Gait variability in multiple sclerosis: a better falls predictor than EDSS in patients with low disability

Comparison of physical performance, gait, balance, falls efficacy, and step reaction time in individuals with multiple sclerosis

OBJECTIVE

The study aimed to investigate the physical performance, gait, balance, falls efficacy, and step reaction time in individuals with MS.

METHODS

A total of 60 individuals (30 individuals with MS and 30 age and sex-matched healthy controls) were enrolled. Individuals' physical performance was evaluated with the Timed Up and Go Test (TUG) and Five-Times-Sit-to-Stand Test (FTSTS). Activities-specific Balance Confidence (ABC) Scale, 12-item Multiple Sclerosis Walking Scale (MSWS-12v2) and Falls Efficacy Scale International (FES-I) were used to assess the balance, gait and fall efficacy of the participants. Individuals' step reaction time (SRT) was calculated with video-based software. The time between the step command and the first contact of the foot with the ground in the first step was recorded.

RESULTS

The mean age of the individuals with MS and the control group was 38.5 ± 9.4 years and 33.9 ± 11.7 years, respectively. Significant differences existed between the groups in SRT, FES-I, ABC, and FTSTS (p < 0.05). There was no significant correlation between SRT with any other parameter (p > 0.05). TUG was moderately correlated with MSWS-12 and FES-I (r1 =0.426, r2 =0.495, p < 0.05). Besides, there was a moderate correlation between ABC with TUG and FTSTS (r1 =-0.605, r2 =-0.468, p < 0.05). A high degree correlation was found between MSWS-12 with FES-I and ABC (r1 =0.843, r2 =-0.834, p < 0.05).

CONCLUSION

Individuals with MS have decreased SRTs. However, this condition was not found to be related to physical performance. Further studies should focus on the association of SRT with cognitive and psychosocial parameters.

How Much Data Is Enough? A Reliable Methodology to Examine Long-Term Wearable Data Acquisition in Gait and Postural Sway

Wearable sensors facilitate the evaluation of gait and balance impairment in the free-living environment, often with observation periods spanning weeks, months, and even years. Data supporting the minimal duration of sensor wear, which is necessary to capture representative variability in impairment measures, are needed to balance patient burden, data quality, and study cost. Prior investigations have examined the duration required for resolving a variety of movement variables (e.g., gait speed, sit-to-stand tests), but these studies use differing methodologies and have only examined a small subset of potential measures of gait and balance impairment. Notably, postural sway measures have not yet been considered in these analyses. Here, we propose a three-level framework for examining this problem. Difference testing and intra-class correlations (ICC) are used to examine the agreement in features computed from potential wear durations (levels one and two). The association between features and established patient reported outcomes at each wear duration is also considered (level three) for determining the necessary wear duration. Utilizing wearable accelerometer data continuously collected from 22 persons with multiple sclerosis (PwMS) for 6 weeks, this framework suggests that 2 to 3 days of monitoring may be sufficient to capture most of the variability in gait and sway; however, longer periods (e.g., 3 to 6 days) may be needed to establish strong correlations to patient-reported clinical measures. Regression analysis indicates that the required wear duration depends on both the observation frequency and variability of the measure being considered. This approach provides a framework for evaluating wear duration as one aspect of the comprehensive assessment, which is necessary to ensure that wearable sensor-based methods for capturing gait and balance impairment in the free-living environment are fit for purpose.

Sex-Based Differences in Oxygen Cost of Walking and Energy Equivalents in Minimally Disabled Individuals With Multiple Sclerosis and Controls

BACKGROUND

Elevated oxygen cost of walking and energy equivalents are reported for highly and moderately disabled individuals with multiple sclerosis (MS). However, less is known about minimally impaired individuals. Moreover, no sex-based data on the metabolic rates of individuals with MS are available. In this cross-sectional study, the metabolic rates and temporospatial parameters of gait during overground walking in minimally disabled individuals with MS versus matched controls were quantified and whether sex-based differences occur was examined.

METHODS

Sixty-nine minimally impaired adults with MS (37, relapsing-remitting MS [RRMS]; 32, clinically isolated syndrome [CIS]) and 25 matched controls completed two 6-minute walking bouts at comfortable and fast speeds. The oxygen cost of walking, energy equivalents, and respiratory exchange ratio were recorded through breath-by-breath open-circuit spirometry. Gait analysis was performed via a portable electronic walkway.

RESULTS

At comfortable but not at fast speed, men with RRMS showed higher oxygen cost of walking than men with CIS (+17.9%, P = .04) and male controls (+21.3%, P = .03). In the RRMS group, men showed higher oxygen cost of walking (+19.2%, P = .04) and energy equivalents (+19.2%, P = .02) than women. Elevated oxygen cost of walking and energy equivalents in men were paralleled by significantly larger base of support and step time asymmetry during walking.

