Markedly impaired bilateral coordination of gait in post-stroke patients: Is this deficit distinct from asymmetry? A cohort study

You didn't answer the obvious question. What protocols cure these problems? Or don't you understand you are to solve stroke problems? Not just describe them. 

Markedly impaired bilateral coordination of gait in post-stroke patients: Is this deficit distinct from asymmetry? A cohort study

2011, Journal of NeuroEngineering and Rehabilitation

 Ronald Meijer 1,2,3*, 

Meir Plotnik4,5, 

Esther Groot Zwaaftink 1, 

Rob C van Lummel 6, 

Erik Ainsworth 6, 

Juan D Martina 1

and Jeffrey M Hausdorff  4,7

Abstract

Background:
 Multiple aspects of gait are typically impaired post-stroke. Asymmetric gait is common as a consequence of unilateral brain lesions. The relationship between the resulting asymmetric gait and impairments in the ability to properly coordinate the reciprocal stepping activation of the legs is not clear. The objective of this exploratory study is to quantify the effects of hemiparesis on two putatively independent aspects of the bilateral coordination of gait to gain insight into mechanisms and their relationship and to assess their potential as clinical markers.
Methods:
 Twelve ambulatory stroke patients and age-matched healthy adults wore a triaxial piezo-resistive accelerometer and walked back and forth along a straight path in a hall at a comfortable walking speed during 2minutes. Gait speed, gait asymmetry (GA), and aspects of the bilateral coordination of gait (BCG) were determined.Bilateral coordination measures included the left-right stepping phase for each stride Ø_i, consistency in the phase generationØ_CV, accuracy in the phase generationØ_ABS, and Phase Coordination Index (PCI), a combination of accuracy and consistency of the phase generation.
Results:
 Group differences (p < 0.001) were observed for gait speed (1.1 ± 0.1 versus 1.7 ± 0.1 m/sec for patients and controls, respectively), GA (26.3 ± 5.6 versus 5.5 ± 1.2, correspondingly) and PCI (19.5 ± 2.3 versus 6.2 ± 1.0,correspondingly). A significant correlation between GA and PCI was seen in the stroke patients (r = 0.94; p <0.001), but not in the controls.
Conclusions:
 In ambulatory post-stroke patients, two gait coordination properties, GA and PCI, are markedly impaired. Although these features are not related to each other in healthy controls, they are strongly related in stroke patients, which is a novel finding. A measurement approach based on body-fixed sensors apparently may provide sensitive markers that can be used for clinical assessment and for enhancing rehabilitation targeting in post stroke patients.

Background

Among patients who experience a stroke, an altered gait pattern and impaired functional mobility are common,even at the conclusion of the typical rehabilitation process. Changes in gait post-stroke include reduced speed and increased energy expenditure. Gait asymmetry (GA)is also quite prevalent and is recognized as a key to understanding of the post-stroke deficits in gait and to improving the rehabilitation process in order to maximize mobility after a stroke [1,2]. However, a complete understanding of all of the factors that contribute to GA in post-stroke patients is lacking [2]. GA is only one aspect of bilateral activation of gait.When evaluating symmetry of walking, we address the question as to what extent the limbs perform similar walking movements. For example, one can compare the swing times performed by each leg. Usually, these measures are compared over series of steps and not per
 individual gait cycles [3]. Another feature is the timingof the left-right coordination of gait, namely the bilateralcoordination of gait (BCG). This feature is distinctivefrom GA since it evaluates the level of coordination between the ongoing stepping movements of both legs.In other words: the individual performance of each leg is not evaluated but rather the interaction between their activation. Evaluating the left-right stepping phasing pat-tern (ideally 180°) is a convenient way to assess this interaction and is also done based on a series of steps.These two aspects of bilateral activation of gait are not necessarily strongly correlated with one another nor are they simply synonymous terms [4,5]. In amputees, for example, the relative timing pattern of the gait cycle, the BCG, can remain constant while one leg will have much shorter swing times than the other, implying high asymmetry  [6]. Consistent with the idea that these two properties are independent, only a weak correlation between GA and BCG was observed in patients with Parkinson’s disease (PD)[4]; in these patients, unlike in amputees, a central nervous system asymmetric degenerative process likely leads both to increased GA and impaired BCG.The present exploratory study was designed to investigate the nature of the relationship between BCG and GA in patients with hemiparesis due to stroke and to examine the potential clinical utility of measures based on BCG. For this purpose, we utilized recently introduced metrics of BCG that were found to be sensitive in other cohorts of subjects (e.g., elderly and young), but have not yet been applied to post stroke patients [4]. In addition, we based our methods on body-fixed sensors(an accelerometer), an approach that could, theoretically,allow for easy implementation in clinical settings. We hypothesized that BCG and GA would both be impaired, compared to age-matched control subjects.Moreover, in contrast to what was observed in other populations, we speculated that impairment of BCG and increased GA are the result of the same underlying pathology in post stroke patients, and, therefore, that these measures would be closely related to each other. 

