An exploration of impaired walking dynamics and fatigue in multiple sclerosis

Manifestations of walking fatigability in people with multiple sclerosis based on gait quality and distance walked during the six minutes walking test

BACKGROUND

Distance walking fatigability (DWF) in people with multiple sclerosis (pwMS) is defined as a decrease in the distance walking over time. However, declines in gait quality (i.e., gait quality fatigability- GQF) may occur independently or alongside DWF.

OBJECTIVE

i) to investigate how walking fatigability manifests and its prevalence in pwMS; ii) to describe the temporal pattern of the changes of specific gait characteristics during the 6-minute walking test (6MWT) METHODS: Eighty-eight pwMS (EDSS 4[0-6.5], 49[21-70] years) and 47 healthy controls (HC- 46[25-60] years) performed the 6MWT wearing inertial measurement units. Gait characteristics (stride length, sensor-based gait speed, cadence, double support, step duration, stance phase, step duration asymmetry, step duration variability, foot-strike, toe-off, and leg circumduction) and walking distance were recorded in 1-minute intervals. A fatigability index was calculated by comparing the last and first minute of the 6MWT to identify abnormal worsening based on cutoff scores. The manifestation of walking fatigability was counted. The temporal pattern of worsening of gait characteristics during the 6MWT was examined in pwMS exceeding the cutoff values, compared to pwMS without abnormal changes and HC, using a two-way ANOVA (group vs. minutes) RESULTS: Thirty-five pwMS presented both DWF and GQF, 2 presented isolated DWF, 27 presented isolated GQF, and 24 presented non-walking fatigability. PwMS having GQF presented worsening in gait characteristics (cadence, step duration, step duration variability, or toe-off angle) from minute 2 onwards of the 6MWT, while HCs and pwMS without abnormal changes stabilized gait from minute 2 towards the end of the 6MWT.

CONCLUSION

Walking fatigability in pwMS manifests not only as a decrease in walking distance but also as changes in gait quality. Understanding changes in gait characteristics during walking can help tailor rehabilitation interventions.

The measurement of fatigability severity in individuals with multiple sclerosis and healthy controls

BACKGROUND

Multiple Sclerosis (MS) is a chronic disease that substantially diminishes one's ability to undertake daily living activities. Fatigue has been reported by at least 80 % of persons with MS (PwMS). Yet, little is known concerning the quantification of fatigability using prolonged walking tests.

OBJECTIVES

To compare fatigability severity measures using the 10-minute walk test for PwMS against age- and gender-matched healthy controls (HCs).

METHODS

Participants included 53 ambulatory PwMS and 49 HCs. Perceived fatigability was measured by dividing a participant's change in self-reported tiredness by the number of meters walked. Performance fatigability was calculated by dividing the change in walking speed (at 2.5 and 10 min) by the total distance walked in meters.

RESULTS

There was a significant difference in perceived fatigability between PwMS and HCs (mean difference: 2.73 ± 0.83; p = 0.001) and in performance fatigability (mean difference: 0.24 ± 0.11; p = 0.01). Moreover, there were significant differences in speed and distance at all time points (p ≤ 0.05) between PwMS and HCs.

CONCLUSIONS

PwMS have significant walking deficits as reflected by greater fatigability in both perceived and performance measures. These methods can enhance therapeutic strategies that improve the walking performances of PwMS.

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.

Stability of sensor-based gait parameters reassessed after a period of one year in people with multiple sclerosis

BACKGROUND

Currently, there are several studies showing that wearable inertial sensors are highly sensitive in the detection of gait disturbances in people with multiple sclerosis (PwMS), showing excellent reliability within one or 7-14 days. However, it is not known how stable these gait parameters remain over a longer period of time. This is surprising, because many treatments last longer than two weeks. Thus, the purpose of the current study was to examine gait parameters obtained by means of wearable inertial sensors during a 6-min walk and to reassess these parameters after a period of one year.

METHODS

Fifty PwMS (without a relapse or a recent change in the Expanded Disability Status Scale (EDSS) or treatment) and 20 healthy participants were examined at two assessment points (interval between assessments: 14.4 ± 6.6 months). At each assessment point, all participants had to complete a 6-min walking test, an observer-rater test (Berg Balance Scale, BBS) and a Timed-up and Go Test (TUG). To measure mean gait parameters (i.e. walking speed, stride length, stride time, the duration of the stance and swing phase and minimum toe-to-floor distance), as well as the intraindividual standard deviation of each mean gait parameter, wearable inertial sensors were utilized.

RESULTS

We found that even after one year all mean gait parameters showed excellent Intraclass Correlation Coefficients (ICC between 0.75 and 0.95) in PwMS. Looking at MS subgroups, the ICCs were slightly higher in MS subgroup 2 (EDSS 2.0-5.0) than those in MS subgroup 1 (EDSS 0.0-1.5) and healthy controls. Compared to the mean gait parameters, parameters of gait variability showed only good-to-fair ICC values in PwMS. Concerning BBS and TUG, the ICC values after one year were close to the ICC values of the measured mean gait parameters.

CONCLUSIONS

Due to the excellent stability of mean gait parameters after one year, these sensor-based gait parameters can be identified as clinically relevant markers to evaluate treatment effects over a longer (several months) period of time in MS.

Multimodal-neuroimaging machine-learning analysis of motor disability in multiple sclerosis

Motor disability is a dominant and restricting symptom in multiple sclerosis, yet its neuroimaging correlates are not fully understood. We apply statistical and machine learning techniques on multimodal neuroimaging data to discriminate between multiple sclerosis patients and healthy controls and to predict motor disability scores in the patients. We examine the data of sixty-four multiple sclerosis patients and sixty-five controls, who underwent the MRI examination and the evaluation of motor disability scales. The modalities used comprised regional fractional anisotropy, regional grey matter volumes, and functional connectivity. For analysis, we employ two approaches: high-dimensional support vector machines run on features selected by Fisher Score (aiming for maximal classification accuracy), and low-dimensional logistic regression on the principal components of data (aiming for increased interpretability). We apply analogous regression methods to predict symptom severity. While fractional anisotropy provides the classification accuracy of 96.1% and 89.9% with both approaches respectively, including other modalities did not bring further improvement. Concerning the prediction of motor impairment, the low-dimensional approach performed more reliably. The first grey matter volume component was significantly correlated (R = 0.28-0.46, p < 0.05) with most clinical scales. In summary, we identified the relationship between both white and grey matter changes and motor impairment in multiple sclerosis. Furthermore, we were able to achieve the highest classification accuracy based on quantitative MRI measures of tissue integrity between patients and controls yet reported, while also providing a low-dimensional classification approach with comparable results, paving the way to interpretable machine learning models of brain changes in multiple sclerosis.

