Examination of spatiotemporal gait parameters during the 6-min walk in individuals with multiple sclerosis

Between-Day Reliability of the Gait Characteristics and Their Changes During the 6-Minute Walking Test in People With Multiple Sclerosis

BACKGROUND

Gait characteristics and their changes during the 6-minute walking test (6MWT) in people with multiple sclerosis (pwMS) have been described in the literature, which one may refer to as walking fatigability in the body function level of the International Classification of Functioning, Disability, and Health. However, whether these metrics are reliable is unknown.

OBJECTIVE

To investigate the between-day reliability of the gait characteristics and their changes in pwMS and healthy controls (HCs).

METHODS

Forty-nine pwMS (EDSS 4.82 ± 1.22 and 54.7 ± 9.36 years) and 23 HCs (50.6 ± 6.1 years) performed the 6MWT, as fast as possible but safely while wearing Inertial Measurement Units. Gait characteristics were measured in the pace, rhythm, variability, asymmetry, kinematics, coordination, and postural control domains and were obtained in intervals of 1 minute during the 6MWT. In addition, gait characteristics change in the last minute compared with the first minute were calculated for all gait variables using a fatigability index (ie, distance walking index). The intraclass correlation coefficient (ICC), Bland-Altman Plots, and Standard error of measurement were applied to investigate reliability.

RESULTS

Reliability of gait characteristics, minute-by-minute, and for their changes (ie, using the fatigability index) ranged from poor to excellent (pwMS: ICC 0.46-0.96; HC: ICC 0.09-0.97 and pwMS: ICC 0-0.72; HC: ICC 0-0.77, respectively).

CONCLUSION

Besides coordination, at least 1 variable of each gait domain showed an ICC of moderate or good reliability for gait characteristics changes in both pwMS and HC. These metrics can be incorporated into future clinical trials and research on walking fatigability.Clinical Trial Registration: NCT05412043.

Deep Learning for Multiple Sclerosis Differentiation Using Multi-Stride Dynamics in Gait

OBJECTIVE

Multiple sclerosis (MS) is a chronic neurological condition of the central nervous system leading to various physical, mental and psychiatric complexities. Mobility limitations are amongst the most frequent and early markers of MS. We evaluated the effectiveness of a DeepMS2G (deep learning (DL) for MS differentiation using multistride dynamics in gait) framework, which is a DL-based methodology to classify multi-stride sequences of persons with MS (PwMS) from healthy controls (HC), in order to generalize over newer walking tasks and subjects.

METHODS

We collected single-task Walking and dual-task Walking-while-Talking gait data using an instrumented treadmill from a balanced collection of 20 HC and 20 PwMS. We utilized domain knowledge-based spatiotemporal and kinetic gait features along with two normalization schemes, namely standard size-based and multiple regression normalization strategies. To differentiate between multi-stride sequences of HC and PwMS, we compared 16 traditional machine learning and DL algorithms. Further, we studied the interpretability of our highest-performing models; and discussed the association between the lower extremity function of participants and our model predictions.

RESULTS

We observed that residual neural network (ResNet) based models with regression-based normalization were the top performers across both task and subject generalization classification designs. Considering regression-based normalization, a multi-scale ResNet attained a subject classification accuracy and F 1-score of 1.0 when generalizing from single-task Walking to dual-task Walking-while-Talking; and a ResNet resulted in the top subject-wise accuracy and F 1 of 0.83 and 0.81 (resp.), when generalizing over unseen participants.

CONCLUSION

We used advanced DL and dynamics across domain knowledge-based spatiotemporal and kinetic gait parameters to successfully classify MS gait across distinct walking trials and unseen participants.

SIGNIFICANCE

Our proposed DL algorithms might contribute to efforts to automate MS diagnoses.

Locomotor Strategy to Perform 6-Minute Walk Test in People with Multiple Sclerosis: A Prospective Observational Study

Two-thirds of people with Multiple Sclerosis (PwMS) have walking disabilities. Considering the literature, prolonged tests, such as the 6 min walk test, better reflect their everyday life walking capacities and endurance. However, in most studies, only the distance traveled during the 6MWT was measured. This study aims to analyze spatio-temporal (ST) walking patterns of PwMS and healthy people in the 6MWT. Participants performed a 6MWT with measures of five ST variables during three 1 min intervals (initial: 0'-1', middle: 2'30″-3'30″, end: 5'-6') of the 6MWT, using the GAITRite system. Forty-five PwMS and 24 healthy people were included. We observed in PwMS significant changes between initial and final intervals for all ST parameters, whereas healthy people had a rebound pattern but the changes between intervals were rather negligible. Moreover, ST variables' changes were superior to the standard measurement error only for PwMS between initial and final intervals for all ST parameters. This result suggests that the modification in PwMS' walking pattern is effectively due to their walking ability and not to a measurement, and suggests that PwMS could not manage their walking efficiently compared to healthy people, who could maintain their rhythm throughout the 6MWT. Further studies are needed to detect these patterns changes in the early evolution of the disease, identify clinical determinants involved in PwMS' walking pattern, and investigate whether interventions can positively impact this pattern.