CONCLUSIONS

Metabolic demands are elevated while walking in minimally disabled individuals with RRMS. Furthermore, higher energy demands occur in men, probably due to increased step symmetry and base of support. Clinicians are advised to follow energy expenditure metrics collected while walking because they can indicate a decrease in fitness, even in the early phase of MS.

Walking on common ground: a cross-disciplinary scoping review on the clinical utility of digital mobility outcomes

Physical mobility is essential to health, and patients often rate it as a high-priority clinical outcome. Digital mobility outcomes (DMOs), such as real-world gait speed or step count, show promise as clinical measures in many medical conditions. However, current research is nascent and fragmented by discipline. This scoping review maps existing evidence on the clinical utility of DMOs, identifying commonalities across traditional disciplinary divides. In November 2019, 11 databases were searched for records investigating the validity and responsiveness of 34 DMOs in four diverse medical conditions (Parkinson's disease, multiple sclerosis, chronic obstructive pulmonary disease, hip fracture). Searches yielded 19,672 unique records. After screening, 855 records representing 775 studies were included and charted in systematic maps. Studies frequently investigated gait speed (70.4% of studies), step length (30.7%), cadence (21.4%), and daily step count (20.7%). They studied differences between healthy and pathological gait (36.4%), associations between DMOs and clinical measures (48.8%) or outcomes (4.3%), and responsiveness to interventions (26.8%). Gait speed, step length, cadence, step time and step count exhibited consistent evidence of validity and responsiveness in multiple conditions, although the evidence was inconsistent or lacking for other DMOs. If DMOs are to be adopted as mainstream tools, further work is needed to establish their predictive validity, responsiveness, and ecological validity. Cross-disciplinary efforts to align methodology and validate DMOs may facilitate their adoption into clinical practice.

Gait Variability Is Associated With the Strength of Functional Connectivity Between the Default and Dorsal Attention Brain Networks: Evidence From Multiple Cohorts

BACKGROUND

In older adults, elevated gait variability when walking has been associated with both cognitive impairment and future falls. This study leveraged 3 existing data sets to determine relationships between gait variability and the strength of functional connectivity within and between large-scale brain networks in healthy older adults, those with mild-to-moderate functional impairment, and those with Parkinson's disease (PD).

METHOD

Gait and resting-state functional magnetic resonance imaging data were extracted from existing data sets on: (i) 12 older adults without overt disease yet with slow gait and mild executive dysfunction; (ii) 12 older adults with intact cognitive-motor function and age- and sex-matched to the first cohort; and (iii) 15 individuals with PD. Gait variability (%, coefficient of variation of stride time) during preferred walking speed was measured and correlated with the degree of functional connectivity within and between 7 established large-scale functional brain networks.

RESULTS

Regression models adjusted for age and sex revealed that in each cohort, those with less gait variability exhibited greater negative correlation between fluctuations in resting-state brain activity between the default network and the dorsal attention network (functionally limited older: β = 4.38, p = .027; healthy older: β = 1.66, p = .032; PD: β = 1.65, p = .005). No other within- or between-network connectivity outcomes were consistently related to gait variability across all 3 cohorts.

CONCLUSION

These results provide strong evidence that gait variability is uniquely related to functional connectivity between the default network and the dorsal attention network, and that this relationship may be independent of both functional status and underlying brain disease.

A Preliminary Investigation of the Effects of Obstacle Negotiation and Turning on Gait Variability in Adults with Multiple Sclerosis

Many falls in persons with multiple sclerosis (PwMS) occur during daily activities such as negotiating obstacles or changing direction. While increased gait variability is a robust biomarker of fall risk in PwMS, gait variability in more ecologically related tasks is unclear. Here, the effects of turning and negotiating an obstacle on gait variability in PwMS were investigated. PwMS and matched healthy controls were instrumented with inertial measurement units on the feet, lumbar, and torso. Subjects completed a walk and turn (WT) with and without an obstacle crossing (OW). Each task was partitioned into pre-turn, post-turn, pre-obstacle, and post-obstacle phases for analysis. Spatial and temporal gait measures and measures of trunk rotation were captured for each phase of each task. In the WT condition, PwMS demonstrated significantly more variability in lumbar and trunk yaw range of motion and rate, lateral foot deviation, cadence, and step time after turning than before. In the OW condition, PwMS demonstrated significantly more variability in both spatial and temporal gait parameters in obstacle approach after turning compared to before turning. No significant differences in gait variability were observed after negotiating an obstacle, regardless of turning or not. Results suggest that the context of gait variability measurement is important. The increased number of variables impacted from turning and the influence of turning on obstacle negotiation suggest that varying tasks must be considered together rather than in isolation to obtain an informed understanding of gait variability that more closely resembles everyday walking.