Validity of an inertial sensor-based system for the assessment of spatio-temporal parameters in people with multiple sclerosis

Background

Gait variability in people with multiple sclerosis (PwMS) reflects disease progression or may be used to evaluate treatment response. To date, marker-based camera systems are considered as gold standard to analyze gait impairment in PwMS. These systems might provide reliable data but are limited to a restricted laboratory setting and require knowledge, time, and cost to correctly interpret gait parameters. Inertial mobile sensors might be a user-friendly, environment- and examiner-independent alternative. The purpose of this study was to evaluate the validity of an inertial sensor-based gait analysis system in PwMS compared to a marker-based camera system.

Methods

A sample N = 39 PwMS and N = 19 healthy participants were requested to repeatedly walk a defined distance at three different self-selected walking speeds (normal, fast, slow). To measure spatio-temporal gait parameters (i.e., walking speed, stride time, stride length, the duration of the stance and swing phase as well as max toe clearance), an inertial sensor system as well as a marker-based camera system were used simultaneously.

Results

All gait parameters highly correlated between both systems (r > 0.84) with low errors. No bias was detected for stride time. Stance time was marginally overestimated (bias = -0.02 ± 0.03 s) and gait speed (bias = 0.03 ± 0.05 m/s), swing time (bias = 0.02 ± 0.02 s), stride length (0.04 ± 0.06 m), and max toe clearance (bias = 1.88 ± 2.35 cm) were slightly underestimated by the inertial sensors.

Discussion

The inertial sensor-based system captured appropriately all examined gait parameters in comparison to a gold standard marker-based camera system. Stride time presented an excellent agreement. Furthermore, stride length and velocity presented also low errors. Whereas for stance and swing time, marginally worse results were observed.

The effect of intermittent vs. continuous walking on distance to fatigue in persons with multiple sclerosis

PURPOSE

Previous studies provided evidence that persons with Multiple Sclerosis (pwMS) who walk intermittently experience less fatigue and walk longer distances than when walking continuously. However, total distance pwMS can walk in either condition is unknown. We examined time and distance to fatigability in pwMS comparing intermittent walking (IW) to continuous walking (CW).

MATERIALS AND METHODS

18 pwMS, with Expanded Disability Status Scale median of 4.75 [range = 2-6.5, IQR = 2.5] participated in this randomized crossover study. The IW condition consisted of alternating 30 s treadmill walking and 30 s seated rests. The CW condition consisted of treadmill walking without breaks. Treadmill speed (TS) was determined by an overground 2-min walk test. Walking fatigability was determined by participants walking on the treadmill, until gait fatigue was noted by patient or examiners. Total time and distance to gait fatigue, and subjective fatigue as measured by the Visual analog scale of fatigue were recorded.

RESULTS

Participants had significantly longer duration and distance to fatigue in the IW condition than the CW condition (ps ≤ 0.037). No difference in VASF scores between the two conditions were noted.

CONCLUSION

In this sample, IW allowed pwMS to perform a greater volume of walking and can be an option to improve walking endurance in this population.IMPLICATIONS FOR REHABILITATIONMultiple sclerosis (MS) is a disease that progressively impacts walking, resulting in a decrease in the maximum distance that a person with MS can walk.Intermittent walking has been shown to improve 6-min walk test performance in persons with MS (pwMS) compared to continuous walking, but its effects on longer and shorter walks is not known.The use of distance to fatigue should be considered a viable option for measuring walking fatigability in pwMS as it does not exclude persons based on their ability to complete a 6-min walk, nor would it be too easy for persons with pwMS with mild disability.By using distance to fatigue as an outcome measure, this study provides evidence that intermittent walking results in less fatigability regardless of walking ability.PwMS, regardless of their walking ability, can walk longer distances intermittently than continuously, suggesting that clinical treatment of walking fatigability in pwMS should utilize intermittent rather than continuous walking training.

Gait Variability to Phenotype Common Orthopedic Gait Impairments Using Wearable Sensors

Mobility impairments are a common symptom of age-related degenerative diseases. Gait features can discriminate those with mobility disorders from healthy individuals, yet phenotyping specific pathologies remains challenging. This study aims to identify if gait parameters derived from two foot-mounted inertial measurement units (IMU) during the 6 min walk test (6MWT) can phenotype mobility impairment from different pathologies (Lumbar spinal stenosis (LSS)-neurogenic diseases, and knee osteoarthritis (KOA)-structural joint disease). Bilateral foot-mounted IMU data during the 6MWT were collected from patients with LSS and KOA and matched healthy controls (N = 30, 10 for each group). Eleven gait parameters representing four domains (pace, rhythm, asymmetry, variability) were derived for each minute of the 6MWT. In the entire 6MWT, gait parameters in all four domains distinguished between controls and both disease groups; however, the disease groups demonstrated no statistical differences, with a trend toward higher stride length variability in the LSS group (p = 0.057). Additional minute-by-minute comparisons identified stride length variability as a statistically significant marker between disease groups during the middle portion of 6WMT (3rd min: p ≤ 0.05; 4th min: p = 0.06). These findings demonstrate that gait variability measures are a potential biomarker to phenotype mobility impairment from different pathologies. Increased gait variability indicates loss of gait rhythmicity, a common feature in neurologic impairment of locomotor control, thus reflecting the underlying mechanism for the gait impairment in LSS. Findings from this work also identify the middle portion of the 6MWT as a potential window to detect subtle gait differences between individuals with different origins of gait impairment.

Six-Minute Walk as a Measure of Walking Capacity and Endurance in Patients With Pediatric-Onset Multiple Sclerosis

BACKGROUND AND OBJECTIVES

Despite low levels of disability, youth with pediatric-onset multiple sclerosis (POMS) engage in less physical activity compared with peers. The contribution of walking capacity, endurance, behavior, and MS comorbidities remains relatively undefined and may provide valuable insights into the limitations toward physical activity in youth with MS. The primary objective of this study was to investigate differences in walking capacity, endurance, and real-world behaviors of daily activity between youth with POMS and controls.

METHODS

Youth diagnosed with MS prior to 18 years and aged 21 years or younger were recruited in addition to healthy controls. Participants completed questionnaires to quantify fatigue, depression, and physical activity levels and the timed 2- and 6-minute walk (6MW) as an assessment of walking capacity and endurance. Participants completed questionnaires to quantify fatigue, depression, and physical activity levels. Participants also completed the timed 2- and 6-minute walk (6MW) as an assessment of walking capacity and endurance and were sent home with a waist-worn accelerometer to assess real-world walking behavior.

RESULTS

Forty-five patients with POMS and 85 control participants were enrolled. The POMS cohort had a mean age of 16.9 ± 2.7 years, with a mean disease duration of 2.8 ± 2.6 years. A greater proportion of the POMS cohort was overweight/obese compared with controls (75% vs 33%). Participants with MS walked a significantly shorter distance in 6 minutes compared with controls (1,848 feet vs 2,134 feet, p < 0.0001) and, unlike controls, were unable to accelerate to their peak speed at the end of the 6MW. Body mass index category and MS disease significantly affected 6MW performance. Using continuous accelerometry, participants with MS spent less time in moderate-to-vigorous physical activity compared with controls (20.4 vs 35.4 min/d, p = 0.0003). The POMS cohort reported significantly higher levels of depression and fatigue but self-reported similar levels of daily physical activity as controls.

