Diagnosis and management of Duchenne muscular dystrophy, part 2: implementation of multidisciplinary care

Biomarkers for Duchenne muscular dystrophy: myonecrosis, inflammation and oxidative stress

Duchenne muscular dystrophy (DMD) is a lethal, X-linked disease that causes severe loss of muscle mass and function in young children. Promising therapies for DMD are being developed, but the long lead times required when using clinical outcome measures are hindering progress. This progress would be facilitated by robust molecular biomarkers in biofluids, such as blood and urine, which could be used to monitor disease progression and severity, as well as to determine optimal drug dosing before a full clinical trial. Many candidate DMD biomarkers have been identified, but there have been few follow-up studies to validate them. This Review describes the promising biomarkers for dystrophic muscle that have been identified in muscle, mainly using animal models. We strongly focus on myonecrosis and the associated inflammation and oxidative stress in DMD muscle, as the lack of dystrophin causes repeated bouts of myonecrosis, which are the key events that initiate the resultant severe dystropathology. We discuss the early events of intrinsic myonecrosis, along with early regeneration in the context of histological and other measures that are used to quantify its incidence. Molecular biomarkers linked to the closely associated events of inflammation and oxidative damage are discussed, with a focus on research related to protein thiol oxidation and to neutrophils. We summarise data linked to myonecrosis in muscle, blood and urine of dystrophic animal species, and discuss the challenge of translating such biomarkers to the clinic for DMD patients, especially to enhance the success of clinical trials.

Summary: This Review discusses biomarkers in blood and urine linked to myonecrosis, inflammation and oxidative stress, to enhance development of therapies for DMD, and the challenges to be overcome for clinical translation.

Clinical practice with steroid therapy for Duchenne muscular dystrophy: An expert survey in Asia and Oceania

BACKGROUND

Several studies on clinical practice for Duchenne muscular dystrophy (DMD) have been conducted in Western countries. However, there have been only a few similar studies in Asia and Oceania. Here, we investigate the steroid therapy-related clinical practice for DMD among the local experts. In 2015, we conducted a DMD expert survey in Asia and Oceania to acquire information regarding patients with DMD and to assess current clinical practice with the cooperation of Asian and Oceanian Myology Centre, a neuromuscular disease research network.

RESULTS

We obtained survey responses from 87 out of 148 clinicians (62%) from 13 countries and regions. In China, 1385 DMD patients were followed-up by 5 respondent neurologists, and 84% were between 0 and 9 years of age (15% were 10-19 years, 1% > 19 years). While in Japan, 1032 patients were followed-up by 20 clinicians, and the age distribution was similar between the 3 groups (27% were 0-9 years, 35% were 10-19 years, 38% were >19 years). Most respondent clinicians (91%) were aware of DMD standard of care recommendations. Daily prednisolone/prednisone administration was used most frequently at initiation (N = 45, 64%). Inconsistent opinion on steroid therapy after loss of ambulation and medication for bone protection was observed.

CONCLUSIONS

Rare disease research infrastructures have been underdeveloped in many of Asian and Oceanian countries. In this situation, our results show the snapshots of current medical situation and clinical practice in DMD. For further epidemiological studies, expansion of DMD registries is necessary.

Timed immersion expiration measures in patients with muscular dystrophies

Introduction

Muscular dystrophies (MD) cause muscle weakness, affecting motor and respiratory functions. Aquatic activities maintain strength and ventilatory function and may require immersion expiration control.

Objectives

(1) To describe the evolution of timed immersion expiration in patients with MD in one-year follow-up. (2) to describe motor and respiratory outcomes in one-year follow-up. (3) to investigate possible relationships between timed immersion expiration and age, motor and respiratory functions.

Method

Fifty-seven patients with MD (12-35 years, Vignos scale 2-8) were evaluated twice, with one-year interval. Immersion expiration control was timed with a chronometer. Motor function was assessed by Motor Function Measure. The respiratory function was evaluated by spirometry. Analysis of variance compared assessments and Pearson tests investigated relationships between variables and age.

Results

Motor and respiratory functions decreased (p < 0.001) but timed immersion expiration was maintained. Timed immersion expiration was not correlated to motor and respiratory functions.

Conclusion

As patients maintained timed immersion expiration in the one-year follow-up, aquatic therapy might be a facilitator for people with MD.

Molecular and Clinical Characteristics of a National Cohort of Paediatric Duchenne Muscular Dystrophy Patients in Norway

BACKGROUND

As new gene-related treatment options for Duchenne muscular dystrophy (DMD) are being developed, precise information about the patients' genetic diagnosis and knowledge about the diversities of natural history in DMD is vital.

OBJECTIVE

To obtain detailed insight into the genetic and clinical characteristics of paediatric DMD in Norway.

METHODS

94 boys with DMD, aged 0-18 years, were identified over a period of 3.5 years, yielding a national prevalence of 13.5×10-5 boys. 73 boys (78%) were recruited to full genetic and clinical or limited (genetic only) evaluation.

RESULTS

Molecular analysis disclosed 64% deletions, 18% duplications and 18% point mutations. The mean age of diagnosis was 3.9±2.0 years. 78% were treated with glucocorticoids from age 5.8±1.5 years. 23 boys (35%) had lost ambulation at an age of 10.7±2.0 years. 17% were treated for left ventricular dysfunction from age 12.1±3.0 years and 12% had received night-time non-invasive positive pressure ventilation from age 13.0±2.5 years.

CONCLUSIONS

The distribution of mutation types and sites was similar to previous studies but with more duplications and fewer point mutations. Any genotype-phenotype correlations were not uncovered. The boys were diagnosed early but there is still diagnostic delay among boys presenting with late motor development. Glucocorticoid treatment was widespread, especially among the younger boys. The clinical results of this comprehensive nationwide study highlight the large variability of disease progression in DMD.

Cough peak flow with different mechanically assisted coughing approaches under different conditions in patients with neuromuscular disorders

PURPOSE

Mechanically assisted coughing (MAC) is an airway clearance method in which the thorax/abdomen is compressed in synchronization with mechanical insufflation-exsufflation (MI-E). MAC can be performed with manual assistance at the upper thorax (MAC-UT), lower thorax (MAC-LT), and upper thorax + abdomen (MAC-UT/A). This study aimed to determine the most effective approach under different conditions (air stacking or tracheostomy) in patients with neuromuscular disorders (NMDs).

METHODS

The study included 34 patients with NMDs. The patients were categorized into air stacking group (n=15), no air stacking group (n=9), and tracheostomy/tracheostomy positive-pressure ventilation (TPPV) group (n=10).

RESULTS

In each group, the cough peak flow (CPF) at 75% of the forced vital capacity (V̇75), V̇50, V̇25, and V̇10 were investigated during the approaches. In the air stacking group, the CPF was higher with MAC-UT, MAC-LT, and MAC-UT/A than with MI-E (p < 0.05). Additionally, V̇75 was higher with MAC-LT and MAC-UT/A than with MI-E (p < 0.05 and p < 0.01, respectively). In the no air stacking group, V̇75 was higher with MAC-UT/A than with MI-E (p < 0.05). In the tracheotomy/TPPV group, there were no significant differences.

CONCLUSIONS

MAC approaches, especially MAC-LT and MAC-UT/A, are preferred in air stacking patients. However, in tracheostomy/TPPV patients, the CPF might not increase with MAC.

Chemical Proteomics and Phenotypic Profiling Identifies the Aryl Hydrocarbon Receptor as a Molecular Target of the Utrophin Modulator Ezutromid

Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disease arising from mutations in the dystrophin gene. Upregulation of utrophin to compensate for the missing dystrophin offers a potential therapy independent of patient genotype. The first-in-class utrophin modulator ezutromid/SMT C1100 was developed from a phenotypic screen through to a Phase 2 clinical trial. Promising efficacy and evidence of target engagement was observed in DMD patients after 24 weeks of treatment, however trial endpoints were not met after 48 weeks. The objective of this study was to understand the mechanism of action of ezutromid which could explain the lack of sustained efficacy and help development of new generations of utrophin modulators. Using chemical proteomics and phenotypic profiling we show that the aryl hydrocarbon receptor (AhR) is a target of ezutromid. Several lines of evidence demonstrate that ezutromid binds AhR with an apparent KD of 50 nm and behaves as an AhR antagonist. Furthermore, other reported AhR antagonists also upregulate utrophin, showing that this pathway, which is currently being explored in other clinical applications including oncology and rheumatoid arthritis, could also be exploited in future DMD therapies.