The application of principal component analysis to characterize gait and its association with falls in multiple sclerosis

People with multiple sclerosis (PwMS) demonstrate gait impairments that are related to falls. However, redundancy exists when reporting gait outcomes. This study aimed to develop an MS-specific model of gait and examine differences between fallers and non-fallers. 122 people with relapsing-remitting MS and 45 controls performed 3 timed up-and-go trials wearing inertial sensors. 21 gait parameters were entered into a principal component analysis (PCA). The PCA-derived gait domains were compared between MS fallers (MS-F) and MS non-fallers (MS-NF) and correlated to cognitive, clinical, and quality-of-life outcomes. Six distinct gait domains were identified: pace, rhythm, variability, asymmetry, anterior-posterior dynamic stability, and medial-lateral dynamic stability, explaining 79.15% of gait variance. PwMS exhibited a slower pace, larger variability, and increased medial-lateral trunk motion compared to controls (p < 0.05). The pace and asymmetry domains were significantly worse (i.e., slower and asymmetrical) in MS-F than MS-NF (p < 0.001 and p = 0.03, respectively). Fear of falling, cognitive performance, and functional mobility were associated with a slower gait (p < 0.05). This study identified a six-component, MS-specific gait model, demonstrating that PwMS, particularly fallers, exhibit deficits in pace and asymmetry. Findings may help reduce redundancy when reporting gait outcomes and inform interventions targeting specific gait domains.

Measuring Gait Stability in People with Multiple Sclerosis Using Different Sensor Locations and Time Scales

The evaluation of local divergence exponent (LDE) has been proposed as a common gait stability measure in people with multiple sclerosis (PwMS). However, differences in methods of determining LDE may lead to different results. Therefore, the purpose of the current study was to determine the effect of different sensor locations and LDE measures on the sensitivity to discriminate PwMS. To accomplish this, 86 PwMS and 30 healthy participants were instructed to complete a six-minute walk wearing inertial sensors attached to the foot, trunk and lumbar spine. Due to possible fatigue effects, the LDE short (~50% of stride) and very short (~5% of stride) were calculated for the remaining first, middle and last 30 strides. The effect of group (PwMS vs. healthy participants) and time (begin, mid, end) and the effect of Expanded Disability Status Scale (EDSS) and time were assessed with linear random intercepts models. We found that perturbations seem to be better compensated in healthy participants on a longer time scale based on trunk movements and on a shorter time scale (almost instantaneously) according to the foot kinematics. Therefore, we suggest to consider both sensor location and time scale of LDE when calculating local gait stability in PwMS.

Wearables and Deep Learning Classify Fall Risk From Gait in Multiple Sclerosis

Falls are a significant problem for persons with multiple sclerosis (PwMS). Yet fall prevention interventions are not often prescribed until after a fall has been reported to a healthcare provider. While still nascent, objective fall risk assessments could help in prescribing preventative interventions. To this end, retrospective fall status classification commonly serves as an intermediate step in developing prospective fall risk assessments. Previous research has identified measures of gait biomechanics that differ between PwMS who have fallen and those who have not, but these biomechanical indices have not yet been leveraged to detect PwMS who have fallen. Moreover, they require the use of laboratory-based measurement technologies, which prevent clinical deployment. Here we demonstrate that a bidirectional long short-term (BiLSTM) memory deep neural network was able to identify PwMS who have recently fallen with good performance (AUC of 0.88) based on accelerometer data recorded from two wearable sensors during a one-minute walking task. These results provide substantial improvements over machine learning models trained on spatiotemporal gait parameters (21% improvement in AUC), statistical features from the wearable sensor data (16%), and patient-reported (19%) and neurologist-administered (24%) measures in this sample. The success and simplicity (two wearable sensors, only one-minute of walking) of this approach indicates the promise of inexpensive wearable sensors for capturing fall risk in PwMS.

A Multifactorial Model of Multiple Sclerosis Gait and Its Changes Across Different Disability Levels

OBJECTIVE

Mobility assessment is critical in the clinical management of people with Multiple Sclerosis (pwMS). Instrumented gait analysis provides a plethora of metrics for quantifying concurrent factors contributing to gait deterioration. However, a gait model discriminating underlying features contributing to this deterioration is lacking in pwMS. This study aimed at developing and validating such a model.

METHODS

The gait of 24 healthy controls and 114 pwMS with mild, moderate, or severe disability was measured with inertial sensors on the shanks and lower trunk while walking for 6 minutes along a hospital corridor. Twenty out of thirty-six initially explored metrics computed from the sensor data met the quality criteria for exploratory factor analysis. This analysis provided the sought model, which underwent a confirmatory factor analysis before being used to characterize gait impairment across the three disability groups.