DISCUSSION

Youth with POMS exhibit slower 6MW performance and less daily engagement in moderate-to-vigorous physical activity, suggesting limitations in functional walking capacity, endurance, and daily activity behavior. Limitations in walking endurance and capacity are most prominent in those youth who are overweight/obese and living with MS.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that, compared with healthy controls, patients with POMS walk shorter distances on the 6MW test, are less able to accelerate to peak speed at the end of the test, and are less physically active.

Restless legs syndrome severity associated with reduced physical function in adults with multiple sclerosis

BACKGROUND

Restless legs syndrome (RLS) is a sleep disorder that occurs in approximately 26 % of adults with multiple sclerosis (MS) and may be associated with reduced physical function.

RESEARCH QUESTION

The present study examined the relationship between RLS symptomology (i.e., overall severity, frequency, and occurrence) and physical function outcomes in adults with MS who had RLS.

METHODS

Participants (N = 22) with MS who had RLS came into the laboratory for a single session wherein a rater performed a brief neurological examination for scoring the Expanded Disability Status Scale (EDSS) and completed a demographics questionnaire, the International Restless Legs Syndrome Study Group Scale (IRLS), and the Restless Legs Syndrome Scale-6 (RLS-6) followed by the Short Physical Performance Battery (SPPB) and the Six-minute Walk Test (6 MW).

RESULTS

Bivariate Spearman's rho correlation analyses indicated total IRLS had a strong, negative association with total distance traveled during the 6 MW (ρ = -0.50) and a moderate association with SPPB scores (ρ = -0.43), but not EDSS scores (ρ = 0.28). RLS severity during the day while active had strong, negative associations with total distance traveled during the 6 MW (ρ = -0.61) and SPPB scores (ρ = -0.52), but not EDSS scores (ρ = 0.13).

SIGNIFICANCE

We observed associations between worse overall RLS severity and RLS severity during the day while active with reduced performance during the 6 MW and lower SPPB scores. The management of RLS may offer an opportunity for mitigating reductions in physical function in adults with MS who have RLS.

The Role of Remote Monitoring in Evaluating Fatigue in Multiple Sclerosis: A Review

Fatigue is one of the most common multiple sclerosis (MS) symptoms. Despite this, monitoring and measuring fatigue (subjective lack of energy)- and fatigability (objectively measurable and quantifiable performance decline)- in people with MS have remained challenging. Traditionally, administration of self-report questionnaires during in-person visits has been used to measure fatigue. However, remote measurement and monitoring of fatigue and fatigability have become feasible in the past decade. Traditional questionnaires can be administered through the web in any setting. The ubiquitous availability of smartphones allows for momentary and frequent measurement of MS fatigue in the ecological home-setting. This approach reduces the recall bias inherent in many traditional questionnaires and demonstrates the fluctuation of fatigue that cannot be captured by standard measures. Wearable devices can assess patients' fatigability and activity levels, often influenced by the severity of subjective fatigue. Remote monitoring of fatigue, fatigability, and activity in real-world situations can facilitate quantifying symptom-severity in clinical and research settings. Combining remote measures of fatigue as well as objective fatigability in a single construct, composite score, may provide a more comprehensive outcome. The more granular data obtained through remote monitoring techniques may also help with the development of interventions aimed at improving fatigue and lowering the burden of this disabling symptom.

Instrumented Assessment of Motor Performance Fatigability During the 6-Min Walk Test in Mildly Affected People With Multiple Sclerosis

There are conflicting results regarding the changes in spatio-temporal gait parameters during the 6-min walk test (6MWT) as indicators of gait-related motor performance fatigability (PF) in people with Multiple Sclerosis (pwMS). To further analyze if gait-related motor PF can be quantified using instrumented gait analysis during the 6MWT, we investigated: (i) whether gait parameters recorded during the first or second minute were more stable and thus the better baseline to assess motor PF and (ii) if the minimum toe clearance (MTC) together with “classical” spatio-temporal gait parameters can be used to quantify motor PF in pwMS. Nineteen mildly affected pwMS [12 women/7 men; 47.8 ± 9.0 years; the Expanded Disability Status Scale (EDSS): 2.7 ± 1.0] and 24 healthy controls (HC; 15 women/9 men; 48.8 ± 7.6 years) completed the 6MWT equipped with inertial measurement units. Data were analyzed using the attractor method to compare the stability of gait parameters and, besides “classical” spatio-temporal gait parameters, the MTC was calculated as a potential new marker for motor PF in pwMS as this was shown in healthy older adults. It was found that (i) gait parameters were more stable in the second than in the first minute and (ii) gait-related motor PF could not be detected based on spatio-temporal gait parameters, including the MTC. Descriptive analysis indicated a decrease in MTC variability, which is assumed to be indicative for motor PF, toward the end of the 6MWT in some pwMS. Future studies should investigate gait parameters for the assessment of motor PF in pwMS recorded during more intense and/or longer walking protocols, taking the level of disability into account. Furthermore, using gait parameters recorded in the first minute of the 6MWT as a baseline for the assessment of motor PF should be avoided.

Effects of a 6-Min Treadmill Walking Test on Dual-Task Gait Performance and Prefrontal Hemodynamics in People With Multiple Sclerosis

Fatigue is one of the most limiting symptoms in people with multiple sclerosis (pwMS) and can be subdivided into trait and state fatigue. Activity-induced state fatigue describes the temporary decline in motor and/or cognitive performance (motor and cognitive performance fatigability, respectively) and/or the increase in the perception of fatigue (perceived fatigability) in response to motor or cognitive tasks. To the best of our knowledge, the effects of a 6-min walk test (6MWT), which was often used to assess motor performance fatigability in pwMS, on motor-cognitive dual-task performance (i.e., walking + arithmetic task) and prefrontal cortex (PFC) hemodynamics are not well-known. This is of importance, since daily activities are often performed as multitasks and a worse dual-task walking performance is associated with an increased risk of falling. Consequently, we investigated the effect of a fast 6MWT (comfort velocity + 15%) performed on a treadmill on motor-cognitive performance fatigability (spatio-temporal gait parameters/accuracy during the arithmetic task) and perceived fatigability measures (rating of perceived exhaustion; RPE) as well as PFC hemodynamics recorded during dual-task walking in pwMS and healthy controls (HCs). Twenty pwMS (48.3 ± 9.0 years; 13 females/7 males; expanded disability status scale 2.7 ± 1.0, first diagnosis 13.8 ± 8.8 years) and 24 HC with similar age and sex (48.6 ± 7.9 years; 17 females/7 males) were included. Only cognitive performance fatigability (increased error rate) during dual-task walking was found after the fast 6MWT on the treadmill in pwMS. However, the changes in gait parameters did not indicate motor performance fatigability, although both the groups reported perceived fatigability (increased RPE) after the fast 6MWT. Moreover, no change in the PFC activation was detected in both groups. Our results suggest that the intensity and/or duration of the fast 6MWT was not sufficient to induce motor performance fatigability in pwMS. These factors should be addressed by future studies on this topic, which should also consider further parameters, e.g., muscular oxygenation and/or myoelectrical activity, to verify that exercise intensity and/or duration was appropriate to induce motor performance fatigability in pwMS.

