A New Functional Scale and Ambulatory Functional Classification of Duchenne Muscular Dystrophy: Scale Development and Preliminary Analyses of Reliability and Validity

Timed rolling and rising tests in Duchenne muscular dystrophy ambulant boys: a feasibility study

BACKGROUND

Functional activities are extensively used in motor assessments of patients with Duchenne muscular dystrophy. The role of timed items has been reported as an early prognostic factor for disease progression. However, there are two functional activities that are not widely assessed in clinical practice among Duchenne muscular dystrophy patients: rolling and bed rising. This study aimed to investigate whether the 360-degree roll (roll) and supine to sit-to-edge (bed rise) measurements are feasible tools reflecting the functional status of ambulatory DMD children by establishing possible correlations between validated measures: the Vignos Scale (VS), timed rise from floor and the 6-Minute Walk Test (6MWT).

METHODS

A total of 32 ambulant boys with DMD were assessed using timed items, the 6MWT and VS.

RESULTS

The roll and bed rise are correlated with each other. The 6MWT, the floor rise and VS are correlated with the roll and with the bed rise.

CONCLUSIONS

Findings offer preliminary empirical evidence addressing feasibility and safety of roll and bed rise measurements. There is a potential clinical utility of these tests in assessing functional status of DMD ambulant patients.

Trunk-oriented Exercises Versus Whole-body Vibration on Abdominal Thickness and Balance in Children with Duchene Muscular Dystrophy

OBJECTIVES

Progressive proximal muscle weakening in children with Duchenne muscular dystrophy (DMD) impairs postural adjustments by impairing motor function and preventing ambulation. During daily activities, for gait and dynamic balance, certain postural modifications are required. The objective was to compare the impact of trunk-oriented exercises versus whole-body vibration on abdominal muscle thickness and balance in children with DMD.

METHODS

Participants in this study were 30 boys with DMD, aged 6 to 10 years old. Children were divided into two groups (A and B) randomly. Children in group (A) underwent a prescribed regimen of physical therapy along with trunk-oriented exercises, whereas group (B) received the same regimen as group (A) together with whole-body vibration three times per week for three consecutive months. Balance and the thickness of the abdominal muscles were measured using the Biodex balance system and ultrasonography, respectively, before and after therapy.

RESULTS

When compared to the pre-treatment results in both groups, the post-treatment results showed a significant difference in all measured variables (p<0.05). Post-treatment values showed that all of the measured variables significantly differed in favor of group A.

CONCLUSIONS

Trunk-oriented exercises can improve abdominal thickness and balance more effectively than whole-body vibration in children with DMD.

CLINICALTRIALS

gov ID: NCT05688072.

Draft Guidance for Industry Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, and Related Dystrophinopathies - Developing Potential Treatments for the Entire Spectrum of Disease

Background

Duchenne muscular dystrophy (DMD) and related dystrophinopathies are neuromuscular conditions with great unmet medical needs that require the development of effective medical treatments.

Objective

To aid sponsors in clinical development of drugs and therapeutic biological products for treating DMD across the disease spectrum by integrating advancements, patient registries, natural history studies, and more into a comprehensive guidance.

Methods

This guidance emerged from collaboration between the FDA, the Duchenne community, and industry stakeholders. It entailed a structured approach, involving multiple committees and boards. From its inception in 2014, the guidance underwent revisions incorporating insights from gene therapy studies, cardiac function research, and innovative clinical trial designs.

Results

The guidance provides a deeper understanding of DMD and its variants, focusing on patient engagement, diagnostic criteria, natural history, biomarkers, and clinical trials. It underscores patient-focused drug development, the significance of dystrophin as a biomarker, and the pivotal role of magnetic resonance imaging in assessing disease progression. Additionally, the guidance addresses cardiomyopathy's prominence in DMD and the burgeoning field of gene therapy.

Conclusions

The updated guidance offers a comprehensive understanding of DMD, emphasizing patient-centric approaches, innovative trial designs, and the importance of biomarkers. The focus on cardiomyopathy and gene therapy signifies the evolving realm of DMD research. It acts as a crucial roadmap for sponsors, potentially leading to improved treatments for DMD.

Development and Validation of an Outpatient Clinical Predictive Score for the Diagnosis of Duchenne Muscular Dystrophy/Becker Muscular Dystrophy in Children Aged 2-18 Years

Introduction

There is no bedside clinical examination-based prediction score for Duchenne muscular dystrophy/Becker muscular dystrophy (DMD/BMD) in children with neuromuscular diseases (NMDs) presenting with proximal limb-girdle weakness.

Methods

We compared the details of 200 cases of lower motor neuron type of weakness and had some proximal limb-girdle muscle weakness and divided them into 2 groups: with/without a confirmed diagnosis of DMD/BMD. We determined the predictive factors associated with a diagnosis of DMD/BMD using multivariate binary logistic regression. We assessed our proposed prognostic model using both discrimination and calibration and subsequently used the bootstrap method to successfully validate the model internally.

Results

A total of 121 patients had DMD/BMD and the rest of the patients had other diagnoses. Male gender, presence of Gower's sign, valley sign, toe walking, calf pseudohypertrophy, and tongue hypertrophy were independent predictors for a confirmed diagnosis of DMD/BMD and included in the final CVT2MG score (Calf pseudohypertrophy, Valley sign, Toe walking, Tongue hypertrophy, Male gender, and Gower's sign). The final model showed good discrimination (AUC = 87.4% [95% CI: 80.5-92.3%, P < 0.001]) and calibration (P = 0.57). A score of 6 or above appeared to be the best cutoff for discriminating between the DMD/BMD group and the rest of the group with both sensitivity and specificity of 98%. The interrater reliability was almost perfect between two pediatric neurologists and strong between a pediatric neurologist and a pediatric neurology trainee resident (k = 0.91 and 0.87).

