Kara K. Patterson

Evaluation of gait symmetry after stroke: a comparison of current methods and recommendations for standardization.

Symmetry is a gait characteristic that is increasingly measured and reported, particularly in the stroke patient population. However, there is no accepted standard for assessing symmetry making it difficult to compare across studies and establish criteria to guide clinical decision making. This study compares the most common expressions of spatiotemporal gait symmetry to describe post-stroke gait and makes recommendations regarding the most suitable measure for standardization. The following symmetry equations were compared: symmetry ratio, symmetry index, gait asymmetry and symmetry angle using step length, swing time, stance time, double support time and an intra-limb ratio of swing: stance time. Comparisons were made within a group of 161 community-dwelling, ambulatory individuals with stroke and 81 healthy adults as a reference group. Our analysis supports the recommendations of the symmetry ratio as the equation for standardization and step length, swing time and stance time as the gait parameters to be used in the equation. Future work should focus on establishing the intra-individual variability of these measures and linking them to mechanisms of gait dysfunction.

Gait Asymmetry in Community-Ambulating Stroke Survivors

OBJECTIVESnTo determine the prevalence and severity of asymmetry among independently ambulating stroke survivors and to establish the association between velocity and asymmetry.nnnDESIGNnDescriptive analysis.nnnSETTINGnResearch gait laboratory in a Canadian hospital.nnnPARTICIPANTSnCommunity-dwelling, independently ambulating participants (N=54) with chronic stroke.nnnINTERVENTIONSnNot applicable.nnnMAIN OUTCOME MEASURESnOverground gait velocity, symmetry ratios for temporal and spatial step parameters, and motor impairment of the foot and leg. Spatiotemporal parameters were collected with a pressure-sensitive mat. Motor impairment was measured clinically with the Chedoke-McMaster Stroke Assessment.nnnRESULTSnThirty (55.5%) participants showed statistically significant temporal asymmetry and 18 (33.3%) exhibited statistically significant spatial asymmetry. Preferred velocity was negatively associated with temporal asymmetry (r=-.583, df=52, P<.001) but not spatial asymmetry (r=-.146, df=52, P=.29). Temporal asymmetry was also associated with motor recovery of the leg (r=-.644, df=35, P<.001) and foot (r=-.628, df=35, P<.001).nnnCONCLUSIONSnThe results of the current study illustrate that temporal asymmetry can be found in many independently ambulating stroke patients. The work highlights the need for a standard assessment of poststroke gait symmetry in light of the complex relationship with motor impairment and velocity.

Changes in Gait Symmetry and Velocity After Stroke: A Cross-Sectional Study From Weeks to Years After Stroke:

Background. There is little information about the quality of gait in the years following stroke. Long-term changes in mobility, using global indices of function, suggest a decline well after initial rehabilitation. However, global indices of mobility do not reveal more specific changes in walking competency or underlying gait-specific impairment. Objectives. The authors used a cross-sectional design with gait-specific measures (velocity and symmetry) to investigate whether deterioration in gait occurs over the long term poststroke. Methods. Data were abstracted from a standardized database containing clinical assessments and spatiotemporal gait analyses for 171 individuals with stroke. Velocity and 3 expressions of symmetry ratios (swing time, stance time, and step length) were calculated for each individual; they were then assigned to 1 of the 5 following groups: 0 to 3, 3 to 12, 12 to 24, 24 to 48, and >48 months poststroke. Results. Swing time, stance time, and step length symmetry demonstrated a systematic linear trend toward greater asymmetry in groups in the later stages poststroke, whereas velocity, neurological deficit, and lower-extremity (LE) motor impairment did not. Conclusions. The quality of gait, as measured by spatial and temporal symmetry, appears to worsen in later years. These results suggest a dissociation between quantitative measures of gait, such as velocity versus symmetry, and that these parameters may measure independent features. A longitudinal study is needed to confirm the presence and to interpret the clinical meaning of a long-term decline in specific parameters of poststroke gait.

