Interventions to prevent and treat corticosteroid-induced osteoporosis and prevent osteoporotic fractures in Duchenne muscular dystrophy

The Use of Whole-Body Vibration, Electrical Stimulation, and Magnetic Stimulation in Muscle Dystrophy Patients: A Scoping Review

The purpose of this scoping review was to report the effects of vibration therapy, electrical stimulation, and transcranial magnetic stimulation on patients with muscle dystrophies. The outcome measures were muscle strength, body composition, balance, and functional mobility of these patients. We used the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and the Arksey and O'Malley framework. The literature review was conducted on PubMed. We included studies that were written in English, were peer-reviewed, without regard to the publication date, and implemented a form of "vibration therapy" or "electrical stimulation" or "magnetic stimulation" as an intervention program of any duration. Overall, 14 studies were retrieved. Most of the studies applied whole-body vibration (WBV) therapy or electrical stimulation and only one was found that implemented transcranial magnetic stimulation. The interventions were reported but there was a variety in duration or the frequency of the program, as well as in the disease progression of the patients. It seems that WBV, electrical stimulation, and magnetic stimulation have positive outcomes, but these vary depending on the muscle deficits and limitations of the patients with muscle dystrophy. It is recommended that future studies should be conducted in order to determine the ideal prescription of each intervention, so as to be as beneficial as possible.

Different bone health progression patterns and early-stage risk marker in glucocorticoid-treated ambulatory Duchenne muscular dystrophy

Fractures often cause irreversible harm in Duchenne muscular dystrophy (DMD). This study investigated the trajectory of bone mineral density (BMD) using group-based trajectory modeling and identified that BMD acts as an early-stage indicator of clinically significant bone fragility. The greater the early-stage BMD, the better the 4-year bone health outcome.

PURPOSE

Most Duchenne muscular dystrophy (DMD) children suffer bone loss after long-term glucocorticoid (GC) exposure, which induces scoliosis and fragility fractures. To assess the BMD progression pattern and individual medical risk markers for these phenotypes in young ambulatory boys with DMD, and provide evidence-based suggestions for clinical management of bone health.

METHODS

A retrospective longitudinal cohort study of 153 boys with DMD in West China Second University Hospital (2016-2023) was performed. Group-based trajectory modeling was used to study the BMD progression pattern, and potential predictors were further analyzed by logistic regression and survival analysis.

RESULTS

One hundred and fifty-three participants were included, 71 of which had more than 3 BMD records. Three BMD trajectories were identified. Baseline BMD and age-started GC and were independent predictors of trajectory attribution. The median survival time of the first observation of low BMD in GC-treated DMD boys was 5.32 (95% CI 4.05-6.59) years, and a significant difference was tested (P < 0.001) among the three trajectory groups.

CONCLUSION

BMD may serve as a novel early indicating marker for monitoring bone fragility for DMD. We proposed a bone health risk stratification through BMD progression trajectory that allows us to adapt the osteoporosis warning sign in DMD from a fixed threshold approach to a more individualized strategy, where baseline BMD and age of glucocorticoid initiation can provide an earlier prediction of bone loss. Better management of primary BMD may be able to delay or avoid the onset of adverse bone health outcomes in the fifth year in children with DMD.

Osteoporosis in children and adolescents: how to treat and monitor?

Osteoporosis is a condition of increased bone fragility associated with fractures. Apart from primary genetic osteoporotic conditions, secondary osteoporosis in children is being increasingly recognized. As a result, there is growing interest in its prevention and treatment. Important goals of care are to prevent fractures, increase bone mass and trabecular and cortical thickness, reshape vertebral fractures, prevent (or correct) skeletal deformities, and improve mobility, independence, and quality of life. Secondary pediatric osteoporosis is often of multifactorial origin since affected children frequently have more than one acquired factor that is detrimental to bone health. Typical conditions causing osteoporosis are leukemias, progressive muscle or neurological disorders, as well as chronic inflammatory conditions and their treatment. Management of children with osteoporosis involves a multidisciplinary team involving pediatric experts from different subspecialties. With regard to prevention and early intervention, it is important to provide optimal management of any underlying systemic conditions including avoidance, or dose-reduction, of osteotoxic medications. Basic supporting life-style measures, such as appropriate nutrition, including adequate calcium intake and vitamin D, and physical activity are recommended, where possible. When pediatric treatment criteria for osteoporosis are met, antiresorptive drugs constitute the first pharmacological line treatment.

CONCLUSION

This clinical review focuses on the prevention, treatment, and follow-up of children with, or at risk of developing, osteoporosis and the transition from pediatric to adult care.

WHAT IS KNOWN

• Osteoporosis and associated fractures can cause significant morbidity and reduce the quality of life. • The developing skeleton has huge potential for recovery and reshaping, thus early detection of fractures, assessment of recovery potential, and treatment of children with osteoporosis can prevent future fractures, deformities, and scoliosis, improve function and mobility, and reduce pain.

