Does visuospatial neglect contribute to standing balance within the first 12 weeks post-stroke? A prospective longitudinal cohort study.

BACKGROUND: Visuospatial neglect (VSN) has been suggested to limit standing balance improvement post-stroke. However, studies investigating this association longitudinally by means of repeated within-subject measurements early post-stroke are lacking. This prospective longitudinal cohort study evaluates the longitudinal association of egocentric and allocentric VSN severity with 1) standing balance independence and 2) postural control and weight-bearing asymmetry (WBA) during quiet standing, in the first 12 weeks post-stroke. METHODS: Thirty-six hemiplegic individuals after a first-ever unilateral stroke were evaluated at weeks 3, 5, 8 and 12 post-stroke. Egocentric and allocentric VSN severity were evaluated using the Broken Hearts Test. The standing unperturbed item of the Berg Balance Scale (BBS-s) was used to clinically evaluate standing independence. Posturographic measures included measures of postural control (mediolateral (ML)/anteroposterior (AP) net center-of-pressure velocities (COPvel)) and WBA during quiet standing. A linear mixed model was used to examine longitudinal associations between egocentric and allocentric VSN, and BBS-s, COPvel-ML, COPvel-AP and WBA within the first 12 weeks post-stroke. RESULTS: Egocentric (ß = -0.08, 95%CI[-0.15;-0.01], P = .029) and allocentric VSN severity (ß = -0.09, 95%CI[-0.15; -0.04], P = .002) were significant independent factors for BBS-s scores in the first 12 weeks post-stroke. Egocentric and allocentric VSN were no significant independent factors for COPvel-ML, COPvel-AP and WBA in the first 12 weeks post-stroke. CONCLUSIONS: Allocentric and egocentric VSN severity were significantly associated with decreased standing independence, but not impaired postural control or greater asymmetric weight-bearing, in the early subacute post-stroke phase. This may involve traditional VSN measures being not sensitive enough to detect fine-grained VSN deficits due to a ceiling effect between 5 and 8 weeks post-stroke, once the individual regains standing ability. Future studies may require more sensitive VSN measurements to detect such deficits. Trial registration Clinicaltrials.gov. unique identifier NCT05060458.

The effectiveness of trunk training on trunk control, sitting and standing balance and mobility post-stroke: a systematic review and meta-analysis.

OBJECTIVE: To investigate the effectiveness of trunk training on trunk control, sitting and standing balance and mobility. DATA SOURCES: PubMed/MEDLINE, Web of Science, Physiotherapy Evidence Database (PEDro), Cochrane Library, Rehab+ and ScienceDirect were searched until January 2019. REVIEW METHODS: Randomized controlled trials were included if they investigated the effect of trunk exercises on balance and gait after stroke. Four reviewers independently screened and performed data extraction and risk of bias assessment with the PEDro scale. Disagreements were resolved by a fifth independent reviewer. A meta-analysis was performed to quantitatively describe the results. RESULTS: After screening of 1881 studies, 22 studies and 394 participants met the inclusion criteria. Trunk training was executed as core stability, reaching, weight-shift or proprioceptive neuromuscular facilitation exercises. The amount of therapy varied from a total of 3-36 hours between studies. The median PEDro score was 6 out of 10 which corresponds with a low risk of bias. Meta-analysis was performed with a random-effects model due to differences in study population, interventions received and follow-up length. The overall treatment effect was large for trunk control standardized mean differences (SMD) 1.08 (95% confidence interval (CI): 0.96-1.31), standing balance SMD 0.84 (95% CI: 0.04-0.98) and mobility SMD 0.88 (95% CI: 0.67-1.09). CONCLUSIONS: In patients suffering from stroke, there is a strong amount of evidence showing that trunk training is able to improve trunk control, sitting and standing balance and mobility.

Is a portable pressure plate an alternative to force plates for measuring postural stability and interlimb coordination of quiet standing balance control?

