Walking Function Research Articles

Harmonic functions for singular quadrant walks

We consider discrete (time and space) random walks confined to the quarter plane, with jumps only in directions (i,j) with i+j≥0 and small negative jumps, i.e., i,j≥−1. These walks are called singular, and were recently intensively studied from a combinatorial point of view. In this paper, we show how the compensation approach introduced in the 90ies by Adan, Wessels and Zijm may be applied to compute positive harmonic functions with Dirichlet boundary conditions. In particular, in case the random walks have a drift with positive coordinates, we derive an explicit formula for the escape probability, which is the probability to tend to infinity without reaching the boundary axes. These formulas typically involve famous recurrent sequences, such as the Fibonacci numbers. As a second step, we propose a probabilistic interpretation of the previously constructed harmonic functions and prove that they allow us to compute all positive harmonic functions of these singular walks. To that purpose, we derive the asymptotics of the Green functions in all directions of the quarter plane and use Martin boundary theory.

Clinical Outcomes After Tracheobronchoplasty With Ringed Polytetrafluoroethylene Vascular Graft

BackgroundThis report describes the surgical technique and outcomes of tracheobronchoplasty (TBP) with ringed polytetrafluoroethylene (PTFE) vascular graft. MethodsWe identified all patients who underwent PTFE-TBP for severe expiratory central airway collapse from January 1, 2018 to August 2021 at Mayo Clinic, Florida. Preoperative and postoperative St George’s Respiratory Questionnaire (SGRQ), Cough-Specific Quality of Life Questionnaire (CSQLQ), pulmonary function testing, 6-minute walk test, and blinded dynamic bronchoscopy videos at 3-month follow-up were used to assess outcomes. ResultsFourteen patients (median age, 62.5 years; 64.3% female) underwent PTFE-TBP. The median operative time was 355 minutes, median hospital length of stay was 5 days, and median intensive care unit stay was 1 day. One patient had a Clavien-Dindo grade ≥3 complication. Comparison of preoperative and postoperative questionnaire scores demonstrated improvement in median SGRQ score by 14.79 (P = .013) and CSQLQ score by 22 (P = .005). Preoperative and postoperative pulmonary function and 6-minute walk test results showed no significant difference. Postoperative bronchoscopy demonstrated improvement in median collapsibility of mid trachea by 39.6% (P < .001), distal trachea by 50% (P < .001), left main bronchus by 38.2% (P < .001), right main bronchus by 37.9% (P < .001), and bronchus intermedius by 30.7% (P < .001). ConclusionsPTFE-TBP provides significant improvement in patients' symptoms and expiratory central airway collapse as judged by preoperative and postoperative quality of life questionnaires and bronchoscopy.

#3296 ADVERSE MUSCLE COMPOSITION ASSESSED BY MRI ASSOCIATES TO POOR FUNCTIONAL PERFORMANCE AND METABOLIC COMORBIDITIES IN CKD