Spatiotemporal gait changes in people with multiple sclerosis with different disease progression subtypes

BACKGROUND

Gait impairment is common in people with multiple sclerosis (MS), but less is known about gait differences between MS disease progression subtypes. The objective here was to examine differences in spatiotemporal gait in MS and between relapsing-remitting and progressive subtypes during the timed-25-ft-walk test. Our specific aims were to investigate (1) spatiotemporal, (2) spatiotemporal variability, and (3) gait modulation differences between healthy controls and MS subtypes at preferred and fast walking speed.

METHODS

This study included 27 controls, 18 relapsing-remitting MS, and 13 progressive MS participants. Participants wore six inertial sensors and walked overground without walking aids at preferred and fast-as-possible speeds.

FINDINGS

Both MS groups had significantly lower walking speed than controls, with a trend towards lower preferred gait speed in progressive compared to relapsing-remitting MS (ES = 0.502). Although most spatiotemporal gait parameters differed between controls and MS groups, differences were not significant between MS subtypes in these parameters and their variability, with low to moderate effect sizes during preferred and fast walking. Both MS groups showed reduced modulation in gait compared to controls and no significant differences between MS subtypes.

INTERPRETATION

Gait in MS is altered compared to controls. Although gait may change with progressive MS, the overall small differences in the gait parameters between the MS subtypes observed in this sample suggests that those with the progressive form of MS who are independently ambulatory and without further clinically meaningful changes in gait speed may not show gait decrements greater than the relapsing-remitting form of the disease.

Changes in Gait Characteristics During and Immediately After the 6-Minute Walk Test in Persons With Multiple Sclerosis: A Systematic Review

OBJECTIVE

There is limited information about gait patterns during prolonged walking in people with multiple sclerosis (PwMS). The aim of this review was to report on gait metrics during and immediately after the 6-Minute Walk Test (6MWT) in PwMS with different levels of disability.

METHODS

The systematic search was performed in 3 databases (PubMed, Web of Science, and SCOPUS) using keywords related to multiple sclerosis and 6MWT. Studies that reported on quantitative gait outcomes before and after the 6MWT or multiple time points during the 6MWT were included. The Hedges g effect size (ES) was calculated to determine the magnitude of change in each gait parameter.

RESULTS

Fourteen studies (n = 534 PwMS; n = 166 healthy controls) were eligible. Five studies investigated gait parameters prior to and immediately after the 6MWT. Nine studies collected gait measures during the 6MWT. Speed (ES = -0.43 to 0.19), cadence (ES = -0.46 to 0.16), step length (ES = -0.46 to 0.14), stability (ES = -0.35 to 0.33), and regularity (ES = -0.25 to -0.15) decreased in most studies. In the majority of included studies, step time (ES = 0 to 0.35), stance period (ES = 0.12 to 0.58), double support phase (ES = 0.03 to 0.62), variability (ES = -0.19 to 1.13), and asymmetry (ES = -0.79 to 0.62) increased following the 6MWT. The kinetic and kinematic (mainly in dorsiflexion angle [ES = -0.08 to -0.36]) features of gait were also negatively changed after 6 minutes of walking. Walking speed, cadence, step length, stride length, and stride time after 6MWT at a comfortable speed all increased. Changes in the majority of spatiotemporal parameters were more pronounced in PwMS with moderate-to-severe disability compared with PwMS with mild disability.

CONCLUSION

Most quantitative gait parameters deteriorated during the 6MWT, especially in PwMS with moderate-to-severe disability.

IMPACT

The deterioration of gait patterns should be considered when designing therapeutic interventions to increase sustained walking capacity.

Changes in trunk and head acceleration during the 6-minute walk test and its relation to falls risk for adults with multiple sclerosis

For persons with multiple sclerosis (MS), the general decline in neuromuscular function underlies diminished balance, impaired gait and consequently, increased risk of falling. During gait, optimal control of head motion is an important feature which is achieved partly through control of the trunk-neck region to dampen gait-related oscillations. The primary aim of this study was to examine the effect performing a 6-minute walk test (6MWT) has on head, neck and trunk accelerations in individuals with MS. This was addressed using a repeated measures generalized linear model. We were also interested in assessing whether the 6MWT has an impact on a person's falls risk and specific physiological measures related to falls. Finally the relation between the amplitude (i.e., mean RMS) of head and trunk accelerations and falls risk was examined using linear regression. The main results were that over the course of the 6MWT, individuals progressively slowed down coupled with a concurrent increase in gait-related upper body accelerations (p's > 0.05). Despite the increased acceleration, no significant changes in attenuation from the trunk to the head were observed, indicating that persons were able to maintain an optimal level of control over these oscillations. Performing the 6MWT also had a negative impact on posture, with falls risk significantly increasing following this test (p > 0.05). Interestingly, the overall falls risk values were strongly linked with vertical accelerations about the trunk and head, but not average walking speed during the 6MWT. Overall, performing the 6MWT leads to changes in walking speed, upper body acceleration patterns and increases in overall falls risk.

