroke of the right hemisphere, who underwent 20 therapy sessions of 45 min each. Cortical-excitability and clinical-scales: Fugl-Mayer (FM), Modified Ashworth Scale (MAS), Brunnstrom-Stage (BS), Barthel-Index (BI), Range of Motion (ROM), were assessed pre-and post-therapy to quantitatively assess the motor recovery. Clinical Rehabilitation Impact: Increase in FM wrist/hand by 6, BI by 10, and decrease in MAS by 1 were reported. Ipsilesional Motor Evoked Potential (MEP) (obtained using Transcranial Magnetic Stimulation) was increased by 98 μV with a decrease in RMT by 6% and contralesional MEP was increased by 43 μV with a decrease in RMT by 4%. Laterality Index of Sensorimotor Cortex (SMC) reduced in precentral- gyrus (from 0.152 to -0.707) and in postcentral-gyrus (from 0.203 to -0.632). Conclusion: The novel exoskeleton-based training showed improved motor outcomes, cortical excitability, and neuronal activation. The research encourages the further investigation of the potential of exoskeleton training.

Effectiveness of a combined transcranial direct current stimulation and virtual reality-based intervention on upper limb function in chronic individuals post-stroke with persistent severe hemiparesis: a randomized controlled trial

BACKGROUND

Functional impairments derived from the non-use of severely affected upper limb after stroke have been proposed to be mitigated by action observation and imagination-based techniques, whose effectiveness is enhanced when combined with transcranial direct current stimulation (tDCS). Preliminary studies in mildly impaired individuals in the acute phase post-stroke show intensified effects when action is facilitated by tDCS and mediated by virtual reality (VR) but the effectiveness in cases of severe impairment and chronic stroke is unknown. This study investigated the effectiveness of a combined tDCS and VR-based intervention in the sensorimotor function of chronic individuals post-stroke with persistent severe hemiparesis compared to conventional physical therapy.

METHODS

Twenty-nine participants were randomized into an experimental group, who received 30 minutes of the combined tDCS and VR-based therapy and 30 minutes of conventional physical therapy, or a control group, who exclusively received conventional physical therapy focusing on passive and active assistive range of motion exercises. The sensorimotor function of all participants was assessed before and after 25 one-hour sessions, administered three to five times a week, using the upper extremity subscale of the Fugl-Meyer Assessment, the time and ability subscales of the Wolf Motor Function Test, and the Nottingham Sensory Assessment.

RESULTS

A clinically meaningful improvement of the upper limb motor function was consistently revealed in all motor measures after the experimental intervention, but not after conventional physical therapy. Similar limited effects were detected in the sensory function in both groups.

CONCLUSION

The combined tDCS and VR-based paradigm provided not only greater but also clinically meaningful improvement in the motor function (and similar sensory effects) in comparison to conventional physical therapy.

Evidence of neuroplasticity with robotic hand exoskeleton for post-stroke rehabilitation: a randomized controlled trial

Background

A novel electromechanical robotic-exoskeleton was designed in-house for the rehabilitation of wrist joint and Metacarpophalangeal (MCP) joint.

Objective

The objective was to compare the rehabilitation effectiveness (clinical-scales and neurophysiological-measures) of robotic-therapy training sessions with dose-matched conventional therapy in patients with stroke.

Methods

A pilot prospective parallel randomized controlled study at clinical settings was designed for patients with stroke within 2 years of chronicity. Patients were randomly assigned to receive an intervention of 20 sessions of 45 min each, five days a week for four weeks, in Robotic-therapy Group (RG) (n = 12) and conventional upper-limb rehabilitation in Control-Group (CG) (n = 11). We intended to evaluate the effects of a novel exoskeleton based therapy on the functional rehabilitation outcomes of upper-limb and cortical-excitability in patients with stroke as compared to the conventional-rehabilitation. Clinical-scales– Modified Ashworth Scale, Active Range of Motion, Barthel-Index, Brunnstrom-stage and Fugl-Meyer (FM) scale and neurophysiological measures of cortical-excitability (using Transcranial Magnetic Stimulation) –Motor Evoked Potential and Resting Motor threshold, were acquired pre- and post-therapy.

Results

No side effects were noticed in any of the patients. Both RG and CG showed significant (p < 0.05) improvement in all clinical motor-outcomes except Modified Ashworth Scale in CG. RG showed significantly (p < 0.05) higher improvement over CG in Modified Ashworth Scale, Active Range of Motion and Fugl-Meyer scale and FM Wrist-/Hand component. An increase in cortical-excitability in ipsilesional-hemisphere was found to be statistically significant (p < 0.05) in RG over CG, as indexed by a decrease in Resting Motor Threshold and increase in the amplitude of Motor Evoked Potential. No significant changes were shown by the contralesional-hemisphere. Interhemispheric RMT-asymmetry evidenced significant (p < 0.05) changes in RG over CG indicating increased cortical-excitability in ipsilesional-hemisphere along with interhemispheric changes.

Conclusion

Robotic-exoskeleton training showed improvement in motor outcomes and cortical-excitability in patients with stroke. Neurophysiological changes in RG could most likely be a consequence of plastic reorganization and use-dependent plasticity.

Trial registry number: ISRCTN95291802

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00867-7.

The modulatory effects of bilateral arm training (BAT) on the brain in stroke patients: a systematic review

OBJECTIVE

To systematically review the modulatory effects of bilateral arm training (BAT) on the brain of stroke patients in contrast to unilateral arm training (UAT) or regular motor training.

METHODS

We conducted a literature search using PubMed, EMBASE, MEDLINE, and Science Citation Index Expanded databases from the inception to March 2019 for identifying any relevant studies. Two authors independently screened the literature, extracted data, and qualitatively described the included studies.

RESULTS

Eleven studies with a total of 225 stroke patients were included in this review. 156 out of those participants received neuroimaging or neurophysiological examinations. Six studies reported enhanced activation of the ipsilesional primary motor area (M1) induced by BAT, as measured by MEP and fMRI. Beyond the M1, three studies showed that supplementary motor area (SMA) was activated, and three studies found the primary sensory cortex area (S1) was activated by BAT in stroke patients, as measured by fMRI. One article showed that the inter-/intra-hemispheric functional connections of the sensorimotor network were more highly strengthened after BAT than regular motor training, in particular the functional connectivity between the SMA and the M1 in the bi-hemispheres. Three studies reported that BAT increased the inhibitory flow from the ipsilesional hemisphere to the contralesional hemisphere, as measured by interhemispheric transcallosal inhibition (IHI). However, the superiority of BAT in inducing a symmetric IHI than UAT was controversial.