Cardiac Intervention Improves Heart Disease and Clinical Outcomes in Patients With Muscular Dystrophy in a Multidisciplinary Care Setting

Background

Patients with muscular dystrophy (MD) represent a vulnerable patient population with no clearly defined care model in modern‐day clinical practice to manage a high burden of heart disease and comorbidities. We demonstrate the effectiveness of cardiac interventions, namely the initiation and optimization of medical and device therapies, as part of a multidisciplinary care approach to improve clinical outcomes in patients with MD.

Methods and Results

We conducted a prospective cohort study at the Neuromuscular Multidisciplinary clinic following patients with dystrophinopathies, limb‐girdle MD, type 1 myotonic dystrophy, and facioscapulohumeral MD. A negative control group classified as non‐MD myopathies without heart disease, was also tracked. Our cohort of 185 patients (median age: 42 years; 79 [42.7%] women), included 145 patients with MD. Cardiomyopathy was present in 65.6% of the patients with dystrophinopathies (21 of 32) and 27.3% of the patients with limb‐girdle MD (9 of 33). Conduction abnormalities were common in type 1 myotonic dystrophy (33.3% [20/60] patients). Cardiac intervention reversed systolic dysfunction, with left ventricular ejection fraction improving from 43% to 50.0% over a 3‐year period. A sustained reduction in healthcare utilization was also observed. The number of outpatient clinic visits decreased from 3.0 to 1.5 visits per year, the duration of hospitalizations was reduced from 14.2 to 0.9 days per year, and the number of cardiac‐related hospitalizations decreased from 0.4 to 0.1 hospitalizations per year associated with low mortality.

Conclusions

Our study demonstrates that cardiac intervention as part of a comprehensive multidisciplinary care approach to treating patients with MD leads to a sustained improvement in clinical outcomes.

Increased Blood Pressure and Body Mass Index as Potential Modifiable Factors in The Progression of Myocardial Dysfunction in Duchenne Muscular Dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is characterized by progressive cardiomyopathy. Left ventricular (LV) function may worsen by factors increasing LV afterload such as hypertension and obesity.

OBJECTIVE

To identify potential modifiable risk factors for progression of cardiomyopathy in Duchenne muscular dystrophy (DMD).

METHODS

We retrospectively analysed systolic blood pressures (SBP) and body-mass indexes (BMI) from 273 visits of 65 DMD patients aged 4-18 years between 2003 and 2016, divided in 14 age groups. Values were normalized using Z-scores (Z-SBP and Z-BMI). A linear mixed model was used to analyse correlations between Z-SBP and BMI, steroid use, age, ambulatory status and cardiac medication (CM) use. To study the relationship between SBP and BMI and myocardial deformation prior to the onset of clinical cardiomyopathy, LV deformation, defined by global longitudinal strain (GLS), was quantified in a subset of 36 patients <11 years. Multiple linear regression was used to study the relation between GLS and clinical parameters.

RESULTS

Median follow-up was 5 years. SBP was significantly elevated in all age groups under 14 years (p≤0.04) and 15-16 years (p = 0.033) and correlated positively with BMI (p = 0.001) and negatively with CM use over time (p = 0.018). Z-BMI followed a bell-shaped distribution and plotted approximately one standard deviation above the mean in patients between 7 and 15 years. In the subset of younger patients, reduced GLS was associated with higher BMI (β= 0.348, p = 0.004).

CONCLUSIONS

SBP and BMI may be potentially modifiable factors to retard deterioration of LV function in DMD.

Left Ventricular End-Diastolic Diameter and Cardiac Mortality in Duchenne Muscular Dystrophy

PURPOSE

This study aimed to examine weather left ventricular end-diastolic diameter (LVDd) could predict mortality from heart failure in patients with Duchenne muscular dystrophy (DMD) receiving standard cardio-protective therapies.

PATIENTS AND METHODS

One hundred thirty-three patients with DMD aged ≥10 years who underwent echocardiography from 2011 to 2015 were included in this study and retrospectively followed until August 2018. Patients were divided into two groups according to LVDd at initial echocardiography: ≤ 54 mm (Group 1: n=119) and ≥ 55 mm (Group 2: n=14). To identify factors other than LVDd that may affect heart failure-related mortality, Group 2 patients who developed no left atrial (LA) enlargement, moderate mitral regurgitation (MR), or pulmonary hypertension (PH) during the observation period (Group 2A: n=5) were compared with those who newly developed one or more of those complications (Group 2B: n=7). Clinical outcomes were all-cause mortality and mortality from heart failure.

RESULTS

Mean observation period was 5.5±1.5 years in Group 1 and 4.4±1.9 years in Group 2. A total of 14 patients (10.5%) died, including 6 of 119 (5.0%) patients in Group 1 and 8 of 14 (57.1%) patients in Group 2 (p<0.001). Among these, 1 (0.8%) patient in Group 1 and 8 (57.1%) patients in Group 2 died from heart failure (p<0.001). Group 2B patients had shorter survival compared to Group 2A patients (p=0.006).

CONCLUSION

LVDd ≥ 55 mm is a predictive factor for mortality from heart failure in patients with DMD. Complications including LA enlargement, moderate MR, and PH were found to be predictive factors for mortality from heart failure in a short period.

Noninvasive Ventilation and Mechanical Insufflator-Exsufflator for Acute Respiratory Failure in Children With Neuromuscular Disorders

Children with neuromuscular disorder (NMD) usually have pulmonary involvement characterized by weakened respiratory muscles, insufficient coughing, and inability to clear airway secretions. When suffering from community-acquired pneumonia, these patients are more likely to develop acute respiratory failure (ARF). Therefore, recurrent pneumonias leading to acute on chronic respiratory failure accounts for a common cause of mortality in children with NMD. For many years, noninvasive ventilation (NIV) has been regarded as a life-prolonging tool and has been used as the preferred intervention for treating chronic hypoventilation in patients with advanced NMD. However, an increasing number of studies have proposed the utility of NIV as first-line management for acute on chronic respiratory failure in NMD patients. The benefits of NIV support in acute settings include avoiding invasive mechanical ventilation, shorter intensive care unit or hospital stays, facilitation of extubation, and improved overall survival. As the difficulty in clearing respiratory secretions is considered a significant risk factor attributing to NIV failure, combined coughing assistance of mechanical insufflator-exsufflator (MI-E) with NIV has been recommended the treatment of acute neuromuscular respiratory failure. Several recent studies have demonstrated the feasibility and effectiveness of combined NIV and MI-E in treating ARF of children with NMD in acute care settings. However, to date, only one randomized controlled study has investigated the efficacy of NIV in childhood ARF, but subjects with underlying NMD were excluded. It reflects the need for more studies to elaborate evidence-based practice, especially the combined NIV and MI-E use in children with acute neuromuscular respiratory failure. In this article, we will review the feasibility, effectiveness, predictors of outcome, and perspectives of novel applications of combined NIV and MI-E in the treatment of ARF in NMD children.

Blood-derived biomarkers correlate with clinical progression in Duchenne muscular dystrophy

BACKGROUND

Duchenne Muscular Dystrophy is a severe, incurable disorder caused by mutations in the dystrophin gene. The disease is characterized by decreased muscle function, impaired muscle regeneration and increased inflammation. In a clinical context, muscle deterioration, is evaluated using physical tests and analysis of muscle biopsies, which fail to accurately monitor the disease progression.

OBJECTIVES

This study aims to confirm and asses the value of blood protein biomarkers as disease progression markers using one of the largest longitudinal collection of samples.

