Mechanisms of neural reorganization in chronic stroke subjects after virtual reality training

Combined robot-assisted therapy virtual reality for upper limb rehabilitation in stroke survivors: a systematic review of randomized controlled trials

BACKGROUND

Upper limb impairments are among the most common consequences following a stroke. Recently, robot-assisted therapy (RT) and virtual reality (VR) have been used to improve upper limb function in stroke survivors.

OBJECTIVES

This review aims to investigate the effects of combined RT and VR on upper limb function in stroke survivors and to provide recommendations for researchers and clinicians in the medical field.

METHODS

We searched PubMed, SCOPUS, REHABDATA, PEDro, EMBASE, and Web of Science from inception to March 28, 2024. Randomized controlled trials (RCTs) involving stroke survivors that compared combined RT and VR interventions with either passive (i.e., sham, rest) or active (i.e., traditional therapy, VR, RT) interventions and assessed outcomes related to upper limb function (e.g., strength, muscle tone, or overall function) were included. The Cochrane Collaboration tool was used to evaluate the methodological quality of the included studies.

RESULTS

Six studies were included in this review. In total, 201 patients with stroke (mean age 57.84 years) were involved in this review. Four studies were considered 'high quality', while two were considered as 'moderate quality' on the Cochrane Collaboration tool. The findings showed inconsistent results for the effects of combined RT and VR interventions on upper limb function poststroke.

CONCLUSION

In conclusion, there are potential effects of combined RT and VR interventions on improving upper limb function, but further research is needed to confirm these findings, understand the underlying mechanisms, and assess the consistency and generalizability of the results.

Does noninvasive brain stimulation combined with other therapies improve upper extremity motor impairment, functional performance, and participation in activities of daily living after stroke? A systematic review and meta-analysis of randomized controlled trial

BACKGROUND

Several studies have investigated the effect of noninvasive brain stimulation (NIBS) on upper limb motor function in stroke, but the evidence so far is conflicting.

OBJECTIVE

We aimed to determine the effect of NIBS on upper limb motor impairment, functional performance, and participation in activities of daily living after stroke.

METHOD

Literature search was conducted for randomized controlled trials (RCTs) assessing the effect of "tDCS" or "rTMS" combined with other therapies on upper extremity motor recovery after stroke. The outcome measures were Fugl-Meyer Assessment of Upper Extremity (FMA-UE), Wolf Motor Function Test (WMFT), and Barthel Index (BI). The mean difference (MD) and 95%CI were estimated for motor outcomes. Cochrane risk of bias tool was used to assess the quality of evidence.

RESULT

Twenty-five RCTs involving 1102 participants were included in the review. Compared to sham stimulation, NIBS combined with other therapies has effectively improved FMA-UE (MD0.97 [95%CI, 0.09 to 1.86; p = .03]) and BI score (MD9.11 [95%CI, 2.27 to 15.95; p = .009]) in acute/sub-acute stroke (MD1.73 [95%CI, 0.61 to 2.85; p = .003]) but unable to modify FMA-UE score in chronic stroke (MD-0.31 [95%CI, -1.77 to 1.15; p = .68]). Only inhibitory (MD3.04 [95%CI, 1.76 to 4.31; I² = 82%, p < .001] protocol is associated with improved FMA-UE score. Twenty minutes of stimulation/session for ≥20 sessions was found to be effective in improving FMA-UE score (Stimulation time: ES0.45; p ≤ .001; Sessions: ES0.33; p ≤ .001). The NIBS did not produce any significant improvement in WMFT as compared to sham NIBS (MD0.91 [95% CI, -0.89 to 2.70; p = .32]).

CONCLUSION

Moderate to high-quality evidence suggested that NIBS combined with other therapies is effective in improving upper extremity motor impairment and participation in activities of daily living after acute/sub-acute stroke.

Enhancing Brain Plasticity to Promote Stroke Recovery

Stroke disturbs both the structural and functional integrity of the brain. The understanding of stroke pathophysiology has improved greatly in the past several decades. However, effective therapy is still limited, especially for patients who are in the subacute or chronic phase. Multiple novel therapies have been developed to improve clinical outcomes by improving brain plasticity. These approaches either focus on improving brain remodeling and restoration or on constructing a neural bypass to avoid brain injury. This review describes emerging therapies, including modern rehabilitation, brain stimulation, cell therapy, brain-computer interfaces, and peripheral nervous transfer, and highlights treatment-induced plasticity. Key evidence from basic studies on the underlying mechanisms is also briefly discussed. These insights should lead to a deeper understanding of the overall neural circuit changes, the clinical relevance of these changes in stroke, and stroke treatment progress, which will assist in the development of future approaches to enhance brain function after stroke.