CONCLUSION

BAT is potentially more effective than UAT in improving upper limb recovery after stroke by activating the ipsilesional primary motor area (M1), supplementary motor area (SMA), and primary sensory cortex (S1) and enhancing the intra-hemispheric and interhemispheric connectivity within the sensorimotor network and the cortical motor system.

The Impact of Robotic Rehabilitation on the Motor System in Neurological Diseases. A Multimodal Neurophysiological Approach

Motor disability is a key feature of many neurological diseases, influencing the social roles of affected patients and their ability to perform daily life activities. Current rehabilitation capacities are overwhelmed by the age-related increase of motor dysfunctions seen, for example, in stroke, extrapyramidal or neuromuscular diseases. As the patient to rehabilitation personnel ration increases, robotic solutions might establish the possibility to rapidly satisfy the increasing demand for rehabilitation. This paper presents an inaugural exploratory study which investigates the interchangeability of a novel experimental robotic rehabilitation device system with classical physical therapy, using a multimodal neurophysiological assessment of the motor system-quantitative electroencephalogram (EEG), motor conduction times and turn/amplitude analysis. Preliminary results show no significant difference between the two methods; however, a significant effect of the therapy was found on different pathologies (beneficial for vascular and extrapyramidal, or limited, and only on preventing reduction of joint movements in neuromuscular).

Differential corticomotor mechanisms of ankle motor control in post stroke individuals with and without motor evoked potentials

OBJECTIVE

Deficits in ankle motor control has been identified as a significant contributor to impaired walking after stroke. Corticomotor excitability has been related to impaired upper limb motor control and poor recovery in stroke, however contributions to lower limb function are still unclear. This study used transcranial magnetic stimulation (TMS) to determine the influence of corticomotor characteristics on lower limb motor control in chronic stroke survivors.

METHODS

This retrospective study assessed 28 individuals with post stroke hemiparesis. Motor evoked potentials (MEP) measured from the paretic and non-paretic tibialis anterior (TA) muscles were used to calculate corticomotor excitability symmetry (CME_sym) and relative ipsilateral corticomotor excitability (ICE). Participants were assigned to MEP+ and MEP- groups depending on the presence (+) or absence (-) of MEPs. Ankle motor control was quantified by the ability of participants to track a sinusoidal target using dorsiflexion-plantarflexion movements of the paretic ankle and tracking error was calculated using root mean square error (RMSE).

RESULTS

Multiple linear regression model for all participants revealed only CME_sym and FMLE (p < 0.01) to significantly predict RMSE. In the MEP+ group, CME_sym significantly predicted RMSE (p = 0.03) while FMLE (p = 0.02) was a significant predictor for the MEP-.

CONCLUSION

Our results indicate that CME_sym between the ipsilesional and contralesional hemispheres does not necessarily translate to better paretic ankle motor control in chronic stroke. Presence or absence of a MEP in the TA muscle did not affect the ankle tracking performance, however, it was noted that different strategies maybe used by those with and without a MEP.

Using Cutaneous Receptor Vibration to Uncover the Effect of Transcranial Magnetic Stimulation (TMS) on Motor Cortical Excitability

Background

Little is known about how vibrational stimuli applied to hand digits affect motor cortical excitability. The present transcranial magnetic stimulation (TMS) study investigated motor evoked potentials (MEPs) in the upper extremity muscle following high-frequency vibratory digit stimulation.

Material/Methods

High-frequency vibration was applied to the upper extremity digit II utilizing a miniature electromagnetic solenoid-type stimulator-tactor in 11 healthy study participants. The conditioning stimulation (C) preceded the test magnetic stimulation (T) by inter-stimulus intervals (ISIs) of 5–500 ms in 2 experimental sessions. The TMS was applied over the primary motor cortex for the hand abductor pollicis-brevis (APB) muscle.

Results

Dunnett’s multiple comparisons test indicated significant suppression of MEP amplitudes at ISIs of 200 ms (P=0.001), 300 ms (P=0.023), and 400 ms (P=0.029) compared to control.

Conclusions

MEP amplitude suppression was observed in the APB muscle at ISIs of 200–400 ms, applying afferent signaling that originates in skin receptors following the vibratory stimuli. The study provides novel insight on the time course and MEP modulation following cutaneous receptor vibration of the hand digit. The results of the study may have implications in neurology in the neurorehabilitation of patients with increased amplitude of MEPs.

Development of a flickering action video based steady state visual evoked potential triggered brain computer interface-functional electrical stimulation for a rehabilitative action observation game

BACKGROUND:

This study focused on developing an upper limb rehabilitation program. In this regard, a steady state visual evoked potential (SSVEP) triggered brain computer interface (BCI)-functional electrical stimulation (FES) based action observation game featuring a flickering action video was designed.

OBJECTIVE:

In particular, the synergetic effect of the game was investigated by combining the action observation paradigm with BCI based FES.

METHODS:

The BCI-FES system was contrasted under two conditions: with flickering action video and flickering noise video. In this regard, 11 right-handed subjects aged between 22–27 years were recruited. The differences in brain activation in response to the two conditions were examined.

RESULTS:

The results indicate that T3 and P3 channels exhibited greater Mu suppression in 8–13 Hz for the action video than the noise video. Furthermore, T4, C4, and P4 channels indicated augmented high beta (21–30 Hz) for the action in contrast to the noise video. Finally, T4 indicated suppressed low beta (14–20 Hz) for the action video in contrast to the noise video.

CONCLUSION:

The flickering action video based BCI-FES system induced a more synergetic effect on cortical activation than the flickering noise based system.

The addition of the MEP amplitude of finger extension muscles to clinical predictors of hand function after stroke: A prospective cohort study

BACKGROUND

Within the first 72 hours after stroke, active finger extension is a strong predictor of long-term dexterity. Transcranial magnetic stimulation may add prognostic value to clinical assessment, which is especially relevant for patients unable to follow instructions.

OBJECTIVE

The current prospective cohort study aims at determining whether amplitude of motor evoked potentials of the extensor digitorum communis (EDC) can improve clinical prediction after stroke when added to clinical tests.