METHODS

A total of 560 samples, both serum and plasma, collected at three clinical sites are analyzed using a suspension bead array platform to assess 118 proteins targeted by 250 antibodies in microliter amount of samples.

RESULTS

Nine proteins are confirmed as disease progression biomarkers in both plasma and serum. Abundance of these biomarkers decreases as the disease progresses but follows different trajectories. While carbonic anhydrase 3, microtubule associated protein 4 and collagen type I alpha 1 chain decline rather constantly over time, myosin light chain 3, electron transfer flavoprotein A, troponin T, malate dehydrogenase 2, lactate dehydrogenase B and nestin plateaus in early teens. Electron transfer flavoprotein A, correlates with the outcome of 6-minutes-walking-test whereas malate dehydrogenase 2 together with myosin light chain 3, carbonic anhydrase 3 and nestin correlate with respiratory capacity.

CONCLUSIONS

Nine biomarkers have been identified that correlate with disease milestones, functional tests and respiratory capacity. Together these biomarkers recapitulate different stages of the disorder that, if validated can improve disease progression monitoring.

Fisioterapia aquática em indivíduos com distrofia muscular: uma revisão sistemática do tipo escopo

RESUMO O objetivo deste estudo foi mapear o uso da fisioterapia aquática em indivíduos com distrofias musculares, de forma a caracterizar as intervenções no meio aquático e identificar componentes mensurados (variáveis estudadas e instrumentos utilizados nos estudos). A revisão sistemática do tipo de escopo incluiu estudos experimentais, descritivos e observacionais (em inglês, português e espanhol). As buscas foram realizadas nas plataformas Medline (PubMed), CINAHL, Embase, PEDro, Lilacs, ERIC, Scopus, Web of Science e Google Scholar. Os dados extraídos foram alocados em três categorias: (1) caracterização dos registros, (2) informações referentes a fisioterapia aquática e (3) componentes mensurados. Foram encontrados 556 registros e, destes, selecionados 20. As amostras dos estudos selecionados incluíram, na maioria, indivíduos com distrofia muscular de Duchenne, com idade entre 5 e 22 anos, que fizeram fisioterapia aquática com duração média de 45 minutos uma ou duas vezes por semana, por 21 semanas. Essas características corroboram estudos feitos em diferentes populações. A maioria dos estudos investigou alterações pulmonares e controle postural/desempenho funcional, poucos avaliaram os efeitos no sistema cardíaco. Recomenda-se usar a Egen Klassifikation, a North Star Ambulatory Assessment e fazer o teste de caminhada de seis minutos.

S-nitrosylation of connexin43 hemichannels elicits cardiac stress-induced arrhythmias in Duchenne muscular dystrophy mice

Patients with Duchenne muscular dystrophy (DMD) commonly present with severe ventricular arrhythmias that contribute to heart failure. Arrhythmias and lethality are also consistently observed in adult Dmdmdx mice, a mouse model of DMD, after acute β-adrenergic stimulation. These pathological features were previously linked to aberrant expression and remodeling of the cardiac gap junction protein connexin43 (Cx43). Here, we report that remodeled Cx43 protein forms Cx43 hemichannels in the lateral membrane of Dmdmdx cardiomyocytes and that the β-adrenergic agonist isoproterenol (Iso) aberrantly activates these hemichannels. Block of Cx43 hemichannels or a reduction in Cx43 levels (using Dmdmdx Cx43+/- mice) prevents the abnormal increase in membrane permeability, plasma membrane depolarization, and Iso-evoked electrical activity in these cells. Additionally, Iso treatment promotes nitric oxide (NO) production and S-nitrosylation of Cx43 hemichannels in Dmdmdx heart. Importantly, inhibition of NO production prevents arrhythmias evoked by Iso. We found that NO directly activates Cx43 hemichannels by S-nitrosylation of cysteine at position 271. Our results demonstrate that opening of remodeled and S-nitrosylated Cx43 hemichannels plays a key role in the development of arrhythmias in DMD mice and that these channels may serve as therapeutic targets to prevent fatal arrhythmias in patients with DMD .

Eteplirsen Treatment Attenuates Respiratory Decline in Ambulatory and Non-Ambulatory Patients with Duchenne Muscular Dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) patients experience skeletal muscle degeneration, including respiratory muscles. Respiratory decline in glucocorticoid-treated DMD patients, measured by percent predicted forced vital capacity (FVC% p), is typically 5% annually in patients aged 10 to 18 years.

OBJECTIVE

Evaluate the effects of eteplirsen on FVC% p annual change in 3 trials versus matched Cooperative International Neuromuscular Research Group Duchenne Natural History Study (CINRG DNHS) controls.

METHODS

Eteplirsen studies 201/202 evaluated eligible ambulatory DMD patients for at least 4 years, study 204 evaluated primarily non-ambulatory DMD patients for 2 years, and ongoing study 301 is evaluating ambulatory DMD patients for 2 years (interim analysis is included). Eteplirsen-treated patients (n = 74) were amenable to exon 51 skipping and were receiving glucocorticoids. Three CINRG DNHS cohorts included: glucocorticoid-treated patients amenable to exon 51 skipping (Exon 51 CINRG DNHS; n = 20), all glucocorticoid-treated CINRG patients (All CINRG DNHS; n = 172), and all glucocorticoid-treated genotyped CINRG DNHS patients (Genotyped CINRG DNHS; n = 148). FVC% p assessments between ages 10 and <18 years were included for all patients; mixed-model analyses characterized FVC% p annual change.

RESULTS

FVC% p annual change was greater for CINRG DNHS Exon 51 controls (- 6.00) versus patients in studies 201/202, study 204, and study 301 (- 2.19, P < 0.001; - 3.66, P 0.004; and - 3.79, P 0.017, respectively). FVC% p annual change in all eteplirsen studies suggested treatment benefit compared with the Genotyped CINRG DNHS (- 5.67) and All CINRG DNHS (- 5.56) cohorts (P < 0.05, all comparisons).

CONCLUSIONS

Significant, clinically meaningful attenuation of FVC%p decline was observed in eteplirsen-treated patients versus CINRG DNHS controls.

A Case Study With Symbihand: An sEMG-Controlled Electrohydraulic Hand Orthosis for Individuals With Duchenne Muscular Dystrophy

With recent improvements in healthcare, individuals with Duchenne muscular dystrophy (DMD) have prolonged life expectancy, and it is therefore vital to preserve their independence. Hand function plays a central role in maintaining independence in daily living. This requires sufficient grip force and the ability to modulate it with no substantially added effort. Individuals with DMD have low residual grip force and its modulation is challenging and fatiguing. To assist their hand function, we developed a novel dynamic hand orthosis called SymbiHand, where the user's hand motor intention is decoded by means of surface electromyography, enabling the control of an electrohydraulic pump for actuation. Mechanical work is transported using hydraulic transmission and flexible structures to redirect interaction forces, enhancing comfort by minimizing shear forces. This paper outlines SymbiHand's design and control, and a case study with an individual with DMD. Results show that SymbiHand increased the participant's maximum grasping force from 2.4 to 8 N. During a grasping force-tracking task, muscular activation was decreased by more than 40% without compromising task performance. These results suggest that SymbiHand has the potential to decrease muscular activation and increase grasping force for individuals with DMD, adding to the hand a total mass of no more than 241 g. Changes in mass distributions and an active thumb support are necessary for improved usability, in addition to larger-scale studies for generalizing its assistive potential.