RESULTS

A gait model consisting of five domains (rhythm/variability, pace, asymmetry, and forward and lateral dynamic balance) was revealed by the factor analysis, which was able to highlight gait abnormalities across the disability groups: significant alterations in rhythm/variability-, asymmetry-, and pace-based features were present in the mild group, but these were more profound in the moderate and severe groups. Deterioration in dynamic balance-based features was only noted in pwMS with a moderate and severe disability.

CONCLUSION

A conceptual model of gait for disease-specific mobility assessment in pwMS was successfully developed and tested.

SIGNIFICANCE

The new model, built with metrics that represent gait impairment in pwMS, highlighted clinically relevant changes across different disability levels, including those with no clinically observable walking disability. This shows the clear potential as a monitoring biomarker in pwMS.

Cognitive and motor slowing mediate the relationship between depression and falls in multiple sclerosis patients

OBJECTIVE

Given the limited research concerning the relationship between depression and falls in multiple sclerosis (MS), this study aimed to examine the direct and indirect association between fall history and depressive symptoms.

METHODS

One hundred and forty seven MS patients had completed at least one neuropsychological assessment that included detailed information regarding fall history, as well as measures of depression, motor function, and cognitive processing speed.

RESULTS

Fall history was associated with higher depressive symptoms and poorer overall motor function. Higher self-reported depressive symptoms were associated with higher odds of falls in the last year (OR = 1.64, 95% CI 1.16, 2.31) in an age adjusted model. Cognitive and motor slowing serially mediated the relationship between depressive symptoms and fall history (estimate = 0.060, 95% CI = 0.01, 0.15).

CONCLUSIONS

With the extensive research on the cognitive and motor correlates of falls in MS, our findings suggest that depressive symptoms are also associated with falls in people with MS. Moreover, this study provides preliminary support for a pathway by which depressive symptoms are related to falls in part through their relationships with cognitive and motor slowing.

Does gait bout definition influence the ability to discriminate gait quality between people with and without multiple sclerosis during daily life?

BACKGROUND

There is currently no consensus about standardized gait bout definitions when passively monitoring walking during normal daily life activities. It is also not known how different definitions of a gait bout in daily life monitoring affects the ability to distinguish pathological gait quality. Specifically, how many seconds of a pause with no walking indicates an end to one gait bout and the start of another bout? In this study, we investigated the effect of 3 gait bout definitions on the discriminative ability to distinguish quality of walking in people with multiple sclerosis (MS) from healthy control subjects (HC) during a week of daily living.

METHODS

15 subjects with MS and 16 HC wore instrumented socks on each foot and one Opal sensor over the lower lumbar area for a week of daily activities for at least 8 h/day. Three gait bout definitions were based on the length of the pause between the end of one gait bout and start of another bout (1.25 s, 2.50 s, and 5.0 s pause). Area under the curve (AUC) was used to compare gait quality measures in MS versus HC.

RESULTS

Total number of gait bouts over the week were statistically significantly different across bout definitions, as expected. However, AUCs of gait quality measures (such as gait speed, stride length, stride time) discriminating people with MS from HC were not different despite the 3 bout definitions.

SIGNIFICANCE

Quality of gait measures that discriminate MS from HC during daily life are not influenced by the length of a gait bout, despite large differences in quantity of gait across bout definitions. Thus, gait quality measures in people with MS versus controls can be compared across studies using different gait bout definitions with pause lengths ≤5 s.

Influence of Multiple Sclerosis on Spatiotemporal Gait Parameters: A Systematic Review and Meta-Regression

OBJECTIVE

To quantify the effect of multiple sclerosis (MS) on spatiotemporal gait characteristics accounting for disability severity and fall classification.

DATA SOURCES

MEDLINE (1946-August 2018), Allied and Complementary Medicine Database (1985-2018 August), and PsycINFO (1806-August 2018) were searched for terms on MS and gait.

STUDY SELECTION

Dual independent screening was conducted to identify observational, cross-sectional studies that compared adults with MS grouped according to Expanded Disability Status Scale (EDSS) level or fall history, reported on spatiotemporal gait characteristics, and were published in English. The search retrieved 5891 results, of which 12 studies satisfied the inclusion criteria.

DATA EXTRACTION

Two authors worked independently to extract and verify data on publication details, study methodology, participant characteristics, gait outcomes, conclusions, and limitations. Risk of bias was assessed using the QualSyst critical appraisal tool. A random-effects meta-regression and meta-analysis were conducted on pooled data.