Wearable inertial sensors are highly sensitive in the detection of gait disturbances and fatigue at early stages of multiple sclerosis

Background

The aim of the current study was to examine multiple gait parameters obtained by wearable inertial sensors and their sensitivity to clinical status in early multiple sclerosis (MS). Further, a potential correlation between gait parameters and subjective fatigue was explored.

Methods

Automated gait analyses were carried out on 88 MS patients and 31 healthy participants. To measure gait parameters (i.e. walking speed, stride length, stride duration, duration of stance and swing phase, minimal toe-to-floor distance), wearable inertial sensors were utilized throughout a 6-min 25-ft walk. Additionally, self-reported subjective fatigue was assessed.

Results

Mean gait parameters consistently revealed significant differences between healthy participants and MS patients from as early as an Expanded Disability Status Scale (EDSS) value of 1.5 onwards. Further, MS patients showed a significant linear trend in all parameters, reflecting continuously deteriorating gait performance throughout the test. This linear deterioration trend showed significant correlations with fatigue.

Conclusions

Wearable inertial sensors are highly sensitive in the detection of gait disturbances, even in early MS, where global scales such as the EDSS do not provide any clinical information about deviations in gait behavior. Moreover, these measures provide a linear trend parameter of gait deterioration that may serve as a surrogate marker of fatigue. In sum, these results suggest that classic timed walking tests in routine clinical practice should be replaced by readily and automatically applicable gait assessments, as provided by inertial sensors.

Evaluation of Prolonged Walking in Persons with Multiple Sclerosis: Reliability of the Spatio-Temporal Walking Variables during the 6-Minute Walk Test

Background: Walking disorders represent the most disabling condition in persons with Multiple Sclerosis (PwMS). Several studies showed good reliability of the 6-min walk test (6MWT) (i.e., especially distance traveled), but little is known about the reliability of the Spatio-temporal (ST) variables in the 6MWT. Objective: To evaluate the test-retest reliability of ST variables and perceived exertion during the 6MWT in PwMS and comparable healthy persons. Methods: We explored three 1-min intervals (initial: 0′–1′, middle: 2′30″–3′30″, end: 5′–6′) of the 6MWT. Six ST variables and perceived exertion were measured (respectively, using the GAITRite system and the Borg Scale). These measurements were performed twice, 1 week apart. The test-retest effects were assessed using the intraclass correlation coefficient (ICC) or the weighted kappa. Results: Forty-five PwMS and 24 healthy persons were included. The test-retest reliability of ST variables values was good-to-excellent for PwMS (ICC range: 0.858–0.919) and moderate-to-excellent for healthy persons (ICC range: 0.569–0.946). The test-retest reliability values of perceived exertion were fair for PwMS (weighted kappa range: 0.279–0.376) and substantial for healthy persons (weighted kappa range: 0.734–0.788). Conclusion: The measurement of ST variables during these 6MWT intervals is reliable and applicable in clinical practice and research to adapt rehabilitation care in PwMS.

Multi-level modeling with nonlinear movement metrics to classify self-injurious behaviors in autism spectrum disorder

Self-injurious behavior (SIB) is among the most dangerous concerns in autism spectrum disorder (ASD), often requiring detailed and tedious management methods. Sensor-based behavioral monitoring could address the limitations of these methods, though the complex problem of classifying variable behavior should be addressed first. We aimed to address this need by developing a group-level model accounting for individual variability and potential nonlinear trends in SIB, as a secondary analysis of existing data. Ten participants with ASD and SIB engaged in free play while wearing accelerometers. Movement data were collected from > 200 episodes and 18 different types of SIB. Frequency domain and linear movement variability measures of acceleration signals were extracted to capture differences in behaviors, and metrics of nonlinear movement variability were used to quantify the complexity of SIB. The multi-level logistic regression model, comprising of 12 principal components, explained > 65% of the variance, and classified SIB with > 75% accuracy. Our findings imply that frequency-domain and movement variability metrics can effectively predict SIB. Our modeling approach yielded superior accuracy than commonly used classifiers (~ 75 vs. ~ 64% accuracy) and had superior performance compared to prior reports (~ 75 vs. ~ 69% accuracy) This work provides an approach to generating an accurate and interpretable group-level model for SIB identification, and further supports the feasibility of developing a real-time SIB monitoring system.