Evaluation of gait in Duchenne Muscular Dystrophy: Relation of 3D gait analysis to clinical assessment

Walking ability in Duchenne Muscular Dystrophy (DMD) deteriorates progressively until complete loss of the function. Interventions aimed at maintaining ambulatory ability relies on accurate clinical-based scores and evaluations of walking. This kind of assessment has intrinsic limitations. A 3D optoelectronic system could provide elements useful for the functional evaluation of patients with DMD. Nineteen boys with DMD were evaluated using the 6-Minutes Walking Test, North Star Ambulatory Assessment and 3D gait analysis. Participants' gait parameters were compared to those of an age-matched control group and correlated with standard clinical scores. Seventeen kinematic variables differed between DMD and control groups. Strong correlations with North Star Ambulatory Assessment were found for stride width, gait velocity and ankle angles on the sagittal plane. The 6-Minutes Walking test did not correlate with investigated kinematic variables but showed a correlation with North Star Ambulatory Assessment. Our data support the reported DMD gait pattern characterized by increased anterior pelvic tilt and ankle plantar flexion. The stride width and ankle kinematics emerged as the main representative gait parameters of DMD global ambulatory status. Although preliminary, our findings suggest that 3D gait analysis may provide useful objective and accurate parameters reflecting the functional ability of individuals with DMD.

Using an Online, Modified Delphi Approach to Engage Patients and Caregivers in Determining the Patient-Centeredness of Duchenne Muscular Dystrophy Care Considerations

Purpose. To determine the patient-centeredness of endocrine and bone health Duchenne muscular dystrophy (DMD) care considerations using the RAND/PPMD Patient-Centeredness Method (RPM), which is a novel, online, modified-Delphi approach to engaging patients and caregivers in clinical guideline development. Methods. We solicited input on the patient-centeredness of care considerations from 28 individuals with DMD and 94 caregivers, randomly assigned to 1 of 2 mixed panels. During a 3-round online modified-Delphi process, participants rated the importance and acceptability of 19 DMD care considerations (round 1), reviewed and discussed the initial results (round 2), and revised their original ratings (round 3). Patient-centeredness was operationalized as importance and acceptability of recommendations. We considered a care consideration to be patient-centered if both panels deemed it important and acceptable. Results. Ninety-five panelists (78%) participated in this study. Of these, 88 (93%) participated in round 1, 74 (78%) in round 2, and 56 (59%) in round 3. Panelists deemed 12 care considerations to be patient-centered: 3 weight management, 3 bone health, 4 vertical growth, and 2 puberty recommendations. Seven care considerations did not meet patient-centeredness criteria. Common reasons were lack of evidence specific to DMD and concerns about insurance coverage, access to treatment, and patient safety. Conclusions. Using the RPM, Duchenne families considered most care considerations to be patient-centered. Besides being clinically appropriate, these considerations are likely to be consistent with the preferences, needs, and values of Duchenne families. While all relevant care considerations should be discussed during patient-provider encounters, those that did not meet patient-centeredness criteria in particular should be carefully considered as part of joint decision making between Duchenne families and their providers. Study Registration: HSRProj 20163126.

Cheer* in Health Care Practice: What It Excludes and Why It Matters

Clinicians' positive demeanor and "strengths based" focus can include working to create a cheerful atmosphere in health care environments, cheering for improvements in assessment outcomes, and cheering up clients in situations of decline. Drawing from philosopher Karen Barad's theories of inclusions and exclusions, we investigated what comes to matter (and what is excluded from mattering) when there is cheerfulness, cheering, and so forth (cheer*) in the day-to-day practices of a neuromuscular clinic. We worked collaboratively with clinicians, young people with Duchenne muscular dystrophy, and their families to co-examine the clinic in three iterative exploratory method spaces: (a) group "dialogues" with clinicians; (b) consultative interviews with children, families, and clinicians; and (c) transdisciplinary research team analysis sessions. Cheer* made some things matter in the clinic ("normal" physical function, "positive" emotions, test scores, compliance); and excluded others (grief and loss, "non-normative" bodies and lives, alternative practices, embodied knowledge). We discuss implications across health care settings.

Motor impairment in a rare form of spastic paraplegia (Spoan syndrome): a 10-year follow-up

Background

Spastic paraplegia, optic atrophy and neuropathy (Spoan syndrome) is an autosomal recessive disease with approximately 70 cases recorded in Brazil and Egypt.

Methods

This is a prospective longitudinal study performed with 47 patients affected with Spoan syndrome of seven communities of Rio Grande do Norte (Brazil) to investigate changes in motor function based on comparative data obtained from a 10-year follow-up.

Results

The mean age of the participants was 47.21 ± 12.42 years old, and the mean age at loss of ambulation and hand function were 10.78 ± 5.55 and 33.58 ± 17.47 years old, respectively. Spearman’s correlation analysis between the score on the Modified Barthel Index and the investigated variables evidenced statistical significance for age (p < 0.001) and right- and left-hand grip strength (p = 0.042 and p = 0.021, respectively). Statistical significance was not evidenced for the remainder of the variables, including age at onset of symptoms (p = 0.634), age at loss of ambulation (p = 0.664) and age at loss of hand function (p = 0.118).

Conclusions

Our analysis allows asserting that the participants exhibited slight dependence until age 35. The greatest losses occurred from ages 35 to 41, and starting at 50, practically all patients become completely dependent. These findings are relevant for determining the prognosis as well as suitable treatment, rehabilitation and assistive technology for these individuals.

[Study of medical management for patients with Duchenne muscular dystrophy in Japan: what was changed by a practical guideline]

In order to clarify the changes in the medical management of patients with Duchenne muscular dystrophy after publication of a practical guideline, questionnaire surveys targeting Japanese certified neurologists and child neurologists before and four years after publication of the guideline were conducted. The practical guideline was evaluated by the majority of specialists as their preferred information source. After the guideline, a more aggressive trend was seen in steroid treatment, rehabilitation, regular assessment of spinal deformity, etc., and significant differences were observed in respiratory care and nutritional management. Although there were concerns that it would be hard to produce useful guidelines due to the lack of high-level evidence for a rare disease, guidelines including expert recommendations have proved to be an important tool for disseminating best practicable care. We are planning to revise the guideline based on the results of the analysis.

Ankle bracing practices in ambulatory, corticosteroid-naive boys with Duchenne muscular dystrophy

INTRODUCTION

Loss of ambulation in Duchenne muscular dystrophy presages scoliosis, respiratory failure, and death. Strategies to maintain ankle range of motion are employed, but little evidence exists to support these approaches and limited information is available concerning current practice.

METHODS

In this study we assessed baseline bracing data from 187 boys participating in a multicenter, international clinical trial.

RESULTS

Ankle-foot orthoses (AFOs) were recommended for 54% of the boys, with nighttime static AFOs and nighttime dynamic AFOs utilized in 94% and 6% of these boys, respectively. Daytime static AFOs were recommended for 3 boys. Compliance with bracing recommendations was 54% for nighttime static braces and 67% for nighttime dynamic braces.

DISCUSSION

The basis for the variation in recommended AFO use is unknown and requires further study. Long-term follow-up of boys may permit assessment of the effects of AFO use.

Influence of β2 adrenergic receptor genotype on risk of nocturnal ventilation in patients with Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease resulting in severe respiratory derangements. As such, DMD patients are at a high risk of nocturnal hypoventilation, thereby requiring nocturnal ventilation (NV). To this end, NV is an important clinical milestone in the management of DMD. Emerging evidence suggests that ß₂ adrenergic receptors (ADRB2) may play a role in determining respiratory function, whereby more functional ADRB2 genotype variants (e.g., Gly16) are associated with improved pulmonary function and respiratory muscle strength. These findings suggest that the more functional ADRB2 genotype may help to preserve respiratory function in patients with DMD. The purpose of this study was to identify the influence of ADRB2 genotype on the risk of NV use in DMD. Data from the CINRG Duchenne Natural History Study including 175 DMD patients (3–25 yrs) were analyzed focusing on ADRB2 genotype variants. Time-to-event analyses were used to examine differences in the age at prescription of full-time NV use between genotypes. There were no differences between genotype groups in age, height, weight, corticosteroid use, proportion of ambulatory patients, or age at loss of ambulation. DMD patients expressing the Gly16 polymorphism had a significantly (P < 0.05) lower mean age at NV prescription compared with those patients expressing the Arg16 polymorphism (21.80 ± 0.59 yrs. vs 25.91 ± 1.31 yrs., respectively). In addition, a covariate-adjusted Cox model revealed that the Gly16 variant group possessed a 6.52-fold higher risk of full-time NV use at any given age compared with the Arg16 polymorphism group. These data suggest that genetic variations in the ADRB2 gene may influence the age at which DMD patients are first prescribed NV, whereby patients with the Gly16 polymorphism are more likely to require NV assistance at an earlier age than their Arg16 counterparts.