DATA SYNTHESIS

All studies received quality ratings of very good to excellent and collectively examined 1513 individuals with MS. With every 1-point increase in EDSS, significant changes (P<.05) were observed in gait speed (-0.12 m/s; 95% confidence interval (CI), 0.08-0.15), step length (-0.04 m; 95% CI, 0.03-0.05), step time (+0.04 seconds; 95% CI, 0.02-0.06), step time variability (+0.009 seconds; 95% CI, 0.003-0.016), stride time (+0.08 seconds; 95% CI, 0.03-0.12), cadence (-4.4 steps per minute; 95% CI, 2.3-6.4), stance phase duration (+0.8% gait cycle; 95% CI, 0.1-1.5), and double support time (+3.5% gait cycle; 95% CI, 1.5-5.4). Recent fallers exhibited an 18% (95% CI, 13%-23%) reduction in gait speed compared with nonfallers (P<.001).

CONCLUSIONS

This review provides the most accurate reference values to-date that can be used to assess the effectiveness of MS gait training programs and therapeutic techniques for individuals who differ on disability severity and fall classification. Some gait adaptations could be part of adopting a more cautious gait strategy and should be factored into the design of future interventions.

Fall-related functional impairments in patients with neurological gait disorder

Falls are common in patients with neurological disorders and are a primary cause of injuries. Nonetheless, fall-associated gait characteristics are poorly understood in these patients. Objective, quantitative gait analysis is an important tool to identify the principal fall-related motor characteristics and to advance fall prevention in patients with neurological disorders. Fall incidence was assessed in 60 subjects with different neurological disorders. Patients underwent a comprehensive set of functional assessments including instrumented gait analysis, computerized postural assessments and clinical walking tests. Determinants of falls were assessed by binary logistic regression analysis and receiver operator characteristics (ROC). The best single determinant of fallers was a step length reduction at slow walking speed reaching an accuracy of 67.2% (ROC AUC: 0.669; p = 0.027). The combination of 4 spatio-temporal gait parameters including step length and parameters of variability and asymmetry were able to classify fallers and non-fallers with an accuracy of 81.0% (ROC AUC: 0.882; p < 0.001). These findings suggest significant differences in specific spatio-temporal gait parameters between fallers and non-fallers among neurological patients. Fall-related impairments were mainly identified for spatio-temporal gait characteristics, suggesting that instrumented, objective gait analysis is an important tool to estimate patients' fall risk. Our results highlight pivotal fall-related walking deficits that might be targeted by future rehabilitative interventions that aim at attenuating falls.

Serum neurofilament light chains in MS: Association with the Timed Up and Go

OBJECTIVE

This cross-sectional study aims to assess the association between neuroaxonal damage assessed by serum neurofilament light chain (sNfL) and the Timed Up and Go (TUG)-a reliable and rapid measure of global neurologic disability-in patients with MS.

METHODS

A total of 41 consecutive patients with MS (38.0 ± 10.4 years; 57% women) with low level of disability (Expanded Disability Status Scale [EDSS] score 0-3) (EDSS score 1.0, interquartile range [IQR] 0.0-2.0) were included in this study. The TUG and sNfL were measured in a 6-month interval, together with a comprehensive neuropsychological and quantitative gait evaluation. The association of sNfL (dependant variable) with TUG, and other gait, cognitive, and behavioral measures (independent variables) were evaluated with multiple linear regressions adjusted for age, sex, and EDSS score.

RESULTS

The sNfL concentration was 23.51 pg/mL (IQR 16.51-32.21 pg/mL), and the mean TUG was 9.27 ± 1.70 seconds. Only the TUG was associated with sNfL (β = 0.021; 95% CI 0.003-0.037; p = 0.022) (after adjusting for age, sex, and EDSS score), whereas this was not the case for gait and neuropsychological measures.

CONCLUSIONS

The TUG-an easy and unexpansive measure of disability-is associated with the degree of neuroaxonal damage, as measured by sNfL, in patients with MS with low level of disability. These findings confirm the validity of the TUG as a reliable bedside measure of global neurologic disability as a result of neuroaxonal damage.

A wearable sensor identifies alterations in community ambulation in multiple sclerosis: contributors to real-world gait quality and physical activity

People with multiple sclerosis (pwMS) often suffer from gait impairments. These changes in gait have been well studied in laboratory and clinical settings. A thorough investigation of gait alterations during community ambulation and their contributing factors, however, is lacking. The aim of the present study was to evaluate community ambulation and physical activity in pwMS and healthy controls and to compare in-lab gait to community ambulation. To this end, 104 subjects were studied: 44 pwMS and 60 healthy controls (whose age was similar to the controls). The subjects wore a tri-axial, lower back accelerometer during usual-walking and dual-task walking in the lab and during community ambulation (1 week) to evaluate the amount, type, and quality of activity. The results showed that during community ambulation, pwMS took fewer steps and walked more slowly, with greater asymmetry, and larger stride-to-stride variability, compared to the healthy controls (p < 0.001). Gait speed during most of community ambulation was significantly lower than the in-lab usual-walking value and similar to the in-lab dual-tasking value. Significant group (pwMS /controls)-by-walking condition (in-lab/community ambulation) interactions were observed (e.g., gait speed). Greater disability was associated with fewer steps and reduced gait speed during community ambulation. In contrast, physical fatigue was correlated with sedentary activity, but was not related to any of the measures of community ambulation gait quality including gait speed. This disparity suggests that more than one mechanism contributes to community ambulation and physical activity in pwMS. Together, these findings demonstrate that during community ambulation, pwMS have marked gait alterations in multiple gait features, reminiscent of dual-task walking measured in the laboratory. Disease-related factors associated with these changes might be targets of rehabilitation.