Introduction: Center-of-pressure (COP) synchronization and symmetry can inform adaptations in balance control following one-sided sensorimotor impairments (e.g., stroke). As established force plates are impossible to transport, we aimed to criterion validate a portable pressure plate for obtaining reliable COP synchronization and symmetry measures, next to conventional postural stability measures. Methods: Twenty healthy adults participated. In a single session, three 40-s eyes-open and eyes-closed quiet stance trials were performed per plate-type, randomly ordered. Individual-limb COPs were measured to calculate between-limb synchronization (BLS) and dynamic control asymmetry (DCA). Net COP (i.e., limbs combined) area, amplitude, and velocity were used to describe anteroposterior (AP) and mediolateral (ML) postural stability. Criterion validity was evaluated using Spearman correlations (r) and Bland-Altman plots. Test-retest reliability was tested using intraclass correlation coefficients (ICC). Results: Strong correlations (r > 0.75) and acceptable reliability (ICC > 0.80) were found regarding individual-limb COP velocity and DCA, net COP ML amplitude and AP and ML velocities. Bland-Altman plots yielded possible proportional bias; the pressure plate systematically underestimated COP scores by force plates and a larger error associated with a larger measurement. Conclusions: Despite correlations between instruments and sufficient reliability for measuring postural stability and DCA, this technical note strongly suggests, due to a systematic deviation, using the same plate-type to accurately assess performance change within subjects longitudinally over time.

Standardized measurement of balance and mobility post-stroke: Consensus-based core recommendations from the third Stroke Recovery and Rehabilitation Roundtable.

BACKGROUND: Mobility is a key priority for stroke survivors. Worldwide consensus of standardized outcome instruments for measuring mobility recovery after stroke is an essential milestone to optimize the quality of stroke rehabilitation and recovery studies and to enable data synthesis across trials. METHODS: Using a standardized methodology, which involved convening of 13 worldwide experts in the field of mobility rehabilitation, consensus was established through an a priori defined survey-based approach followed by group discussions. The group agreed on balance- and mobility-related definitions and recommended a core set of outcome measure instruments for lower extremity motor function, balance and mobility, biomechanical metrics, and technologies for measuring quality of movement. RESULTS: Selected measures included the Fugl-Meyer Motor Assessment lower extremity subscale for motor function, the Trunk Impairment Scale for sitting balance, and the Mini Balance Evaluation System Test (Mini-BESTest) and Berg Balance Scale (BBS) for standing balance. The group recommended the Functional Ambulation Category (FAC, 0-5) for walking independence, the 10-meter Walk Test (10 mWT) for walking speed, the 6-Minute Walk Test (6 MWT) for walking endurance, and the Dynamic Gait Index (DGI) for complex walking. An FAC score of less than three should be used to determine the need for an additional standing test (FAC < 3, add BBS to Mini-BESTest) or the feasibility to assess walking (FAC < 3, 10 mWT, 6 MWT, and DGI are "not testable"). In addition, recommendations are given for prioritized kinetic and kinematic metrics to be investigated that measure recovery of movement quality of standing balance and walking, as well as for assessment protocols and preferred equipment to be used. CONCLUSIONS: The present recommendations of measures, metrics, technology, and protocols build on previous consensus meetings of the International Stroke Recovery and Rehabilitation Alliance to guide the research community to improve the validity and comparability between stroke recovery and rehabilitation studies as a prerequisite for building high-quality, standardized "big data" sets. Ultimately, these recommendations could lead to high-quality, participant-specific data sets to aid the progress toward precision medicine in stroke rehabilitation.

Standardized measurement of balance and mobility post-stroke: Consensus-based core recommendations from the third Stroke Recovery and Rehabilitation Roundtable.

BACKGROUND: Mobility is a key priority for stroke survivors. Worldwide consensus of standardized outcome instruments for measuring mobility recovery after stroke is an essential milestone to optimize the quality of stroke rehabilitation and recovery studies and to enable data synthesis across trials. METHODS: Using a standardized methodology, which involved convening of 13 worldwide experts in the field of mobility rehabilitation, consensus was established through an a priori defined survey-based approach followed by group discussions. The group agreed on balance- and mobility-related definitions and recommended a core set of outcome measure instruments for lower extremity motor function, balance and mobility, biomechanical metrics, and technologies for measuring quality of movement. RESULTS: Selected measures included the Fugl-Meyer Motor Assessment lower extremity subscale for motor function, the Trunk Impairment Scale for sitting balance, and the Mini Balance Evaluation System Test (Mini-BESTest) and Berg Balance Scale (BBS) for standing balance. The group recommended the Functional Ambulation Category (FAC, 0-5) for walking independence, the 10-meter Walk Test (10 mWT) for walking speed, the 6-Minute Walk Test (6 MWT) for walking endurance, and the Dynamic Gait Index (DGI) for complex walking. An FAC score of less than three should be used to determine the need for an additional standing test (FAC < 3, add BBS to Mini-BESTest) or the feasibility to assess walking (FAC < 3, 10 mWT, 6 MWT, and DGI are "not testable"). In addition, recommendations are given for prioritized kinetic and kinematic metrics to be investigated that measure recovery of movement quality of standing balance and walking, as well as for assessment protocols and preferred equipment to be used. CONCLUSIONS: The present recommendations of measures, metrics, technology, and protocols build on previous consensus meetings of the International Stroke Recovery and Rehabilitation Alliance to guide the research community to improve the validity and comparability between stroke recovery and rehabilitation studies as a prerequisite for building high-quality, standardized "big data" sets. Ultimately, these recommendations could lead to high-quality, participant-specific data sets to aid the progress toward precision medicine in stroke rehabilitation.