Spp1 (osteopontin) promotes TGFβ processing in fibroblasts of dystrophin-deficient muscles through matrix metalloproteinases

Duchenne muscular dystrophy (DMD) is caused by mutations in the gene encoding dystrophin. Prior work has shown that DMD progression can vary, depending on the genetic makeup of the patient. Several modifier alleles have been identified including LTBP4 and SPP1. We previously showed that Spp1 exacerbates the DMD phenotype in the mdx mouse model by promoting fibrosis and by skewing macrophage polarization. Here, we studied the mechanisms involved in Spp1's promotion of fibrosis by using both isolated fibroblasts and genetically modified mice. We found that Spp1 upregulates collagen expression in mdx fibroblasts by enhancing TGFβ signaling. Spp1's effects on TGFβ signaling are through induction of MMP9 expression. MMP9 is a protease that can release active TGFβ ligand from its latent complex. In support for activation of this pathway in our model, we showed that treatment of mdx fibroblasts with MMP9 inhibitor led to accumulation of the TGFβ latent complex, decreased levels of active TGFβ and reduced collagen expression. Correspondingly, we found reduced active TGFβ in Spp1-/-mdxB10 and Mmp9-/-mdxB10 muscles in vivo. Taken together with previous observations of reduced fibrosis in both models, these data suggest that Spp1 acts upstream of TGFβ to promote fibrosis in mdx muscles. We found that in the context of constitutively upregulated TGFβ signaling (such as in the mdxD2 model), ablation of Spp1 has very little effect on fibrosis. Finally, we performed proof-of-concept studies showing that postnatal pharmacological inhibition of Spp1 reduces fibrosis and improves muscle function in mdx mice.

Predicting gait adaptations due to ankle plantarflexor muscle weakness and contracture using physics-based musculoskeletal simulations

Deficits in the ankle plantarflexor muscles, such as weakness and contracture, occur commonly in conditions such as cerebral palsy, stroke, muscular dystrophy, Charcot-Marie-Tooth disease, and sarcopenia. While these deficits likely contribute to observed gait pathologies, determining cause-effect relationships is difficult due to the often co-occurring biomechanical and neural deficits. To elucidate the effects of weakness and contracture, we systematically introduced isolated deficits into a musculoskeletal model and generated simulations of walking to predict gait adaptations due to these deficits. We trained a planar model containing 9 degrees of freedom and 18 musculotendon actuators to walk using a custom optimization framework through which we imposed simple objectives, such as minimizing cost of transport while avoiding falling and injury, and maintaining head stability. We first generated gaits at prescribed speeds between 0.50 m/s and 2.00 m/s that reproduced experimentally observed kinematic, kinetic, and metabolic trends for walking. We then generated a gait at self-selected walking speed; quantitative comparisons between our simulation and experimental data for joint angles, joint moments, and ground reaction forces showed root-mean-squared errors of less than 1.6 standard deviations and normalized cross-correlations above 0.8 except for knee joint moment trajectories. Finally, we applied mild, moderate, and severe levels of muscle weakness or contracture to either the soleus (SOL) or gastrocnemius (GAS) or both of these major plantarflexors (PF) and retrained the model to walk at a self-selected speed. The model was robust to all deficits, finding a stable gait in all cases. Severe PF weakness caused the model to adopt a slower, "heel-walking" gait. Severe contracture of only SOL or both PF yielded similar results: the model adopted a "toe-walking" gait with excessive hip and knee flexion during stance. These results highlight how plantarflexor weakness and contracture may contribute to observed gait patterns.

Targeting RyR Activity Boosts Antisense Exon 44 and 45 Skipping in Human DMD Skeletal or Cardiac Muscle Culture Models

Systemic delivery of antisense oligonucleotides (AO) for DMD exon skipping has proven effective for reframing DMD mRNA, rescuing dystrophin expression, and slowing disease progression in animal models. In humans with Duchenne muscular dystrophy treated with AOs, low levels of dystrophin have been induced, and modest slowing of disease progression has been observed, highlighting the need for improved efficiency of human skipping drugs. Here, we demonstrate that dantrolene and Rycals S107 and ARM210 potentiate AO-mediated exon skipping of exon 44 or exon 45 in patient-derived myotube cultures with appropriate mutations. Further, dantrolene is shown to boost AO-mediated exon skipping in patient-derived, induced cardiomyocyte cultures. Our findings further validate the ryanodine receptors (RyR) as the likely target responsible for exon skip boosting and demonstrate potential applicability beyond exon 51 skipping. These data provide preclinical support of dantrolene trial as an adjuvant to AO-mediated exon-skipping therapy in humans and identify a novel Rycal, ARM210, for development as a potential exon-skipping booster. Further, they highlight the value of mutation-specific DMD culture models for basic discovery, preclinical drug screening and translation of personalized genetic medicines.

Importance of muscle biopsy to establish pathogenicity of DMD missense and splice variants

A precise genetic diagnosis of a dystrophinopathy has far-reaching implications for affected boys and their families. We present three boys with DMD single nucleotide variants associated with Becker muscular dystrophy presenting with myalgia, reduced exercise capacity, neurodevelopmental symptoms and elevated creatine kinase. The DMD variants were difficult to classify: AIII:1 a synonymous variant in exon 13 c.1602G>A, p.Lys534Lys; BIII:1 an essential splice-site variant in intron 33 c.4674+1G>A, and CII:1 a missense mutation within the cysteine-rich domain, exon 66 c.9619T>C, p.Cys3207Arg. Complementary DNA (cDNA) analysis using muscle-derived mRNA established splice-altering effects of variants for AIII:1 and BIII:1, and normal splicing in CII:1. Western blot analysis demonstrated mildly to moderately reduced dystrophin levels (17.6 - 36.1% the levels of controls), supporting dystrophinopathy as a probable diagnosis. These three cases highlight the diagnostic utility of muscle biopsy for mRNA studies and western blot to investigate DMD variants of uncertain pathogenicity, by exploring effects on splicing and dystrophin protein levels.

Systemic administration of the antisense oligonucleotide NS-065/NCNP-01 for skipping of exon 53 in patients with Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a lethal hereditary muscle disease caused by mutations in the gene encoding the muscle protein dystrophin. These mutations result in a shift in the open reading frame leading to loss of the dystrophin protein. Antisense oligonucleotides (ASOs) that induce exon skipping correct this frame shift during pre-mRNA splicing and partially restore dystrophin expression in mouse and dog models. We conducted a phase 1, open-label, dose-escalation clinical trial to determine the safety, pharmacokinetics, and activity of NS-065/NCNP-01, a morpholino ASO that enables skipping of exon 53. Ten patients with DMD (6 to 16 years old), carrying mutations in the dystrophin gene whose reading frame would be restored by exon 53 skipping, were administered NS-065/NCNP-01 at doses of 1.25, 5, or 20 mg/kg weekly for 12 weeks. The primary endpoint was safety; the secondary endpoints were pharmacokinetics and successful exon skipping. No severe adverse drug reactions were observed, and no treatment discontinuation occurred. Muscle biopsy samples were taken before and after treatment and compared by reverse transcription polymerase chain reaction (RT-PCR), immunofluorescence, and Western blotting to assess the amount of exon 53 skipping and dystrophin expression. NS-065/NCNP-01 induced exon 53 skipping in dystrophin-encoding mRNA in a dose-dependent manner and increased the dystrophin/spectrin ratio in 7 of 10 patients. Furthermore, the amount of exon skipping correlated with the maximum drug concentration in plasma (C_max) and the area under the concentration-time curve in plasma (AUC_0-t ). These results indicate that NS-065/NCNP-01 has a favorable safety profile and promising pharmacokinetics warranting further study in a phase 2 clinical trial.