Gait asymmetry, and bilateral coordination of gait during a six-minute walk test in persons with multiple sclerosis

Gait impairments in persons with multiple sclerosis (pwMS) leading to decreased ambulation and reduced walking endurance remain poorly understood. Our objective was to assess gait asymmetry (GA) and bilateral coordination of gait (BCG), among pwMS during the six-minute walk test (6MWT), and determine their association with disease severity. We recruited 92 pwMS (age: 46.6 ± 7.9; 83% females) with a range of clinical disability, who completed the 6MWT wearing gait analysis system. GA was assessed by comparing left and right swing times, and BCG was assessed by the phase coordination index (PCI). Several functional and subjective gait assessments were performed. Results show that gait is more asymmetric and less coordinated as the disease progresses (p < 0.0001). Participants with mild MS showed significantly better BCG as reflected by lower PCI values in comparison to the other two MS severity groups (severe: p = 0.001, moderate: p = 0.02). GA and PCI also deteriorated significantly each minute during the 6MWT (p < 0.0001). GA and PCI (i.e., BCG) show weaker associations with clinical MS status than associations observed between functional and subjective gait assessments and MS status. Similar to other neurological cohorts, GA and PCI may be important parameters to assess and target in interventions among pwMS.

Wearable sensors can reliably quantify gait alterations associated with disability in people with progressive multiple sclerosis in a clinical setting

Gait disability in people with progressive multiple sclerosis (MS) is difficult to quantify using existing clinical tools. This study aims to identify reliable and objective gait-based biomarkers to monitor progressive multiple sclerosis (MS) in clinical settings. During routine clinical visits, 57 people with secondary progressive MS and 24 healthy controls walked for 6 minutes wearing three inertial motion sensors. Fifteen gait measures were computed from the sensor data and tested for between-session reliability, for differences between controls and people with moderate and severe MS disability, and for correlation with Expanded Disability Status Scale (EDSS) scores. The majority of gait measures showed good to excellent between-session reliability when assessed in a subgroup of 23 healthy controls and 25 people with MS. These measures showed that people with MS walked with significantly longer step and stride durations, reduced step and stride regularity, and experienced difficulties in controlling and maintaining a stable walk when compared to controls. These abnormalities significantly increased in people with a higher level of disability and correlated with their EDSS scores. Reliable and objective gait-based biomarkers using wearable sensors have been identified. These biomarkers may allow clinicians to quantify clinically relevant alterations in gait in people with progressive MS within the context of regular clinical visits.

Association Between Fatigue and Motor Exertion in Patients With Multiple Sclerosis-a Prospective Study

Background: Fatigue in multiple sclerosis (MS) is conceived as a multidimensional construct.

Objectives: This study aims to describe the changes of balance and gait parameters after 6 min of walking (6 MW) as potential quantitative markers for perceptions of state fatigue and trait fatigue in MS.

Methods: A total of 19 patients with MS (17 with fatigue) and 24 healthy subjects underwent static posturography, gait analysis, and ratings of perceived exertion before and after 6 MW.

Results: 6 MW was perceived as exhaustive, but both groups featured more dynamic comfortable speed walking after 6 MW. Shorter stride length at maximum speed and increased postural sway after 6 MW indicated fatigability of balance and gait in MS group only. While most changes were related to higher levels of perceived exertion after 6 MW (state fatigue), higher fatigue ratings (trait fatigue) were only associated with less increase in arm swing at comfortable speed. Further analysis revealed different associations of trait fatigue and performance fatigability with disability and motor functions. Performance fatigability was most closely related to the Expanded Disability Status Scale, while for trait fatigue, the strongest correlations were seen with balance function and handgrip strength.

Conclusions: Fatigability of performance was closely related to perceptions of exertion after 6 MW (state fatigue) and disability in MS but distinct from fatigue ratings, conceived as trait fatigue. Our study identified postural sway, arm swing during gait, and hand grip strength as unexpected potential motor indicators of fatigue ratings in MS.

Can optical flow perturbations detect walking balance impairment in people with multiple sclerosis?

People with multiple sclerosis (PwMS) who exhibit minimal to no disability are still over twice as likely to fall as the general population and many of these falls occur during walking. There is a need for more effective ways to detect preclinical walking balance deficits in PwMS. Therefore, the purpose of this study was to investigate the effects of optical flow perturbations applied using virtual reality on walking balance in PwMS compared to age-matched controls. We hypothesized that susceptibility to perturbations–especially those in the mediolateral direction–would be larger in PwMS compared to controls. Fourteen PwMS and fourteen age-matched controls walked on a treadmill while viewing a virtual hallway with and without optical flow perturbations in the mediolateral or anterior-posterior directions. We quantified foot placement kinematics, gait variability, lateral margin of stability and, in a separate session, performance on the standing sensory organization test (SOT). We found only modest differences between groups during normal, unperturbed walking. These differences were larger and more pervasive in the presence of mediolateral perturbations, evidenced by higher variability in step width, sacrum position, and margin of stability at heel-strike in PwMS than controls. PwMS also performed worse than controls on the SOT, and there was a modest correlation between step width variability during perturbed gait and SOT visual score. In conclusion, mediolateral optical flow perturbations revealed differences in walking balance in PwMS that went undetected during normal, unperturbed walking. Targeting this difference may be a promising approach to more effectively detect preclinical walking balance deficits in PwMS.