Effects of transcranial direct current stimulation with virtual reality on upper limb function in patients with ischemic stroke: a randomized controlled trial

BACKGROUND

Non-invasive brain stimulation techniques have been shown in several studies to improve the motor recovery of the affected upper-limbs in stroke patients. This study aims to investigate whether or not cathodal transcranial direct current stimulation (c-tDCS), combined with virtual reality (VR), is superior to VR alone in reducing motor impairment and improving upper limb function and quality of life in stroke patients.

METHODS

Forty patients who suffered ischemic stroke between 2 weeks to 12 months were recruited for this single-blind randomized control trial. The patients were randomly assigned either to an experimental group who receiving c-tDCS and VR, or a control group receiving sham stimulation and VR. The cathodal electrode was positioned over the primary motor cortex (M1) of the unaffected hemisphere. The treatment session consisted of 20 min of daily therapy, for 10 sessions over a 2-week period. The outcome measures were the Fugl-Meyer Upper Extremity (FM-UE), the Action Research Arm Test (ARAT) and the Barthel Index (BI).

RESULTS

The two groups were comparable in demographic characteristic and motor impairment. After 2 weeks of intervention, both groups demonstrated significant improvement in FM-UE, ARAT and BI scores (P<0.05).The experiment group demonstrated more improvement in FM-UE than the control group (10.1 vs. 6.4, p = 0.003) and, ARAT (7.0 vs 3.6, p = 0.026) and BI (12.8 vs 8.5, p = 0.043).

CONCLUSIONS

The findings from our study support that c-tDCS, along with VR, can facilitate a stronger beneficial effect on upper limb motor impairment, function and quality of life than VR alone in patients with ischemic stroke.

TRIAL REGISTRATION

The study was registered in the Chinese Clinical Trial Registry (ChiCTR1800019386) in November 8, 2018-Retrospectively registered.

The medical avatar and its role in neurorehabilitation and neuroplasticity: A review

BACKGROUND

One of the most interesting emerging medical devices is the medical avatar - a digital representation of the patient that can be used toward myriad ends, the full potential of which remains to be explored. Medical avatars have been instantiated as telemedical tools used to establish a representation of the patient in tele-space, upon which data about the patient's health can be represented and goals and progress can be visually tracked. Manipulation of the medical avatar has also been explored as a means of increasing motivation and inducing neural plasticity.

OBJECTIVE

The article reviews the literature on body representation, simulation, and action-observation and explores how these components of neurorehabilitation are engaged by an avatar-based self-representation.

METHODS

Through a review of the literature on body representation, simulation, and action-observation and a review of how these components of neurorehabilitation can be engaged and manipulated with an avatar, the neuroplastic potential of the medical avatar is explored. Literature on the use of the medical avatar for neurorehabilitation is also reviewed.

RESULTS

This review demonstrates that the medical avatar has vast potentialities in neurorehabilitation and that further research on its use and effect is needed.

Evaluating the use of robotic and virtual reality rehabilitation technologies to improve function in stroke survivors: A narrative review

This review evaluates the effectiveness of robotic and virtual reality technologies used for neurological rehabilitation in stroke survivors. It examines each rehabilitation technology in turn before considering combinations of these technologies and the complexities of rehabilitation outcome assessment. There is high-quality evidence that upper-limb robotic rehabilitation technologies improve movement, strength and activities of daily living, whilst the evidence for robotic lower-limb rehabilitation is currently not as convincing. Virtual reality technologies also improve activities of daily living. Whilst the benefit of these technologies over dose-controlled conventional rehabilitation is likely to be small, there is a role for both technologies as part of a broader rehabilitation programme, where they may help to increase the intensity and amount of therapy delivered. Combining robotic and virtual reality technologies in a rehabilitation programme may further improve rehabilitation outcomes and we would advocate randomised controlled trials of these technologies in combination.

Virtual Reality Enhances Gait in Cerebral Palsy: A Training Dose-Response Meta-Analysis

Virtual-reality-based training can influence gait recovery in children with cerebral palsy. A consensus concerning its influence on spatiotemporal gait parameters and effective training dosage is still warranted. This study analyzes the influence of virtual-reality training (relevant training dosage) on gait recovery in children with cerebral palsy. A search was performed by two reviewers according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines on nine databases: PEDro, EBSCO, PubMed, Cochrane, Web of Science, EMBASE, ICI, Scopus, and PROQUEST. Of 989 records, 16 studies involving a total of 274 children with cerebral palsy met our inclusion criteria. Eighty-eight percent of the studies reported significant enhancements in gait performance after training with virtual reality. Meta-analyses revealed positive effects of virtual-reality training on gait velocity (Hedge's g = 0.68), stride length (0.30), cadence (0.66), and gross motor function measure (0.44). Subgroup analysis reported a training duration of 20–30 min per session, ≤4 times per week across ≥8 weeks to allow maximum enhancements in gait velocity. This study provides preliminary evidence for the beneficial influence of virtual-reality training in gait rehabilitation for children with cerebral palsy.