Association Between Gait Asymmetry and Brain Lesion Location in Stroke Patients

Background and Purpose— Associations between the site of brain injury and poststroke gait impairment are poorly understood. Temporal gait asymmetry after stroke is a salient index of gait dysfunction that has important functional consequences. The current study investigated whether subtraction lesion analysis could distinguish brain regions associated with persisting temporal gait asymmetry in chronic stroke patients. Methods— Analysis was conducted on 37 chronic ambulatory stroke patients (17 symmetrical gait, 20 asymmetrical gait). Spatiotemporal gait parameters were recorded using an instrumented walking surface. Lesions were traced from 3D T1-MRI, and region of interest images were generated. The lesion overlay of patients with symmetrical gait was subtracted from patients with asymmetrical gait to highlight voxels more frequently lesioned in asymmetrical patients and relatively spared in symmetrical patients. Results— Demographic data were comparable between the 2 groups. Asymmetrical patients exhibited significantly higher National Institute of Health Stroke Scale neglect scores and more severe motor impairment. Gait asymmetry was significantly correlated to Chedoke-McMaster Stroke Scale leg (r=−0.767, P<0.001) and foot (r=−0.759, P<0.001) scores, whereas gait speed correlated less strongly. After subtraction analysis, injury to the posterolateral putamen was evident 60% to 80% more frequently in the asymmetrical group compared to the symmetrical group. Conclusions— In this sample of ambulatory chronic stroke patients, damage to the posterolateral putamen was associated with temporal gait asymmetry. Further advances in our understanding of the neural correlates of gait asymmetry may provide prognostic markers for future persistent gait dysfunction and lead to early targeted rehabilitation when key regions are damaged.

Relationship between asymmetry of quiet standing balance control and walking post-stroke

Spatial and temporal gait asymmetry is common after stroke. Such asymmetric gait is inefficient, can contribute to instability and may lead to musculoskeletal injury. However, understanding of the determinants of such gait asymmetry remains incomplete. The current study is focused on revealing if there is a link between asymmetry during the control of standing balance and asymmetry during walking. This study involved review of data from 94 individuals with stroke referred to a gait and balance clinic. Participants completed three tests: (1) walking at their usual pace; (2) quiet standing; and (3) standing with maximal loading of the paretic side. A pressure sensitive mat recorded placement and timing of each footfall during walking. Standing tests were completed on two force plates to evaluate symmetry of weight bearing and contribution of each limb to balance control. Multiple regression was conducted to determine the relationships between symmetry during standing and swing time, stance time, and step length symmetry during walking. Symmetry of antero-posterior balance control and weight bearing were related to swing time and step length symmetry during walking. Weight-bearing symmetry, weight-bearing capacity, and symmetry of antero-posterior balance control were related to stance time symmetry. These associations were independent of underlying lower limb impairment. The results support the hypothesis that impaired ability of the paretic limb to control balance may contribute to gait asymmetry post-stroke. Such work suggests that rehabilitation strategies that increase the contribution of the paretic limb to standing balance control may increase symmetry of walking post-stroke.

Gait symmetry and velocity differ in their relationship to age

UNLABELLEDnMeasurement of gait is essential for identifying underlying deficits contributing to gait dysfunction, guiding clinical decisions and measuring rehabilitation outcomes. Velocity is commonly used to measure gait, however, its interpretation in patient populations is complicated by the confound of age. Gait symmetry may be an additional and valuable measure since it may not feature the same age-related changes as velocity. The purpose of this study was to determine if gait symmetry is related to age.nnnMETHODSnSpatiotemporal gait parameters were recorded for 172 individuals with stroke and 81 healthy adults walking across a pressure sensitive mat at their preferred speed. Swing time, stance time and step length symmetry ratios were calculated. The relationship of age to velocity and symmetry was examined using Pearson correlations.nnnRESULTSnThere was a significant negative association between velocity and age in the healthy group (r=-0.57, p<0.01). There were no significant relationships between age and any of the three symmetry ratios for either the stroke or healthy groups.nnnCONCLUSIONSnThe main finding of the current study is that gait symmetry ratios are not significantly associated with age in either a healthy or a post-stroke group. Gait symmetry ratios may therefore, allow the clinician and the researcher to make judgments about the effects of disease (such as stroke) on the control of an individuals gait without the confound of age.

Does perturbation-based balance training prevent falls? Systematic review and meta-analysis of preliminary randomized controlled trials.