Transcranial Direct Current Stimulation (tDCS) to Improve Gait in Multiple Sclerosis: A Timing Window Comparison

Unilateral weakness of the lower limb is a hallmark of multiple sclerosis (MS) and a significant contributor to the progressive worsening of walking ability. There are currently no effective rehabilitation strategies targeting strength asymmetries and/or gait impairments in people with MS (PwMS). Transcranial direct current stimulation (tDCS) has improved motor outcomes in various populations, but the effect of tDCS on gait in PwMS and the ideal timing window of tDCS application are still unknown. This study investigated the effects of tDCS, either before or during a 6 min walk test (6MWT), on the distance walked and gait characteristics in PwMS. Twelve participants were recruited and randomly assigned into BEFORE or DURING groups (both n = 6). The BEFORE group received stimulation before performing a 6MWT (sham/2 mA, 13 min). The DURING group received stimulation only during a 6MWT (sham/2 mA, 6 min). Stimulation was over the more MS-affected primary motor cortex (M1). Distance walked and gait characteristics of the walk were the primary and secondary outcomes. The results indicated a significant decrease in distance walked in the DURING group (p = 0.026) and a significant increase in gait velocity in the BEFORE group (p = 0.04). These changes were accompanied by trends (p < 0.1) in distance walked, gait velocity, and stride length. Overall, the results of this study suggest that tDCS performed before a 6MWT might be more effective than tDCS during a 6MWT and that a single session of tDCS may not be sufficient to influence gait. Clinical Trial Registration: www.ClinicalTrials.gov, identifier #NCT03757819.

Test-retest reliability and minimal detectable change of ankle kinematics and spatiotemporal parameters in MS population

BACKGROUND

Many people with multiple sclerosis (pwMS) experience walking impairments often including foot drop, evident as either reduced dorsiflexion at initial contact and/or at the swing phase of the gait cycle. To measure even subtle differences in ankle kinematics, 3D gait analysis is considered a 'gold' standard. However, the psychometric properties of ankle kinematics in the MS population have not yet been examined.

OBJECTIVE

The aim of the study was to examine test-retest relative and absolute reliability of sagittal ankle kinematics and spatiotemporal parameters in two groups of pwMS with different levels of walking impairment.

METHODS

Two groups of pwMS underwent 3D gait analysis on two occasions 7-14 days apart. Group A consisted of 21 (14 female) people with Expanded Disability Status Scale (EDSS) 1-3.5 and group B consisted of 28 participants (14 female) with EDSS 4-6. The Intraclass Correlation Coefficient (ICC_2,2), standard error of measurement (SEM) and minimal detectable change (MDC_95%) were calculated for peak dorsiflexion (DF) in swing, ankle angle at initial contact (IC), gait profile score (GPS), walking speed, cadence and step length.

RESULTS

Both groups presented 'excellent' ICC values (>0.75) for DF in swing, IC and step length of most and least affected limbs, walking speed and cadence, with GPS for both limbs exhibiting 'fair' to 'good' ICCs (0.489-0.698). The MDC_95% values for all ankle kinematic parameters in group A were lower (1.9°-4.2°) than those in group B (2.2°-7.7°).

CONCLUSION

The present results suggest that ankle kinematic and spatiotemporal parameters derived from 3D gait analysis are reliable outcome measures to be used in the MS population. Further, this study provides indices of reliability that can be applied to both clinical decision making and in the design of studies aimed at treating foot drop in people with MS.

Deterioration of specific aspects of gait during the instrumented 6-min walk test among people with multiple sclerosis

Prolonged walking is typically impaired among people with multiple sclerosis (pwMS), however, it is unclear what the contributing factors are or how to evaluate this deterioration. We aimed to determine which gait features become worse during sustained walking and to examine the clinical correlates of gait fatigability in pwMS. Fifty-eight pwMS performed the 6-min walk test while wearing body-fixed sensors. Multiple gait domains (e.g., pace, rhythm, variability, asymmetry and complexity) were compared across each minute of the test and between mild- and moderate-disability patient groups. Associations between the decline in gait performance (i.e., gait fatigability) and patient-reported gait disability, fatigue and falls were also determined. Cadence, stride time variability, stride regularity, step regularity and gait complexity significantly deteriorated during the test. In contrast, somewhat surprisingly, gait speed and swing time asymmetry did not change. As expected, subjects with moderate disability (n = 24) walked more poorly in most gait domains compared to the mild-disability group (n = 34). Interestingly, a group × fatigue interaction effect was observed for cadence and gait complexity; these measures decreased over time in the moderate-disability group, but not in the mild group. Gait fatigability rate was significantly correlated with physical fatigue, gait disability, and fall history. These findings suggest that sustained walking affects specific aspects of gait, which can be used as markers for fatigability in MS. This effect on gait depends on the degree of disability, and may increase fall risk in pwMS. To more fully understand and monitor correlates that reflect everyday walking in pwMS, multiple domains of gait should be quantified.