Abstract Background and Aims CKD is associated with alterations in body composition, such as reduced muscle mass, increased amount of fat or both simultaneously. Furthermore, both sarcopenia and sarcopenic obesity are associated with worse physical functioning, poor quality of life, increased morbidity and mortality in CKD. Magnetic resonance imaging (MRI) is considered an accurate method for the study of body composition. A water/fat separated MRI scan with automated image analysis can quantify the skeletal muscle volume and allows a quantitative measure of muscle quality by assessing muscle fat infiltration. The combined observation of low muscle volume and high muscle fat infiltration, i.e. adverse muscle composition (AMC), has been shown to be linked to poor function and metabolic comorbidities within subjects with non-alcoholic fatty liver disease. The aim of this study was to investigate the prevalence of AMC and its association with poorer muscle function and metabolic comorbidity within CKD in the large UK Biobank imaging study. Method This is a cross-sectional and prospective study including a total of 647 UK Biobank participants with eGFR cystatin C &amp;lt; 60 ml/min/1,73 m2. A control group was created by selecting participants (matched on sex, age, and BMI) with an eGFR cystatin ≥ 60 ml/min/1,73 m2. Fat-tissue free muscle volume and muscle fat infiltration (MFI) were quantified using a rapid whole-body water and fat separated MRI protocol and automated image analysis (AMRA® Researcher). For each participant, a personalized muscle volume z-score (sex- and body size-specific) was calculated and combined with muscle fat infiltration for AMC detection. AMC was defined as having low muscle volume in combination with high muscle fat infiltration. Sarcopenia was calculated according to the last published recommendation by the European Working Group on Sarcopenia in Older People. Data describing muscle function (hand strength, walking test, stair climbing and number of falls) and metabolic comorbidity (coronary heart disease (CHD) and type 2 diabetes (T2D) have been included and obtained from the study database linked to the study participants' electronic health records. A Cox proportional hazards ratio model, corrected for age, sex, BMI, low hand grip strength, T2D, smoking, and alcohol consumption, was used to assess the association between AMC and CHD incidence. Results • The prevalence of AMC was 1,4x higher in CKD participants compared with the control group without CKD (27.7% vs 20.4%, p&amp;lt;0.001). CKD participants had significantly higher prevalence of sarcopenia (7.2% vs 4.4%, p = 0.004), low hand grip strength (16.0% vs 11.8%, p = 0.006), slow walking pace (17.3% vs 9.9%, p &amp;lt;0.001), CHD (17.4% vs 8.9%, p &amp;lt;0.001) and T2D (13.7% vs 9.2%, p = 0.001) compared with the control group without CKD (Fig. 1). • CKD participants with AMC (179 out of 647) had a significantly higher prevalence of sarcopenia (17.3% vs 3.5%, p&amp;lt;0.001), low hand grip strength (22.8% vs 13.4%, p = 0.006), slow walking pace (27.0% vs 13.6%, p &amp;lt;0.001), as well as prevalence of CHD (23.6% vs 15.0%, p = 0.014) and T2D (18.6% vs 11.8%, p = 0.033) compared with CKD participants without AMC (Fig. 2). • CKD participants with prevalent CHD at the study had higher prevalence of AMC (37.5% vs 25.5%, p = 0.014) compared to CKD participants without CHD. • AMC was associated with 1.9x higher incidence of CHD (95% confidence interval 1.15–3.15, p = 0.012) compared to those without AMC. Conclusion AMC, as determined by MRI with automated image segmentation, is highly prevalent within CKD and associates with poor function, high prevalence of metabolic comorbidities and an increased risk for CHD. CKD patients with poor muscle health is a highly vulnerable group and this technique enables them to be targeted for accurate interventions in order to improve outcomes.

Six-month outcomes and patterns of recovery for people with lateropulsion following stroke

Purpose This study investigated the (1) six-month outcomes of individuals with lateropulsion; (2) the relationship between baseline measures (from in-patient hospitalisation) and six-month functional abilities; and (3) recovery patterns for lateropulsion in stroke survivors. Materials and methods Forty-one individuals with lateropulsion participated in this study. Measures of lateropulsion, postural function, and weight-bearing asymmetry in standing were taken initially and fortnightly over eight weeks. Functional independence and walking abilities were assessed at six months post-stroke. Results Compared to individuals with moderate to severe lateropulsion, those with mild lateropulsion achieved higher levels of functional outcome at six months. However, there were a wide range of scores. Baseline lateropulsion severity explained 26% of the variation in functional outcome. A stronger correlation with functional outcome was observed for lateropulsion (−0.526) than function independence at baseline (0.384). For the task of standing with arm support, patterns of asymmetry were divergent at baseline, favouring either the paretic or non-paretic leg. Over the eight-week period, asymmetry moved towards the non-paretic leg and lateropulsion reduced consistently. Conclusions Individuals with lateropulsion can recover from lateropulsion and make meaningful functional gains, including some individuals with more severe lateropulsion. Lateropulsion severity is a key indicator of functional outcome post-stroke. IMPLICATIONS FOR REHABILITATION Individuals with lateropulsion can make significant gains in terms of mobility and functional abilities by six months post-stroke, learning to compensate for their verticality impairment in standing by loading their non-paretic leg. It is important that stroke survivors with lateropulsion, including those with moderate and severe lateropulsion, are provided with adequate rehabilitation to optimise their longer-term mobility and functional abilities. Routine screening of acute stroke survivors for lateropulsion is recommended, given lateropulsion may negatively impact longer-term functional outcomes in stroke survivors. Therapists should carefully analyse the weight-bearing pattern which an individual with lateropulsion adopts in standing and subsequently tailor treatment to target this.