Glycine administration attenuates progression of dystrophic pathology in prednisolone-treated dystrophin/utrophin null mice

Duchenne muscular dystrophy (DMD) is an X-linked genetic disease characterized by progressive muscle wasting and weakness and premature death. Glucocorticoids (e.g. prednisolone) remain the only drugs with a favorable impact on DMD patients, but not without side effects. We have demonstrated that glycine preserves muscle in various wasting models. Since glycine effectively suppresses the activity of pro-inflammatory macrophages, we investigated the potential of glycine treatment to ameliorate the dystrophic pathology. Dystrophic mdx and dystrophin-utrophin null (dko) mice were treated with glycine or L-alanine (amino acid control) for up to 15 weeks and voluntary running distance (a quality of life marker and strong correlate of lifespan in dko mice) and muscle morphology were assessed. Glycine increased voluntary running distance in mdx mice by 90% (P < 0.05) after 2 weeks and by 60% (P < 0.01) in dko mice co-treated with prednisolone over an 8 week treatment period. Glycine treatment attenuated fibrotic deposition in the diaphragm by 28% (P < 0.05) after 10 weeks in mdx mice and by 22% (P < 0.02) after 14 weeks in dko mice. Glycine treatment augmented the prednisolone-induced reduction in fibrosis in diaphragm muscles of dko mice (23%, P < 0.05) after 8 weeks. Our findings provide strong evidence that glycine supplementation may be a safe, simple and effective adjuvant for improving the efficacy of prednisolone treatment and improving the quality of life for DMD patients.

Hyperbaric therapy provides no benefit for skeletal muscle and respiratory function and accelerates cardiac injury in mdx mice

Duchenne muscular dystrophy (DMD) is a uniformly fatal condition of striated muscle wasting resulting in premature death from respiratory and/or cardiac failure. Symptomatic therapy has prolonged survival by limiting deaths resulting from respiratory insufficiency, but there is currently no effective therapy for most patients with DMD. This grim prognosis has led patients and their families to seek unproven therapeutic approaches. One such approach is the use of hyperbaric therapies, which 14% of DMD patients self-report using. The primary goal of this study was to determine if intermittent hyperbaric exposure altered the muscle function of the mdx mouse, a genetic model of DMD. To do this, mdx mice were exposed to three daily 90-minute 1.3 atmosphere hyperbaric exposures for 4 weeks. Skeletal muscle, respiratory, and cardiac function were assessed in treated and untreated wild type and dystrophic mice. The results of these studies find that hyperbaric and hyperoxic approaches resulted in increased cardiac fibrosis in dystrophic mice and no beneficial effects on the functional parameters measured. These data suggest that these oxygen-based therapies are unlikely to provide therapeutic benefit to DMD patients.

Emergency room visits and admission rates of children with neuromuscular disorders: A 10-year experience in a medical center in Taiwan

BACKGROUND

No previous studies have explored emergency medical care for children with chronic neuromuscular disorders (NMDs). We aimed to determine the major reasons for the emergency room (ER) readmission of pediatric patients with NMDs and suggest changes to the care plan to decrease readmissions.

METHODS

Children with chronic NMDs (aged <18 years) who visited a medical center-based ER between January 2005 and January 2015 were included. The following data were extracted from the patient's ER records: presentations; demographic data, including sex and age; NMD diagnosis; triage classification; emergency examination; initial management and outcomes. The outcomes were death inside or outside the ER, admission to the ward or pediatric intensive care unit (PICU), uneventful discharge, and repeated ER visits.

RESULTS

In 10 years, 44 children with heterogeneous NMDs (boys/girls: 30/14, mean age: 9.9 years) visited the ER for a total of 204 times. Repeated ER visits and readmissions occurred in 56.8% and 55.6% of the patients, respectively. Most NMD children belonged to triage class 3 (35.3%), with underlying congenital hereditary muscular dystrophy (44.1%). The major symptoms were usually multiple and concurrent, and primarily respiratory (62.3%) or gastrointestinal (28.9%). The most common causes of hospitalization were pneumonia (48.5%) or acute gastritis (20.4%), and approximately half of the ER visits required further hospitalization, of which 28.2% involved PICU admission. Twenty of the 36 children admitted to the ER required readmission. The most commonly prescribed examinations were complete blood count (38%) and C-reactive protein (38%), and the most common therapy was intravenous fluid administration (34%). Although respiratory compromise caused most ER visits and admissions, pulmonary assessments, including chest films (28%), pulse oximetry (15%), and blood gas analysis (11%), were performed in a relatively small proportion.

CONCLUSION

The ER staff must recognize patients' unmet needs for respiratory and gastrointestinal care related to underlying NMDs.

Transition to adult care in young people with neuromuscular disease on non-invasive ventilation

BACKGROUND

Long-term mechanical ventilation (LTV) with non-invasive ventilation (NIV) prolongs survival in patients with Neuromuscular Diseases (NMDs). Transition from paediatric to adult healthcare system is an undervalued and challenging issue for children with chronic conditions on mechanical ventilation.

METHODS

this retrospective study aims to compare issues of young adults in age to transition to adult care (≥ 15 years old) affected by NMDs on NIV in two different Paediatric Respiratory Units in two different countries: Bambino Gesù Children's Hospital, Research Institute, (Rome, Italy) (BGCH) and the Paediatric Respiratory Unit of the Royal Brompton Hospital (London, UK) (RBHT).

RESULTS

The median (min-max) age at starting ventilation was significantly different in the two groups (16 years old vs 12, p = 0.0006). We found significant difference in terms of median age at the time of observation (18 (15-22) vs 17 (15-19) years, p = 0.0294) and of type of referral (all the patients from the BGCH group were referred to paediatric services (n = 15, 100%), median age 18 (15-22); only 6 patients, in the RBHT group, with a median age 15.50 (15-17) years, were entirely referred to paediatric service). We found different sleep-disordered breathing assessments 6 full Polysomnographies, 7 Cardio-Respiratory Polygraphies and 2 oximetry with capnography (SpO2-tcCO2) studies in the BCGH group, while all patients of RBHT group were assessed with an SpO2-tcCO2 study. All patients from both groups underwent multidisciplinary assessment.

CONCLUSIONS

In conclusion, patients with NMDs on NIV in age to transition to adult require complex multidisciplinary management: significant efforts are needed to achieve the proper transition to adult care.

Diaphragm Involvement in Duchenne Muscular Dystrophy (DMD): An MRI Study

BACKGROUND

Duchenne muscular dystrophy (DMD) is characterized by progressive weakness and wasting of skeletal, cardiac, and respiratory muscles, with consequent cardiopulmonary failure as the main cause of death. Reliable outcome measures able to demonstrate specific trends over disease progression are essential.

PURPOSE

To investigate MRI as a noninvasive imaging modality to assess diaphragm impairment in DMD. In particular, we sought to correlate MRI measurement of diaphragm structure and function with pulmonary function tests and with the abdominal volumes (V_AB ) measured by optoelectronic plethysmography, being an index of the action of the diaphragm.

STUDY TYPE

Cross-sectional study.

POPULATION

Twenty-six DMD patients (17.9 ± 6.2 years) and 12 age-matched controls (17.8 ± 5.9 years).

FIELD STRENGTH/SEQUENCE

3-Point gradient echo Dixon sequence at 3T.

ASSESSMENT

Images were acquired in breath-hold at full-expiration (EXP) and full-inspiration (INSP). INSP and EXP lung volumes were segmented and the diaphragm surface was reconstructed as the bottom surface of the left and the right lung. The inspiratory and the expiratory diaphragm surfaces were aligned by a nonrigid iterative closest point algorithm. On MRI we measured: 1) craniocaudal diaphragmatic excursion; 2) diaphragm fatty infiltration.

STATISTICAL TESTS

Three-parameter sigmoid regression, one-way analysis of variance (ANOVA), Spearman's correlation.

