Development and Reliability of the Functional Evaluation Scale for Duchenne Muscular Dystrophy, Gait Domain: A Pilot Study

Ambient floor vibration sensing advances the accessibility of functional gait assessments for children with muscular dystrophies

Muscular dystrophies (MD) are a group of genetic neuromuscular disorders that cause progressive weakness and loss of muscles over time, influencing 1 in 3500-5000 children worldwide. New and exciting treatment options have led to a critical need for a clinical post-marketing surveillance tool to confirm the efficacy and safety of these treatments after individuals receive them in a commercial setting. For MDs, functional gait assessment is a common approach to evaluate the efficacy of the treatments because muscle weakness is reflected in individuals' walking patterns. However, there is little incentive for the family to continue to travel for such assessments due to the lack of access to specialty centers. While various existing sensing devices, such as cameras, force plates, and wearables can assess gait at home, they are limited by privacy concerns, area of coverage, and discomfort in carrying devices, which is not practical for long-term, continuous monitoring in daily settings. In this study, we introduce a novel functional gait assessment system using ambient floor vibrations, which is non-invasive and scalable, requiring only low-cost and sparsely deployed geophone sensors attached to the floor surface, suitable for in-home usage. Our system captures floor vibrations generated by footsteps from patients while they walk around and analyzes such vibrations to extract essential gait health information. To enhance interpretability and reliability under various sensing scenarios, we translate the signal patterns of floor vibration to pathological gait patterns related to MD, and develop a hierarchical learning algorithm that aggregates insights from individual footsteps to estimate a person's overall gait performance. When evaluated through real-world experiments with 36 subjects (including 15 patients with MD), our floor vibration sensing system achieves a 94.8% accuracy in predicting functional gait stages for patients with MD. Our approach enables accurate, accessible, and scalable functional gait assessment, bringing MD progressive tracking into real life.

Development of a new instrument to evaluate gait characteristics of individuals with Duchenne Muscular Dystrophy: Gait Assessment Scale for Duchenne Muscular Dystrophy, and its validity and reliability

BACKGROUND

Patients with Duchenne Muscular Dystrophy (DMD) have gait disorders. Therefore, specific gait assessment tools are needed.

AIMS

The aim of this study was to develop a gait assessment instrument for DMD patients (DMD-GAS), and investigate its validity and reliability.

STUDY DESIGN

The scale was developed considering the expert opinions which included 10 physiotherapists who had experience in the management of patients with DMD, and the Content Validity Index (CVI) was calculated. The final version of the DMD-GAS that was agreed upon the experts consisted of 10 items, and each item scored between 0 and 2. The intra-rater reliability was established by the video analysis of children with a 1-month interval and inter-rater reliability was determined by the scores of 3 physiotherapists.

SUBJECTS

The study included 56 patients with DMD.

OUTCOME MEASURES

The criterion validity was determined by investigating the relationship between the total score of the DMD-GAS and Motor Function Measure (MFM), 6 Minute Walk Test (6MWT), and the data obtained from GAITRite.

RESULTS

The CVI of the DMD-GAS was 0.90 (p < 0.05). The construct validity and internal consistency of the DMD-GAS were excellent as well as the intra- and inter-rater reliability (>0.90). Moderate-to-very strong correlations were found between the total score of the DMD-GAS and the MFM-total score (r = 0.78), 6MWT (r = 0.71), gait speed (r = 0.50), stride length (r = 0.56), and base of support (r = -0.70) (p < 0.01).

CONCLUSIONS

The results indicated that DMD-GAS was a reliable and valid instrument to determine gait characteristics of the patients with DMD in clinical settings.

CLINICAL TRIAL NUMBER

NCT05244395.

Forward and Backward Walking: Multifactorial Characterization of Gait Parameters

Although extensive literature exists on forward and backward walking, a comprehensive assessment of gait parameters on a wide and homogenous population is missing. Thus, the purpose of this study is to analyse the differences between the two gait typologies on a relatively large sample. Twenty-four healthy young adults participated in this study. By means of a marker-based optoelectronic system and force platforms, differences between forward and backward walking were outlined in terms of kinematics and kinetics. Statistically, significant differences were observed in most of the spatial-temporal parameters, evidencing some adaptation mechanisms in backward walking. Differently from the ankle joint, the hip and knee range of motion was significantly reduced when switching from forward to backward walking. In terms of kinetics, hip and ankle moment patterns for forward and backward walking were approximately mirrored images of each other. Moreover, joint powers appeared drastically reduced during reversed gait. Specifically, valuable differences in terms of produced and absorbed joint powers between forward and backward walking were pointed out. The outcomes of this study could represent a useful reference data for future investigation evaluating the efficacy of backward walking as a rehabilitation tool for pathological subjects.