Conclusion

The CVT2MG score has good sensitivity and specificity in predicting a confirmed diagnosis of DMD/BMD in subsequent tests.

The Effect of Adiposity on Cardiovascular Function and Myocardial Fibrosis in Patients With Duchenne Muscular Dystrophy

Background

Patients with Duchenne muscular dystrophy (DMD) develop cardiomyopathy because of a dystrophin deficiency causing fibrofatty replacement of the myocardium. Corticosteroid use and mobility limitations place these patients at risk for increased adiposity. We sought to determine the association of adiposity with cardiovascular dysfunction in patients with DMD.

Methods and Results

This was a retrospective review of patients with DMD who underwent both cardiac magnetic resonance imaging and dual‐energy x‐ray absorptiometry within 1 year. The cardiac magnetic resonance imaging parameters included left ventricular ejection fraction and the presence of late gadolinium enhancement (LGE positive [LGE+]). The adiposity indices, measured by dual‐energy x‐ray absorptiometry, included percentage of body fat, whole body fat mass indexed to height, and body mass index. A total of 324 patients were identified. Fifty‐two percent had LGE+, and 36% had cardiac dysfunction (left ventricular ejection fraction <55%). Patients with cardiac dysfunction had higher whole body fat mass indexed to height and body mass index on univariate analysis (mean difference between patients with and without cardiac dysfunction: +2.9 kg/m, P=0.001; and +1.5 kg/m², P=0.03, respectively). whole body fat mass indexed to height remained independently associated with cardiac dysfunction on multivariable analysis after adjusting for age, LGE+, and corticosteroid duration. High whole body fat mass indexed to height and percentage of body fat were associated with LGE+ on univariate analysis (mean difference between patients with and without LGE+: +2.0 kg/m, P=0.02; and +2.4%, P=0.02, respectively). Using multivariable analysis, including age and cardiac dysfunction, high percentage of body fat remained independently associated with LGE+.

Conclusions

This study demonstrates an independent association of adiposity with cardiac dysfunction and LGE+ in patients with DMD. Preventing adiposity may mitigate the later development of ventricular dysfunction in DMD.

Efficacy of two intervention approaches on functional walking capacity and balance in children with Duchene muscular dystrophy

OBJECTIVES

Children with Duchene muscular dystrophy have weak muscles, which may impair postural adjustments. These postural adjustments are required for gait and dynamic balance during the daily living activities. The aim was to compare between the effect of bicycle ergometer versus treadmill on functional walking capacity and balance in children with Duchenne muscular dystrophy.

METHODS

Thirty boys aged from 6 to 10 years old diagnosed as Duchene muscular dystrophy participated in this study. Children were assigned randomly into two groups (A&B). Children in group (A) underwent a designed program of physical therapy plus aerobic exercise training in form of bicycle ergometer while, group (B) received the same program as group (A) and aerobic exercise training by treadmill for one hour, at three times a week for three successive months. Functional walking capacity and balance were assessed before and after treatment by using the 6-minute walk test and Biodex balance system equipment respectively.

RESULTS

The post treatment results revealed significant difference in all measured variables (P<0.05) as compared with its pre-treatment results. Post-treatment values indicated that there was a significant difference in all measured variables in favor of group B.

CONCLUSIONS

treadmill training as an aerobic exercise can improve walking capacity and balance more effectively than bicycle ergometer in children with Duchenne muscular dystrophy.

Revisiting the pathogenic role of insulin resistance in Duchenne muscular dystrophy cardiomyopathy subphenotypes

Introduction

Duchenne muscular dystrophy (DMD) is known to impact the subepicardial layer of the myocardium through chronic inflammation. Recent animal studies have shown predominant subendocardial involvement in rats with DMD. The primary outcome parameter was to determine by cardiovascular MRI (CMR) if two differential patterns of myocardial involvements exist in DMD; the secondary outcome parameters were to correlate the observed pattern with metabolic markers such as insulin resistance measures.

Methods

Forty patients with DMD were screened using CMR to determine which of them had predominantly subendocardial dysfunction (SENDO group), or subepicardial/midmyocardial involvement (SEPMI group). Patients were subjected to body mass index measurement, serum creatinine kinase, serum lactate dehydrogenase enzyme, fasting glucose-insulin ratio (FGIR), full lipid profile, left ventricular ejection fraction (LVEF), left ventricle E/E´ ratio (the ratio of early mitral inflow velocity to average early diastolic velocities of the basal septum and mitral annulus) for left ventricle diastolic function, and myocardial layer strain discriminating echocardiography (MLSD-STE). Results: 26 patients displayed SENDO while 34 displayed SEPMI. SENDO group displayed overt insulin resistance; (FGIR (SENDO: 7 ± 1 vs. SEPMI: 5 ± 1, P < 0.001). FGIR was negatively correlated with Subendocardial Global Longitudinal Strain (ENDO-LS) with r = -0.75.

Conclusion

DMD does not seem to influence the heart uniformly; DMD cardiomyopathy probably has two separate phenotypes with different mechanisms. Insulin resistance might be implicated in its pathogenesis and its reversal may help to slow disease progression.