METHODS

the amplitude of motor evoked potentials of the affected EDC muscle at rest was measured in 18 participants within 4 weeks after stroke, as were the ability to perform finger extension and the Fugl-Meyer Motor Assessment of the upper extremity (FMA_UE). These three determinants were related to the FMA_UE at 26 weeks after stroke (FMA_UE26), both directly, and via the proportional recovery prediction model. The relation between amplitude of the motor evoked potentials and FMA_UE26 was evaluated for EDC. For comparison, also the MEP amplitudes of biceps brachii and adductor digiti minimi muscles were recorded.

RESULTS

Patients' ability to voluntarily extend the fingers was strongly related to FMA_UE26, in our cohort there were no false negative results for this predictor. Our data revealed that the relation between amplitude of motor evoked potential of EDC and FMA_UE26 was significant, but moderate (rs = 0.58) without added clinical value. The other tested muscles did not correlate significantly to FMA_UE26.

CONCLUSIONS

Our study demonstrates no additional value of motor evoked potential amplitude of the affected EDC muscle to the clinical test of finger extension, the latter being more strongly related to FMA_UE26.

Intensive virtual reality and robotic based upper limb training compared to usual care, and associated cortical reorganization, in the acute and early sub-acute periods post-stroke: a feasibility study

BACKGROUND

There is conflict regarding the benefits of greater amounts of intensive upper limb rehabilitation in the early period post-stroke. This study was conducted to test the feasibility of providing intensive therapy during the early period post-stroke and to develop a randomized control trial that is currently in process. Specifically, the study investigated whether an additional 8 h of specialized, intensive (200-300 separate hand or arm movements per hour) virtual reality (VR)/robotic based upper limb training introduced within 1-month post-stroke resulted in greater improvement in impairment and behavior, and distinct changes in cortical reorganization measured via Transcranial Magnetic Stimulation (TMS), compared to that of a control group.

METHODS

Seven subjects received 8-1 h sessions of upper limb VR/robotic training in addition to their inpatient therapy (PT, OT, ST). Six subjects only received their inpatient therapy. All were tested on measures of impairment [Upper Extremity Fugl-Meyer Assessment (UEFMA), Wrist AROM, Maximum Pinch Force], behavior [Wolf Motor Function Test (WMFT)], and also received TMS mapping until 6 months post training. ANOVAs were conducted to measure differences between groups across time for all outcome measures. Associations between changes in ipsilesional cortical maps during the early period of enhanced neuroplasticity and long-term changes in upper limb impairment and behavior measures were evaluated.

RESULTS

The VR/robotic group made significantly greater improvements on UEFMA and Wrist AROM scores compared to the usual care group. There was also less variability in the association between changes in the First Dorsal Interosseus (FDI) muscle map area and WMFT and Maximum Force change scores for the VR/robotic group.

CONCLUSIONS

An additional 8 h of intensive VR/robotic based upper limb training initiated within the first month post-stroke may promote greater gains in impairment compared to usual care alone. Importantly, the data presented demonstrated the feasibility of conducting this intervention and multiple outcome measures (impairment, behavioral, neurophysiological) in the early period post-stroke.

Effects of a tailored strength training program of the upper limb combined with transcranial direct current stimulation (tDCS) in chronic stroke patients: study protocol for a randomised, double-blind, controlled trial

Background

A significant proportion of individuals are left with poor residual functioning of the affected arm after a stroke. This has a great impact on the quality of life and the ability for stroke survivors to live independently. While strengthening exercises have been recommended to improve arm function, their benefits are generally far from optimal due to the lack of appropriate dosing in terms of intensity. One way to address this problem is to develop better tools that could predict an individual’s potential for recovery and then adjust the intensity of exercise accordingly. In this study, we aim at determining whether an individualized strengthening program based on the integrity of the corticospinal tract, as reflected in the amplitude of motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS), in conjunction with transcranial direct current stimulation (tDCS), could lead to more optimal outcomes in terms of arm function in chronic stroke patients.

Methods

This multicentre, double-blinded, randomised controlled trial will aim to recruit 84 chronic stroke patients. Before and after training, participants will undergo a clinical evaluation, assessing motor recovery of the affected arm (Fugl-Meyer Stroke Assessment-FMA) and a TMS evaluation to assess the integrity of the corticospinal tract, as reflected in MEP amplitude. Based on their baseline MEPs amplitude, participants will be stratified into three groups of training intensity levels determined by the one-repetition maximum (1RM); 1) low: 35–50% 1 RM (MEPs < 50 μV); 2) moderate: 50–65% 1RM (MEPs 50-120 μV); and 3) high: 70–80% 1RM (MEPs > 120 μV). Training will target the affected arm (3 times/week for 4 weeks). In addition, participants will be randomly allocated into two tDCS groups (real vs. sham) and tDCS will be applied in an anodal montage during the exercise.

Discussion

This study will determine whether an individualized strength training intervention in chronic stroke survivors can lead to improved arm function. In addition, we will also determine whether combining anodal tDCS over the lesioned hemisphere with strength training can lead to further improvement in arm function, when compared to sham tDCS.

Trial registration

ClinicalTrials.gov Identifier: NCT02915185. Registered September 21 2016.

The Association Between Reorganization of Bilateral M1 Topography and Function in Response to Early Intensive Hand Focused Upper Limb Rehabilitation Following Stroke Is Dependent on Ipsilesional Corticospinal Tract Integrity

Transcranial magnetic stimulation (TMS) induced motor evoked potentials (MEPs) are an established proxy of corticospinal excitability. As a binary measure, the presence (MEP+) or absence (MEP-) of ipsilesional hemisphere MEPs early following stroke is a robust indicator of long-term recovery, however this measure does not provide information about spatial cortical reorganization. MEPs have been systematically acquired over the sensorimotor cortex to "map" motor topography. In this investigation we compared the degree to which functional improvements resulting from early (<3 months post-stroke) intensive hand focused upper limb rehabilitation correlate with changes in motor topography between MEP+ and MEP- individuals. Following informed consent, 17 individuals (4 Female, 60.3 ± 9.4 years, 24.6 ± 24.01 days post first time stroke) received 8 one hour-sessions of training with virtual reality (VR)/Robotic simulations. Clinical tests [Box and Blocks Test (BBT), Wolf Motor Function Test (WMFT), Upper Extremity Fugl-Meyer (UEFMA)], kinematic and kinetic assessments [finger Active Range of Motion (finger AROM), Maximum Pinch Force (MPF)], and bilateral TMS mapping of 5 hand muscles were performed prior to (PRE), directly following (POST), and 1 month following (1M) training. Participants were divided into two groups (MEP+, MEP-) based on whether an MEP was present in the affected first dorsal interosseous (FDI) at any time point. MEP+ individuals improved significantly more than MEP- individuals from PRE to 1M on the WMFT, BBT, and finger AROM scores. Ipsilesional hemisphere FDI area increased significantly with time in the MEP+ group. FDI area of the contralesional hemisphere was not significantly different across time points or groups. In the MEP+ group, significant correlations were observed between PRE-1M changes in ipsilesional FDI area and WMFT, BBT, and finger AROM, and contralesional FDI area and UEFMA and MPF. In the MEP- group, no significant correlations were found between changes in contralesional FDI area and functional outcomes. We report preliminary evidence in a small sample that patterns of recovery and the association of recovery to bilateral changes in motor topography may depend on integrity of the ipsilesional cortical spinal tract as assessed by the presence of TMS evoked MEPs.