Gait and Sit-To-Stand Motor Compensation Strategies in Children and Adolescents With Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy (DMD), the most common form of muscular dystrophies, is characterized by progressive and generalized muscle weakness. The weakness of the trunk and other muscle groups leads these patients to perform motor compensation strategies to maintain their lower limb functionality for gait quality and for tasks such as getting up from a sitting position. In this cross-sectional observational study, we described and quantified trunk, gait, and sit-to-stand motor compensation strategies in different stages of this disease. Thirty-one ambulatory 5-18-year-old children and adolescents with a diagnosis of DMD, underwent cognitive assessment with the Mental Mini-Examination (MMSE) and motor assessment with the Vignos scale, Segmental Assessment of Trunk Control (SATCo-BR), Timed Up and Go test (TUG Test), and 10-m walk test. We found strong correlations between trunk and gait compensations, and identified motor compensation strategies characteristic of certain DMD classifications. Also, these lower limb and trunk compensations related to disease staging (Vignos) such that compensations were fewer for patients at relatively better disease staging.

Cost of Illness in Patients with Duchenne Muscular Dystrophy in Portugal: The COIDUCH Study

OBJECTIVE

The aim of this study was to estimate the cost of illness (COI) of Duchenne muscular dystrophy (DMD) and its relation to disease progression, using age as a proxy, and according to the ambulatory status of patients.

METHODS

We conducted a cross-sectional study of patients diagnosed with DMD identified through the Portuguese Neuromuscular Patients Association (APN). Data regarding patient and caregiver demographics, patient health status, resource utilization and cost, and informal care were collected using a custom semistructured questionnaire. Labor productivity and absenteeism losses were captured using the Work Productivity and Activity Impairment questionnaire. Costs were valued using a societal perspective.

RESULTS

A total of 46 patient-caregiver pairs were included, of which eight of the patients were ambulant and 38 were nonambulant. Age had a decreasing effect on COI, independent of the patient's disease stage. Annualized lifetime costs were at their highest in nonambulant patients around the mean age of loss of ambulation (10 years of age). The mean per patient stage-specific costs (year 2019 values) of DMD were estimated at €48,991 in the nonambulant stage and €19,993 in the ambulant stage. Direct nonmedical costs were the main cost drivers, followed by indirect costs.

CONCLUSIONS

Our results indicate a close relation between overall disease costs and disease progression. DMD is associated with a substantial economic burden, which appears to be larger around the time ambulation is lost (10 years of age). The availability of new therapeutic options that delay disease progression, especially loss of ambulation, may prove to be highly beneficial for not only patients with DMD but also their families and society.

Development of clinical practice guidelines for allied health and nursing assessment and management of Duchenne muscular dystrophy

PURPOSE

To provide evidence-based guidance specific to allied health and nursing practice for the assessment and management of individuals with Duchenne muscular dystrophy (DMD).

MATERIALS AND METHODS

Thirteen key focus areas were identified in consultation with health professionals and consumer advocacy groups. A series of systematic literature reviews were conducted to identify assessment and management strategies for each key focus area. A consensus process using modified Delphi methodology, including an Australia-New Zealand expert consensus meeting, was conducted. Recommendations underwent consultative review with key groups before being finalised and prepared for dissemination.

RESULTS

This clinical practice guideline (CPG) generated 19 evidence-based recommendations, 117 consensus-based recommendations and five research recommendations across the 13 focus areas to inform allied health assessment and management of individuals with DMD.

CONCLUSIONS

The resulting recommendations can be used in conjunction with existing medical CPGs to improve, standardise and advocate for allied health and rehabilitation care in DMD. The process used here may be useful for the development of CPGs in other rare diseases.Implications for rehabilitationImplementation-ready evidence-based statements to guide clinical care of individuals with DMD are provided with the potential to improve participation, function in the community and quality of life.A model for developing best practice statements for other rare neurological diseases is described.Allied health and nursing health professionals should focus research efforts to generate quality evidence to support rehabilitation practice.