Recovery of Quiet Standing Balance and Lower Limb Motor Impairment Early Poststroke: How Are They Related?

BACKGROUND: Recovery of quiet standing balance early poststroke has been poorly investigated using repeated measurements. OBJECTIVE: To investigate (1) the time course of steady-state balance in terms of postural stability and inter-limb symmetry, and (2) longitudinal associations with lower limb motor recovery in the first 3 months poststroke. METHODS: Forty-eight hemiparetic subjects (age: 58.9 ± 16.1 years) were evaluated at weeks 3, 5, 8, and 12 poststroke. Motor impairments concerned the Fugl-Meyer assessment (FM-LE) and Motricity Index total score (MI-LE) or ankle item separately (MI-ankle). Postural stability during quiet 2-legged stance was calculated as the net center-of-pressure area (COPArea) and direction-dependent velocities (COPVel-ML and COPVel-AP). Dynamic control asymmetry (DCA) and weight-bearing asymmetry (WBA) estimated inter-limb symmetries in balance control and loading. Linear mixed models determined (1) time-dependent change and (2) the between- and within-subject associations between motor impairments and postural stability or inter-limb symmetry. RESULTS: Time-dependent improvements were significant for FM-LE, MI-LE, MI-ankle, COPArea, COPVel-ML, and COPVel-AP, and tended to plateau by week 8. DCA and WBA did not exhibit significant change. Between-subject analyses yielded significant regression coefficients for FM-LE, MI-LE, and MI-ankle scores with COPArea, COPVel-ML, and COPVel-AP up until week 8, and with WBA until week 12. Within-subject regression coefficients of motor recovery with change in COPArea, COPVel-ML, COPVel-AP, DCA, or WBA were generally non-significant. CONCLUSIONS: Postural stability improved significantly in the first 8 weeks poststroke, independent of lower limb motor recovery at the most affected side within subjects. Our findings suggest that subjects preferred to compensate with their less affected side, making metrics reflecting inter-limb asymmetries in balance invariant for change early poststroke.Clinical Trial Registration: Clinicaltrials.gov. unique identifier NCT03728036.

Advanced Characterisation of Soft Polymers under Cyclic Loading in Context of Engine Mounts.

The experimental investigation of viscoelastic behavior of cyclically loaded elastomeric components with respect to the time and the frequency domain is critical for industrial applications. Moreover, the validation of this behavior through numerical simulations as part of the concept of virtual prototypes is equally important. Experiments, combined measurements and test setups for samples as well as for rubber-metal components are presented and evaluated with regard to their industrial application. For application in electric vehicles with relevant excitation frequencies substantially higher than by conventional drive trains, high-frequency dynamic stiffness measurements are performed up to 3000 Hz on a newly developed test bench for elastomeric samples and components. The new test bench is compared with the standard dynamic measurement method for characterization of soft polymers. A significant difference between the measured dynamic stiffness values, caused by internal resonance of the bushing, is presented. This effect has a direct impact on the acoustic behavior of the vehicle and goes undetected by conventional measurement methods due to their lower frequency range. Furthermore, for application in vehicles with internal combustion engine, where the mechanical excitation amplitudes are significantly larger than by vehicles with electric engines, a new concept for the identification of viscoelastic material parameters that is suitable for the representation of large periodic deformations under consideration of energy dissipation is described. This dissipated energy causes self-heating of the polymer and leads to the precocious aging and failure of the elastomeric component. The validation of this concept is carried out thermally and mechanically on specimen and component level. Using the approaches developed in this work, the behavior of cyclically loaded elastomeric engine mounts in different applications can be simulated to reduce the time spent and save on the costs necessary for the production of prototypes.

Time Course and Mechanisms Underlying Standing Balance Recovery Early After Stroke: Design of a Prospective Cohort Study With Repeated Measurements.