RESULTS

In patients, diaphragm excursion decreased with age (r² = 0.68, P < 0.0001) and fat fraction increased (r² = 0.51, P = 0.0002). In healthy subjects, diaphragm excursion and fat fraction had no relationship with age. Diaphragm excursion decreased with decreasing FEV₁ %pred (r = 0.78, P < 0.0001) and FVC %pred (r = 0.76, P < 0.0001) and correlated with V_AB (r = 0.60, P = 0.0002). Fatty infiltration increased with decreasing FEV1 %pred (r = -0.88, P < 0.0001) and FVC %pred (r = -0.88, P < 0.0001).

DATA CONCLUSION

The progressive structural and functional diaphragm impairment is highly related to pulmonary function tests and to V_AB . The results suggest that MRI might represent a new and noninvasive tool for the functional and structural assessment of the diaphragm.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2020;51:461-471.

Clinical Outcomes in Duchenne Muscular Dystrophy: A Study of 5345 Patients from the TREAT-NMD DMD Global Database

BACKGROUND

Recent short-term clinical trials in patients with Duchenne Muscular Dystrophy (DMD) have indicated greater disease variability in terms of progression than expected. In addition, as average life-expectancy increases, reliable data is required on clinical progression in the older DMD population.

OBJECTIVE

To determine the effects of corticosteroids on major clinical outcomes of DMD in a large multinational cohort of genetically confirmed DMD patients.

METHODS

In this cross-sectional study we analysed clinical data from 5345 genetically confirmed DMD patients from 31 countries held within the TREAT-NMD global DMD database. For analysis patients were categorised by corticosteroid background and further stratified by age.

RESULTS

Loss of ambulation in non-steroid treated patients was 10 years and in corticosteroid treated patients 13 years old (p = 0.0001). Corticosteroid treated patients were less likely to need scoliosis surgery (p < 0.001) or ventilatory support (p < 0.001) and there was a mild cardioprotective effect of corticosteroids in the patient population aged 20 years and older (p = 0.0035). Patients with a single deletion of exon 45 showed an increased survival in contrast to other single exon deletions.

CONCLUSIONS

This study provides data on clinical outcomes of DMD across many healthcare settings and including a sizeable cohort of older patients. Our data confirm the benefits of corticosteroid treatment on ambulation, need for scoliosis surgery, ventilation and, to a lesser extent, cardiomyopathy. This study underlines the importance of data collection via patient registries and the critical role of multi-centre collaboration in the rare disease field.

Progression of Duchenne Cardiomyopathy Presenting with Chest Pain and Troponin Elevation

BACKGROUND

Improved neuromuscular and respiratory therapies have altered the natural history of Duchenne muscular dystrophy (DMD) such that the most common cause of mortality is progressive cardiomyopathy. Despite imaging evidence of progressive cardiomyopathy, troponin I (cTn) is not significantly elevated in asymptomatic DMD patients.

RESULTS

We describe eight boys with DMD evaluated for acute chest pain (ACP) and found to have acute cTn elevation with depressed left ventricular ejection fraction (LVEF). Of our eight patients, five presented with a primary complaint of ACP, while three presented with secondary myocardial injury in the context of systemic illness requiring hospitalization. Electrocardiograms showed diffuse ST changes and mean peak cTn level was 44±15.4 ng/mL (reference range <0.03 ng/mL). cTn levels normalized with only supportive care. Cardiac magnetic resonance imaging (CMR) was performed during the event on all but one patient, demonstrating increased late gadolinium enhancement (LGE) from 12.4±11.4% to 36.5±10.3% with associated deterioration of LVEF from 61±4.4% to 47.6±6.6% which remained depressed on follow-up CMR study (49.1±7.8%). All viral studies were negative. Additional investigations varied among patients, but no causative findings were demonstrated.

CONCLUSIONS

ACP with cTn elevation occurs in DMD boys and may be indicative of cardiomyopathy progression as evidenced by acute left ventricular dysfunction and development or progression of myocardial fibrosis. This clinical presentation is under recognized. These events may represent an important pathophysiological mechanism in cardiomyopathy progression.

Sonoelastography of the trunk and lower extremity muscles in a case of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a rare genetic disorder typically presenting with muscle weakness and reduced tone of trunk and lower extremities. The sonoelastographic properties of DMD are poorly understood. We describe sonoelastographic characteristics of a patient's trunk and lower extremity musculature. An 8-year-old male presented with a 5-year history of DMD. Sonoelastographic measures of the gluteus maximus and medius, lumbar erector spinae, rectus abdominis, rectus femoris, biceps femoris, tibialis anterior, medial and lateral gastrocnemius muscles were obtained. Sonoelastography demonstrated increased elasticity by elevated kiloPascals (kPa) across all muscles, except the lumbar erector spinae. Patient values were compared to an age-matched healthy control. These abnormal sonoelastographic findings reflected the pathological mechanical properties of DMD. Sonoelastography was valuable for characterizing the mechanical properties of normal and abnormal muscle tissue. There is limited information on the sonoelastography application to DMD. Sonoelastography may serve as a useful measure for diagnosis and monitoring clinical outcomes for DMD.

RNA delivery biomaterials for the treatment of genetic and rare diseases

Genetic and rare diseases (GARDs) affect more than 350 million patients worldwide and remain a significant challenge in the clinic. Hence, continuous efforts have been made to bridge the significant gap between the supply and demand of effective treatments for GARDs. Recent decades have witnessed the impressive progress in the fight against GARDs, with an improved understanding of the genetic origins of rare diseases and the rapid development in gene therapy providing a new avenue for GARD therapy. RNA-based therapeutics, such as RNA interference (RNAi), messenger RNA (mRNA) and RNA-involved genome editing technologies, demonstrate great potential as a therapy tool for treating genetic associated rare diseases. In the meantime, a variety of RNA delivery vehicles were established for boosting the widespread applications of RNA therapeutics. Among all the RNA delivery platforms which enable the systemic applications of RNAs, non-viral RNA delivery biomaterials display superior properties and a few biomaterials have been successfully exploited for achieving the RNA-based gene therapies on GARDs. In this review article, we focus on recent advances in the development of novel biomaterials for delivery of RNA-based therapeutics and highlight their applications to treat GARDs.

Scientific methodology of the development of the Guidelines for the Care of People with Spina Bifida: An initiative of the Spina Bifida Association

BACKGROUND

We combined literature review and consensus-building methodologies to develop health care guidelines for people with Spina Bifida across the life span.

OBJECTIVE

The present paper describes the methodology used to update and expand this fourth edition of the Guidelines for the Care of People with Spina Bifida ("Guidelines"). This process was a fundamental initiative within the Spina Bifida Collaborative Care Network.

METHODS

Working groups were formed consisting of international, multidisciplinary teams of clinical and research experts. A systematic review of multiple databases was conducted. The consensus building methodology, One-Text Procedure, was followed to draft and revise documents. Each section of the Guidelines was presented by working group chairs at a face-to-face meeting using the Nominal Group Technique (NGT).

RESULTS

The Level 1 review resulted in 2449 abstracts being reviewed, and the Level 2 review resulted in 874 full text articles being archived for working groups. After working groups added and eliminated articles, a total of 803 manuscripts were included in the bibliography of the Guidelines. The final version of the Guidelines was then released in 2018.

CONCLUSIONS

Evidenced based-research and consensus methodologies were used to develop the fourth edition of the Guidelines. It is hoped that this document will guide not only health care providers, but also patients and families, so that people with Spina Bifida can have the best and most scientifically-based care and treatments throughout ever-longer and higher-quality lives.