Oxygen Cost of Walking in People With Multiple Sclerosis and Its Association With Fatigue: A Systematic Review and Meta-analysis

BACKGROUND

This systematic review and meta-analysis aimed to compare the oxygen cost of walking in individuals with multiple sclerosis (MS) and controls and to assess the relationship between oxygen cost of walking and fatigue in individuals with MS.

METHODS

Four databases (CINAHL, MEDLINE, ProQuest, Web of Science) were searched up to September 2020. Studies were included if they recruited adults with MS and either compared oxygen cost of walking in those with MS and a control population or determined the relationship between oxygen cost of walking and fatigue. Meta-analysis of the standardized mean difference in oxygen cost of walking between individuals with MS and controls was performed.

RESULTS

Nine studies were included in this review, of which 7 compared oxygen cost of walking in individuals with MS (n = 176) and controls (n = 142) and 4 investigated the relationship between oxygen cost of walking and fatigue. Meta-analysis revealed that individuals with MS (with predominantly mild-to-moderate disability) had a significantly higher oxygen cost of walking compared with controls (standardized mean difference = 2.21, 95% CI = 0.88 to 3.54, P = .001). In addition, 3 studies found a significant yet weak positive association between oxygen cost of walking and fatigue.

CONCLUSIONS

Individuals with MS expend more energy when walking compared with controls. This increase in energy expenditure may contribute to the development of fatigue, as some studies found that higher oxygen costs of walking were associated with greater fatigue. Future studies should investigate whether reducing energy expenditure during movement improves fatigue.

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.

A Study Protocol for Occupational Rehabilitation in Multiple Sclerosis

Digital medical solutions can be very helpful in restorative neurology, as they allow the patients to practice their rehabilitation activities remotely. This work discloses ReMoVES, an IoMT system providing telemedicine services, in the context of Multiple Sclerosis rehabilitation, within the frame of the project STORMS. A rehabilitative protocol of exercises can be provided as ReMoVES services and integrated into the Individual Rehabilitation Project as designed by a remote multidimensional medical team. In the present manuscript, the first phase of the study is described, including the definition of the needs to be addressed, the employed technology, the design and the development of the exergames, and the possible practical/professional and academic consequences. The STORMS project has been implemented with the aim to act as a starting point for the development of digital telerehabilitation solutions that support Multiple Sclerosis patients, improving their living conditions. This paper introduces a study protocol and it addresses pre-clinical research needs, where system issues can be studied and better understood how they might be addressed. It also includes tools to favor remote patient monitoring and to support the clinical staff.

Mindfulness training during brief periods of hospitalization in multiple sclerosis (MS): beneficial alterations in fatigue and the mediating role of depression

OBJECTIVES

Persons with MS (PwMS) are frequently affected by fatigue and depression. Mindfulness-based interventions may reduce these symptoms in PwMS and consequently their application has been extended to various settings. Only few efforts have been made to explore effects of short-term mindfulness training during brief periods of hospitalization. In the current study, the feasibility and potential effects of short-term mindfulness training on depression, fatigue, rumination and cognition were explored in PwMS in an acute-care hospital setting. Based on previous work, it was further examined whether the relation between trait mindfulness and fatigue prior to and following the intervention was mediated by depression and whether a mediation effect was also observable throughout the intervention.

METHODS

A short-term mindfulness training protocol was developed, tailored to the requirements of the acute-care setting. Subsequently, 30 PwMS were recruited sequentially and received mindfulness training during the routine clinical process (median duration in hospital: eight days, number of sessions: four). Participants completed relevant self-report measures (depression, fatigue, rumination) and a neuropsychological assessment before and after training.

RESULTS

Participants reported significantly increased trait mindfulness and decreased depression and fatigue following the intervention. Respective change scores were highly correlated so that increased trait mindfulness was associated with decreased symptoms. In the rumination domain, patients reported a tendency for an increased adaptive ability to engage in distractive behavior during arising negative mood. Other measures of trait rumination and cognition remained relatively stable. Results of the mediation analyses indicated that depression mediated the negative relationship between trait mindfulness and fatigue symptoms at pre and post assessments. With regards to the change scores, an association between mindfulness and cognitive fatigue ceased to be significant when depression was controlled, albeit in this case, the mediation effect did not reach significance.

CONCLUSION

Results of the current study indicate that short-term mindfulness training during brief periods of hospitalization may be beneficial for PwMS. They further complement previous work by identifying depression as a potential mediator of the antagonistic relationship between mindfulness and fatigue. Based on the current exploratory study, future trials are warranted to address this mechanism of mindfulness training in more detail.

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.

Gait Speed Trajectory During the Six-Minute Walk Test in Multiple Sclerosis: A Measure of Walking Endurance

Background: The six-minute walk (6MW) test is a validated assessment method in Multiple Sclerosis (MS) research. While the total distance covered during six minutes (6MW^TD) is often used as the standard measurement of gait capacity (i.e., the maximum distance one can achieve), we hypothesize that endurance (i.e., ability to maintain speed over a prolonged time) can be inferred by the gait speed trajectory (GST) during the 6MW test (6MW^GST).

Objective: To characterize group differences in 6MW^GST between MS patients and healthy controls (HCs), and to assess information added by 6MW^GST for discerning between MS patients and HCs.

Methods: We performed a secondary data analysis on a cross-sectional cohort of 40 MS and 20 HC subjects with three repeated 6MW tests. We modeled 6MW^GST using a linear mixed-effects model with time in minutes and replicated walks nested within individuals. We compared the discernibility of 6MW^GST with that of conventional metrics using likelihood ratio tests and receiver operating characteristic (ROC) analysis on logistic regression models.

Results: MS subjects showed a concave, quadratic GST during 6MW tests, slowing down more than the HC subjects, especially at the beginning of 6MW tests. Despite accelerating at the end of the 6MW, MS subjects were unable to attain or surpass their initial 6MW gait speeds. 6MW^GST added useful information (p = 0.002) to the conventional metrics (e.g., 6MW^TD) for discerning between MS and HC subjects, and increased the area under the ROC curve from 0.83 to 0.93 (p = 0.037).

Conclusions: The distinctive 6MW^GST pattern of MS patients provided increased discernibility compared with currently used gait metrics. Both gait capacity measured by the 6MW^TD, and gait endurance measured by parameters of 6MW^GST, are significant functional indicators for the MS population.

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.

Physical fatigability and muscle pain in patients with Hashimoto thyroiditis

Introduction

Hashimoto thyroiditis (HT) may lead to muscle weakness due to hypothyroid dysfunction. However, clinical experience treating patients with HT suggests that neuromuscular symptoms may develop in these patients despite long-standing euthyroidism.