SURGICAL PROCEDURE FOR PELVIC PERIACETABULAR BONE TUMOR DEFECTS

Pelvic bone tumor and traumatic injuries are causes to a numeric of diagnostic, treatment and subsequent obtaining of positive functionalresults problems, which significantly affects the patientʼs quality of life. The most prognostically difficult are acetabulum areas defects. Its adequate restoration affects the further walking function. Goal. To develop a surgical reconstruction of the periacetabular tumor resection defects. Methods. A new surgical reconstruction procedure of the pelvic periacetabular defects were developed and submitted. It consists in using of artificial material polyethyleneterephthalate («Attachment tube») replacing, which is pre-filled with bone allograft and sutures transosseously fixed to the pubic bone or to the pubic/ischial bones. Another «Attachment tube» fragment is used to fix the femur head to the indicated allograft implant. The strength and bioactive characteristics of the «Attachment tube» in combination with bone allograft make it possible to obtain the equivalent of the acetabulum and restorethe full weight bearing and walking function with a certain range of motion in the restored acetabulum area. Results. The proposed method was clinically tested on 9 patients with evaluated follow up. Satisfactory functional results were obtained: (52.6 ± 20.0) % on the MSTS scale. Complications were analyzed. Conclusions. The use of novel surgical procedure for pelvic periacetabular bone tumor defects has a number of advantages over the existing ones.The biological materials using, restoration of anatomical relations in the «hip joint» makes it possible to restore the lower limb function with a good range of motion. The obtained results prove authorʼs method using can give acceptable results in the treatment of periacetabulum tumor leasions patients.

Clustering trunk movements of children and adolescents with neurological gait disorders undergoing robot-assisted gait therapy: the functional ability determines if actuated pelvis movements are clinically useful

IntroductionRobot-assisted gait therapy is frequently used for gait therapy in children and adolescents but has been shown to limit the physiological excursions of the trunk and pelvis. Actuated pelvis movements might support more physiological trunk patterns during robot-assisted training. However, not every patient is expected to react identically to actuated pelvis movements. Therefore, the aim of the present study was to identify different trunk movement patterns with and without actuated pelvis movements and compare them based on their similarity to the physiological gait pattern.Methods and resultsA clustering algorithm was used to separate pediatric patients into three groups based on different kinematic reactions of the trunk to walking with and without actuated pelvis movements. The three clusters included 9, 11 and 15 patients and showed weak to strong correlations with physiological treadmill gait. The groups also statistically differed in clinical assessment scores, which were consistent with the strength of the correlations. Patients with a higher gait capacity reacted with more physiological trunk movements to actuated pelvis movements.ConclusionActuated pelvis movements do not lead to physiological trunk movements in patients with a poor trunk control, while patients with better walking functions can show physiological trunk movements. Therapists should carefully consider for whom and why they decide to include actuated pelvis movements in their therapy plan.

MODIFI: protocol for randomised feasibility study of eye-movement desensitisation and reprocessing therapy (EMDR) for functional neurological disorder (FND)

IntroductionFunctional neurological disorder (FND) refers to an involuntary loss of control over and/or aberrant perception of the body. Common presenting symptoms are functional (non-epileptic) seizures, and functional motor disorder, for...

Repeating Fast Radio Bursts Reveal Memory from Minutes to an Hour

Fast radio bursts (FRBs) are brief, luminous pulses with unknown physical origin. The repetition pattern of FRBs contains essential information about their physical nature and emission mechanisms. Using the two largest samples of FRB 20121102 and FRB 20201124A, we report that the sources of the two FRBs reveal memory over a large range of timescales, from a few minutes to about an hour. The memory is detected from the coherent growths in burst-rate structures and the Hurst exponent. The waiting time distribution displays an approximate power-law tail, which is consistent with a Poisson model with a time-varying rate. From cellular automaton simulations, we find that these characteristics can be well understood within the physical framework of a self-organized criticality system driven in a correlation way, such as random walk functions. These properties indicate that the triggers of bursts are correlated, preferring the crustal failure mechanism of neutron stars.