The association between gait variability with the energy cost of walking depends on the fall status in people with multiple sclerosis without mobility aids

BACKGROUND

Falls, gait variability and increased energy cost of walking are common in people with multiple sclerosis (PwMS). However, no studies have as yet examined this triple association in PwMS or in other neurological populations.

RESEARCH QUESTION

Does a relationship exist between gait variability, falls and the energy cost of gait in PwMS?

METHODS

This cross sectional study included 88 PwMS (50 women), mean age 39.8 (S.D = 13.0) and mean disease duration of 6.2 (SD = 8.2) years since diagnosis. Energy expenditure during walking was collected via a portable metabolic device (COSMED K5, COSMED Srl, Roma, Italy). Gait variability was measured by an electronic walkway (GAITRite™). Participants were divided into groups based on fall history (fallers and non-fallers). Differences between groups in terms of energy expenditure measures and gait variability metrics were determined by the analysis of variance test. The relationship between gait variability and energy cost of walking was examined by the Pearson's correlation coefficient test.

RESULTS

Thirty-three PwMS were classified as fallers and 55 as non-fallers. Non-significant differences between groups were observed in the energy expenditure measures, including cost of walking. Fallers demonstrated higher step length variability compared with non-fallers (4.58 (S.D. = 2.42 vs. 3.40 (S.D. = 1.40); p-value = 0.005). According to the Pearson's correlation coefficient analysis, a significant relationship was found between step length variability and energy cost of walking in the non-fallers group (Rho = 0.372, P-value = 0.006) and the total group (Rho = 0.296, p-value = 0.005), but not in those PwMS with a history of falls.

SIGNIFICANCE

We demonstrated a significant relationship between increased gait variability and energy expenditure while walking only in MS patients without a history of falls. This is important as there is evidence of the clinical relevance of increased gait variability, poor fitness level and high risk of falling in the MS population.

Gait Variability and Energy Cost of Oveground Walking in Persons With Multiple Sclerosis: A Cross-Sectional Study

OBJECTIVE

This study examined the associations between gait variability based on common spatiotemporal parameters and energetic cost of walking in persons with multiple sclerosis.

DESIGN

Eighty-six persons with multiple sclerosis underwent the 6-min walk while wearing a portable metabolic unit. The cost of walking was generated by dividing the net steady-state VO2 (milliliter per kilogram per minute) by walking speed during the 6-min walk. Participants further completed two trials of walking on the GAITRite mat at a self-selected pace for measuring spatiotemporal parameters. Variability of step length, step time, stride length, swing time, stance time, stride velocity, and single- and double-support time was indexed by the coefficient of variation.

RESULTS

Variability in the spatiotemporal variables and Expanded Disability Status Scale scores were significantly correlated with cost of walking (i.e., ρ = 0.25-0.36). Multivariate analysis revealed that disability (Expanded Disability Status Scale: β = 0.186), stance time variability (β = 1.446), and step length variability (β = -1.216) explained significant variance (R(2) = 0.38, P < 0.001) in cost of walking.

CONCLUSIONS

We provide evidence of the positive association between gait variability and cost of walking during overground walking in persons with multiple sclerosis. The findings highlight the need for interventions aiming to reduce gait variability, thereby reducing the energetic demands of walking in this population.

Falls in paediatric Charcot-Marie-Tooth disease: a 6-month prospective cohort study

OBJECTIVE

To prospectively study falls in children and adolescents with Charcot-Marie-Tooth disease (CMT).

DESIGN

Prospective cohort study.

SETTING

Neuromuscular outpatient clinic of a tertiary paediatric hospital.

PATIENTS

Sixty children and adolescents ('children') aged 4-18 years, 30 with CMT and 30 typically developing (TD).

MAIN OUTCOME MEASURES

Falls rate over 6 months and falls characteristics questionnaire.