Methods

In 24 euthyroid patients with HT and 25 healthy controls, physical fatigability was assessed using the arm movement test (AMT) and 6-min walk test (6MWT). Fatigability was based on calculation of linear trend (LT) reflecting dynamic performance within subsequent constant time intervals. Perception of physical fatigue and muscle pain was analyzed using fatigue (FSMC) and pain questionnaires. Obtained results were correlated with clinical, neurophysiological and lab findings.

Results

HT patients showed a negative LT in 6MWT significantly differing from stable performance in controls. LT in AMT did not differ between HT and controls. FSMC scores and pain perception revealed significantly higher levels in HT patients than in controls. Physical FSMC score was primarily influenced by pain perception (standardized regression coefficient, beta = 0.633, p = 0.002). Neither pain score nor physical fatigue score showed a correlation with LT in 6MWT nor did mood, or anti-TPO antibody titer.

Conclusion

A significant physical fatigability could be shown in euthyroid HT patients despite missing obvious neuromuscular deficits in routine testing. Further, elevated pain and fatigue perception in HT patients seem to contribute to nonspecific muscle complaints in these patients. A possible pathogenic role of thyroid autoimmunity in hidden neuromuscular involvement may be suggested.

Exercise-induced changes in gait kinematics in multiple sclerosis with minimal neurological disability

BACKGROUND

Exercise-induced gait deterioration is a frequently encountered symptom that limits ambulation throughout the clinical course, becoming more prominent with increasing neurological disability in people with MS (pwMS).

OBJECTIVE

We attempted to objectively document exercise-induced gait changes in pwMS with minimal neurological disability and stable disease.

METHODS

Gait kinematics and spatio-temporal parameters were recorded using 3D motion analysis before and after a 20-minute treadmill walk (Group A, n=15)/run (Group B, n=15) at a self-selected speed in pwMS and compared with healthy controls (n=15).

RESULTS

Gait analysis revealed a significant decrease in peak ankle dorsiflexion in swing of the most affected leg, post-exercise task, in both Group A (EDSS 2.5-3.5) and Group B (EDSS 1-2.5) and not in healthy controls. Fourteen out of 30 MS participants showed an exercise-induced gait deterioration, based on minimal detectable change. Pre-exercise gait parameters in Group A showed a significantly higher peak dorsiflexion in swing with shorter step length and higher cadence, whereas Group B was comparable to healthy controls.

CONCLUSION

The detection of exercise-induced gait deterioration (foot drop) in pwMS with minimal neurological disability and stable disease indicates the potential of gait kinematics, before and after an exercise task, to monitor subtle neurological deficits from an early stage of MS.

Pilot trial of speed-intensive gait training on balance and walking in people with multiple sclerosis

Background/Aims

Diminished walking speed and endurance is commonly experienced by individuals with multiple sclerosis. Speed-intensive gait training has led to improvements in walking speed and endurance in other neurological populations; however, its effect in persons with multiple sclerosis is unknown. This pilot study examined the feasibility, safety and efficacy of speed-intensive gait training in a sample of people with multiple sclerosis.

Methods

A total of eight participants (five women, median Expanded Disability Status Scale 3.5) underwent a 6-week, twice weekly speed-intensive gait training programme. Walking speed and endurance, balance and fatigue were measured pre- and post-intervention.

Results

Speed-intensive gait training was feasible, with excellent adherence and safety. It proved effective, with improvements in walking speed (P=0.05), walking endurance (P=0.036) and balance (P=0.041) without an increase in fatigue.

Conclusions

The intermittent design of speed-intensive gait training may enable individuals with multiple sclerosis to achieve higher training volumes than traditional models. Although further study is warranted, rehabilitation clinicians should consider adding speed-intensive gait training as an intervention to improve walking and balance in this patient group.

Associations Between Self-Reported Symptoms and Gait Parameters Using In-Home Sensors in Persons With Multiple Sclerosis

BACKGROUND AND PURPOSE

Multiple sclerosis (MS) is a progressive neurological disorder, characterized by exacerbations and remissions, often resulting in disability affecting multiple neurological functions. The purpose of this article was (1) to describe the frequencies of self-reported symptoms in a natural environment and (2) to determine characteristics and associations between self-reported symptoms and home gait parameters (speed, stride time, and stride length) at baseline and at 3 months in patients with MS.

METHODS

Participants completed the self-report MS-Related Symptom Scale to measure symptoms. A three-dimensional depth imaging system (Foresite Healthcare) was used to measure gait parameters in the home environment.

RESULTS

These data show significant correlations between the following symptoms: knee locking or collapsing, difficulty sleeping, depression, and anxiety with decreased number of average walks per day; however, the symptoms including trouble-making toilet: day and difficulty in starting urine were positively correlated with average walks per day. The symptom numbness was significantly correlated with decreased speed and decreased stride length.

DISCUSSION AND CONCLUSIONS

Our findings suggest that certain groups of symptoms were more frequently reported with certain gait parameters (stride time/speed) in persons with MS. Rehabilitation nurses can provide optimal care to prevent future decline in symptoms and gait.

Quantifying muscle fatigue during walking in people with multiple sclerosis

BACKGROUND

This study aimed to examine muscle fatigue in lower leg muscles in of people with multiple sclerosis and healthy controls, and whether muscle fatigue coincided with potential changes in gait.

METHODS

In this case-control study, people with multiple sclerosis (n = 8; 3male; mean age (SD) = 49.7 (9.6) yr) and age-matched healthy controls (n = 10; 4male; mean age (SD) = 47.4 (8.7) yr) walked on a treadmill for 12-min at self-paced speed. Muscle fatigue was indirectly quantified by a decrease in median frequency and increase in root mean square of surface electromyographic recordings of lower leg muscles. Walking speed, ankle push-off power and net ankle work were calculated from marker positions and force plate data using inverse dynamic calculations.

RESULTS

People with multiple sclerosis showed larger decreases in median frequency of soleus (most affected leg: p = 0.003; least affected leg: p = 0.009) and larger increases in root mean square of soleus (most and least affected leg: p = 0.037), gastrocnemius medialis (most affected leg: p = 0.003; least affected leg: p = 0.005) and lateralis (most and least affected leg: p < 0.001) compared to controls. Walking speed (p = 0.001), ankle push-off power (most affected leg: p = 0.018; least affected leg: p = 0.001) and net work around the ankle (most affected leg: p = 0.046; least affected leg: p = 0.001) were lower in people with multiple sclerosis compared to controls, but increased in both groups.

INTERPRETATION

The results yield preliminary evidence that soleus muscles of people with multiple sclerosis fatigue during prolonged walking. Changes in electromyography of gastrocnemius muscles could however be related to muscle fatigue, changes in gait or a combination.

Day-to-day reliability, agreement and discriminative validity of measuring walking-related performance fatigability in persons with multiple sclerosis

BACKGROUND

Day-to-day reliability and cut-off values to detect abnormal walking fatigability (WF) remain to be investigated in persons with multiple sclerosis (pwMS).