The knee joint deformities in rheumatoid arthritis patients

Knee joints injury in rheumatoid arthritis patients appear in 70 % cases. This is the most common cause of loss of work capacity, the ability to self-care. Patients become severely disabled, in that the disease is accompanied by deformations with the development of discordant positions of the lower limbs, which lead to a partial or complete loss of the function of support and walking, so this problem needs to be studied. Objective. To make an analysis of orthopedic treatment of secondary arthrosis of knee joints in RA patients, complicated by deformities depending on the age and gender of the patient, stage, duration of the disease and activity of the inflammatory process. Methods. In this work we have analyzed the orthopedic treatment of 66 RA patients with secondary arthrosis with axial deformities, who underwent 75 total endoprosthetics between 2013 and 2020. Anamnestic data, clinical, biomechanical and statistical research methods were used. The obtained data were evaluated using the scale of Joseph J., Kaufman E. E. Results. The analysis of the results of knee joint replacement was followed in the period from 6 months to 5 years. The results were carried out according to the 100-point scale Joseph J., Kaufman E. E. (1990). Thus, the analysis of the results of total knee arthroplasty in patients with RA according to the scale of Joseph J., Kaufman E. E. showed that good results were obtained in 46 (79.31 %) patients, satisfactory results in 11 (18.97 %) and unsatisfactory results obtained in 1 (1.72 %) patients. The reliable relationship of the level of joint deformation with the level of disease activity and with the scale of Joseph J., Kaufman E. E. was researched. Other indicators are not reliably correlated with the level of joint deformation. As a result of pairwise comparisons of groups with each other using the Duncan test, a significant increase in the degree of joint deformation was found in the group with activity 3 compared to the group with activity 1. The use of basic or complex therapy does not reliably affect the degree of joint deformation. Conclusions. Total knee joint replacement need patients with II stage of the 2nd phase of the disease and higher. In our opinion, this is the most optimal time for surgical treatment, which allows patients with RA to fully use the possibilities of an implanted endoprosthesis.

Self-modulation of rectus femoris reflex excitability in humans

Hyperreflexia is common after neurological injury such as stroke, yet clinical interventions have had mixed success. Our previous research has shown that hyperreflexia of the rectus femoris (RF) during pre-swing is closely associated with reduced swing phase knee flexion in those with post-stroke Stiff-Knee gait (SKG). Thus, reduction of RF hyperreflexia may improve walking function in those with post-stroke SKG. A non-pharmacological procedure for reducing hyperreflexia has emerged based on operant conditioning of H-reflex, an electrical analog of the spinal stretch reflex. It is currently unknown whether operant conditioning can be applied to the RF. This feasibility study trained 7 participants (5 neurologically intact, 2 post-stroke) to down-condition the RF H-reflex using visual feedback. We found an overall decrease in average RF H-reflex amplitude among all 7 participants (44% drop, p < 0.001, paired t-test), of which the post-stroke individuals contributed (49% drop). We observed a generalized training effect across quadriceps muscles. Post-stroke individuals exhibited improvements in peak knee-flexion velocity, reflex excitability during walking, and clinical measures of spasticity. These outcomes provide promising initial results that operant RF H-reflex conditioning is feasible, encouraging expansion to post-stroke individuals. This procedure could provide a targeted alternative in spasticity management.

Development of an assessment of bilateral locomotor efficacy for individuals post-stroke

BackgroundA common framework is needed to assess walking impairments in older adults and individuals with stroke. This study develops an Assessment of Bilateral Locomotor Efficacy (ABLE) that is a straightforward indicator of walking function. Research questionCan we develop a clinically accessible index of walking function that summarizes gait dysfunction secondary to stroke? MethodsThe ABLE index was developed using a retrospective sample of 14 community-dwelling older adults. Data from 33 additional older adults and 105 individuals with chronic post-stroke hemiparesis were used to validate the index by factor analysis of the score components and correlation with multiple common assessments of lower extremity impairment and function. ResultsThe ABLE consists of four components summed for a maximum possible score of 12. The components include self-selected walking speed (SSWS), speed change from SSWS to fastest speed, non-paretic leg step length change from SSWS to fastest speed, and peak paretic leg ankle power. The ABLE revealed good concurrent validity with all recorded functional assessments. Factor analysis suggested that the ABLE measures two factors: one for forward progression and another for speed adaptability. SignificanceThe ABLE offers a straightforward, objective measure of walking function in adults, including individuals with chronic stroke. The index may also prove useful as a screening tool for subclinical pathology in community-dwelling older adults, but further testing is required. We encourage utilization of this index and reproduction of findings to adapt and refine the instrument for wider use and eventual clinical application.