β-Glucans as Dietary Supplement to Improve Locomotion and Mitochondrial Respiration in a Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a severe X-linked neuromuscular childhood disorder that causes progressive muscle weakness and degeneration. A lack of dystrophin in DMD leads to inflammatory response, autophagic dysregulation, and oxidative stress in skeletal muscle fibers that play a key role in the progression of the pathology. β-glucans can modulate immune function by modifying the phagocytic activity of immunocompetent cells, notably macrophages. Mitochondrial function is also involved in an important mechanism of the innate and adaptive immune responses, owing to high need for energy of immune cells. In the present study, the effects of 1,3-1,6 β-glucans on five-day-old non-dystrophic and dystrophic (sapje) zebrafish larvae were investigated. The effects of the sonication of β-glucans and the dechorionation of embryos were also evaluated. The results showed that the incidence of dystrophic phenotypes was reduced when dystrophic embryos were exposed to 2 and 4 mg L^-1 of 1,3-1,6 β-glucans. Moreover, when the dystrophic larvae underwent 8 mg L^-1 treatment, an improvement of the locomotor performances and mitochondrial respiration were observed. In conclusion, the observed results demonstrated that 1,3-1,6 β-glucans improve locomotor performances and mitochondrial function in dystrophic zebrafish. Therefore, for ameliorating their life quality, 1,3-1,6 β-glucans look like a promising diet supplement for DMD patients, even though further investigations are required.

Progression of muscular co-activation and gait variability in children with Duchenne muscular dystrophy: A 2-year follow-up study

BACKGROUND

Duchenne muscular dystrophy is an X-linked muscle disease caused by dystrophin absence. Muscle weakness is a major determinant of the gait impairments in patients with Duchenne muscular dystrophy and it affects lower limbs more often than upper limbs. Monitoring progression of motor symptoms is key to plan treatments for prolonging ambulation.

METHODS

The progression of gait impairment in a group of ten patients with Duchenne muscular dystrophy was observed longitudinally three times over a period of 2 years by computerized gait analysis system. Spatio-temporal parameters of gait, and variability indicators were extracted from kinematics, while lower limb muscles coactivation were measured at the baseline and at each follow-up evaluation. The 6-min walk test was used to evaluate functional capacity at each time session.

FINDINGS

We found a significant increase in stride width and in both stride width and stride length variability at the 1-and 2-year follow-up evaluations. Furthermore, significant higher values in proximal muscle coactivation and significant lower values in both distal muscle coactivation and functional capacity were found at the 2-year follow-up evaluation. Significant negative correlations between muscle coactivation at proximal level and functional capacity and between muscle coactivation at distal level and gait variability were observed.

INTERPRETATION

Our findings suggest that patients with Duchenne muscular dystrophy exhibit decline in functional capacity after 2 years from the baseline. Moreover, to cope with disease progression, patients try to maintain an effective gait by changing the balance dynamic strategies (i.e. increase in proximal muscle coactivation) during the course of disease.

Functional performance and muscular strength in symptomatic female carriers of Duchenne muscular dystrophy

Abstract Duchenne muscular dystrophy (DMD) usually affects men. However, women are also affected in rare instances. Approximately 8% of female DMD carriers have muscle weakness and cardiomyopathy. The early identification of functional and motor impairments can support clinical decision making. Objective: To investigate the motor and functional impairments of 10 female patients with dystrophinopathy diagnosed with clinical, pathological, genetic and immunohistochemical studies. Methods: A descriptive study of a sample of symptomatic female carriers of DMD mutations. The studied variables were muscular strength and functional performance. Results: The prevalence was 10/118 (8.4%) symptomatic female carriers. Deletions were found in seven patients. The age of onset of symptoms in female carriers of DMD was quite variable. Pseudohypertrophy of calf muscles, muscular weakness, compensatory movements and longer timed performance on functional tasks were observed in most of the cases. Differently from males with DMD, seven female patients showed asymmetrical muscular weakness. The asymmetric presentation of muscle weakness was frequent and affected posture and functionality in some cases. The functional performance presents greater number of compensatory movements. Time of execution of activities was not a good biomarker of functionality for this population, because it does not change in the same proportion as the number of movement compensations. Conclusion: Clinical manifestation of asymmetrical muscle weakness and compensatory movements, or both can be found in female carriers of DMD mutations, which can adversely affect posture and functional performance of these patients.

EMG-based Indicators of Muscular Co-Activation during Gait in Children with Duchenne Muscular Dystrophy

Muscular weakness is one of the main signs associated with the onset and progression of Duchenne Muscular Dystrophy. During motor functions, this disease also determines deviations in muscular activity, especially in terms of coordination and activation between muscles acting on the same joints. In this study, surface EMG activity of the lower limb muscles of 10 children with Duchenne Muscular Dystrophy at different times from disease onset were recorded along with kinematics during unconstrained gait. Muscular co-activation of muscle pairs was then evaluated by extracting different co-activation indicators, and linking them with kinematic markers of motor function. The combination of disease progression and pharmacological treatment resulted in a significant decrease in terms of co-activation indexes for two pairs of agonist-antagonist muscles, and for one of these two pairs the decrease in co-activation was correlated with a decrease in the motor function of gait.