METHODS

In all, 49 pwMS (mean Expanded Disability Status Scale (EDSS) ± standard deviation (SD): 3.3 ± 1.9) and 28 matched healthy controls (HC) performed the six-minute walking test (6MWT) on two different days to determine day-to-day reliability (intraclass correlation coefficient (ICC)) and limits of agreement (LOA) for five different equations of WF.

OBJECTIVE

To examine day-to-day reliability, agreement and discriminative validity for measuring WF.

RESULTS AND CONCLUSION

WF expressed as the ratio between the first and sixth minute had the best day-to-day reliability (ICC's range of 0.76-0.95 and 0.60-0.86, respectively) in both pwMS and HC, while LOA were 15% and 7%, respectively. Ecological validity and clinical importance should be further investigated.

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.

Continuous 12 min walking to music, metronomes and in silence: Auditory-motor coupling and its effects on perceived fatigue, motivation and gait in persons with multiple sclerosis

BACKGROUND

In Persons with Multiple Sclerosis (PwMS), coupling walking to beats/pulses in short bursts is reported to be beneficial for cadence and perceived fatigue. However it is yet to be investigated if coupling and its effects can be sustained for longer durations, required for task-oriented training strategy in PwMS.

AIMS

To investigate if PwMS compared to healthy controls (HC) sustain synchronization for 12 min when walking to music and metronome, and its effects on perceived physical and cognitive fatigue, motivation and gait compared to walking in silence.

METHODS

Participants walked for 12 min in three conditions (music, metronome and silence). The tempo of the auditory conditions was individualized. Auditory-motor coupling and spatio-temporal gait parameters were measured during walking. The visual analogue scale was used for perceived fatigue, and the Likert scale for motivation.

RESULTS

27 PwMS and 28 HC participated. All participants synchronized to both stimuli, yet PwMS synchronized better to music. Overall, participants had lower cadence, speed and stride length when over time all conditions, with an exception of HC, with increasing cadence during the music condition. PwMS perceived less cognitive fatigue, no difference in perceived physical fatigue and a higher motivation walking to music compared to metronomes and silence.

CONCLUSION

12 min of uninterrupted walking was possible in PwMS in all conditions, while better synchronization, low perception of cognitive fatigue and high motivation occurred with music compared to other conditions. Coupling walking to music could offer novel paradigms for motor task-oriented training in PwMS.

Physical activity is associated with neuromuscular and physical function in patients with multiple sclerosis independent of disease severity

PURPOSE

Examine the association between physical activity and neuromuscular and physical function in patients with multiple sclerosis when also considering disease severity.

METHODS

91 patients with multiple sclerosis were enrolled. Assessments included physical activity by 7-day thigh-worn accelerometry, knee extensor neuromuscular function by dynamometry (maximal isometric muscle strength, rate of force development (0-50 ms)), and physical function by 5× sit-to-stand, 2-min walk test, and timed 25 ft walk test. Physical activity tertile comparisons along with simple and multiple regressions (adjusting for age, gender, EDSS, time since diagnosis) were performed.

RESULTS

Physical activity tertiles revealed differences (p < 0.05) in maximal muscle strength (1.77 ≈ 1.97 < 2.28 Nm/kg), rate of force development (4.66 < 8.03 ≈ 10.55 Nm/kg/s), 5× sit-to-stand (11.4 ≈ 9.7 > 8.5 s), 2-min walk test (153 < 183 < 207 m), and timed 25 ft walk test (6.3 > 4.4 > 4.3 s). Moreover, physical activity was associated (p < 0.05) with maximal muscle strength and rate of force development (r²  =  0.13-0.15) along with 5× sit-to-stand, 2-min walk test, and timed 25 ft walk test (r² = 0.18-0.24), also after adjusting for age + gender + EDSS + time since diagnosis (r² = 0.25-0.37 and 0.24-0.52), with physical activity consistently being a strong predictor.

CONCLUSIONS

Higher levels of physical activity are associated with greater neuromuscular and physical function in ambulatory patients with multiple sclerosis independent of disease severity. These findings emphasize the importance of performing regular physical activity at all stages of multiple sclerosis.IMPLICATIONS FOR REHABILITATIONPhysical activity is associated with neuromuscular and physical function, independent of disease severity.Physical activity may be important in improving or preserving neuromuscular and physical function at all stages of ambulatory multiple sclerosis patients, yet longitudinal studies are warranted.Clinicians and rehabilitation professionals should encourage ambulatory patients at all stages of their disease to be as physically active as possible.

Frontal brain activity and cognitive processing speed in multiple sclerosis: An exploration of EEG neurofeedback training

BACKGROUND

Cognitive deficits including impaired information processing speed as assessed by the Symbol Digit Modalities Test (SDMT) are common in multiple sclerosis (MS). Oscillatory markers of processing speed may be extracted from magnetoencephalographic (MEG) and electroencephalographic (EEG) resting-state recordings. In this context, an increased proportion of frontal slow-wave (theta, 4-8 Hz) to fast-wave (beta, 13-30 Hz) EEG activity was indicative of impaired SDMT performance. Such an increased theta/beta ratio may reflect oscillatory slowing associated with deficits in attention control. Therapeutic approaches that consider atypical oscillatory activity in MS remain sparse.

OBJECTIVES

In a cross-sectional design, we examined the relation between SDMT performance, the EEG theta/beta ratio and its components. We also explored longitudinally, whether EEG neurofeedback could be used to induce a putatively adaptive alteration in these EEG parameters, toward a pattern indicative of improved processing speed.

METHODS

N = 58 MS patients (RRMS/SPMS/PPMS N: 18/35/3, 2 cases excluded) participated in a neuropsychological examination and a resting-state EEG recording. Subsequently, N = 10 patients received neurofeedback training for two weeks in a hospitalized setting. The purpose was to reduce the frontal theta/beta ratio through operant conditioning.

RESULTS

In the cross-sectional examination, patients with slow SDMT speed displayed an increased theta/beta ratio, relative to those with normal speed. This involved increased frontal theta power, whereas beta power was equal across groups. The theta/beta ratio remained stable during neurofeedback across sessions of the two-week training period. In an exploratory secondary analysis, within sessions a reduction in the theta/beta ratio during active training blocks relative pre/post session resting-states was observed, driven by reduced theta power.

CONCLUSIONS

These findings provide support for utilizing frontal EEG theta activity as an inverse marker of processing speed in MS. Across sessions, there was no support for successful operant conditioning of the theta/beta ratio during the two-week training period. The observed state-specific shift within sessions, involving a transient reduction in theta activity, nevertheless may provide a rationale for a further investigation of neurofeedback as a treatment approach in MS.