The effect and optimal parameters of repetitive transcranial magnetic stimulation on motor recovery in stroke patients: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

The primary aim of this meta-analysis was to evaluate the effects of repetitive transcranial magnetic stimulation (rTMS) on limb movement recovery post-stroke and cortex excitability, to explore the optimal parameters of rTMS and suitable stroke population. Second, adverse events were also included.

DATA SOURCES

The databases of PubMed, EBSCO, MEDLINE, the Cochrane Central Register of Controlled Trials, EBM Reviews-Cochrane Database, the Chinese National Knowledge Infrastructure, and the Chinese Science and Technology Journals Database were searched for randomized controlled trials exploring the effects of rTMS on limb motor function recovery post-stroke before December 2018.

REVIEW METHODS

The effect sizes of rTMS on limb motor recovery, the effect size of rTMS stimulation parameters, and different stroke population were summarized by calculating the standardized mean difference (SMD) and the 95% confidence interval using fixed/random effect models as appropriate.

RESULTS

For the motor function assessment, 42 eligible studies involving 1168 stroke patients were identified. The summary effect size indicated that rTMS had positive effects on limb motor recovery (SMD = 0.50, P < 0.00001) and activities of daily living (SMD = 0.82, P < 0.00001), and motor-evoked potentials of the stimulated hemisphere differed according to the stimulation frequency, that is, the high-frequency group (SMD = 0.57, P = 0.0006), except the low-frequency group (SMD = -0.27, P = 0.05). No significant differences were observed among the stimulation parameter subgroups except for the sessions subgroup ( P = 0.02). Only 10 included articles reported transient mild discomfort after rTMS.

CONCLUSIONS

rTMS promoted the recovery of limb motor function and changed the cortex excitability. rTMS may be better for early and pure subcortical stroke patients. Regarding different stimulation parameters, the number of stimulation sessions has an impact on the effect of rTMS.

Paired associative stimulation modulates corticomotor excitability in chronic stroke: A preliminary investigation

BACKGROUND

Paired associative stimulation (PAS) combining repeated pairing of electrical stimulation of a peripheral nerve with transcranial magnetic stimulation (TMS) over the primary motor cortex (M1) can induce neuroplastic adaptations in the human brain and enhance motor learning in neurologically-intact individuals. However, the extent to which PAS is an effective technique for inducing associative plasticity and improving motor function in individuals post-stroke is unclear.

OBJECTIVE

The objective of this pilot study was to investigate the effects of a single session of PAS to modulate corticomotor excitability and motor skill performance in individuals post-stroke.

METHODS

Seven individuals with chronic stroke completed two separate visits separated by at least one week. We assessed general corticomotor excitability, intracortical network activity and behavioral outcomes prior to and at three time points following PAS and compared these outcomes to those following a sham PAS condition (PASSHAM).

RESULTS

Following PAS, we found increased general corticomotor excitability but no significant difference in behavioral measures between PAS conditions. There was a relationship between PAS-induced corticomotor excitability increase and enhanced motor skill performance across post-PAS testing time points.

CONCLUSION

These results provide preliminary evidence for the potential of PAS to increase corticomotor excitability that could favorably impact motor skill performance in chronic individuals post-stroke and are an important first step for future studies investigating the clinical application and behavioral relevance of PAS interventions in post stroke patient populations.

Operant conditioning of the tibialis anterior motor evoked potential in people with and without chronic incomplete spinal cord injury

The activity of corticospinal pathways is important in movement control, and its plasticity is essential for motor skill learning and re-learning after central nervous system (CNS) injuries. Therefore, enhancing the corticospinal function may improve motor function recovery after CNS injuries. Operant conditioning of stimulus-induced muscle responses (e.g., reflexes) is known to induce the targeted plasticity in a targeted pathway. Thus, an operant conditioning protocol to target the corticospinal pathways may be able to enhance the corticospinal function. To test this possibility, we investigated whether operant conditioning of the tibialis anterior (TA) motor evoked potential (MEP) to transcranial magnetic stimulation can enhance corticospinal excitability in people with and without chronic incomplete spinal cord injury (SCI). The protocol consisted of 6 baseline and 24 up-conditioning/control sessions over 10 wk. In all sessions, TA MEPs were elicited at 10% above active MEP threshold while the sitting participant provided a fixed preset level of TA background electromyographic activity. During baseline sessions, MEPs were simply measured. During conditioning trials of the conditioning sessions, the participant was encouraged to increase MEP and was given immediate feedback indicating whether MEP size was above a criterion. In 5/8 participants without SCI and 9/10 with SCI, over 24 up-conditioning sessions, MEP size increased significantly to ~150% of the baseline value, whereas the silent period (SP) duration decreased by ~20%. In a control group of participants without SCI, neither MEP nor SP changed. These results indicate that MEP up-conditioning can facilitate corticospinal excitation, which is essential for enhancing motor function recovery after SCI. NEW & NOTEWORTHY We investigated whether operant conditioning of the motor evoked potential (MEP) to transcranial magnetic stimulation can systematically increase corticospinal excitability for the ankle dorsiflexor tibialis anterior (TA) in people with and without chronic incomplete spinal cord injury. We found that up-conditioning can increase the TA MEP while reducing the accompanying silent period (SP) duration. These findings suggest that MEP up-conditioning produces the facilitation of corticospinal excitation as targeted, whereas it suppresses inhibitory mechanisms reflected in SP.