RESULTS

Twenty-two children with CMT reported falling at least once in 6 months compared with eight TD children (CMT 2819 (0-1915), TD 31 (0-6) total falls (range)). Detailed falls characteristics were collected from 242 individual falls (CMT 216, TD 26). Injurious falls were reported by 19 children with CMT (74 falls) compared with 2 TD children (3 falls), with cuts, grazes and bruising most common. No fractures were sustained and no child required hospitalisation. However, 12 injuries from falls in children with CMT required management by a healthcare provider, versus none in TD children. Tripping was the most common mechanism of falls in both groups. Age was the strongest predictor of falls (ρ=-0.53, p=0.006) with all children (CMT and TD) aged <7 years falling. Balance was the strongest impairment-related predictor of falls (ρ=-0.47, p=0.02). The conservative estimate of risk of falls in children and adolescents with CMT was 33 times higher than their TD peers (incidence rate ratio=32.8, 95% CI 10.2 to 106.0).

CONCLUSIONS

Children and adolescents with CMT fall more often than TD peers and sustain more injuries when they fall.

Association of the Dynamic Gait Index to fall history and muscle function in people with multiple sclerosis

Background and purpose: This study examined the association of a commonly used gait assessment, the Dynamic Gait Index, with falls and lower extremity and trunk muscle function in people with multiple sclerosis.Materials and methods: Cross-sectional data from 72 people with multiple sclerosis (Expanded Disability Status Scale 3.5 ± 1.14) were used. The ability of the Dynamic Gait Index to identify fallers was evaluated using the receiver operating characteristic curve. Multiple linear regression determined contributions of muscle function variables to Dynamic Gait Index scores.Results: Thirty-seven participants reported at least one fall in the previous 3 months (51%). The area under the curve for the Dynamic Gait Index was 0.80 (95% CI: 0.69-0.90), indicating a good ability to identify fallers with a cutoff of ≤19/24. After adjusting for age, sex, and disability level, a one standard deviation increase in ankle plantarflexion (15.2 repetitions) and trunk flexion (15.1 repetitions) endurance were associated with an increase in Dynamic Gait Index score of 0.73 (95% CI: 0.07-1.39) and 0.62 (95% CI: 0.002-1.25), respectively.Conclusions: The Dynamic Gait Index may be a useful tool to identify fallers, and was associated with ankle plantarflexion and trunk flexion endurance.Implications for rehabilitationThe Dynamic Gait Index appears to be a useful tool to identify people with multiple sclerosis at increased risk for falls using a cutoff score of ≤19/24.The ability to do fewer than 13 single leg heel raises had a moderate ability to identify fallers in this study.Out of 11 lower extremity and trunk muscles, only ankle plantarflexion and trunk flexion muscle endurance were significant predictors of Dynamic Gait Index scores.Clinicians may consider targeting ankle plantarflexion and trunk muscle endurance to improve dynamic gait and fall risk in patients with multiple sclerosis.

Gait Variability, Not Walking Speed, Is Related to Cognition in Adolescents With Multiple Sclerosis

Gait variability is associated with cognitive performance in people with central neurologic damage illnesses, which includes multiple sclerosis. However, presently, there have been no data available as to whether this association exists in adolescents with multiple sclerosis. Therefore, our objective was to investigate the association between gait variability and cognition in adolescents with multiple sclerosis encompassing 48 recently diagnosed adolescents with multiple sclerosis (26 girls; 22 boys), average age of 16.0 years (SD = 2.2), and an Expanded Disability Status Scale (EDSS) score of 1.6 (SD = 1.3). Walking speed and gait variability expressed by the coefficient of variation of the mean step time was studied using an electronic walkway. A computerized cognitive battery of tests evaluated cognition. Cognitive outcome measurements included verbal and nonverbal memory, executive function, visual spatial processing, verbal function, attention, information processing speed, and motor skills. Mean walking speed was 76.9 cm/s (SD = 57.6); mean step time variability was 3.5 (SD = 1.3) and the global cognitive score was 93.9 (SD = 12.5). According to linear regression analysis, a significant association was found between step time variability, cognitive subdomains of attention, and information processing speed. After incorporating walking speed into the model, the association remained significant. Increased gait variability, not walking speed, is suggested as a clinical marker of cognitive performance in minimally disabled adolescents with multiple sclerosis.

Neural correlates of gait variability in people with multiple sclerosis with fall history

BACKGROUND AND PURPOSE

The aim was to investigate the association between step time variability and related brain structures in accordance with fall status in people with multiple sclerosis (PwMS).

METHODS

The study included 225 PwMS. Whole-brain magnetic resonance imaging was performed with a high-resolution 3.0 T magnetic resonance scanner in addition to volumetric analysis based on 3D T1-weighted images using the FreeSurfer image analysis suite. Step time variability was measured with an electronic walkway. Participants were defined as 'fallers' (at least two falls during the previous year) and 'non-fallers'.