Background Older adults and individuals with neurological conditions are at an increased risk for falls. Although physical exercise can prevent falls, certain types of exercise may be more effective. Perturbation-based balance training is a novel intervention involving repeated postural perturbations aiming to improve control of rapid balance reactions. Purpose The purpose of this study was to estimate the effect of perturbation-based balance training on falls in daily life. Data Sources MEDLINE (1946–July 2014), EMBASE (1974–July 2014), PEDro (all dates), CENTRAL (1991–July 2014), and Google Scholar (all dates) were the data sources used in this study. Study Selection Randomized controlled trials written in English were included if they focused on perturbation-based balance training among older adults or individuals with neurological conditions and collected falls data posttraining. Data Extraction Two investigators extracted data independently. Study authors were contacted to obtain missing information. A PEDro score was obtained for each study. Primary outcomes were proportion of participants who reported one or more falls (ie, number of “fallers”) and the total number of falls. The risk ratio (proportion of fallers) and rate ratio (number of falls) were entered into the analysis. Data Synthesis Eight studies involving 404 participants were included. Participants who completed perturbation-based balance training were less likely to report a fall (overall risk ratio=0.71; 95% confidence interval=0.52, 0.96; P=.02) and reported fewer falls than those in the control groups (overall rate ratio=0.54; 95% confidence interval=0.34, 0.85; P=.007). Limitations Study authors do not always identify that they have included perturbation training in their intervention; therefore, it is possible that some appropriate studies were not included. Study designs were heterogeneous, preventing subanalyses. Conclusions Perturbation-based balance training appears to reduce fall risk among older adults and individuals with Parkinson disease.

Changes in spatiotemporal gait variables over time during a test of functional capacity after stroke.

BackgroundGait dysfunction and fatigue are common post-stroke, though it is unclear how extended walking activity, as would be performed during activities of daily living, may change over time. The purpose of this study was to examine if spatial and temporal gait variables deteriorate during an extended bout of walking in a test of functional capacity after stroke.Methods24 community dwelling, independently ambulating individuals greater than 3 months after stroke performed the Six-Minute Walk Test (6MWT). Participants walked over a pressure-sensitive mat on each pass of the 30 m course which recorded spatial and temporal parameters of gait. Mean gait speed and temporal symmetry ratio during each two-minute interval of the 6MWT were examined. Additional post hoc analyses examined the incidence of rests during the 6MWT and changes in gait speed and symmetry.ResultsOn average, participants demonstrated a 3.4 ± 6.5 cm/s decrease in speed over time (p= 0.02). Participants who rested were also characterized by increased asymmetry in the final two minutes (p= 0.05). 30% of participants rested at some point during the test, and if a rest was taken, duration increased in the final two minutes (p= 0.001). Examination of factors which may have been associated with resting indicated that resters had poorer balance (p= 0.006) than non-resting participants.ConclusionThis study supports previous findings establishing that walking performance after stroke declines over relatively short bouts of functionally-relevant ambulation. Such changes may be associated with both cardiorespiratory and muscular fatigue mechanisms that influence performance. The findings also indicate that rest duration should be routinely quantified during the 6MWT after stroke, and consequently, further research is necessary to determine how to interpret 6MWT scores when resting occurs.

Longitudinal changes in poststroke spatiotemporal gait asymmetry over inpatient rehabilitation.

Background. Little information exists about longitudinal changes in spatiotemporal gait asymmetry during rehabilitation, despite it being a common goal. Objectives. To describe longitudinal changes in spatiotemporal gait asymmetry over rehabilitation and examine relationships with changes in other poststroke impairments. Methods. Retrospective chart reviews were conducted for 71 stroke rehabilitation inpatients. Admission and discharge measures of spatiotemporal symmetry, velocity, motor impairment, mobility and balance were extracted and change scores were calculated. Relationships between changes in spatiotemporal symmetry and other change scores were investigated with Spearman correlations. Individuals were divided into four groups (worse, no change-symmetric, no change-asymmetric, improved) based on (1) symmetry/asymmetry at admission and (2) symmetry change scores >minimal detectable change. Differences in change scores between groups were investigated with analyses of covariance using the admission value as a covariate. Results. At admission, 59% and 49% of individuals were asymmetric in swing time and step length, respectively. Of these individuals, 21% and 14% improved swing symmetry or step symmetry, respectively. In contrast, 30% improved gait velocity, 62% improved functional balance and 73% improved functional mobility. Associations between change in swing symmetry and change in paretic limb weight bearing in standing and change in step symmetry and change in velocity were significant. There were no significant differences in change scores between the symmetry groups. Conclusions. The majority of asymmetric stroke patients did not improve spatiotemporal asymmetry during rehabilitation despite the fact that velocity, balance and functional mobility improved. Future work should investigate other factors associated with improved spatiotemporal symmetry and interventions to specifically improve it.