Biomarkers of Stroke Recovery: Consensus-Based Core Recommendations from the Stroke Recovery and Rehabilitation Roundtable

The most difficult clinical questions in stroke rehabilitation are "What is this patient's potential for recovery?" and "What is the best rehabilitation strategy for this person, given her/his clinical profile?" Without answers to these questions, clinicians struggle to make decisions regarding the content and focus of therapy, and researchers design studies that inadvertently mix participants who have a high likelihood of responding with those who do not. Developing and implementing biomarkers that distinguish patient subgroups will help address these issues and unravel the factors important to the recovery process. The goal of the present paper is to provide a consensus statement regarding the current state of the evidence for stroke recovery biomarkers. Biomarkers of motor, somatosensory, cognitive and language domains across the recovery timeline post-stroke are considered; with focus on brain structure and function, and exclusion of blood markers and genetics. We provide evidence for biomarkers that are considered ready to be included in clinical trials, as well as others that are promising but not ready and so represent a developmental priority. We conclude with an example that illustrates the utility of biomarkers in recovery and rehabilitation research, demonstrating how the inclusion of a biomarker may enhance future clinical trials. In this way, we propose a way forward for when and where we can include biomarkers to advance the efficacy of the practice of, and research into, rehabilitation and recovery after stroke.

Biomarkers of stroke recovery: Consensus-based core recommendations from the Stroke Recovery and Rehabilitation Roundtable

The most difficult clinical questions in stroke rehabilitation are "What is this patient's potential for recovery?" and "What is the best rehabilitation strategy for this person, given her/his clinical profile?" Without answers to these questions, clinicians struggle to make decisions regarding the content and focus of therapy, and researchers design studies that inadvertently mix participants who have a high likelihood of responding with those who do not. Developing and implementing biomarkers that distinguish patient subgroups will help address these issues and unravel the factors important to the recovery process. The goal of the present paper is to provide a consensus statement regarding the current state of the evidence for stroke recovery biomarkers. Biomarkers of motor, somatosensory, cognitive and language domains across the recovery timeline post-stroke are considered; with focus on brain structure and function, and exclusion of blood markers and genetics. We provide evidence for biomarkers that are considered ready to be included in clinical trials, as well as others that are promising but not ready and so represent a developmental priority. We conclude with an example that illustrates the utility of biomarkers in recovery and rehabilitation research, demonstrating how the inclusion of a biomarker may enhance future clinical trials. In this way, we propose a way forward for when and where we can include biomarkers to advance the efficacy of the practice of, and research into, rehabilitation and recovery after stroke.

The influence of motor ability rehabilitation on temporal-spatial parameters of gait in Huntington's disease patients on the basis of a three-dimensional motion analysis system: An experimental trial

OBJECTIVE

There is no existing standard, evidence-based, scientific model for motor ability improvement in Huntington's Disease (HD) patients aimed at maintaining independent gait for as long as possible, or performing activities of daily living, the effectiveness of which would be supported by the results of studies using objective research tools. Under these circumstances, the aim of this study was to analyze the influence of motor ability rehabilitation on the spatial-temporal parameters of gait in HD patients.

DESIGN

It was an experimental trial. The studied group consisted of 30 patients (17 women and 13 men) with HD. In hospital conditions, the patients participated in the 3-week motor ability l rehabilitation programme tailored to individual needs. The study group was tested using the Vicon 250 three-dimensional gait analysis system before and after the physical exercise programme.

RESULTS

Walking speed after therapy increased for the left lower limb from 1.06 (SD 0.24) [m/s] to 1.21 (SD 0.23) [m/s], and for the right lower limb from 1.07 (SD 0.25) [m/s] to 1.20 (SD 0.25) [m/s]. The cycle length increased after the applied therapy for the left lower limb from 1.17 (SD 0.20) [m] to 1.23 (SD 0.19) [m].

CONCLUSION

The three-week motor ability rehabilitation programme positively influences spatial-temporal gait parameters in HD patients.

Effectiveness of central plus peripheral stimulation (CPPS) on post stroke upper limb motor rehabilitation

PURPOSE

This study was to assess the motor-cortex integrity and reaction time of the upper limb in patients early after stroke after CPPS approach with Theta Burst Stimulation (TBS) an repetitive Trans-cranial Magnetic Stimulation (TMS) paradigm and Neuromuscular Electrical Stimulation (NMES).

METHODS

Ten patients and ten age matched controls underwent three experimental sessions in three consecutive weeks. First-week W1 (TBS) with TBS alone, second-week W2 (NMES) with NMES alone and third-week W3 (TBS + NMES) with both TBS and NMES given sequentially. Cortical excitability was assessed with single pulse TMS stimulator before and immediately after the three interventions for Resting Motor Threshold (RMT) from the ipsilesional and contralesional hemisphere in the corresponding first dorsal interossei muscle of the ipsilateral and contralateral hand. Post intervention functional assessment was done with 9 Hole Peg Test (9PHT) for change in reaction time (RT) for both ipsilataral and contralateral hand.

RESULTS

All the three interventions showed significant improvement from the baseline, however W3 (TBS + NMES) showed significantly greater improvement when compared to other interventions in RMT and 9 HPT.

CONCLUSION

CPPS with TBS and NMES showed synergistic effect in both electrophysiological and clinical assessment. A combined approach (CPPS) may be more effective for post-stroke motor rehabilitation.

The Effects of Mirror Feedback during Target Directed Movements on Ipsilateral Corticospinal Excitability

Mirror visual feedback (MVF) training is a promising technique to promote activation in the lesioned hemisphere following stroke, and aid recovery. However, current outcomes of MVF training are mixed, in part, due to variability in the task undertaken during MVF. The present study investigated the hypothesis that movements directed toward visual targets may enhance MVF modulation of motor cortex (M1) excitability ipsilateral to the trained hand compared to movements without visual targets. Ten healthy subjects participated in a 2 × 2 factorial design in which feedback (veridical, mirror) and presence of a visual target (target present, target absent) for a right index-finger flexion task were systematically manipulated in a virtual environment. To measure M1 excitability, transcranial magnetic stimulation (TMS) was applied to the hemisphere ipsilateral to the trained hand to elicit motor evoked potentials (MEPs) in the untrained first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles at rest prior to and following each of four 2-min blocks of 30 movements (B1–B4). Targeted movement kinematics without visual feedback was measured before and after training to assess learning and transfer. FDI MEPs were decreased in B1 and B2 when movements were made with veridical feedback and visual targets were absent. FDI MEPs were decreased in B2 and B3 when movements were made with mirror feedback and visual targets were absent. FDI MEPs were increased in B3 when movements were made with mirror feedback and visual targets were present. Significant MEP changes were not present for the uninvolved ADM, suggesting a task-specific effect. Analysis of kinematics revealed learning occurred in visual target-directed conditions, but transfer was not sensitive to mirror feedback. Results are discussed with respect to current theoretical mechanisms underlying MVF-induced changes in ipsilateral excitability.