More at link.

Using Biofeedback to Reduce Step Length Asymmetry Impairs Dynamic Balance in People Poststroke

 

For me to reduce asymmetry I would need my spasticity cured and my pre-motor cortex rebuilt. Tell me how to accomplish that and I will work on it.

Using Biofeedback to Reduce Step Length Asymmetry Impairs Dynamic Balance in People Poststroke

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Sungwoo Park, PhD, Chang Liu, PhD, Natalia Sánchez, PhD, ...

First Published June 1, 2021 Research Article Find in PubMed 

https://doi.org/10.1177/15459683211019346

Article information

Abstract

Background

People poststroke often walk with a spatiotemporally asymmetric gait, due in part to sensorimotor impairments in the paretic lower extremity. Although reducing asymmetry is a common objective of rehabilitation, the effects of improving symmetry on balance are yet to be determined.

Objective

We established the concurrent validity of whole-body angular momentum as a measure of balance, and we determined if reducing step length asymmetry would improve balance by decreasing whole-body angular momentum.

Methods

We performed clinical balance assessments and measured whole-body angular momentum during walking using a full-body marker set in a sample of 36 people with chronic stroke. We then used a biofeedback-based approach to modify step length asymmetry in a subset of 15 of these individuals who had marked asymmetry and we measured the resulting changes in whole-body angular momentum.

Results

When participants walked without biofeedback, whole-body angular momentum in the sagittal and frontal plane was negatively correlated with scores on the Berg Balance Scale and Functional Gait Assessment supporting the validity of whole-body angular momentum as an objective measure of dynamic balance. We also observed that when participants walked more symmetrically, their whole-body angular momentum in the sagittal plane increased rather than decreased.

Conclusions

Voluntary reductions of step length asymmetry in people poststroke resulted in reduced measures of dynamic balance. This is consistent with the idea that after stroke, individuals might have an implicit preference not to deviate from their natural asymmetry while walking because it could compromise their balance. Clinical Trials Number: NCT03916562.

Keywords stroke, gait, asymmetry, balance, biofeedback, validation, angular momentum

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Self-selected step length asymmetry is not explained by energy cost minimization in individuals with chronic stroke

I could easily fix this myself if my leg/foot spasticity was cured.

Self-selected step length asymmetry is not explained by energy cost minimization in individuals with chronic stroke

• Thu M. Nguyen,
• Rachel W. Jackson,
• Yashar Aucie,
• Digna de Kam,
• Steven H. Collins &
• Gelsy Torres-Oviedo 

Journal of NeuroEngineering and Rehabilitation volume 17, Article number: 119 (2020) Cite this article

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Abstract

Background

Asymmetric gait post-stroke is associated with decreased mobility, yet individuals with chronic stroke often self-select an asymmetric gait despite being capable of walking more symmetrically. The purpose of this study was to test whether self-selected asymmetry could be explained by energy cost minimization. We hypothesized that short-term deviations from self-selected asymmetry would result in increased metabolic energy consumption, despite being associated with long-term rehabilitation benefits. Other studies have found no difference in metabolic rate across different levels of enforced asymmetry among individuals with chronic stroke, but used methods that left some uncertainty to be resolved.