Introduction: Although most stroke survivors show some spontaneous neurological recovery from motor impairments of the most-affected leg, the contribution of this leg to standing balance control remains often poor. Consequently, it is unclear how spontaneous processes of neurological recovery contributes to early improvements in standing balance. Objective: We aim to investigate (1) the time course of recovery of quiet stance balance control in the first 12 weeks poststroke and (2) how clinically observed improvements of lower limb motor impairments longitudinally relate to this limb's relative contribution to balance control. Methods and Analysis: In this prospective longitudinal study, a cohort of 60 adults will be recruited within the first 3 weeks after a first-ever hemispheric stroke and mild-to-severe motor impairments. Individual recovery trajectories will be investigated by means of repeated measurements scheduled at 3, 5, 8, and 12 weeks poststroke. The Fugl-Meyer Motor Assessment and Motricity Index of the lower limb serve as clinical measures of motor impairments at the hemiplegic side. As soon as subjects are able to stand independently, bilateral posturography during quietly standing will be measured. First, the obtained center-of-pressure (COP) trajectories at each foot will be used for synchronization and contribution measures that establish (a-)symmetries between lower limbs. Second, the COP underneath both feet combined will be used to estimate overall stability. Random coefficient analyses will be used to model time-dependent changes in these measures and, subsequently, a hybrid model will be used to investigate longitudinal associations with improved motor impairments. Discussion: The current study aims to investigate how stroke survivors "re-learn" to maintain standing balance as an integral part of daily life activities. The knowledge gained through this study may contribute to recommending treatment strategies for early stroke rehabilitation targeting behavioral restitution of the most-affected leg or learning to compensate with the less-affected leg.

The association between visuospatial neglect and balance and mobility post-stroke onset: A systematic review.

BACKGROUND: Although previous narrative reviews have highlighted a potential association between visuospatial neglect (VSN) and balance disorders, to what extent different areas of balance and mobility could be affected is still unclear. OBJECTIVES: This systematic review updates previous literature findings and systematically reviews sitting balance, standing balance and mobility outcomes. METHODS: PubMed, Web of Science, ScienceDirect, Naric-Rehabdata, PEDro and the Cochrane Trials Library were systematically searched. Methodological quality was assessed by the National Heart, Lung, and Blood Institute Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. The association between VSN and sitting balance, standing balance and mobility (walking, stair climbing/descending and transfers) was investigated. RESULTS: In total, 48 studies were included (4595 stroke survivors): at least 1319 (29%) showed symptoms of VSN. VSN was associated with less independence during sitting, with an asymmetric posture toward the affected body side. For standing balance, we revealed a significant negative association between VSN and mediolateral stability and weight shifting, whereas only activities of daily living-related VSN was associated with weight-bearing asymmetry during static stance. While walking, patients with VSN laterally deviated from their path. Results were inconclusive regarding other aspects of mobility. The association between VSN and balance/mobility seemed to decrease over time. CONCLUSIONS: Despite great heterogeneity in results, this study suggests that stroke survivors with VSN show specific deviations in posture and movement in the mediolateral direction. Although the association between VSN and balance/mobility has been extensively investigated, explanatory studies evaluating underlying mechanisms of the frequently present association are lacking. Future studies should address this by combining clinical and instrumented assessment of balance and gait performance, preferably longitudinally to investigate the associations over time.

Lower limb muscle synergies during walking after stroke: a systematic review.

Purpose: The aim of this systematic review was to determine the number of muscle synergies and the distribution of muscle weightings in stroke patients during gait.Material and Methods: This review is registered on PROSPERO (number: CRD42018088701) and is written following the PRISMA guidelines. A systematic search was conducted using following databases: PubMed, Web of Science, Naric, Cochrane and PEDro. Methodological quality was assessed by the Newcastle-Ottawa Scale and data extraction (subject characteristics, outcome measures and walking protocols) was performed by two independent researchers. The amount and structure of the muscle synergies were the two main outcome measures.Results: In total, ten studies were included in this review. While four synergies are common in healthy controls, stroke patients often showed less synergies during gait. Synergies were determined by the number of muscles measured which varied greatly between studies. Only Tibialis Anterior, Soleus, Gastrocnemius and Rectus Femoris were assessed in all studies.Conclusions: A consensus regarding the amount and composition of muscle synergies in stroke patients is difficult. The majority observed three to four muscle synergies. The decrease in amount of synergies can be explained by merging of synergies, often seen in hip/knee extensors with plantar flexors and hip/knee extensors with knee flexors.IMPLICATIONS FOR REHABILITATIONMuscle synergy analyses are a powerful tool for assessing and classifying neurological deficits.A decreased amount of muscle synergies is related to impaired motor function.Differences in coordinated muscle activity was seen in the paretic and non-paretic side.Merging was often seen in hip/knee extensors with plantar flexors and hip/knee extensors with knee flexors.