Single Session of Functional Electrical Stimulation-Assisted Walking Produces Corticomotor Symmetry Changes Related to Changes in Poststroke Walking Mechanics

BACKGROUND

Recent research demonstrated that the symmetry of corticomotor drive with the paretic and nonparetic plantarflexor muscles was related to the biomechanical ankle moment strategy that people with chronic stroke used to achieve their greatest walking speeds. Rehabilitation strategies that promote corticomotor balance might improve poststroke walking mechanics and enhance functional ambulation.

OBJECTIVE

The study objectives were to test the effectiveness of a single session of gait training using functional electrical stimulation (FES) to improve plantarflexor corticomotor symmetry and plantarflexion ankle moment symmetry and to determine whether changes in corticomotor symmetry were related to changes in ankle moment symmetry within the session.

DESIGN

This was a repeated-measures crossover study.

METHODS

On separate days, 20 people with chronic stroke completed a session of treadmill walking either with or without the use of FES of their ankle dorsi- and plantarflexor muscles. We calculated plantarflexor corticomotor symmetry using transcranial magnetic stimulation and plantarflexion ankle moment symmetry during walking between the paretic and the nonparetic limbs before and after each session. We compared changes and tested relationships between corticomotor symmetry and ankle moment symmetry following each session.

RESULTS

Following the session with FES, there was an increase in plantarflexor corticomotor symmetry that was related to the observed increase in ankle moment symmetry. In contrast, following the session without FES, there were no changes in corticomotor symmetry or ankle moment symmetry.

LIMITATIONS

No stratification was made on the basis of lesion size, location, or clinical severity.

CONCLUSIONS

These findings demonstrate, for the first time (to our knowledge), the ability of a single session of gait training with FES to induce positive corticomotor plasticity in people in the chronic stage of stroke recovery. They also provide insight into the neurophysiologic mechanisms underlying improvements in biomechanical walking function.

Characterizing differential poststroke corticomotor drive to the dorsi- and plantarflexor muscles during resting and volitional muscle activation

Imbalance of corticomotor excitability between the paretic and nonparetic limbs has been associated with the extent of upper extremity motor recovery poststroke, is greatly influenced by specific testing conditions such as the presence or absence of volitional muscle activation, and may vary across muscle groups. However, despite its clinical importance, poststroke corticomotor drive to lower extremity muscles has not been thoroughly investigated. Additionally, whereas conventional gait rehabilitation strategies for stroke survivors focus on paretic limb foot drop and dorsiflexion impairments, most contemporary literature has indicated that paretic limb propulsion and plantarflexion impairments are the most significant limiters to poststroke walking function. The purpose of this study was to compare corticomotor excitability of the dorsi- and plantarflexor muscles during resting and active conditions in individuals with good and poor poststroke walking recovery and in neurologically intact controls. We found that plantarflexor muscles showed reduced corticomotor symmetry between paretic and nonparetic limbs compared with dorsiflexor muscles in individuals with poor poststroke walking recovery during active muscle contraction but not during rest. Reduced plantarflexor corticomotor symmetry during active muscle contraction was a result of reduced corticomotor drive to the paretic muscles and enhanced corticomotor drive to the nonparetic muscles compared with the neurologically intact controls. These results demonstrate that atypical corticomotor drive exists in both the paretic and nonparetic lower limbs and implicate greater severity of corticomotor impairments to plantarflexor vs. dorsiflexor muscles during muscle activation in stroke survivors with poor walking recovery.NEW & NOTEWORTHY The present study observed that lower-limb corticomotor asymmetry resulted from both reduced paretic and enhanced nonparetic limb corticomotor excitability compared with neurologically intact controls. The most asymmetrical corticomotor drive was observed in the plantarflexor muscles of individuals with poor poststroke walking recovery. This suggests that neural function of dorsi- and plantarflexor muscles in both paretic and nonparetic limbs may play a role in poststroke walking function, which may have important implications when developing targeted poststroke rehabilitation programs to improve walking ability.

Improvement in Stroke-induced Motor Dysfunction by Music-supported Therapy: A Systematic Review and Meta-analysis

To conduct a meta-analysis of clinical trials that examined the effect of music-supported therapy on stroke-induced motor dysfunction, comprehensive literature searches of PubMed, Embase and the Cochrane Library from their inception to April 2016 were performed. A total of 10 studies (13 analyses, 358 subjects) were included; all had acceptable quality according to PEDro scale score. The baseline differences between the two groups were confirmed to be comparable. Compared with the control group, the standardized mean difference of 9-Hole Peg Test was 0.28 (-0.01, 0.57), 0.64 (0.31, 0.97) in Box and Block Test, 0.47 (0.08, 0.87) in Arm Paresis Score and 0.35 (-0.04, 0.75) in Action Research Arm Test for upper-limb motor function, 0.11 (-0.24, 0.46) in Berg Balance Scale score, 0.09 (-0.36, 0.54) in Fugl-Meyer Assessment score, 0.30 (-0.15, 0.74) in Wolf Motor Function Test, 0.30 (-0.15, 0.74) in Wolf Motor Function time, 0.65 (0.14, 1.16) in Stride length and 0.62 (0.01, 1.24) in Gait Velocity for total motor function, and 1.75 (0.94, 2.56) in Frontal Assessment Battery score for executive function. There was evidence of a positive effect of music-supported therapy, supporting its use for the treatment of stroke-induced motor dysfunction. This study was registered at PRESPERO (CRD42016037106).