Methods

In this study, ten individuals with chronic stroke walked on a treadmill at participant-specific speeds while voluntarily altering step length asymmetry. We included only participants with clinically relevant self-selected asymmetry who were able to significantly alter asymmetry using visual biofeedback. Conditions included targeting zero asymmetry, self-selected asymmetry, and double the self-selected asymmetry. Participants were trained with the biofeedback system in one session, and data were collected in three subsequent sessions with repeated measures. Self-selected asymmetry was consistent across sessions. A similar protocol was conducted among unimpaired participants.

Results

Participants with chronic stroke substantially altered step length asymmetry using biofeedback, but this did not affect metabolic rate (ANOVA, p = 0.68). In unimpaired participants, self-selected step length asymmetry was close to zero and corresponded to the lowest metabolic energy cost (ANOVA, p = 6e-4). While the symmetry of unimpaired gait may be the result of energy cost minimization, self-selected step length asymmetry in individuals with chronic stroke cannot be explained by a similar least-effort drive.

Conclusions

Interventions that encourage changes in step length asymmetry by manipulating metabolic energy consumption may be effective because these therapies would not have to overcome a metabolic penalty for altering asymmetry.

Background

Stroke often results in hemiparesis and gait asymmetries, such as spatial, temporal, or kinematic differences between the paretic and nonparetic legs [1,2,3]. Asymmetric gait post-stroke has been associated with slower walking speeds [4] and higher metabolic energy consumption [5, 6] compared to unimpaired walking. Conventional gait retraining by physical therapists can reduce gait asymmetries, particularly step length asymmetry, and improve speed and energy economy, but sessions are costly, limiting access. More automated rehabilitation techniques to reduce step length asymmetry have been developed using split-belt treadmills [7,8,9] or rehabilitation robots [10, 11]. These interventions, however, have not been more effective than conventional physiotherapy for individuals with chronic stroke [8, 11,12,13,14,15]. A better understanding of the mechanisms driving step length asymmetry in individuals with chronic stroke could allow for the development of more targeted, effective, and accessible gait interventions.

Unimpaired individuals self-select many gait parameters, such as step frequency [16], step width [17], and even arm swinging characteristics [18], to minimize their energy cost of walking, a strategy that might also explain self-selected asymmetries in post-stroke gait. Deviations from self-selected gait tend to lead to an increase in energy expenditure, creating bowl-like relationships, or cost landscapes, between energy cost and gait parameters, with the energy minimum at the self-selected parameter value [19]. The relationship between step length asymmetry and metabolic rate has not yet been characterized in unimpaired individuals, but studies that enforce absolute differences in step length [20] or asymmetry in step time [21] suggest that they self-select nearly symmetric step lengths that correspond to a lower energy cost than asymmetric gait. Because stroke often leads to physical asymmetries, such as paretic leg muscle weakness [22], muscle spasticity [23], or reduced paretic-leg push-off force [24, 25], an asymmetric gait could be metabolically optimal for individuals with chronic stroke. On the other hand, factors other than effort minimization, such as perceived effort, avoidance of fatigue, comfort, or stability, could be primarily responsible for the observed step length asymmetry in this population.

The effects of acutely changing step length asymmetry may differ from those of slowly changing step length asymmetry through the process of rehabilitation. Long-term rehabilitation interventions that decrease gait asymmetry have shown that cost of transport often improves concurrently [26]. However, other effects of long-term rehabilitation, such as increased muscle strength [27] or improved motor control [28], may enable individuals to walk with reduced asymmetry more efficiently. Therefore, acute reductions in gait asymmetry that are not accompanied by the neuro-musculoskeletal changes often seen in long-term rehabilitation may not correlate with improvements in walking economy. Even for individuals who walk with highly asymmetric gaits, their self-selected asymmetry may be the most energy efficient one, and acute changes in gait asymmetry could still lead to increased energy consumption.

