Use of segmental coordination analysis of nonparetic and paretic limbs during obstacle clearance in community-dwelling persons after stroke

Walking with robot-generated haptic forces in a virtual environment: a new approach to analyze lower limb coordination

Background

Walking with a haptic tensile force applied to the hand in a virtual environment (VE) can induce adaptation effects in both chronic stroke and non-stroke individuals. These effects are reflected in spatiotemporal outcomes such as gait speed. However, the concurrent kinematic changes occurring in bilateral lower limb coordination have yet to be explored.

Methods

Chronic stroke participants were stratified based on overground gait speed into lower functioning (LF < 0.8 m/s, N = 7) and higher functioning (HF ≥ 0.8 m/s, N = 7) subgroups. These subgroups and an age-matched control group (N = 14, CG) walked on a self-paced treadmill in a VE with either robot-generated haptic leash forces delivered to the hand and then released or with an instrumented cane. Walking in both leash (10 and 15 N) and cane conditions were compared to pre-force baseline values to evaluate changes in lower limb coordination outcomes.

Results

All groups showed some kinematic changes in thigh, leg and foot segments when gait speed increased during force and post-force leash as well as cane walking. These changes were also reflected in intersegmental coordination and 3D phase diagrams, which illustrated increased intersegmental trajectory areas (p < 0.05) and angular velocity. These increases could also be observed when the paretic leg transitions from stance to swing phases while walking with the haptic leash. The Sobolev norm values accounted for both angular position and angular velocity, providing a single value for potentially quantifying bilateral (i.e. non-paretic vs paretic) coordination during walking. These values tended to increase (p < 0.05) proportionally for both limbs during force and post-force epochs as gait speed tended to increase.

Conclusions

Individuals with chronic stroke who increased their gait speed when walking with tensile haptic forces and immediately after force removal, also displayed moderate concurrent changes in lower limb intersegmental coordination patterns in terms of angular displacement and velocity. Similar results were also seen with cane walking. Although symmetry was less affected, these findings appear favourable to the functional recovery of gait. Both the use of 3D phase diagrams and assigning Sobolev norm values are potentially effective for detecting and quantifying these coordination changes.

Balance and Gait After First Minor Ischemic Stroke in People 70 Years of Age or Younger: A Prospective Observational Cohort Study

BACKGROUND

Two-thirds of patients with stroke experience only mild impairments in the acute phase, and the proportion of patients <70 years is increasing. Knowledge about balance and gait and predictive factors are scarce for this group.

OBJECTIVE

The objective of this study was to explore balance and gait in the acute phase and after 3 and 12 months in patients ≤70 years with minor ischemic stroke (National Institutes of Health Stroke Scale score ≤3). This study also explored factors predicting impaired balance after 12 months.

DESIGN

This study was designed as an explorative longitudinal cohort study.

METHODS

Patients were recruited consecutively from 2 stroke units. Balance and gait were assessed with the Mini-Balance Evaluation Systems Test (Mini-BESTest), Timed Up and Go, and preferred gait speed. Predictors for impaired balance were explored using logistic regression.

RESULTS

This study included 101 patients. Mean (SD) age was 55.5 (11.4) years, 20% were female, and mean (SD) National Institutes of Health Stroke Scale score was 0.6 (0.9) points. The Mini-BESTest, gait speed, and Timed Up and Go improved significantly from the acute phase to 3 months, and gait speed also improved from 3 to 12 months. At 12 months, 26% had balance impairments and 33% walked slower than 1.0 m/s. Poor balance in the acute phase (odds ratio = 0.92, 95% confidence interval = 0.85-0.95) was the only predictor of balance impairments (Mini-BESTest score ≤22) at 12 months poststroke.

LIMITATIONS

Limitations include lack of information about pre-stroke balance and gait impairment and poststroke exercise. Few women limited the generalizability.

CONCLUSION

This study observed improvements in both balance and gait during the follow-up; still, about one-third had balance or gait impairments at 12 months poststroke. Balance in the acute phase predicted impaired balance at 12 months.