Home-Based Exercise Therapy in the Management of Intermittent Claudication: A Systematic Review and Meta-Analysis.

The current literature strongly supports the use of supervised exercise therapy (SET) as the first-line treatment for symptomatic peripheral arterial disease (PAD) such as intermittent claudication (IC). However, this form of treatment remains underutilised in clinical practice. The home-based exercise therapy (HBET), in which patients must conduct themselves unsupervised is generally less effective than SET in terms of improving functional walking capacity. Nevertheless, it may be a useful alternative where SET is unavailable. The objective of this systematic review is to determine the effectiveness of HBET in reducing symptoms of IC in patients with PAD. Studies eligible for inclusion in this systematic review were parallel-group randomised controlled trials (RCTs) published in the English language that compared the effect of HBET to a comparator arm (SET or no exercise/attention control) in adults with PAD and IC. Studies were eligible if outcome measures were available at baseline and at 12 weeks of follow-up or more. The electronic databases PubMed, Google Scholar, and the Cochrane Library were searched from the earliest records up to January 2021. The Cochrane Collaboration risk of bias tool for RCTs (RoB 2)was used to assess the risk of bias in individual studies, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) classification system was used to appraise the quality of evidence for each outcome across all studies. The primary investigator independently collected, pooled, and analysed the data. The data was then entered into the ReviewManager 5 (RevMan 5) software, and a meta-analysis was performed by using a fixed or random effects model depending on the presence or absence of statistical heterogeneity. The review author identified seven RCTs involving a total of 754 patients which were included in this study. Overall, the risk of bias in the included studies was moderate. Even though the results were variable, this analysis supported the ability of HBET to improve functional walking capacity and self-reported quality of life (QoL) to an extent. This review shows that a home-based exercise intervention with regular professional support and encouragement is beneficial in improving functional walking capacity as well as some aspects of QoL in patients with PAD and IC when compared to no exercise. However, when HBET is compared to hospital-based supervised exercise intervention, SET yields greater benefits.

Can post stroke walking improve via telerehabilitation? A systematic review in adults with stroke.

The purpose of this systematic review is to analyze primary studies investigating the effects of telerehabilitation on walking outcomes for the treatment of adult stroke survivors. Data sources included PubMed, Embase and CINAHL searched until August 2022, using combinations of several keywords such as "telerehabilitation", "stroke", and "gait". Studies were required to have bidirectional form of videoconferencing with assessor presence, and include assessment of walking function (speed, endurance and/or balance). Data extraction was performed from each full text by one author, and quality and bias were assessed using the Physiotherapy Evidence Database (PEDro). Eight studies involving 248 participants met the inclusion criteria. Seven reported significant improvements in outcomes of balance and two showed improvements in endurance after telerehabilitation. Two studies observed greater balance improvements in the telerehabilitation group compared to control and/or in-person therapy. Differences in frequency, training duration, intervention type, and absence of an in-person therapy control group were identified as causes of variation between studies. The effectiveness of telerehabilitation as a mode of therapy for walking could not be definitively determined due to the limited number of studies that directly measured walking speed or endurance. However, strong evidence was found for the use of telerehabilitation for balance improvements, which has implications for walking recovery. Telerehabilitation appears to be safe, feasible and demonstrated high adherence. Our results highlighted limited studies using real-time supervision to administer telerehabilitation and lack of studies focusing on outcomes of walking speed and endurance, needed to fully determine the role of telerehabilitation for gait recovery. PROSPERO number CRD42021238197.

Safety, usability, and performance of a wireless left atrial pressure monitoring system in patients with heart failure: the VECTOR-HF trial.