Perspectives on walking from people with multiple sclerosis and reactions to video self-observation

Purpose: People with multiple sclerosis (MS) rank walking among the most challenging aspects of their condition. A greater understanding of people's perspectives concerning their walking may help to prioritize walking outcomes and strategies for optimizing walking. The purpose was to explore perceptions of walking in people with MS and to describe their reactions after observing themselves walk on video.Materials and methods: An interpretive thematic analysis study using face-to-face, semi-structured interviews was conducted with 14 people who self-identified a change in their walking due to MS. Participants were video-recorded walking and watched their video during the interview.Results: Four themes were identified: "awareness," "acceptance," "constant change," and "increased effort." People with MS develop awareness of how their walking performance looks and awareness of constantly-changing internal factors and external factors which impact their walking. Awareness of change in fatigue, temperature, terrain, and the use of aids in particular are perceived relevant to walking and to impact the effort required to walk. People with MS also describe differences in their acceptance of how others view their walking and the changes related to walking. An analogy with a marionette performing describes how people perceive walking as no longer automatic; instead walking requires the person to consciously pull the strings to walk. An increase in both the physical and cognitive effort is required to walk and an awareness and acceptance of a variety of changes in oneself and the lived world may help or hinder walking. People with MS are willing to watch themselves walk on video and are not surprised by what they observe.Conclusions: People with MS develop a learned self-awareness with variable levels of acceptance about their walking function and what it looks like. The perceptions on walking from persons with MS suggest that focusing on reducing the effort to walk and minimizing the constantly-changing variables may help to optimize walking.Implications for rehabilitationPeople with multiple sclerosis are challenged by the increased effort and constant change required to walk in their day-to-day lives.A focus on minimizing both the effort to walk and the changing variables (i.e., fluctuating symptoms and environmental factors) is warranted.People with multiple sclerosis develop a learned awareness of how they walk and how their walking looks.Acceptance of loss of walking function is variable.Video self-observation is a feasible tool which warrants further exploration for enhancing acceptance of walking function and accommodating strategies.

Ankle Kinematics and Temporal Gait Characteristics over the Duration of a 6-Minute Walk Test in People with Multiple Sclerosis Who Experience Foot Drop

Foot drop is a common gait impairment in people with MS (pwMS) but in some foot drop may only occur after a period of prolonged walking and may be a sign of motor fatigability. The purpose of the study was to explore whether, for pwMS, an adapted six-minute walk test (6minWT) would result in an increase in foot drop as measured using electrogoniometry. Sagittal ankle kinematics were recorded for fifteen participants (10 females and 5 males, aged 37-64) with MS (EDSS 4-6) throughout the 6minWT. Ankle kinematics and temporal stride parameters were compared between the first and last 10 gait cycles of the 6minWT. Peak dorsiflexion in swing was significantly reduced at the end of the 6minWT compared to the start, with six of the fifteen participants having a decrease of two degrees or more. Statistically significant changes in temporal stride parameters suggested a decrease in walking speed. Our results suggest that with the protocol used in this study it is feasible to identify patients who experience increased foot drop as a result of a prolonged exercise task.

Measuring standing balance in multiple sclerosis: Further progress towards an automatic and reliable method in clinical practice

BACKGROUND

Balance deficits in multiple sclerosis (MS) are often monitored by means of observer-rated tests. These may provide reliable data, but may also be time-consuming, subject to inter-rater variability, and potentially insensitive to mild fluctuations throughout the clinical course. On the other hand, laboratory assessments are often not available. The Nintendo Wii Balance Board (WBB) may represent a low-cost solution. The purpose of the current study was to examine the methodological quality of WBB data in MS (internal consistency, test-retest reliability), convergent validity with observer-rated tests (Berg Balance Scale, BBS; Timed-Up and Go Test, TUG), and discriminative validity concerning clinical status (Expanded Disability Status Scale, EDSS).

METHODS

Standing balance was assessed with the WBB for 4min in 63 MS patients at two assessment points, four months apart. Additionally, patients were examined with the BBS, TUG and the EDSS.

RESULTS

A period of 4min on the WBB provided data characterized by excellent internal consistency and test-retest reliability. Significant correlations between WBB data and results of the BBS and TUG were obtained after merely 2min on the board. An EDSS median-split revealed that higher EDSS values (>3) were associated with significantly increased postural sway on the WBB.

CONCLUSIONS

WBB measures reflecting postural sway are methodologically robust in MS, involving excellent internal consistency and test-retest reliability. They are also characterized by convergent validity with other considerably lengthier observer-rated balance measures (BBS) and sensitive to broader clinical characteristics (EDSS). The WBB may hence represent an effective, easy-to-use monitoring tool for MS patients in clinical practice.

A machine learning approach for gait speed estimation using skin-mounted wearable sensors: From healthy controls to individuals with multiple sclerosis

Gait speed is a powerful clinical marker for mobility impairment in patients suffering from neurological disorders. However, assessment of gait speed in coordination with delivery of comprehensive care is usually constrained to clinical environments and is often limited due to mounting demands on the availability of trained clinical staff. These limitations in assessment design could give rise to poor ecological validity and limited ability to tailor interventions to individual patients. Recent advances in wearable sensor technologies have fostered the development of new methods for monitoring parameters that characterize mobility impairment, such as gait speed, outside the clinic, and therefore address many of the limitations associated with clinical assessments. However, these methods are often validated using normal gait patterns; and extending their utility to subjects with gait impairments continues to be a challenge. In this paper, we present a machine learning method for estimating gait speed using a configurable array of skin-mounted, conformal accelerometers. We establish the accuracy of this technique on treadmill walking data from subjects with normal gait patterns and subjects with multiple sclerosis-induced gait impairments. For subjects with normal gait, the best performing model systematically overestimates speed by only 0.01 m/s, detects changes in speed to within less than 1%, and achieves a root-mean-square-error of 0.12 m/s. Extending these models trained on normal gait to subjects with gait impairments yields only minor changes in model performance. For example, for subjects with gait impairments, the best performing model systematically overestimates speed by 0.01 m/s, quantifies changes in speed to within 1%, and achieves a root-mean-square-error of 0.14 m/s. Additional analyses demonstrate that there is no correlation between gait speed estimation error and impairment severity, and that the estimated speeds maintain the clinical significance of ground truth speed in this population. These results support the use of wearable accelerometer arrays for estimating walking speed in normal subjects and their extension to MS patient cohorts with gait impairment.

Cognitive fatigue in patients with myasthenia gravis

INTRODUCTION

Cognitive fatigue has frequently been reported in myasthenia gravis (MG). However, objective assessment of cognitive fatigability has never been evaluated.

METHODS

Thirty-three MG patients with stable generalized disease and 17 healthy controls underwent a test battery including repeated testing of attention and concentration (d2-R) and Paced Auditory Serial Addition Test. Fatigability was based on calculation of linear trend (LT) reflecting dynamic performance within subsequent constant time intervals. Additionally, fatigue questionnaires were used.

RESULTS

MG patients showed a negative LT in second d2-R testing, indicating cognitive fatigability. This finding significantly differed from stable cognitive performance in controls (P < 0.05). Results of Paced Auditory Serial Addition Test testing did not differ between groups. Self-assessed fatigue was significantly higher in MG patients compared with controls (P < 0.001), but did not correlate with LT.

CONCLUSIONS

LT quantifies cognitive fatigability as an objective measurement of performance decline in MG patients. Self-assessed cognitive fatigue is not correlated with objective findings. Muscle Nerve 56: 449-457, 2017.