Intersegmental coordination patterns are differently affected in Parkinson's disease and cerebellar ataxia

The law of intersegmental coordination (Borghese et al. 1996) may be altered in pathological conditions. Here we investigated the contribution of the basal ganglia (BG) and the cerebellum to lower limb intersegmental coordination by inspecting the plane's orientation and other parameters pertinent to this law in patients with idiopathic Parkinson's disease (PD) or cerebellar ataxia (CA). We also applied a mathematical model that successfully accounts for the intersegmental law of coordination observed in control subjects (Barliya et al. 2009). In the present study, we compared the planarity index (PI), covariation plane (CVP) orientation, and CVP orientation predicted by the model in 11 PD patients, 8 CA patients, and two groups of healthy subjects matched for age, height, weight, and gender to each patient group (Ctrl_PD and Ctrl_CA). Controls were instructed to alter their gait speed to match those of their respective patient group. PD patients were examined after overnight withdrawal of anti-parkinsonian medications (PD-off-med) and then on medication (PD-on-med). PI was above 96% in all gait conditions in all groups suggesting that the law of intersegmental coordination is preserved in both BG and cerebellar pathology. However, the measured and predicted CVP orientations rotated in PD-on-med and PD-off-med compared with Ctrl_PD and in CA vs. Ctrl_CA. These rotations caused by PD and CA were in opposite directions suggesting differences in the roles of the BG and cerebellum in intersegmental coordination during human locomotion. NEW & NOTEWORTHY Kinematic and muscular synergies may have a role in overcoming motor redundancies, which may be reflected in intersegmental covariation. Basal ganglia and cerebellar networks were suggested to be involved in crafting and modulating synergies. We thus compared intersegmental coordination in Parkinson's disease and cerebellar disease patients and found opposite effects in some aspects. Further research integrating muscle activities as well as biomechanical and neural control modeling are needed to account for these findings.

Reshaping of Bilateral Gait Coordination in Hemiparetic Stroke Patients After Early Robotic Intervention

Hemiparetic gait is a common condition after stroke which alters importantly the quality of life of stroke survivors. In recent years, several robotic interventions have been developed to support and enhance rehabilitation strategies for such population. The Hybrid Assistive Limb^® (HAL) robot suit is a unique device able to collect in real time bioelectric signals from the patient to support and enhance voluntary gait. HAL has been used before in early stages of stroke showing gait improvement after the intervention. However, evaluation of the coordination of gait has not been done yet. Coordination is a key factor for an adequate gait performance; consequently, its changes may be closely related to gait recovery. In this study, we used planar covariation to evaluate coordination changes in hemiparetic stroke patients after early HAL intervention. Before starting, impaired intersegmental coordination for the paretic and non-paretic side was evident. HAL intervention was able to induce recovery of the covariation loop shape and deviation from the covariation plane improving intersegmental coordination. Also, there was a tendency of recovery for movement range evidenced by comparison of peak elevation angles of each limb segment of the patients before and after HAL intervention, and also when compared to healthy volunteers. Our results suggest that early HAL intervention contributed to the improvement of gait coordination in hemiparetic stroke patients by reinforcing central pattern generators and therefore reshaping their gait pattern. Trial registration: UMIN000022410 2016/05/23.

Walking on uneven terrain in healthy adults and the implications for people after stroke

BACKGROUND

One third of individuals after stroke report an inability to walk in the community. Community mobility requires walking adaptability - the ability to adjust one's stepping pattern to meet environmental demands and task goals. Walking on uneven terrain (e.g. grass, gravel) has unique requirements and is a critical component of walking adaptability that has not been investigated in the post-stroke population.

OBJECTIVE

To summarize current knowledge of biomechanical and neuromuscular modifications during uneven terrain negotiation in healthy individuals and discuss implications of post-stroke impairments.

METHODS

Review of eleven studies, identified through a search of relevant literature on PubMed and CINAHL.