RESULTS

In all, 105 PwMS were defined as fallers and had a greater step time variability compared to non-fallers [5.6% (SD = 3.4) vs. 3.4% (SD = 1.5); P = 0.001]. MS fallers exhibited a reduced volume in the left caudate and both cerebellum hemispheres compared to non-fallers. On using a linear regression analysis no association was found between gait variability and related brain structures in the total cohort and the non-fallers group. However, the analysis found an association between the left hippocampus and left putamen volumes with step time variability in the faller group: P = 0.031, 0.048, respectively, controlling for total cranial volume, walking speed, disability, age and gender. Nevertheless, according to the hierarchical regression model, the contribution of these brain measures to predict gait variability was relatively small compared to walking speed.

CONCLUSIONS

An association between low left hippocampal, putamen volumes and step time variability was found in PwMS with a history of falls, suggesting that brain structural characteristics may be related to falls and increased gait variability in PwMS.

The relationship between gait variability and cognitive functions differs between fallers and non-fallers in MS

The objective of the study was to determine if cognitive function is associated with step time variability in people with multiple sclerosis (PwMS). The study included 355 PwMS (218 women), average age 41.1 (SD = 13.5), disease duration 5.9 (SD = 7.3) years, and a median expanded disability status scale score of 2.5. We separately analyzed the sample group of fallers and non-fallers based on their fall history. Gait variability was measured by an electronic walkway and all participants completed a computerized cognitive test battery designed to evaluate multiple cognitive domains. Fallers (43.7%) demonstrated elevated step time variability (%CV), 5.0 (SD = 3.4) vs. 3.5 (SD = 1.6), P < 0.001 compared to the non-faller subjects. According to the regression analysis in the non-fallers' group, step time variability was found significantly associated with the global cognitive score (P = 0.001), executive function subcategory (P = 0.038), and motor skills subcategory (P < 0.001). No relationship between step time variability and any cognitive domain was demonstrated in the faller group. This study illustrated that the association between gait variability and cognition occurs only in PwMS without a fall history. From a clinical standpoint, these findings might help medical professionals to create improved assessment tests and rehabilitation strategies in the MS population.

Smart watch, smarter EDSS: Improving disability assessment in multiple sclerosis clinical practice

BACKGROUND

Patients' walking ability is critical for assessing the EDSS, the disability scale commonly used in MS clinical practice. Such assessment is usually based on patients' estimates or on the measures the neurologists observe during periodic visits.

OBJECTIVES AND METHODS

We evaluated the agreement between patients' and neurologists' estimates of maximum walking ability and patients' mean maximum walking ability measured in their daily life through a GPS smartwatch, and assessed limitations of the current methods.

RESULTS

Seventy-three patients with a median walking ability of 500m (IQR 400-800) were enrolled in the study. The agreement between patients' estimates and GPS measurements was modest (ICC 0.29, 95% CIs 0.06-0.49) and was influenced by course of the disease, patients' mood and inaccuracy at estimating long distances. A better reliability was found between neurologists' and GPS measures (ICC 0.68, 95% CIs 0.53-0.78), but the variability increased for longer distances and was influenced by patients' depressive symptoms, fatigue and course of the disease.

CONCLUSIONS

This study showed a poor agreement between patients' and neurologists' estimates of maximum walking ability and patients' mean maximum walking ability measured in their daily life through a GPS smartwatch, with many factors affecting patient's and neurologists' estimates of the EDSS. The use of remote measurement technologies may provide a better understanding of the impact of MS in a patient's life.

Impairments of balance, stepping reactions and gait in people with cervical dystonia

BACKGROUND

Impaired balance is common in neurological disorders. Cervical dystonia is a neurological movement disorder affecting the neck. The effect of this aberrant head posture on physical function is unknown.

OBJECTIVES

To compare balance, mobility, gait and stepping reactions between ten people with cervical dystonia and ten control adults.

METHODS

Spatiotemporal gait parameters and walking speed were assessed using a computerised walkway. Step length and time, time in double support and gait variability were calculated, then normalised to gait speed. Centre of pressure path length was assessed with eyes open and eyes closed to calculate a Romberg Quotient. Simple and choice reaction times were measured using customised apparatus while mobility was assessed by the timed up and go. Cervical spine range of motion was measured using a head mounted goniometer. Self-reported scales included Falls Self Efficacy Scale and Dystonia Discomfort Scale.

RESULTS

There was a difference between groups for most outcome measures. The timed up-and-go and walking speed was slower (both P<0.005) and the Romberg Quotient lower (P=0.046) in cervical dystonia. People with cervical dystonia had lower falls self-efficacy (P=0.0002). Reduced cervical range of motion was correlated with balance, stepping reaction time and mobility (all P<0.05). Timed up and go was positively associated with stepping reaction time (P<0.01). Dystonia discomfort did not impact function.

CONCLUSIONS

People with cervical dystonia displayed deficits in balance, gait and stepping reactions, and expressed higher fear of falling. Studies to further elucidate functional limitations and their impact on activity and participation in daily life are required.