The use of the gait profile score and gait variable score in individuals with Duchenne Muscular Dystrophy

Therapeutic gait interventions for individuals with Duchenne Muscular Dystrophy (DMD) should be based on understanding how movement of the individual is affected and whether different clusters of individuals, determined by clinical severity, differ. Gait indexes have been developed to synthesize the data provided by the three-dimensional (3D) gait analysis such as the Gait Deviation Index (GDI) and the Gait Profile Score (GPS) where the gait variable score (GVS) can be calculated. The objective this study was to evaluate the potential use of the GDI and GPS and MAP using data from 3D gait analysis of DMD patients. The dimension 1 score of the Motor Function Measurement defined the groups that composed the cluster analysis. Twenty patients with DMD composed 2 groups according to the cluster analysis (Cluster 1, n = 10; Cluster 2, n = 10). Three-dimensional gait analysis was conducted where GDI, GPS and GVS (pelvic tilt/obliquity; hip flexion-extension/adduction-abduction/rotation; knee flexion-extension; ankle dorsiflexion-plantarflexion, foot progression angle) were calculated. Cluster 1 group presented lower hip flexion-extension and lower pelvic obliquity when compared with Cluster 2 group (p < 0.05). There was no difference between groups for GDI, GPS total and maximum isometric muscle strength of the lower limbs (p > 0.05). This study showed that GVS could detect alterations on the parameters obtained using three-dimensional gait analysis for those DMD patients separated according to motor function regarding pelvic and hip kinematic patterns. The rehabilitation of patients with DMD is recommended from the early stages of the disease (as Cluster 1, with >MFM) with the hip joint being the therapeutic target.

Analysis of motor and respiratory function in Duchenne muscular dystrophy patients

INTRODUCTION

Duchenne muscular dystrophy(DMD) shows motor and respiratory impairment.

METHODS

19 DMD patients (DMDG) (nine ambulatory and 10 non-ambulatory) were evaluated through motor function measure (MFM), 6-minute walk test (6MWT), respiratory muscle strength, cough peak flow, spirometry and volumetric capnography (VCap) tools. Control group that performed spirometry and VCap (CG1-n = 17) were different from those that performed the 6MWT (CG2-n = 8).

RESULTS

The follow tools were assessed (p < 0.05): (i) MFM: Ambulatory patients showed higher values than non-ambulatory patients; (ii) 6MWT: DMDG walked a shorter distance and showed higher respiratory rate at rest and heart rate (HR) at rest than CG2; (iii) Spirometry: DMDG and non-ambulatory patients had minor values achieved in spirometry when compared with CG1 and ambulatory patients, respectively; (iv) VCap: DMDG when compared with CG1 showed: (<11 years-old) lower values in VCap parameters; (>11 years-old): higher HR and lower slope 2. There was correlation between spirometry, mainly for zFEV₁/FVC, and MFM.

CONCLUSION

DMDG showed motor (MFM/6MWT) and respiratory (spirometry/VCap) deterioration when compared with CG. Non-ambulatory condition was associated with worse MFM and spirometry.

How often should sitting and rising from a chair be evaluated in patients with Duchenne muscular dystrophy?

OBJECTIVE

To determine how often sitting/rising from a chair should be assessed in Duchenne muscular dystrophy (DMD) patients to avoid redundant/missing data.

METHODS

Sitting/rising from a chair was evaluated in 26 DMD children (5-12 yrs), in three-month intervals, over twelve months, with the Functional Evaluation Scale (domain sitting/rising from a chair). Scores were compared by effect sizes (ES) and standardized response means (SRM) (responsiveness analysis).

RESULTS

Sit-to-stand showed low-to-moderate responsiveness in three-month intervals (ES:0.23-0.32; SRM:0.36-0.68), moderate-to-high responsiveness in six-month intervals (ES:0.52-0.65; SRM:0.76-1.28), high responsiveness at nine-month (ES:0.84-0.91; SRM:1.26-1.64) and twelve-month intervals (ES:1.27; SRM:1.48). Stand-to-sit showed low responsiveness in three-month intervals (ES:0.26-0.49; SRM:0.37-0.42), moderate responsiveness in six-month intervals (ES:0.50-0.78; SRM:0.56-0.71), high responsiveness in nine-month (ES:0.94-1.00; SRM:0.84-1.02) and twelve-month intervals (ES:1.13; SRM:1.52).

CONCLUSION

Six months or longer intervals for reassessment are indicated to evaluate sitting/standing from a chair in DMD patients.