Step length asymmetry is changed acutely during split-belt walking, but this task change may also change the optimal step length asymmetry. When belt speeds are matched immediately following split-belt training, step length asymmetry is acutely changed, but this washout effect does not persist long enough to collect steady-state metabolic rate measurements [29]. To determine whether self-selected gait asymmetry minimizes energy cost, gait asymmetry would need to be varied independently from other factors affecting metabolic energy consumption, within an individual participant, while metabolic rate is measured.

Previous studies measured metabolic rate while individuals with chronic stroke acutely altered step length asymmetry and step length difference using biofeedback [20, 30]. These studies found no difference in metabolic rate between self-selected and altered step length asymmetries in stroke survivors. However, some uncertainty remains to be resolved. Each prior study included participants with self-selected step length asymmetry values close to zero. This makes differentiating between the potential optimality of self-selected asymmetry and that of absolute symmetry difficult. Prior studies also included some participants who were unable to reliably alter step length asymmetry, so asymmetry values in different conditions could have been similar. This can reduce the power of a numerical analysis intended to identify an effect of step length asymmetry on metabolic rate. In prior studies, participants were instructed to hold onto the treadmill handrails to help with stability and minimize fall risk. However, participants could have relied more heavily on the handrails during more difficult conditions to improve stability or to help maintain the correct speed. Both improved balance [31, 32] and handrail holding [33] during treadmill walking have been shown to reduce metabolic energy consumption. To minimize the amount of walking and number of experimental sessions for participants with chronic stroke, participants in these studies were familiarized with the biofeedback on the same day as the data collection. However, motor learning can have an effect on metabolic rate during a novel task; as individuals learn a new task, metabolic power [34, 35] and muscle activity [36] typically decrease, with steady state reached after hours or days of practice. For example, Sánchez et al. recently showed that split-belt treadmill training takes longer than originally thought [37], and training over multiple sessions can facilitate better learning because memory consolidation occurs during sleep [38].

The purpose of this study was to characterize the relationship between step length asymmetry and metabolic energy consumption during walking in individuals with chronic stroke and unimpaired individuals. We screened for individuals with chronic stroke who exhibited clinically meaningful self-selected step length asymmetry, so as to differentiate between the potential optimality of self-selected asymmetry and perfect symmetry. Only participants who could substantially alter their asymmetry with biofeedback were included, which ensured that the effects of changes in asymmetry could be robustly analyzed. We disallowed participants from using handrails during all conditions to avoid uncertainty related to the potential benefits of improved balance or forward pulling during more difficult conditions. Participants with chronic stroke received training on the biofeedback system during the first session to facilitate task learning and ensure that all participants could alter their baseline asymmetry with biofeedback. Data were collected in three subsequent sessions. During each collection session, conditions were presented in a different order to avoid ordering effects, and the first condition of the session was repeated to reduce within-session training effects. We hypothesized that individuals with chronic stroke would self-select the step length asymmetry that minimized their metabolic energy consumption during walking, and that more symmetric or asymmetric gaits would result in a higher metabolic cost. We hypothesized that unimpaired individuals would self-select the step length asymmetry, near symmetric, that minimized their metabolic cost, and more asymmetric gaits would increase metabolic cost. The results from this study were expected to improve our understanding of the mechanisms driving self-selected step length asymmetry and influence the development of new gait retraining techniques.

 

Individual Differences in Locomotor Function Predict the Capacity to Reduce Asymmetry and Modify the Energetic Cost of Walking Poststroke

I got nothing out of this. For me to reduce asymmetry I would need my spasticity cured and my pre-motor cortex rebuilt. Tell me how to accomplish that and I will work on it.  Visual feedback does absolutely nothing for me except to see that my gait is screwed up.