In heart failure (HF), implantable hemodynamic monitoring devices have been shown to optimize therapy, anticipating clinical decompensation and preventing hospitalization. Direct left-sided hemodynamic sensors offer theoretical benefits beyond pulmonary artery pressure (PAP) monitoring systems. We evaluated the safety, usability, and performance of a novel left atrial pressure (LAP) monitoring system in HF patients. The VECTOR-HF study(NCT03775161) was a first-in-human, prospective, multicenter, single-arm, clinical trial enrolling 30 patients with HF. The device consisted of an interatrial positioned leadless sensor, able to transmit LAP data wirelessly. After three months, a right heart catheterization (RHC) was performed to correlate mean pulmonary capillary wedge pressure (PCWP) with simultaneous mean LAP obtained from the device. Remote LAP measurements were then used to guide patient management. The miniaturized device was successfully implanted in all 30 patients, without acute Major Adverse Cardiac and Neurological Events (MACNE). At 3 months, freedom from short-term MACNE was 97%. Agreement between sensor-calculated LAP and PCWP was consistent, with a mean difference of -0.22±4.92mmHg, the correlation coefficient and the Lin's Concordance Correlation Coefficient values were equal to 0.79 (P<0.0001) and 0.776 (95%CI=0.582-0.886), respectively. Preliminary experience with VLAP-based HF management was associated with significant improvements in NYHA functional class (32% of patients reached NYHA II class at 6 months, P<0.005; 60% of patients at 12 months, P<0.005) and 6-minute walk-test distance (from 244.59±119.59m at baseline to 311.78±129.88m after 6 months, P<0.05, and 343.95±146.15m after 12 months, P<0.05). The V-LAP™ monitoring system proved to be generally safe and provided a good correlation with invasive PCWP. Initial evidence also suggests possible improvement in HF clinical symptoms. This article is protected by copyright. All rights reserved.

Impaired Voluntary Activation of an Ankle Dorsiflexor Muscle Predicts Walking Capacity in Multiple Sclerosis

Background and Purpose Walking impairments are highly prevalent in people with Multiple Sclerosis (pwMS) and are related to factors including motor deficits and balance. Reductions in voluntary activation (VA) (i.e., reduced neural drive known as central fatigability) is a key contributor to motor deficits during fatiguing tasks in pwMS; however, the relationship between central fatigability and walking function is poorly understood. The purpose of this study was to determine associations between reductions in VA after a fatiguing task and walking capacity (WC) in pwMS and controls. Methods 19 pwMS (female=9) and 10 age-matched controls (female=6) participated. PwMS were sub-grouped for disease severity into those mildly affected (n=11, female=5, EDSS=2.5-4.0) and moderately affected (n=8, female=4, EDSS= 4.5-6.5). Twitch interpolation during a maximal voluntary contraction quantified VA of the tibialis anterior muscle before and immediately after a fatiguing time-to-task failure isometric task performed at 50% of maximal strength. The 6-minute walk test determined baseline WC. Values are mean ± SD. Results Moderately affected pwMS showed greater central fatigability after the fatiguing task compared with mildly affected pwMS (p=0.01), and controls (p=0.07) (moderately affected= 23.5% ± 24.9, mildly affected= 0.3% ± 5.4, controls= 6.4% ± 14.4). Both groups of pwMS showed lower WC than controls (moderately affected= 299.5m ± 75.2, mildly affected= 527.7m ± 68.9, controls= 613.7m ± 88.9, p<0.001). Further analyses revealed an association between central fatigability and WC, but only in the moderately affected pwMS (R2= 0.7, standardized estimate= -0.8, t=-3.8, p=0.009). Discussion Impaired neural drive of the ankle dorsiflexor muscles is a predictor of WC in pwMS who experience greater disease severity. Thus, mechanisms for limitation in walking function may be different based on disease severity in pwMS and this knowledge may assist in optimizing rehabilitation strategies to improve walking function in pwMS. Walking impairments are highly prevalent in people with Multiple Sclerosis (pwMS) and are related to factors including motor deficits and balance. Reductions in voluntary activation (VA) (i.e., reduced neural drive known as central fatigability) is a key contributor to motor deficits during fatiguing tasks in pwMS; however, the relationship between central fatigability and walking function is poorly understood. The purpose of this study was to determine associations between reductions in VA after a fatiguing task and walking capacity (WC) in pwMS and controls. 19 pwMS (female=9) and 10 age-matched controls (female=6) participated. PwMS were sub-grouped for disease severity into those mildly affected (n=11, female=5, EDSS=2.5-4.0) and moderately affected (n=8, female=4, EDSS= 4.5-6.5). Twitch interpolation during a maximal voluntary contraction quantified VA of the tibialis anterior muscle before and immediately after a fatiguing time-to-task failure isometric task performed at 50% of maximal strength. The 6-minute walk test determined baseline WC. Values are mean ± SD. Moderately affected pwMS showed greater central fatigability after the fatiguing task compared with mildly affected pwMS (p=0.01), and controls (p=0.07) (moderately affected= 23.5% ± 24.9, mildly affected= 0.3% ± 5.4, controls= 6.4% ± 14.4). Both groups of pwMS showed lower WC than controls (moderately affected= 299.5m ± 75.2, mildly affected= 527.7m ± 68.9, controls= 613.7m ± 88.9, p<0.001). Further analyses revealed an association between central fatigability and WC, but only in the moderately affected pwMS (R2= 0.7, standardized estimate= -0.8, t=-3.8, p=0.009). Impaired neural drive of the ankle dorsiflexor muscles is a predictor of WC in pwMS who experience greater disease severity. Thus, mechanisms for limitation in walking function may be different based on disease severity in pwMS and this knowledge may assist in optimizing rehabilitation strategies to improve walking function in pwMS.