RESULTS

On uneven terrain, healthy adults demonstrate numerous gait modifications including a lowered center of mass, increased muscle co-contraction during stance and exaggerated or increased toe clearance during swing. After stroke, changes in muscle activity and limb coordination will likely result in difficulty or inability performing these modifications that healthy adults use to maintain stability and safety when walking on uneven terrain.

CONCLUSIONS

Studies of biomechanical and neuromuscular control of walking on uneven terrain are needed to quantify mobility limitations in adults post-stroke. Such investigations will contribute to the understanding of mobility impairments after stroke and the design of critically important intervention strategies.

Postural asymmetry correlated with lateralization of cerebellar perfusion in persons with chronic stroke: A role of crossed cerebellar diaschisis in left side

OBJECTIVE

Hemiplegia after stroke leads to impairment of the affected limbs and induces more weight on the non-paretic lower limb to form postural asymmetry. Studies of asymmetric cerebral functions have found similarly asymmetric functions in the cerebellum. Crossed cerebellar diaschisis (CCD) is defined as reduced blood flow and hypometabolism in the cerebellar hemisphere contralateral to supratentorial cerebral pathology. No study explored the relationship between posture (standing balance) and CCD in those persons yet. It was hypothesized that CCD would impair postural control and tend toward lateralization of cerebellar perfusion.

METHODS

To determine the relationship between postural asymmetry and CCD among patients with chronic stroke while testing in the upright position. Based on images from Tc-99m-ECD brain perfusion, 42 patients were retrospectively allocated into three groups: left CCD, right CCD and no CCD. The ability to maintain an upright stance as assessed by postural parameters was evaluated using a force platform.

RESULTS

The sway intensity differed significantly between the groups with left CCD and no CCD (p = 0.0052), as did the sway velocities (p = 0.0010). The association between the duration of stroke and sway intensity was highly significant (p < 0.0001). The interval from the stroke onset to the postural analysis was significantly associated with sway intensity and velocity.

CONCLUSIONS

This study indicates that the impairment of posture sway control was more severe in left CCD than the other CCD types. The results support a relationship between the postural asymmetry and lateralization of CCD in patients with chronic stroke.

Comparison of kinetic strategies for avoidance of an obstacle with either the paretic or non-paretic as leading limb in persons post stroke

The task of stepping over obstacles is known to be particularly risky for persons post stroke. A kinetic analysis informing on the movement strategies used to ensure clearance of the leading limb over an obstacle is, however, lacking. We examined obstacle avoidance strategies in six community dwelling stroke survivors comparing the use of paretic and non-paretic limb as the leading limb for clearance over obstacles measuring 7.5% and 15% of their total leg length. Subjects were able to increase foot clearance height in both limbs in order to avoid the two obstacles. Obstacle clearance with the non-paretic limb leading was associated with positive knee flexor work that increased when stepping over each obstacle, thus showing a normal knee strategy that flexes both the knee and the hip for foot clearance. There was also slightly increased hip flexor contribution for non-paretic obstacle clearance that was the same for both obstacle heights. When the paretic limb led during obstacle clearance, there was also evidence of an increased knee flexor moment, suggesting a residual knee strategy, but it was less pronounced than for the non-paretic limb and was assisted by greater vertical hip elevation and additional positive hip flexor work that both gained greater importance with increased obstacle height. These findings suggest that rehabilitation should explore the ability to improve the residual, but less powerful, knee flexor strategy in the paretic limb in specific patients, with further promotion of a hip flexor and limb elevation strategy depending on patient deficits and obstacle height.