Clinician's Commentary.

Gait deficits greatly contribute to functional disability after stroke; of all stroke-related impairments, improvement of walking function is the goal most often stated by patients.1 Therefore, gait is a primary focus of physiotherapy intervention post-stroke. Most of the research on post-stroke gait focuses on velocity or endurance. By contrast, temporal and spatial symmetry (although not new to clinical practice) receive relatively less attention. To date, most studies have only reported symmetry values. Very few studies have included gait symmetry as their main focus, and fewer still have attempted to understand the underlying mechanisms of asymmetry.2 n nPost-stroke gait asymmetry is the main focus of the study by Beauchamp et al. in this issue of Physiotherapy Canada.3 More specifically, the investigators examined the immediate effects of cane use on the symmetry of patients with stroke in the subacute stage. According to their results, a standard cane, but not a quad cane, improves symmetry in individuals with an asymmetrical gait pattern.3 By contrast, there was no observed effect of cane use in those patients with a symmetrical gait pattern.3 n nThe study by Beauchamp et al. illustrates two important issues relevant to clinical practice and research in stroke rehabilitation. First, it demonstrates the value of categorizing patients with stroke in finer detail than is possible using velocity or a measure of motor impairment, such as the Chedoke-McMaster Stroke Assessment (CMSA), alone. Typical gait deficits associated with stroke include decreased velocity, increased step variability, increased or decreased joint displacement, and altered EMG timing and amplitude.4 Although any given individual with stroke will likely display some unique combination of the common deviations described above, he or she is unlikely to display all the deviations. More simply, no two persons with stroke are alike. This presents a challenge for both clinicians and researchers. For clinicians, no one therapeutic approach will be appropriate for all patients. Developing a method for classification of individuals with stroke that uses a composite of key measurements (e.g., velocity, gait variability, and gait symmetry as well as motor impairment) will assist the clinician in designing physiotherapy programs tailored to the individual patient. For researchers, results can be attenuated by an averaging effect of responders and non-responders within a study sample. A priori classification of study participants can circumvent this challenge, as Beauchamp et al.’s study clearly demonstrates. Using gait symmetry as the basis for categorization, the authors were able to demonstrate the effects of cane use in a subset of the subjects they recruited, something previous studies were unable to show.3 n nThe second important point highlighted by Beauchamp et al. is the issue of gait asymmetry itself. Considerable attention has been focused on the measurement and improvement of gait velocity post-stroke. As a clinical measure, velocity reflects overall performance; however, it is limited in its value to document post-stroke recovery. In addition, velocity provides no information on the underlying impairments contributing to gait dysfunction.5,6 Gait symmetry is a complementary measure that may reflect the quality of gait. Brandstater et al.7 suggested that symmetry may characterize post-stroke gait better than unilateral values. In addition to its value as a clinical gait measure, asymmetry is an important issue to address therapeutically because of its possible negative consequences, which include increased challenge to balance control, increased energy expenditure during walking, and negative impact on the musculoskeletal health of the non-paretic limb.8 In addition, individuals post-stroke may decrease their overall activity levels, over time, in response to any one or combination of these factors.8 In light of these possible effects, gait asymmetry should be addressed by post-stroke gait rehabilitation programs. n nA commonly identified barrier to taking objective, quantitative measures of gait (such as gait symmetry) in the clinical setting is cost. The Beauchamp et al. study measured spatiotemporal gait parameters using the GAITRite mat, which costs approximately