NMOSDCopilot: Feasibility of Smartphone-Based Digital Biomarkers for the Self-Assessment of Vision, Motor and Cognitive Functions in Neuromyelitis Optica Spectrum Disorder (S50.002)

NMOSDCopilot: Feasibility of Smartphone-Based Digital Biomarkers for the Self-Assessment of Vision, Motor and Cognitive Functions in Neuromyelitis Optica Spectrum Disorder (S50.002)

Multicentric investigation on the safety, feasibility and usability of the ABLE lower-limb robotic exoskeleton for individuals with spinal cord injury: a framework towards the standardisation of clinical evaluations

BackgroundRobotic lower-limb exoskeletons have the potential to provide additional clinical benefits for persons with spinal cord injury (SCI). However, high variability between protocols does not allow the comparison of study results on safety and feasibility between different exoskeletons. We therefore incorporated key aspects from previous studies into our study protocol and accordingly conducted a multicentre study investigating the safety, feasibility and usability of the ABLE Exoskeleton in clinical settings.MethodsIn this prospective pretest-posttest quasi-experimental study across two SCI centres in Germany and Spain, in- and outpatients with SCI were recruited into a 12-session training and assessment protocol, utilising the ABLE Exoskeleton. A follow-up visit after 4 weeks was included to assess after-training outcomes. Safety outcomes (device-related adverse events (AEs), number of drop-outs), feasibility and usability measures (level of assistance, donning/doffing-time) were recorded at every session together with changes in gait parameters and function. Patient-reported outcome measures including the rate of perceived exertion (RPE) and the psychosocial impact of the device were performed. Satisfaction with the device was evaluated in both participants and therapists.ResultsAll 24 participants (45 ± 12 years), with mainly subacute SCI (< 1 year after injury) from C5 to L3, (ASIA Impairment Scale A to D) completed the follow-up. In 242 training sessions, 8 device-related AEs (pain and skin lesions) were reported. Total time for don and doff was 6:50 ± 2:50 min. Improvements in level of assistance and gait parameters (time, steps, distance and speed, p < 0.05) were observed in all participants. Walking function and RPE improved in participants able to complete walking tests with (n = 9) and without (n = 6) the device at study start (p < 0.05). A positive psychosocial impact of the exoskeleton was reported and the satisfaction with the device was good, with best ratings in safety (participants), weight (therapists), durability and dimensions (both).ConclusionsOur study results prove the feasibility of safe gait training with the ABLE Exoskeleton in hospital settings for persons with SCI, with improved clinical outcomes after training. Our study protocol allowed for consistent comparison of the results with other exoskeleton trials and can serve as a future framework towards the standardisation of early clinical evaluations.Trial Registrationhttps://trialsearch.who.int/, DRKS00023503, retrospectively registered on November 18, 2020.