The relationships of motor-evoked potentials to hand dexterity, motor function, and spasticity in chronic stroke patients: a transcranial magnetic stimulation study

The standardization of patient evaluation and monitoring methods has a special importance in evaluating the effectiveness of therapeutic methods using drugs or rehabilitative techniques in stroke rehabilitation. The aim of this study was to investigate the relationships between clinical instruments and transcranial magnetic stimulation (TMS)-evoked neurophysiological parameters in stroke patients. This study included 22 chronic post-stroke patients who were clinically assessed using the Motricity Index (MI), finger-tapping test (FTT), Motor Activity Log (MAL) 28, Brunnstrom motor staging and Ashworth Scale (ASH). Motor-evoked potential (MEP) latency and amplitude, resting motor threshold (rMT) and central motor conduction time (CMCT) were measured with TMS. Shorter MEP-latency, shorter CMCT, higher motor-evoked potential amplitude, and diminished rMT exhibited significant correlations with clinical measures evaluating motor stage, dexterity, and daily life functionality. rMT exhibited a negative correlation with hand and lower extremity Brunnstrom stages (r = -0.64, r = -0.51, respectively), MI score (r = -0.48), FTT score (r = -0.69), and also with amount of use scale and quality of movement scale of MAL 28 scores (r = -0.61, r = -0.62, respectively). Higher MEP amplitude and diminished rMT showed positive correlations with reduced ASH score (r = -0.65, r = 0.44, respectively). The TMS-evoked neurophysiologic parameters including MEP latency, amplitude, rMT and CMCT generally have positive correlation with clinical measures which evaluate motor stage, dexterity and daily life functionality. Additionally, spasticity has also remarkable relationships with MEP amplitude and rMT. These results suggest that TMS-evoked neurophysiological parameters were useful measures for monitoring post-stroke patients.

Effects of a Single Session of High Intensity Interval Treadmill Training on Corticomotor Excitability following Stroke: Implications for Therapy

Objective. High intensity interval treadmill training (HIITT) has been gaining popularity for gait rehabilitation after stroke. In this study, we examined the changes in excitability of the lower limb motor cortical representation (M1) in chronic stroke survivors following a single session of HIITT. We also determined whether exercise-induced changes in excitability could be modulated by transcranial direct current stimulation (tDCS) enhanced with a paretic ankle skill acquisition task. Methods. Eleven individuals with chronic stroke participated in two 40-minute treadmill-training sessions: HIITT alone and HITT preceded by anodal tDCS enhanced with a skill acquisition task (e-tDCS+HIITT). Transcranial magnetic stimulation (TMS) was used to assess corticomotor excitability of paretic and nonparetic tibialis anterior (TA) muscles. Results. HIIT alone reduced paretic TA M1 excitability in 7 of 11 participants by ≥ 10%. e-tDCS+HIITT increased paretic TA M1 excitability and decreased nonparetic TA M1 excitability. Conclusions. HIITT suppresses corticomotor excitability in some people with chronic stroke. When HIITT is preceded by tDCS in combination with a skill acquisition task, the asymmetry of between-hemisphere corticomotor excitability is reduced. Significance. This study provides preliminary data indicating that the cardiovascular benefits of HIITT may be achieved without suppressing motor excitability in some stroke survivors.

Predictors and brain connectivity changes associated with arm motor function improvement from intensive practice in chronic stroke

Background and Purpose: The brain changes that underlie therapy-induced improvement in motor function after stroke remain obscure. This study sought to demonstrate the feasibility and utility of measuring motor system physiology in a clinical trial of intensive upper extremity rehabilitation in chronic stroke-related hemiparesis. Methods: This was a substudy of two multi-center clinical trials of intensive robotic and intensive conventional therapy arm therapy in chronic, significantly hemiparetic, stroke patients. Transcranial magnetic stimulation was used to measure motor cortical output to the biceps and extensor digitorum communus muscles. Magnetic resonance imaging (MRI) was used to determine the cortical anatomy, as well as to measure fractional anisotropy, and blood oxygenation (BOLD) during an eyes-closed rest state. Region-of-interest time-series correlation analysis was performed on the BOLD signal to determine interregional connectivity. Functional status was measured with the upper extremity Fugl-Meyer and Wolf Motor Function Test. Results: Motor evoked potential (MEP) presence was associated with better functional outcomes, but the effect was not significant when considering baseline impairment. Affected side internal capsule fractional anisotropy was associated with better function at baseline. Affected side primary motor cortex (M1) activity became more correlated with other frontal motor regions after treatment. Resting state connectivity between affected hemisphere M1 and dorsal premotor area (PMAd) predicted recovery. Conclusions: Presence of motor evoked potentials in the affected motor cortex and its functional connectivity with PMAd may be useful in predicting recovery. Functional connectivity in the motor network shows a trends towards increasing after intensive robotic or non-robotic arm therapy. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifiers: NCT00372411 \& NCT00333983.

Can Neurological Biomarkers of Brain Impairment Be Used to Predict Poststroke Motor Recovery? A Systematic Review

Background There is growing interest to establish recovery biomarkers, especially neurological biomarkers, in order to develop new therapies and prediction models for the promotion of stroke rehabilitation and recovery. However, there is no consensus among the neurorehabilitation community about which biomarker(s) have the highest predictive value for motor recovery. Objective To review the evidence and determine which neurological biomarker(s) meet the high evidence quality criteria for use in predicting motor recovery. Methods We searched databases for prognostic neuroimaging/neurophysiological studies. Methodological quality of each study was assessed using a previously employed comprehensive 15-item rating system. Furthermore, we used the GRADE approach and ranked the overall evidence quality for each category of neurologic biomarker. Results Seventy-one articles met our inclusion criteria; 5 categories of neurologic biomarkers were identified: diffusion tensor imaging (DTI), transcranial magnetic stimulation (TMS), functional magnetic resonance imaging (fMRI), conventional structural MRI (sMRI), and a combination of these biomarkers. Most studies were conducted with individuals after ischemic stroke in the acute and/or subacute stage (~70%). Less than one-third of the studies (21/71) were assessed with satisfactory methodological quality (80% or more of total quality score). Conventional structural MRI and the combination biomarker categories ranked "high" in overall evidence quality. Conclusions There were 3 prevalent methodological limitations: (a) lack of cross-validation, (b) lack of minimal clinically important difference (MCID) for motor outcomes, and (c) small sample size. More high-quality studies are needed to establish which neurological biomarkers are the best predictors of motor recovery after stroke. Finally, the quarter-century old methodological quality tool used here should be updated by inclusion of more contemporary methods and statistical approaches.

Mapping cortical hand motor representation using TMS: A method to assess brain plasticity and a surrogate marker for recovery of function after stroke?

OBJECTIVE

Stroke is associated with reorganization within motor areas of both hemispheres. Mapping the cortical hand motor representation using transcranial magnetic stimulation may help to understand the relationship between motor cortex reorganization and motor recovery of the affected hand after stroke.

METHODS

A standardized review of the pertinent literature was performed.

RESULTS

We identified 20 trials, which analyzed the relationship between the extent and/or location of cortical hand motor representation using transcranial magnetic stimulation and motor function and recovery of the affected hand. Several correlations were found between cortical reorganization and measures of hand motor impairment and recovery.