Individual Differences in Locomotor Function Predict the Capacity to Reduce Asymmetry and Modify the Energetic Cost of Walking Poststroke 

Natalia Sánchez PhD, James M. Finley, PhD

First Published July 12, 2018 Research Article

https://doi.org/10.1177/1545968318787913

Article information

Abstract

Changes in the control of the lower extremities poststroke lead to persistent biomechanical asymmetries during walking. These asymmetries are associated with an increase in energetic cost, leading to the possibility that reducing asymmetry can improve walking economy. However, the influence of asymmetry on economy may depend on the direction and cause of asymmetry. For example, impairments with paretic limb advancement may result in shorter paretic steps, whereas deficits in paretic support or propulsion result in shorter nonparetic steps. Given differences in the underlying impairments responsible for step length asymmetry, the capacity to reduce asymmetry and the associated changes in energetic cost may not be consistent across this population. Here, we identified factors explaining individual differences in the capacity to voluntarily reduce step length asymmetry and modify energetic cost during walking. A total of 24 individuals poststroke walked on a treadmill, with visual feedback of their step lengths to aid explicit modification of asymmetry. We found that individuals who took longer paretic steps had a greater capacity to reduce asymmetry and were better able to transfer the effects of practice to overground walking than individuals who took shorter paretic steps. In addition, changes in metabolic cost depended on the direction of asymmetry, baseline cost of transport, and reductions in specific features of spatiotemporal asymmetry. These results demonstrate that many stroke survivors retain the residual capacity to voluntarily walk more symmetrically on a treadmill and overground. However, whether reductions in asymmetry reduce metabolic cost depends on individual differences in impairments affecting locomotor function.

Keywords asymmetry, gait, metabolic cost, stroke

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Individual Differences in Locomotor Function Predict the Capacity to Reduce Asymmetry and Modify the Energetic Cost of Walking Poststroke

I'm sure that the asymmetry in my walking is caused by the dead area in my pre-motor cortex. Nothing here helps survivors get better
http://journals.sagepub.com/doi/abs/10.1177/1545968318787913

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Natalia Sánchez, PhD¹

Natalia Sánchez

1University of Southern California, Los Angeles, CA, USA
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, James M. Finley, PhD¹

James M. Finley

1University of Southern California, Los Angeles, CA, USA
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, Natalia Sánchez, PhD¹

Natalia Sánchez

1University of Southern California, Los Angeles, CA, USA
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James M. Finley, PhD¹

James M. Finley

1University of Southern California, Los Angeles, CA, USA
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First Published July 12, 2018 Research Article

https://doi.org/10.1177/1545968318787913

Article information

Article Information

Article first published online: July 12, 2018

https://doi.org/10.1177/1545968318787913

Natalia Sánchez, PhD¹, James M. Finley, PhD¹

¹University of Southern California, Los Angeles, CA, USA

Corresponding Author: James M. Finley, PhD, Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 E Alcazar St, CHP 155, Los Angeles, CA 90033, USA. Email: jmfinley@usc.edu

• Abstract

Abstract

Changes in the control of the lower extremities poststroke lead to persistent biomechanical asymmetries during walking. These asymmetries are associated with an increase in energetic cost, leading to the possibility that reducing asymmetry can improve walking economy. However, the influence of asymmetry on economy may depend on the direction and cause of asymmetry. For example, impairments with paretic limb advancement may result in shorter paretic steps, whereas deficits in paretic support or propulsion result in shorter nonparetic steps. Given differences in the underlying impairments responsible for step length asymmetry, the capacity to reduce asymmetry and the associated changes in energetic cost may not be consistent across this population. Here, we identified factors explaining individual differences in the capacity to voluntarily reduce step length asymmetry and modify energetic cost during walking. A total of 24 individuals poststroke walked on a treadmill, with visual feedback of their step lengths to aid explicit modification of asymmetry. We found that individuals who took longer paretic steps had a greater capacity to reduce asymmetry and were better able to transfer the effects of practice to overground walking than individuals who took shorter paretic steps. In addition, changes in metabolic cost depended on the direction of asymmetry, baseline cost of transport, and reductions in specific features of spatiotemporal asymmetry. These results demonstrate that many stroke survivors retain the residual capacity to voluntarily walk more symmetrically on a treadmill and overground. However, whether reductions in asymmetry reduce metabolic cost depends on individual differences in impairments affecting locomotor function.