Walking endurance in multiple sclerosis: Meta-analysis of six-minute walk test performance

BACKGROUND

The 6-minute walk (6 MW) is the most commonly applied measure of endurance walking capacity in persons with multiple sclerosis (MS); however, we are not aware of a quantitative synthesis of 6 MW performance in MS.

RESEARCH QUESTION

We undertook a meta-analysis quantifying the overall magnitude of difference in 6 MW performance between MS and healthy controls (HCs), and then within MS as a function of disability status. We further examined possible moderator variables of 6 MW performance.

METHODS

The systematic search was conducted for articles that included the 6 MW in persons with MS and involved comparison groups (i.e., HCs or MS disability subgroups (i.e., mild vs moderate-to-severe disability status)). The mean and standard deviation of the distance traveled during the 6 MW as well as sample sizes were entered into Comprehensive Meta-Analysis software and we estimated the overall effect size (Cohen's d) using a random effects model and examined categorical variables as possible moderators (e.g., instruction protocol, provision of encouragement, method of distance measurement, and course description).

RESULTS

Thirty-four studies met inclusion criteria with a total sample size of 3204 persons (MS: 2683; HC: 521) yielding 42 total comparisons. Persons with MS walked a shorter distance than HCs (mean difference = -177.2 ± 19.1 m) with a large effect size (d = - 1.87). Persons with mild disability walked further than those with moderate-to-severe disability (mean difference = 185.19 ± 9.2 m) with a large effect (d = 1.83). The categorical variables of provision of encouragement and course layout moderated the effect of MS and course layout moderated the effect of disability status on 6 MW performance.

SIGNIFICANCE

This meta-analysis of 6 MW performance defines mean difference in 6 MW performance in MS compared with HCs and provides an estimate of the disease-related effect of MS on endurance walking capacity for application within clinical research and practice.

Models for temporal-spatial parameters in walking with cadence ratio as the independent variable

Accurate models that describe temporal-spatial parameters are desirable in gait estimation and rehabilitation. This study aimed to explore simple but relatively accurate models to describe stride length (SL), speed (SP) and walk ratio (WR) at various cadences. Twenty-four able-bodied participants (16 in a test group and 8 in a validation group) walked at seven cadence ratios (CRs). The individual and group mean SL, SP and WR were studied. Suitable temporal-spatial model structures were proposed and used to approximate the individual SL, SP and WR at various CRs. After the temporal-spatial model structures were found to be feasible, the general temporal-spatial models were analysed using the test group mean SL, SP and WR. Accuracy was assessed using the validation group mean values. Individual approximation accuracies showed that the proposed model structure deduced from the linear SL model was suitable for WR approximation. The linear, deduced quadratic and power functions approximated the individual SL, SP and WR, respectively, with high accuracy. Based on the test group mean SL, SP and WR, the general temporal-spatial models were obtained and produced comparable approximation accuracies in the validation group. The general temporal-spatial models predicted well the individual gait parameters with similar individual errors for both groups. These temporal-spatial models clearly describe SL, SP and especially WR at various cadences. They provide accurate reference data for gait estimation and have potential to guide speed modulation in robot-assisted gait rehabilitation.

Graphical abstract

Gait pattern changes after six-minute walk test in persons with multiple sclerosis

OBJECTIVE

To examine the effect of induced fatigue on spatiotemporal gait parameters in persons with multiple sclerosis (PwMS) by using 6-min walk test (6MWT).

METHODS

A cross-sectional study with a control group (25 healthy persons) was performed. Fifty-six PwMS (37 female) were divided into three groups according to their level of disability, as measured by the expanded disability status scale (EDSS): mild (n = 23, EDSS = 1.0-3.5), moderate (n = 19, EDSS = 4.0-5.5), and severe (n = 12, EDSS = 6.0-6.5). Spatiotemporal gait parameters were measured by the GAITRite electronic walkway before and after 6MWT performance. In addition, to determine the level of fatigue in PwMS, the participants completed the questionnaire modified fatigue impact scale (MFIS) before performing the 6MWT. Statistical analyses were performed to compare intragroup and intergroup differences.

RESULTS

Fatigue level was lower in the mild (37.6 ± 20.5) versus moderate (54.3 ± 17.2) versus severe (53.6 ± 12.9) groups (p < 0.05). Significant differences were found among all the groups in terms of the distance walked during the 6MWT (p = 0.001) and of the spatiotemporal gait parameters: gait velocity (cm/s), cadence (steps/min), and step length (cm) decreased and, on the contrary, step time (sec), stance, and double support time (% gait cycle) increased when EDSS scores were higher (p < 0.05). The percentage of change (%) in the spatiotemporal gait parameters, after 6MWT performance, was statistically significant in the moderate and severe groups: gait velocity (-8.8%, -25.9%) and step length (-6.5%, -13.4%) decreased, whereas step time (3.0%, 15.0%), double support time (8.8%, 19.1%), step time asymmetry (32.1%, 64.0%), and single support asymmetry (60.0%, 74.7%) increased (p < 0.05).