Frontiers in Clinical Practice of Long-Term Care of Chronic Ventilatory Failure

Home mechanical ventilation (HMV) is an effective long-term treatment for chronic hypercapnic respiratory failure. In addition to the established practice of providing HMV for the treatment of chronic ventilatory failure in slowly progressive neuromuscular and chest wall disease, there is accumulating evidence for improvement of quality of life and prolongation of survival by HMV in highly prevalent diseases like chronic obstructive pulmonary disease and ever-increasing obesity hypoventilation syndrome as well as rapidly progressive neuromuscular disease. The key concepts for successful HMV are an experienced team selecting the right patients, timely initiation of adequate ventilation via an appropriate interface, and monitoring effectiveness during regular long-term follow-up. Coaching of patients with chronic respiratory failure on long-term HMV within a dedicated service and collaborations with community services for home care are essential. The current review describes various important practical aspects of HMV that remain frontiers in the implementation of the current knowledge in clinical practice and may help in providing effective HMV to all those in need.

Long-term treatment with eteplirsen in nonambulatory patients with Duchenne muscular dystrophy

This analysis aims to describe the outcomes of two nonambulatory patients with Duchenne muscular dystrophy (DMD) who participated in two clinical studies. The two consecutive trials of eteplirsen (studies 201 and 202) were conducted in patients with DMD (N = 12) and confirmed genetic mutations amenable to exon 51 skipping.In study 201, 12 patients were randomized to receive once-weekly, double-blind intravenous infusions of eteplirsen 30 or 50 mg/kg or placebo for 24 weeks; patients then received open-label eteplirsen during weeks 25 through 28. All 12 patients continued onto open-label extension study 202 and received long-term treatment with eteplirsen. We compared cardiac, pulmonary, and upper limb function and dystrophin production in the nonambulatory twin patients versus the 10 ambulatory patients through 240 combined treatment weeks.Ten study patients remained ambulatory through both studies, while the identical twin patients both experienced early, rapid loss of ambulation. The twin patients had greater disease severity at baseline (6-minute walk test [6MWT], 330 and 256 m) versus the other patients (n = 10; 6MWT range, 341-418 m). They maintained cardiac and upper limb function through combined week 240, with outcomes similar to those of the patients who remained ambulatory. Dystrophin production was confirmed following eteplirsen treatment.Despite the loss of ambulation, other markers of disease progression remained relatively stable in the eteplirsen-treated twin patients and were similar to those of the ambulatory patients.

Pubertal abnormalities in adolescents with chronic disease

Pubertal disorders in the context of chronic disease especially in those with chronic inflammatory disorders or those requiring prolonged periods of treatment with glucocorticoid are common reasons for referral to the paediatric endocrine clinic. Disorders of puberty are also common in adolescents with disability requiring management by paediatric endocrinologists. In these adolescents, impaired skeletal development is also observed and this can be associated with fragility fractures. Chronic inflammation, glucocorticoid and sub-optimal nutrition all impact on the hypothalamic-pituitary gonadal axis, and can also impact on skeletal development locally by their effects on the growth plate and bone. Addressing pubertal disorders is important to ensure adolescents with chronic disease are matched with their peers, promote adequate bone mass accrual and linear growth. Careful discussion with primary clinicians, the young person and the family is needed when instituting endocrine therapies to address puberty and manage bone health.

Effectiveness of High-Speed T2-Corrected Multiecho MR Spectroscopic Method for Quantifying Thigh Muscle Fat Content in Boys With Duchenne Muscular Dystrophy

OBJECTIVE. The purpose of this study was to investigate the potential of high-speed T2-corrected multiecho (HISTO) MR spectroscopy (MRS) for rapidly quantifying the fat content of thigh muscles in children with Duchenne muscular dystrophy (DMD). SUBJECTS AND METHODS. This study prospectively enrolled 58 boys with DMD (mean age, 7.5 years; range, 4-11 years) and 30 age-matched healthy boys (mean age, 7.2 years; range, 4-11 years) at one institution over a 1-year period. T1- and T2-weighted, multiecho Dixon, and HISTO sequences were performed on the right adductor magnus and vastus lateralis muscles. The fat fractions of these muscles were acquired from HISTO and multiecho Dixon images. An experienced radiologist graded the degree of fat infiltration of the adductor magnus and vastus lateralis muscles on axial T1-weighted images. The Bland-Altman method was used to assess the consistency and repeatability of the HISTO sequence. Pearson linear correlation analysis was used to determine the correlation coefficient relating HISTO fat fraction to multiecho Dixon fat fraction values. Spearman rank correlation analysis was used to assess the relation between the HISTO fat fraction values and T1-weighted image fat infiltration grades. The independent t test was used to compare the HISTO fat fraction values of the boys with DMD with those of the healthy control subjects. RESULTS. Bland-Altman analysis showed that 95.5% of the HISTO fat fraction values of the adductor magnus were within the 95% CI. HISTO fat fraction and multiecho Dixon fat fraction values of the adductor magnus and vastus lateralis muscles were highly positively correlated (adductor magnus, r = 0.983; vastus lateralis, r = 0.967; p < 0.0001). HISTO fat fraction values were also highly positively correlated with the grades of fat infiltration on T1-weighted images (adductor magnus, r = 0.911; vastus lateralis, r = 0.937; p < 0.0001). The HISTO fat fraction of the adductor magnus muscle was 33.3% ± 22.6% and of the vastus lateralis muscle was 25.6% ± 20.3% in patients with DMD. The corresponding values were 2.9% ± 2.1% and 2.3% ± 1.9% in the control group. The differences were statistically significant (p < 0.0001). CONCLUSION. The HISTO sequence is a rapid and feasible noninvasive MRS technique for quantifying the fat infiltration of thigh muscles in children with known or suspected DMD. It is useful for diagnosis and for assessment of disease activity and prognosis.

Effect and safety of treatment with ACE-inhibitor Enalapril and β-blocker metoprolol on the onset of left ventricular dysfunction in Duchenne muscular dystrophy - a randomized, double-blind, placebo-controlled trial

BACKGROUND

X-linked Duchenne muscular dystrophy (DMD), the most frequent human hereditary skeletal muscle myopathy, inevitably leads to progressive dilated cardiomyopathy. We assessed the effect and safety of a combined treatment with the ACE-inhibitor enalapril and the β-blocker metoprolol in a German cohort of infantile and juvenile DMD patients with preserved left ventricular function.

METHODS TRIAL DESIGN

Sixteen weeks single-arm open run-in therapy with enalapril and metoprolol followed by a two-arm 1:1 randomized double-blind placebo-controlled treatment in a multicenter setting.

INCLUSION CRITERIA

DMD boys aged 10-14 years with left ventricular fractional shortening [LV-FS] ≥ 30% in echocardiography. Primary endpoint: time from randomization to first occurrence of LV-FS < 28%. Secondary: changes of a) LV-FS from baseline, b) blood pressure, c), heart rate and autonomic function in ECG and Holter-ECG, e) cardiac biomarkers and neurohumeral serum parameters, f) quality of life, and g) adverse events.

RESULTS

From 3/2010 to 12/2013, 38 patients from 10 sites were centrally randomized after run-in, with 21 patients continuing enalapril and metoprolol medication and 17 patients receiving placebo. Until end of study 12/2015, LV-FS < 28% was reached in 6/21 versus 7/17 patients. Cox regression adjusted for LV-FS after run-in showed a statistically non-significant benefit for medication over placebo (hazard ratio: 0.38; 95% confidence interval: 0.12 to 1.22; p = 0.10). Analysis of secondary outcome measures revealed a time-dependent deterioration of LV-FS with no statistically significant differences between the two study arms. Blood pressure, maximal heart rate and mean-NN values were significantly lower at the end of open run-in treatment compared to baseline. Outcome analysis 19 months after randomization displayed significantly lower maximum heart rate and higher noradrenalin and renin values in the intervention group. No difference between treatments was seen for quality of life. As a single, yet important adverse event, the reversible deterioration of walking abilities of one DMD patient during the run-in period was observed.

CONCLUSIONS

Our analysis of enalapril and metoprolol treatment in DMD patients with preserved left ventricular function is suggestive to delay the progression of the intrinsic cardiomyopathy to left ventricular failure, but did not reach statistical significance, probably due to insufficient sample size.

CLINICAL TRIAL REGISTRATION

DRKS-number 00000115, EudraCT-number 2009-009871-36.