CONCLUSION

A better understanding of the relationships between the extent and location of cortical hand motor representation and the motor impairment and motor recovery of the affected hand after stroke may contribute to a targeted use of non-invasive brain stimulation protocols. In the future motor mapping may help to guide brain stimulation techniques to the most effective motor area in an affected individual.

Brain plasticity and rehabilitation in stroke patients

In recent years, our understanding of motor learning, neuroplasticity and functional recovery after the occurrence of brain lesion has grown significantly. Novel findings in basic neuroscience have provided an impetus for research in motor rehabilitation. The brain reveals a spectrum of intrinsic capacities to react as a highly dynamic system which can change the properties of its neural circuits. This brain plasticity can lead to an extreme degree of spontaneous recovery and rehabilitative training may modify and boost the neuronal plasticity processes. Animal studies have extended these findings, providing insight into a broad range of underlying molecular and physiological events. Neuroimaging studies in human patients have provided observations at the systems level that often parallel findings in animals. In general, the best recoveries are associated with the greatest return toward the normal state of brain functional organization. Reorganization of surviving central nervous system elements supports behavioral recovery, for example, through changes in interhemispheric lateralization, activity of association cortices linked to injured zones, and organization of cortical representational maps. Evidence from animal models suggests that both motor learning and cortical stimulation alter intracortical inhibitory circuits and can facilitate long-term potentiation and cortical remodeling. Current researches on the physiology and use of cortical stimulation animal models and in humans with stroke related hemiplegia are reviewed in this article. In particular, electromyography (EMG) -controlled electrical muscle stimulation improves the motor function of the hemiparetic arm and hand. A multi-channel near-infrared spectroscopy (NIRS) studies in which the hemoglobin levels in the brain were non-invasively and dynamically measured during functional activity found that the cerebral blood flow in the injured sensory-motor cortex area is greatest during an EMG-controlled FES session. Only a few idea is, however, known for the optimal timing of the different processes and therapeutic interventions and for their interactions in detail. Finding optimal rehabilitation paradigms requires an optimal organization of the internal processes of neural plasticity and the therapeutic interventions in accordance with defined plastic time windows. In this review the mechanisms of spontaneous plasticity after stroke and experimental interventions to enhance plasticity are summarized, with an emphasis on functional electrical stimulation therapy.

Models to Tailor Brain Stimulation Therapies in Stroke

A great challenge facing stroke rehabilitation is the lack of information on how to derive targeted therapies. As such, techniques once considered promising, such as brain stimulation, have demonstrated mixed efficacy across heterogeneous samples in clinical studies. Here, we explain reasons, citing its one-type-suits-all approach as the primary cause of variable efficacy. We present evidence supporting the role of alternate substrates, which can be targeted instead in patients with greater damage and deficit. Building on this groundwork, this review will also discuss different frameworks on how to tailor brain stimulation therapies. To the best of our knowledge, our report is the first instance that enumerates and compares across theoretical models from upper limb recovery and conditions like aphasia and depression. Here, we explain how different models capture heterogeneity across patients and how they can be used to predict which patients would best respond to what treatments to develop targeted, individualized brain stimulation therapies. Our intent is to weigh pros and cons of testing each type of model so brain stimulation is successfully tailored to maximize upper limb recovery in stroke.

Symmetry of corticomotor input to plantarflexors influences the propulsive strategy used to increase walking speed post-stroke

OBJECTIVE

A deficit in paretic limb propulsion has been identified as a major biomechanical factor limiting walking speed after stroke. The purpose of this study was to determine the influence of corticomotor symmetry between paretic and nonparetic plantarflexors on the propulsive strategy used to increase walking speed.

METHODS

Twenty-three participants with post-stroke hemiparesis underwent transcranial magnetic stimulation and biomechanical testing at their self-selected and fastest walking speeds. Plantarflexor corticomotor symmetry (CS(PF)) was calculated as a ratio of the average paretic versus nonparetic soleus motor evoked potential amplitude. The ratio of the paretic and nonparetic peak ankle plantarflexion moments (PF(sym)) was calculated at each speed.

RESULTS

CS(PF) predicted the ΔPF(sym) from self-selected and fastest speeds (R(2)=.629, F(1,21)=35.56, p<.001). An interaction between CS(PF) and ΔPF(sym) (β=.596, p=.04) was observed when predicting Δspeed ((adj)R(2)=.772, F(3,19)=20.48, p<.001). Specifically, the ΔPF(sym) with speed modulation was positively related to the Δspeed (p=.03) in those with greater CS(PF), but was not related in those with poor CS(PF) (p=.30).

CONCLUSIONS

Symmetry of the corticomotor input to the plantarflexors influences the propulsive strategy used to increase post-stroke walking speed.

SIGNIFICANCE

Rehabilitation strategies that promote corticomotor symmetry may positively influence gait mechanics and enhance post-stroke walking function.

Sensorimotor cortex reorganization in subacute and chronic stroke: A neuronavigated TMS study

The integrity of the corticospinal system is an important biomarker for recovery from stroke. However, mapping the topography of the corticospinal system in subacute stroke is not trivial and how it changes over the course of recovery is poorly understood. We intend to use a transcranial magnetic stimulation (TMS) based mapping approach to quantify the topographic landscape of corticospinal activation in the ipsi- and contralesional sensorimotor cortices in the subacute and chronic phase of stroke. Mapping was conducted before (PRE) and after (POST), intervention in 10 chronic subjects and 8 subacute subjects. Reorganization was quantified in a unique way by dissociating reorganization attributed to changes in the expanse (area) of the sensorimotor territory, from that attributed to changes in the robustness of the activation (amplitude). In doing so, we observed differences in reorganization in the subacute and chronic stages indicating that recovery in different stages may not be guided by similar neurophysiological mechanisms of neuroplasticity.

Stroke Rehabilitation Using Virtual Environments

This review covers the rationale, mechanisms, and availability of commercially available virtual environment-based interventions for stroke rehabilitation. It describes interventions for motor, speech, cognitive, and sensory dysfunction. Also discussed are the important features and mechanisms that allow virtual environments to facilitate motor relearning. A common challenge is the inability to translate success in small trials to efficacy in larger populations. The heterogeneity of stroke pathophysiology has been blamed, and experts advocate for the study of multimodal approaches. Therefore, this article also introduces a framework to help define new therapy combinations that may be necessary to address stroke heterogeneity.