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

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

Gait adaptation to visual kinematic perturbations using a real-time closed-loop brain-computer interface to a virtual reality avatar

OBJECTIVE

The control of human bipedal locomotion is of great interest to the field of lower-body brain-computer interfaces (BCIs) for gait rehabilitation. While the feasibility of closed-loop BCI systems for the control of a lower body exoskeleton has been recently shown, multi-day closed-loop neural decoding of human gait in a BCI virtual reality (BCI-VR) environment has yet to be demonstrated. BCI-VR systems provide valuable alternatives for movement rehabilitation when wearable robots are not desirable due to medical conditions, cost, accessibility, usability, or patient preferences.

APPROACH

In this study, we propose a real-time closed-loop BCI that decodes lower limb joint angles from scalp electroencephalography (EEG) during treadmill walking to control a walking avatar in a virtual environment. Fluctuations in the amplitude of slow cortical potentials of EEG in the delta band (0.1-3 Hz) were used for prediction; thus, the EEG features correspond to time-domain amplitude modulated potentials in the delta band. Virtual kinematic perturbations resulting in asymmetric walking gait patterns of the avatar were also introduced to investigate gait adaptation using the closed-loop BCI-VR system over a period of eight days.

MAIN RESULTS

Our results demonstrate the feasibility of using a closed-loop BCI to learn to control a walking avatar under normal and altered visuomotor perturbations, which involved cortical adaptations. The average decoding accuracies (Pearson's r values) in real-time BCI across all subjects increased from (Hip: 0.18 ± 0.31; Knee: 0.23 ± 0.33; Ankle: 0.14 ± 0.22) on Day 1 to (Hip: 0.40 ± 0.24; Knee: 0.55 ± 0.20; Ankle: 0.29 ± 0.22) on Day 8.

SIGNIFICANCE

These findings have implications for the development of a real-time closed-loop EEG-based BCI-VR system for gait rehabilitation after stroke and for understanding cortical plasticity induced by a closed-loop BCI-VR system.

Resting state functional connectivity and task-related effective connectivity changes after upper extremity rehabilitation: a pilot study

In this study we investigated the effect of 2 weeks of robot-aided virtual reality therapy for the paretic upper limb in stroke patients on changes in brain activation. Brain activation was acquired during the resting state and during visually-guided hand movement. fMRI analysis focused on characterizing functional connectivity with ipsilesional primary motor cortex (iM1) at rest and during execution of paretic hand movement. Two subjects who sustained a stroke more than 6 months ago participated. Before and after the training period, motor function was evaluated (Wolf Motor Function Test [WMFT], Jebsen Test of Hand Function [JTHF]). After the training period, clinical outcomes (WMFT and JTHF) improved in both subjects. The resting state functional connectivity (rsFC) maps and task-related functional connectivity with iM1 showed different magnitudes of activation, however, the general directionality of the pattern (increases versus decreases) was similar. Specifically, both the rsFC and the task-related functional connectivity between iM1 and contralesional primary motor cortex (cM1) decreased after the therapy for the first subject and increased for the second subject. Our preliminary data suggest that resting state functional connectivity may be a useful measure of brain reorganization, particularly for subjects with limited volitional control of the paretic limb.

Visuomotor discordance during visually-guided hand movement in virtual reality modulates sensorimotor cortical activity in healthy and hemiparetic subjects

We investigated neural effects of visuomotor discordances during visually-guided finger movements. A functional magnetic resonance imaging (fMRI)-compatible data glove was used to actuate (in real-time) virtual hand models shown on a display in first person perspective. In Experiment 1, we manipulated virtual hand motion to simulate either hypometric or unintentional (actuation of a mismatched finger) feedback of sequential finger flexion in healthy subjects. Analysis of finger motion revealed no significant differences in movement behavior across conditions, suggesting that between-condition differences in brain activity could only be attributed to varying modes of visual feedback rather than motor output. Hypometric feedback and mismatched finger feedback (relative to veridical) were associated with distinct activation. Hypometric feedback was associated with activation in the contralateral motor cortex. Mismatched feedback was associated with activation in bilateral ventral premotor, left dorsal premotor, and left occipitotemporal cortex. The time it took the subject to evaluate visuomotor discordance was positively correlated with activation in bilateral supplementary motor area, bilateral insula, right postcentral gyrus, bilateral dorsal premotor areas, and bilateral posterior parietal lobe. In Experiment 2, we investigated the effects of hypo- and hypermetric visual feedback in three stroke subjects. We observed increased activation of ipsilesional motor cortex in both hypometric and hypermetric feedback conditions. Our data indicate that manipulation of visual feedback of one's own hand movement may be used to facilitate activity in select brain networks. We suggest that these effects can be exploited in neurorehabilition to enhance the processes of brain reorganization after injury and, specifically, might be useful in aiding recovery of hand function in patients during virtual reality-based training.