Unitary matrix integrals, symmetric polynomials, and long-range random walks

Unitary matrix integrals over symmetric polynomials play an important role in a wide variety of applications, including random matrix theory, gauge theory, number theory, and enumerative combinatorics. We derive novel results on such integrals and apply these and other identities to correlation functions of long-range random walks (LRRW) consisting of hard-core bosons. We generalize an identity due to Diaconis and Shahshahani which computes unitary matrix integrals over products of power sum polynomials. This allows us to derive two expressions for unitary matrix integrals over Schur polynomials, which can be directly applied to LRRW correlation functions. We then demonstrate a duality between distinct LRRW models, which we refer to as quasi-local particle-hole duality. We note a relation between the multiplication properties of power sum polynomials of degree n and fermionic particles hopping by n sites. This allows us to compute LRRW correlation functions in terms of auxiliary fermionic rather than hard-core bosonic systems. Inverting this reasoning leads to various results on long-range fermionic models as well. In principle, all results derived in this work can be implemented in experimental setups such as trapped ion systems, where LRRW models appear as an effective description. We further suggest specific correlation functions which may be applied to the benchmarking of such experimental setups.

Targeted training of the function of walking according to the stance and single support phase in patients in the early recovery period of cerebral stroke

Background: The phases of support and single support on a limb are significant basic parameters of walking (phase of support means the whole limb support time, while the phase of single support is when only one limb is on the ground). Both can be used as targets for biofeedback training. Aim: to investigate the effectiveness of both target parameters for training the function of walking with biofeedback in patients in the early recovery period of cerebral stroke. Methods: The study involved 40 patients, 20 in each group, who underwent a training course to harmonize walking: the first group for the period of support, and the second group for the period of single support. The control group of healthy people also consisted of 20 people. We studied the spatiotemporal parameters of walking at an arbitrary pace at the beginning and after the end of the training course, as well as classical clinical scales. The treadmill training consisted of 10 sessions. Results: The clinical and biomechanical parameters of walking changed their values in the direction of a significant improvement in the performance. At the same time, the biomechanical parameters of the second group indicated a more severe functional state before the start of the treatment, with the same clinical parameters according to the Barthel scale, Rivermead Mobility Index, modified Rankin scale, rehabilitation routing scale, and manual muscle testing. In the first group, indirect data were obtained on the possible effect of the target indicator on the training and direct data on its effect on the function of a healthy limb, which also allows increasing the load on the paretic one. In the second group, there were no reliable data on the effect of biofeedback training on the functional outcome. Conclusion: The conducted study showed that the classical clinical assessment of the patient's condition may not correspond to the instrumental functional study of walking. When using the support period as the training target parameter, indirect evidence was obtained that such a training is effective.

Walking Outcome After Traumatic Paraplegic Spinal Cord Injury: The Function of Which Myotomes Makes a Difference?

Background Accurate prediction of walking function after a traumatic spinal cord injury (SCI) is crucial for an appropriate tailoring and application of therapeutical interventions. Long-term outcome of ambulation is strongly related to residual muscle function acutely after injury and its recovery potential. The identification of the underlying determinants of ambulation, however, remains a challenging task in SCI, a neurological disorder presented with heterogeneous clinical manifestations and recovery trajectories. Objectives Stratification of walking function and determination of its most relevant underlying muscle functions based on stratified homogeneous patient subgroups. Methods Data from individuals with paraplegic SCI were used to develop a prediction-based stratification model, applying unbiased recursive partitioning conditional inference tree (URP–CTREE). The primary outcome was the 6-minute walk test at 6 months after injury. Standardized neurological assessments ≤15 days after injury were chosen as predictors. Resulting subgroups were incorporated into a subsequent node-specific analysis to attribute the role of individual lower extremity myotomes for the prognosis of walking function. Results Using URP–CTREE, the study group of 361 SCI patients was divided into 8 homogeneous subgroups. The node specific analysis uncovered that proximal myotomes L2 and L3 were driving factors for the differentiation between walkers and non-walkers. Distal myotomes L4–S1 were revealed to be responsible for the prognostic distinction of indoor and outdoor walkers (with and without aids). Conclusion Stratification of a heterogeneous population with paraplegic SCI into more homogeneous subgroups, combined with the identification of underlying muscle functions prospectively determining the walking outcome, enable potential benefit for application in clinical trials and practice.