CONCLUSIONS

Gait pattern worsen after performing a walking-induced fatigue test, such as 6MWT, in moderate-severe PwMS (EDSS ≥ 4.0). Identifying these gait alterations will allow physiotherapists to determine specific therapeutic objectives.

Impaired postural balance correlates with complex walking performance in mildly disabled persons with multiple sclerosis

BACKGROUND

It is relevant to understand the possible influence of impaired postural balance on walking performance in multiple sclerosis (MS) gait rehabilitation.

OBJECTIVE

We expected associations between impaired postural balance and complex walking performance in mildly disabled persons with MS, but not in healthy controls.

METHODS

Thirteen persons with MS (Expanded Disability Status Scale = 2.5) and 13 healthy controls' walking performance were measured at fast walking speed, Timed Up & Go and Timed 25 Feet Walking. Postural balance was measured by stabilometry, 95% confidence ellipse sway area and sway velocity.

RESULTS

Except from sway velocity (p = 0.07), significant differences were found between persons with MS and healthy controls in postural balance and walking. Significant correlations were observed between sway area and Timed Up & Go (r = 0.67) and fastest safe walking speed (r = -0.63) in persons with MS but not in healthy controls (r = 0.52 and r = 0.24, respectively). No other significant correlations were observed between postural balance and walking performance in neither persons with MS nor healthy controls.

CONCLUSION

Findings add to the understanding of postural balance and walking in persons with MS, as impaired postural balance was related to complex walking performance. Exercises addressing impaired postural balance are encouraged in early MS gait rehabilitation.

Dynamic Balance Is Related to Physiological Impairments in Persons With Multiple Sclerosis

OBJECTIVES

To compare physiological impairments between persons with multiple sclerosis (MS) with a history of falls and persons with MS without a history of falls, and to investigate the association between physiological impairments and dynamic balance.

DESIGN

Cross-sectional study.

SETTING

University motion analysis laboratory.

PARTICIPANTS

Persons with MS (N=55; 27 recurrent fallers and 28 nonfallers). Participants were classified as fallers if they self-reported ≥2 falls in the previous 6 months.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Physiological impairment was assessed with sensorimotor delays, spasticity, plantar cutaneous sensation, and the sensory, cerebellar, and pyramidal subscales of the Expanded Disability Status Scale (EDSS). Dynamic balance was assessed using the average and variability of margin of stability and variability of trunk accelerations.

RESULTS

Compared with nonfallers, fallers had lower plantar sensation, longer sensorimotor delays, more spasticity, and more impairment in the pyramidal and cerebellar subscales of the EDSS. Additionally, these impairments were all moderately to strongly correlated with worse dynamic balance.

CONCLUSIONS

This study highlights the multifactorial nature of instability in persons with MS. A better understanding of the physiological mechanisms of dynamic instability in persons with MS can be used to improve methods of monitoring disease progression, identifying which impairments to target through interventions, and appropriately evaluating intervention efficacy.

Gait deficits in people with multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Multiple Sclerosis (MS) results in postural instability and gait abnormalities which are associated with accidental falls.

OBJECTIVE

This systematic review and meta-analysis aims to quantify the effect of MS on gait to inform the development of falls prevention interventions.

METHODS

A systematic literature search identified case-control studies investigating differences in gait variables between people with MS and healthy controls. Meta-analysis examined the effect of MS on gait under normal and fast paced conditions.

RESULTS

Forty-one studies of people with Expanded Disability Status Scale (EDSS) 1.8 to 4.5 were included, of which 32 contributed to meta-analysis. A large effect of MS was found on stride length (Standardised Mean Difference, SMD=1.27, 95% CI{0.93, 1.61}), velocity (SMD=1.12, 95% CI{0.85, 1.39}), double support duration (SMD=0.85, 95% CI{0.51, 1.2}), step length (SMD=1.15, 95% CI{0.75, 1.5})and swing phase duration (SMD=1.23, 95% CI{0.06, 2.41}). A moderate effect was found on step width and stride time with the smallest effect found on cadence (SMD=0.43, 95% CI{0.14, 0.72}). All effect sizes increased for variables investigated under a fast walking pace condition (for example the effect on cadence increased to SMD=1.15, 95% CI{0.42, 1.88}).

CONCLUSIONS

MS has a significant effect on gait even for those with relatively low EDSS. This effect is amplified when walking at faster speeds suggesting this condition may be more beneficial for assessment and treatment. No studies investigated the association between these deficits and falls. Further investigation relating to the predictive or protective nature of these deficits in relation to falls is warranted.