Walking adaptability after a stroke and its assessment in clinical settings

Control of walking has been described by a tripartite model consisting of stepping, equilibrium, and adaptability. This review focuses on walking adaptability, which is defined as the ability to modify walking to meet task goals and environmental demands. Walking adaptability is crucial to safe ambulation in the home and community environments and is often severely compromised after a stroke. Yet quantification of walking adaptability after stroke has received relatively little attention in the clinical setting. The objectives of this review were to examine the conceptual challenges for clinical measurement of walking adaptability and summarize the current state of clinical assessment for walking adaptability. We created nine domains of walking adaptability from dimensions of community mobility to address the conceptual challenges in measurement and reviewed performance-based clinical assessments of walking to determine if the assessments measure walking adaptability in these domains. Our literature review suggests the lack of a comprehensive well-tested clinical assessment tool for measuring walking adaptability. Accordingly, recommendations for the development of a comprehensive clinical assessment of walking adaptability after stroke have been presented. Such a clinical assessment will be essential for gauging recovery of walking adaptability with rehabilitation and for motivating novel strategies to enhance recovery of walking adaptability after stroke.

Automated assessment of upper extremity movement impairment due to stroke

Current diagnosis and treatment of movement impairment post-stroke is based on the subjective assessment of select movements by a trained clinical specialist. However, modern low-cost motion capture technology allows for the development of automated quantitative assessment of motor impairment. Such outcome measures are crucial for advancing post-stroke treatment methods. We sought to develop an automated method of measuring the quality of movement in clinically-relevant terms from low-cost motion capture. Unconstrained movements of upper extremity were performed by people with chronic hemiparesis and recorded by standard and low-cost motion capture systems. Quantitative scores derived from motion capture were compared to qualitative clinical scores produced by trained human raters. A strong linear relationship was found between qualitative scores and quantitative scores derived from both standard and low-cost motion capture. Performance of the automated scoring algorithm was matched by averaged qualitative scores of three human raters. We conclude that low-cost motion capture combined with an automated scoring algorithm is a feasible method to assess objectively upper-arm impairment post stroke. The application of this technology may not only reduce the cost of assessment of post-stroke movement impairment, but also promote the acceptance of objective impairment measures into routine medical practice.

Intelligent data analysis of instrumented gait data in stroke patients-a systematic review

Instrumented gait analysis (GA) may be used to analyze the causes of gait deviation in stroke patients but generates a large amount of complex data. The task of transforming this data into a comprehensible report is cumbersome. Intelligent data analysis (IDA) refers to the use of computational methods in order to analyze quantitative data more effectively. The purpose of this review was to identify and appraise the available IDA methods for handling GA data collected from patients with stroke using the standard equipment of a gait lab (3D/2D motion capture, force plates, EMG). Eleven databases were systematically searched and fifteen studies that employed some type of IDA method for the analysis of kinematic and/or kinetic and/or EMG data in populations involving stroke patients were identified. Four categories of IDA methods were employed for the analysis of sensor-acquired data in these fifteen studies: classification methods, dimensionality reduction methods, clustering methods and expert systems. The methodological quality of these studies was critically appraised by examining sample characteristics, measurements and IDA properties. Three overall methodological shortcomings were identified: (1) small sample sizes and underreported patient characteristics, (2) testing of which method is best suited to the analysis was neglected and (3) lack of stringent validation procedures. No IDA method for GA data from stroke patients was identified that can be directly applied to clinical practice. Our findings suggest that the potential provided by IDA methods is not being fully exploited.

Gait and foot clearance parameters obtained using shoe-worn inertial sensors in a large-population sample of older adults

In order to distinguish dysfunctional gait, clinicians require a measure of reference gait parameters for each population. This study provided normative values for widely used parameters in more than 1,400 able-bodied adults over the age of 65. We also measured the foot clearance parameters (i.e., height of the foot above ground during swing phase) that are crucial to understand the complex relationship between gait and falls as well as obstacle negotiation strategies. We used a shoe-worn inertial sensor on each foot and previously validated algorithms to extract the gait parameters during 20 m walking trials in a corridor at a self-selected pace. We investigated the difference of the gait parameters between male and female participants by considering the effect of age and height factors. Besides; we examined the inter-relation of the clearance parameters with the gait speed. The sample size and breadth of gait parameters provided in this study offer a unique reference resource for the researchers.