Feasibility and effectiveness of repetitive gait training early after stroke: A systematic review and meta-analysis.

BACKGROUND: Pre-clinical evidence suggests a period early after stroke during which the brain is most receptive to rehabilitation, if it is provided as high-dose motor training. OBJECTIVE: To evaluate the feasibility of repetitive gait training within the first 3 months post-stroke and the effects on gait-specific outcomes. METHODS: PubMed, Web of Science, Cochrane Library, Rehab Data and PEDro databases were searched systematically. Randomized controlled trials were included to descriptively analyse the feasibility and quantitatively investigate the effectiveness of repetitive gait training compared with conventional therapy. RESULTS: Fifteen randomized controlled trials were included. Repetitive training can safely be provided through body weight support and locomotor assistance from therapists or a robotic device. No difference in drop-out rates was reported despite the demanding nature of the intervention. The meta-analysis yielded significant, but small, effects on walking independence and endurance. Training with end-effector robots appears most effective. CONCLUSION: Robots enable a substantial, yet feasible, increase in the quantity of walking practice early post-stroke, which might enhance functional recovery. However, the mechanisms underlying these effects remain poorly understood.

Combining the benefits of tele-rehabilitation and virtual reality-based balance training: a systematic review on feasibility and effectiveness.

PURPOSE: A motivational surrounding is desirable in stroke rehabilitation considering the need to train repetitively to improve balance, even after discharge from rehabilitation facilities. This review aims to investigate whether it is feasible to combine virtual reality (VR) which allows exercising in game-like environments with tele-rehabilitation in a community-dwelling stroke population. METHODS: Literature searches were conducted in five databases, for example, PubMed and the Cochrane Library. Randomized controlled trial (RCT) and non-RCT investigating feasibility and effectiveness of VR-based tele-rehabilitation were included. Based on the risk of bias and study design, methodological quality is ranked according to the GRADE guidelines. RESULTS: Seven studies (n = 120) were included, of which four are RCTs. Evidence regarding therapy adherence and perceived enjoyment of VR, as well as a cost-benefit of tele-rehabilitation emphasizes feasibility. Equal effects are reported comparing this approach to a therapist-supervised intervention in the clinical setting on balance and functional mobility. CONCLUSIONS: Tele-rehabilitation could be a promising tool to overcome burdens that restrict accessibility to rehabilitation in the future. VR can increase motivation allowing longer and more training sessions in community-dwelling stroke survivors. Therefore, combining the benefits of both approaches seems convenient. Although evidence is still sparse, functional improvements seem to be equal compared to a similar intervention with therapist-supervision in the clinic, suggesting that for cost-efficient rehabilitation parts of therapy can be transferred to the homes. Implications for rehabilitation The use of tele-rehabilitation could be a promising tool to overcome burdens that restrict the access of stroke survivors to long-term rehabilitative care. VR-based interventions are game-like and therefore seem to provide a motivational environment which allows longer exercise sessions and greater adherence to therapy.

Peripheral somatosensory stimulation and postural recovery after stroke - a systematic review.

Purpose It is hypothesized that peripheral somatosensory stimulation (PSS) can promote postural recovery after stroke by increasing afferent input and postural contribution of the paretic leg. Therefore, this systematic review aims to investigate which PSS approaches are documented and investigated on effectiveness. Methods Five databases (PubMed, Web of Science, PEDro, Cochrane Library Trials, RehabData) have been searched on clinical studies in stroke rehabilitation, investigating PSS, which is defined as a non-motor and focal stimulation to the paretic leg aiming an increase in somatosensory input. Results Twenty studies present different PSS approaches (mainly electrical and vibration stimulation) and following results: (I) There is an immediate effect after a single session of PSS on postural stability. In contrast, (II) repetitive sessions of isolated PSS led to highly inconsistent results. Finally, (III) PSS as an adjuvant to exercises did promote long-term postural recovery. Conclusion PSS is found to be effective immediately and on a long-term as an adjuvant therapy only in improving postural stability in a chronic stroke population. However, if PSS enhances paretic leg postural contribution remains unclear. Future research is warranted considering promising results and high prevalence of postural instability impacting daily life of stroke survivors.