Gait variability in people with neurological disorders: A systematic review and meta-analysis

There has been growing evidence showing gait variability provides unique information about gait characteristics in neurological disorders. This study systemically reviewed and quantitatively synthesized (via meta-analysis) existing evidence on gait variability in various neurological diseases, including Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), cerebellar ataxia (CA), Huntington's disease (HD), multiple sclerosis (MS), and Parkinson's disease (PD). Keyword search were conducted in PubMed, Web of science, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library. Meta-analysis was performed to estimate the pooled effect size for gait variability for each neurological group. Meta-regression was performed to compare gait variability across multiple groups with neurological diseases. Gait variability of 777 patients with AD, ALS, CA, HD, MS, or PD participating in 25 studies was included in meta-analysis. All pathological groups had increased amount of gait variability and loss of fractal structure of gait dynamics compared to healthy controls, and gait variability differentiated distinctive neurological conditions. The HD groups had the highest alterations in gait variability among all pathological groups, whereas the PD, AD and MS groups had the lowest. Interventions that aim to improve gait function in patients with neurological disorders should consider the heterogeneous relationship between gait variability and neurological conditions.

Multiple sclerosis influences the precision of the ankle plantarflexon muscular force production

OBJECTIVE

To quantify the precision of the steady-state isometric control of the ankle plantarflexors musculature of individuals with multiple sclerosis (MS), and to evaluate if the precision is related to the mobility impairments.

METHODS

Individuals with MS and healthy adults performed a submaximal steady-state isometric contraction with the ankle plantarflexors. The coefficient of variation was used to assess the amount of variability or error in the precision of the torques generated by the ankle plantarflexor musculature. The participants also walked across a digital mat at their preferred and fast-as-possible walking speeds, which recorded their spatiotemporal gait kinematics.

RESULTS

The individuals with MS: (1) had reduced maximal voluntary torques at the ankle, (2) a greater amount of variability in the precision of the isometric ankle torques, (3) altered and more variable spatiotemporal gait kinematics, and (4) a greater amount of variability in the isometric ankle torques were related to a slower walking speed and cadence, shorter step length and a greater amount of gait variability.

CONCLUSIONS

These results further fuels the impression that a reduction in control of the ankle joint musculature may be a key factor in the mobility and balance impairments seen in individuals with MS.

Gait variability across the disability spectrum in people with multiple sclerosis

BACKGROUND

An alternative method suggested to assess changes in walking in people with multiple sclerosis (PwMS) is evaluating gait variability. This is a credible option since gait variability reflects to some degree the quality of gait control.

OBJECTIVE

Examine the impact of disability on gait variability in PwMS.

METHODS

In this cross-sectional study, the data pool was divided into seven levels of disability based on the Expanded Disability Status Scale (EDSS) score, ranging from 0 to 6.5. Gait variability was studied using an electronic mat.

RESULTS

The final analysis included 381 PwMS (249 women); mean age 44.0years. Non-significant differences were observed between the EDSS subgroups at the lower end of the spectrum (EDSS 0-3.5) in all gait variability parameters. In contrast, PwMS in the EDSS 5.0-5.5 group demonstrated a significant increase in variability of step length (~151%), single support (~93%) and step time (142%) compared with those who scored 0-3.5. Moreover, participants in the EDSS 5.0-5.5 group had elevated step length variability compared to the EDSS 4.0-4.5 group (9.3 (S.E.=2.2) vs. 5.5 (S.E.=0.4), P-value=0.005).

CONCLUSION

We encourage clinicians to follow-up on the gait variability score as it appears to reflect mobility deterioration in PwMS.

The "butterfly diagram": A gait marker for neurological and cerebellar impairment in people with multiple sclerosis

People with multiple sclerosis (PwMS) frequently experience walking and balance impairments. In our previous report, we demonstrated that spatio-temporal gait parameters, collected by the Zebris FDM-T instrumented treadmill (Zebris Medical GmbH, Germany), serve as valid markers of neurological impairment in the MS population. In the current study, we focused on a unique outcome statistic of the instrumented treadmill, the "butterfly" diagram which reflects the variability of the center of pressure trajectory during walking. Therefore, the aim of the study was to examine the relationship between parameters related to the gait butterfly diagram and the level of neurological impairment in PwMS. Specifically we examined whether the gait butterfly parameters can differentiate between MS patients with normal cerebellar function and those suffering from ataxia. Demographic, neurological and gait parameters were collected from 341 PwMS, 213 women, aged 42.3 (S.D.=13.8). MS participants with ataxia demonstrated higher scores relating to the butterfly gait variability parameters compared to PwMS with normal or slightly abnormal cerebellar function. According to the results of the binary regression analysis, gait variability in the ant-post direction was found to explain 18.1% of the variance related to cerebellar function; R(2)=0.181, χ(2)(1)=67.852, P<0.001. Measurements derived from the butterfly diagram are proper estimators for important neurological functions in PwMS and should be considered in order to improve diagnosis and assessment of the MS population.