Keywords asymmetry, gait, metabolic cost, stroke

Determinants of sit-to-stand tasks in individuals with hemiparesis post stroke: A review

I still have to think too much when I do this and lots of times have to use my right leg to pull my left leg further under me since my hamstring on the left is not reliable. A stroke protocol for teaching this would be extremely useful, but that won't occur for 50 years.

Determinants of sit-to-stand tasks in individuals with hemiparesis post stroke: A review

• Amira Boukadida^a,
• France Piotte^b,
• Patrick Dehail^b,
• Sylvie Nadeau^{a, ,}

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doi:10.1016/j.rehab.2015.04.007

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Abstract

Background and purpose

The ability to rise from a chair to reach a standing position is impaired after stroke. This paper aims to review for the first time the factors that impact the ability to rise from a chair and identify recommendations for post-stroke rehabilitation.

Methods

In order to analyse relevant scientific publications (French and English), the search terms “stroke”, “rehabilitation” and “sit-to-stand” (STS and its variations) were used. The initial literature search identified 122 titles and abstracts for full review and 46 were retained because both the junior and senior researchers agreed that they were aligned with the objectives of this review.

Results and conclusion

During STS, most individuals with hemiparesis able to stand independently presented several changes such as lateral deviation of the trunk towards the unaffected side (ipsilesional side), asymmetrical weight bearing (WB) and asymmetry of knee moment forces. Interestingly, the WB asymmetry was observed even before seat-off, when subjects with hemiparesis still had their thighs in contact with the chair suggesting a planned strategy. Among other interesting results, the time to execute the STS was longer than in controls and influenced by the sensorimotor deficits. A greater risk of falling was observed with a need for more time to stabilize the body during STS and especially during the extension phase. Some rehabilitation interventions may be effective in improving STS duration, WB symmetry and the ability to stand independently with repeated practice (mentally or physically) of STS tasks. However, more research is essential to further investigate effects of specific training protocols and pursue better understanding of this complex and demanding task, particularly for stroke patients who need assistance during this transfer.

Repeated Split-Belt Treadmill Training Improves Poststroke Step Length Asymmetry

More research on split-belt. If your therapist is any good they will know about this and already be requesting this for their department. You do have good therapists, don't you?
http://nnr.sagepub.com/content/27/5/460.abstract?etoc

Abstract

Background and objective. Previous studies suggest that error augmentation may be used as a strategy to achieve longer-term changes in gait deficits after stroke. The purpose of this study was to determine whether longer-term improvements in step length asymmetry could be achieved with repeated split-belt treadmill walking practice using an error augmentation strategy. Methods. 13 persons with chronic stroke (> 6 months) participated in testing: (1) prior to 12 sessions of split-belt treadmill training, (2) after the training, and (3) in follow-up testing at 1 and 3 months. Step length asymmetry was the target of training, so belt speeds were set to augment step length asymmetry such that aftereffects resulted in reduced step length asymmetry during overground walking practice. Each individual was classified as a “responder” or “nonresponder” based on whether their reduction in step length asymmetry exceeded day-to-day variability. Results. For the group and for the responders (7 individuals), step length asymmetry improved from baseline to posttesting (P < .05) through an increased step length on both legs but a relatively larger change on the shorter step side (P < .05). Other parameters that were not targeted (eg, stance time asymmetry) did not change over the intervention. Conclusions. This study demonstrates that short-term adaptations can be capitalized on through repetitive practice and can lead to longer-term improvements in gait deficits poststroke. The error augmentation strategy, which promotes stride-by-stride adjustment to reduce asymmetry and results in improved asymmetry during overground walking practice, appears to be critical for obtaining the improvements observed.