Neck flexor muscle strength and its relation with functional performance in Duchenne muscular dystrophy

AIM

The aim of this study was to investigate the relationship between neck flexor muscle strength and functional performance in children with DMD.

METHODS

A total of 70 children with DMD between Level 1 and 3 according to Brooke Lower Extremity Functional Classification (BLEFC) were included in the study. Children were divided into 2 groups according to neck flexor strength measured by Medical Research Council Scale as Group 1 (3⁻ and below) and Group 2 (3 and above). Functional performance was assessed by 6 Minute Walk Distance (6MWD) and timed performance tests, and ambulatory status by North Star Ambulatory Assessment (NSAA). Correlations between neck flexor strength and performance tests were analyzed by using Spearman's correlation coefficient in non-parametric conditions.

RESULTS

Thirty-six and 34 children were included in Group 1 and 2, respectively. No statistically significant difference was found in BLEFC between groups (z = -1.225, p > 0.05). 6MWD (z = -2.574, p = 0.01) was found to be longer and NSAA (z = -2.565, p = 0.01) was higher in Group 2. Positive, moderate, statistically significant correlations were determined between neck flexor muscle strength and 6MWD (p < 0.01, r = 0.374); NSAA (p < 0.01, r = 0.399) while a negative, weak correlation between neck flexor muscle strength and the duration for standing from supine position (p = 0.02, r = -0.290).

CONCLUSIONS

The results indicate the relationship of neck flexor muscle strength and functional performance in DMD children. It is thought that the approaches to maintain neck flexor muscle strength from the early stages of disease process may support functional activities of daily life with less compensation and effort in DMD.

Circulating miRNAs are generic and versatile therapeutic monitoring biomarkers in muscular dystrophies

The development of medical approaches requires preclinical and clinical trials for assessment of therapeutic efficacy. Such evaluation entails the use of biomarkers, which provide information on the response to the therapeutic intervention. One newly-proposed class of biomarkers is the microRNA (miRNA) molecules. In muscular dystrophies (MD), the dysregulation of miRNAs was initially observed in muscle biopsy and later extended to plasma samples, suggesting that they may be of interest as biomarkers. First, we demonstrated that dystromiRs dysregulation occurs in MD with either preserved or disrupted expression of the dystrophin-associated glycoprotein complex, supporting the utilization of dystromiRs as generic biomarkers in MD. Then, we aimed at evaluation of the capacity of miRNAs as monitoring biomarkers for experimental therapeutic approach in MD. To this end, we took advantage of our previously characterized gene therapy approach in a mouse model for α-sarcoglycanopathy. We identified a dose-response correlation between the expression of miRNAs on both muscle tissue and blood serum and the therapeutic benefit as evaluated by a set of new and classically-used evaluation methods. This study supports the utility of profiling circulating miRNAs for the evaluation of therapeutic outcome in medical approaches for MD.

Responsiveness of the domain climbing up and going down stairs of the Functional Evaluation scale for Duchenne Muscular Dystrophy: a one-year follow-up

OBJECTIVE:

To determine the responsiveness of the domain climbing up and going down stairs of the Functional Evaluation Scale for Duchenne Muscular Dystrophy (FES-DMD-D3) in a one-year follow-up study.

METHOD:

The study included 26 patients with DMD. Effect Size (ES) and Standardized Response Mean (SRM) described the scale's responsiveness.

RESULTS:

For climbing up stairs, ES showed that responsiveness was low in the three-month assessments (0.26; 0.35; 0.13; 0.17), low to moderate in the six-month assessments (0.58; 0.48; 0.33), moderate in the nine-month assessments (0.70; 0.68), and high in the 12-month assessment (0.88). SRM showed that responsiveness was low in the three-month assessments (0.29; 0.38; 0.18; and 0.19), low to moderate in the six-month assessments (0.59; 0.51; 0.36), moderate in the nine-month assessments (0.74 and 0.70), and high in the 12-month assessment (0.89). For going down stairs, ES showed that responsiveness was low in the three- and six-month assessments (0.16; 0.25; 0.09; 0.08 and 0.48; 0.35; 0.18, respectively), low to moderate in the nine-month assessments (0.59; 0.44), and moderate in the 12-month assessment (0.71). SRM showed that responsiveness was low in the three- and six-month assessments (0.25; 0.35; 0.12; 0.09 and 0.47; 0.38; 0.21, respectively), low to moderate in the nine-month assessment (0.62; 0.49), and moderate in the 12-month assessment (0.74).

CONCLUSION:

Climbing up stairs should be assessed at intervals of nine months or longer, when responsiveness is moderate to high. Going down stairs should be assessed annually because moderate responsiveness was observed in this period.