The Assessment of Motor Fatigability in Persons With Multiple Sclerosis: A Systematic Review

Background. Persons with multiple sclerosis (PwMS) are often characterized by increased motor fatigability, which is a performance change on an objectively measured criterion after any type of voluntary muscle contractions. This review summarizes the existing literature to determine which protocols and outcome measures are best to detect or study motor fatigability and the underlying mechanisms in MS. Methods. Two electronic databases, PubMed and Web of Science, were searched for relevant articles published until August 2016 with a combination of multiple sclerosis, fatigability, muscle fatigue, and motor fatigue. Results. A total of 48 articles were retained for data extraction. A variety of fatigability protocols were reported; protocols showed differences in type (isometric vs concentric), duration (15 to 180 s), and number of contractions (fixed or until exhaustion). Also, 12 articles reported motor fatigability during functional movements, predominantly assessed by changes in walking speed; 11 studies evaluated the mechanisms underlying motor fatigability, using additional electrical nerve or transcranial magnetic stimulation. Three articles reported psychometrics of the outcomes. Conclusions. The disparity of protocols and outcome measures to study different aspects of motor fatigability in PwMS impedes direct comparison between data. Most protocols use maximal single-joint isometric contractions, with the advantage of high standardization. Because there is no head-to-head comparison of the different protocols and only limited information on psychometric properties of outcomes, there is currently no gold standard to assess motor fatigability. The disability level, disease phenotype, and studied limb may influence the assessment of motor fatigability in PwMS.

Tai chi for health benefits in patients with multiple sclerosis: A systematic review

The aim of this systematic review was to evaluate the existing evidence on the effectiveness and safety of Tai chi, which is critical to provide guidelines for clinicians to improve symptomatic management in patients with multiple sclerosis (MS). After performing electronic and manual searches of many sources, ten relevant peer-reviewed studies that met the inclusion criteria were retrieved. The existing evidence supports the effectiveness of Tai chi on improving quality of life (QOL) and functional balance in MS patients. A small number of these studies also reported the positive effect of Tai chi on flexibility, leg strength, gait, and pain. The effect of Tai chi on fatigue is inconsistent across studies. Although the findings demonstrate beneficial effects on improving outcome measures, especially for functional balance and QOL improvements, a conclusive claim should be made carefully for reasons such as methodological flaws, small sample size, lack of specific-disease instruments, unclear description of Tai chi protocol, unreported safety of Tai chi, and insufficient follow-up as documented by the existing literature. Future research should recruit a larger number of participants and utilize the experimental design with a long-term follow-up to ascertain the benefits of Tai chi for MS patients.

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.

Cognitive screening in Multiple Sclerosis: the Five-Point Test as a substitute for the PASAT in measuring executive function

OBJECTIVE

The Paced Auditory Serial Addition Test (PASAT) is frequently employed to measure executive functions in patients with Multiple Sclerosis (MS). In the past, the PASAT has often been criticized because of its stressful and demanding requirements. Continuous utilization might also reduce its validity. The Five-Point Test (FPT) by Regard, Strauss, and Knapp ((1982) Children's production on verbal and non-verbal fluency tasks. Perceptual and Motor Skills, 55, 839-844.) is a short test of figural fluency which might serve as a substitute.

METHOD

116 patients diagnosed with MS were tested with a short version of the Brief Repeatable Battery (BRB) by Rao and the Cognitive Function Study Group of the National Multiple Sclerosis Society including the PASAT, as well as the FPT. A factor analysis was computed and the frequency of cognitive impairment was calculated for both the original short version of the BRB and the alternative version (involving the FPT).

RESULTS

In the factor analysis, PASAT and FPT loaded highest on the same factor (two factors were extracted). The estimation of the frequency of cognitive impairment showed that replacing the PASAT with the FPT did not considerably alter the proportion of patients identified as cognitively impaired.

CONCLUSIONS

The FPT proved to be a viable alternative to the PASAT in this study. It may be recommended as a possible replacement in neuropsychological screening of MS-patients with the advantage of avoiding the indicated limitations of the PASAT.

Disability and Fatigue Can Be Objectively Measured in Multiple Sclerosis

Background

The available clinical outcome measures of disability in multiple sclerosis are not adequately responsive or sensitive.

Objective

To investigate the feasibility of inertial sensor-based gait analysis in multiple sclerosis.

Methods

A cross-sectional study of 80 multiple sclerosis patients and 50 healthy controls was performed. Lower-limb kinematics was evaluated by using a commercially available magnetic inertial measurement unit system. Mean and standard deviation of range of motion (mROM, sROM) for each joint of lower limbs were calculated in one minute walking test. A motor performance index (E) defined as the sum of sROMs was proposed.

Results

We established two novel observer-independent measures of disability. Hip mROM was extremely sensitive in measuring lower limb motor impairment, being correlated with muscle strength and also altered in patients without clinically detectable disability. On the other hand, E index discriminated patients according to disability, being altered only in patients with moderate and severe disability, regardless of walking speed. It was strongly correlated with fatigue and patient-perceived health status.

Conclusions

Inertial sensor-based gait analysis is feasible and can detect clinical and subclinical disability in multiple sclerosis.

Dynamic walking features and improved walking performance in multiple sclerosis patients treated with fampridine (4-aminopyridine)

BACKGROUND

Impaired walking capacity is a frequent confinement in Multiple Sclerosis (MS). Patients are affected by limitations in coordination, walking speed and the distance they may cover. Also abnormal dynamic walking patterns have been reported, involving continuous deceleration over time. Fampridine (4-aminopyridine), a potassium channel blocker, may improve walking in MS. The objective of the current study was to comprehensively examine dynamic walking characteristics and improved walking capacity in MS patients treated with fampridine.

METHODS

A sample of N = 35 MS patients (EDSS median: 4) underwent an electronic walking examination prior to (Time 1), and during treatment with fampridine (Time 2). Patients walked back and forth a distance of 25 ft for a maximum period of 6 min (6-minute 25-foot-walk). Besides the total distance covered, average speed on the 25-foot distance and on turns was determined separately for each test minute, at Time 1 and Time 2.

RESULTS

Prior to fampridine administration, 27/35 patients (77 %) were able to complete the entire 6 min of walking, while following the administration, 34/35 patients (97 %) managed to walk for 6 min. In this context, walking distance considerably increased and treatment was associated with faster walking and turning across all six test minutes (range of effect sizes: partial eta squared = .34-.72). Importantly, previously reported deceleration across test minutes was consistently observable at Time 1 and Time 2.

DISCUSSION

Fampridine administration is associated with improved walking speed and endurance. Regardless of a treatment effect of fampridine, the previously identified, abnormal dynamic walking feature, i.e. the linear decline in walking speed, may represent a robust feature.

CONCLUSIONS

The dynamic walking feature might hence be considered as a candidate for a new outcome measure in clinical studies involving interventions other than symptomatic treatment, such as immune-modulating medication.

TRIAL REGISTRATION

DRKS00009228 (German Clinical Trials Register). Date obtained: 25.08.2015.