WHAT IS NEW

• Osteoporosis in children and adolescents requires a multidisciplinary approach with a thorough assessment of recovery potential, and indication for therapy should be personalized. • Although bisphosphonates still represent the drug most commonly used to increase bone mass, improve mobility, and reduce pain and recurrence of fractures, new agents are being developed and could be beneficial in children with specific conditions.

Update of the Brazilian consensus recommendations on Duchenne muscular dystrophy

In the last few decades, there have been considerable improvements in the diagnosis and care of Duchenne muscular dystrophy (DMD), the most common childhood muscular dystrophy. International guidelines have been published and recently reviewed. A group of Brazilian experts has developed a standard of care based on a literature review with evidence-based graded recommendations in a two-part publication. Implementing best practice management has helped change the natural history of this chronic progressive disorder, in which the life expectancy for children of the male sex in the past used to be very limited. Since the previous publication, diagnosis, steroid treatment, rehabilitation, and systemic care have gained more significant insights with new original work in certain fields. Furthermore, the development of new drugs is ongoing, and some interventions have been approved for use in certain countries. Therefore, we have identified the need to review the previous care recommendations for Brazilian patients with DMD. Our objective was to create an evidence-based document that is an update on our previous consensus on those topics.

Advances in Diagnosis and Management of Childhood Osteoporosis

Childhood osteoporosis leads to increased propensity to fracture, and thus is an important cause of morbidity, pain and healthcare utilisation. Osteoporosis in children may be caused by a primary bone defect or secondary to an underlying medical condition and/or its treatment. Primary osteoporosis is rare, but there is an increasing number of children with risk factors for secondary osteoporosis. Therefore it is imperative that all paediatricians are aware of the diagnostic criteria and baseline investigations for childhood osteoporosis to enable timely referral to a specialist in paediatric bone health. This review will discuss the approach to diagnosis, investigation and management of childhood osteoporosis, with particular consideration to advances in molecular diagnosis of primary bone disorders, and current and emerging therapies for fracture reduction.

Reduced bone mineral density in adolescents with Duchenne Muscular Dystrophy (DMD) and scoliosis

Duchenne muscular dystrophy is a progressive disease usually associated with loss of ambulation and progressive scoliosis. Immobilisation and glucocorticoid treatment are predisposing factors for reduced bone mineral density (BMD). Analysis of quantitative computed tomography revealed low BMD in thoracic and lumbar vertebrae in comparison to age- and sex-matched healthy controls.

INTRODUCTION

Evaluation of vertebral bone mineral density (BMD) in Duchenne Muscular Dystrophy (DMD) adolescents with untreated advanced scoliosis and comparison with the BMD values of healthy age-matched controls, based on quantitative computer tomography.

METHODS

Thirty-seven DMD adolescents (age 15.6 ± 2.5 years) with spinal deformity were evaluated clinically and radiologically prior to definite spinal fusion and compared to 31 male and age-matched healthy individuals (age 15.7 ± 2.3 years). Data related to previous medical treatment, physiotherapy and ambulatory status was also analysed. Scoliotic curves were measured on plain sitting radiographs of the spine. The BMD Z-scores of the thoracic and lumbar vertebrae were calculated with QCTpro® (Mindways Software Inc., USA), based on data sets of preoperative, phantom pre-calibrated spinal computed tomography scans.

RESULTS

A statistically significant lower BMD could be found in DMD adolescents, when compared to healthy controls, showing an average value for the lumbar spine of 80.5 ± 30.5 mg/cm³. Z-scores deteriorated from the upper thoracic towards the lower lumbar vertebrae. All but the uppermost thoracic vertebrae had reduced BMD values, with the thoracolumbar and lumbar region demonstrating the lowest BMD. No significant correlation was observed between BMD and the severity of the scoliotic curve, previous glucocorticoid treatment, cardiovascular impairment, vitamin D supplementation, non-invasive ventilation or physiotherapy.

CONCLUSION

DMD adolescents with scoliosis have strongly reduced BMD Z-scores, especially in the lumbar spine in comparison to healthy controls. These findings support the implementation of a standardised screening and treatment protocol. Level of evidence/clinical relevance: therapeutic level III.

Bone health in Duchenne muscular dystrophy: clinical and biochemical correlates

PURPOSE

An increased fracture risk is commonly reported in Duchenne muscular dystrophy (DMD). Our aim was to investigate bone mineral density (BMD) and bone turnover, including sclerostin, and their association with markers of cardiac and respiratory performance in a cohort of DMD subjects.

METHODS

In this single center, cross sectional observational study, lumbar spine (LS) BMD Z-scores, C-terminal telopeptide of procollagen type I (CTX) and osteocalcin (BGP), as bone resorption and formation markers, respectively, and sclerostin were assessed. Left ventricular ejection fraction (LVEF) and forced vital capacity (FVC) were evaluated. Clinical prevalent fractures were also recorded.

RESULTS

Thirty-one patients [median age = 14 (12-21.5) years] were studied. Ambulant subjects had higher LS BMD Z-scores compared with non-ambulant ones and subjects with prevalent clinical fractures [n = 9 (29%)] showed lower LS BMD Z-scores compared with subjects without fractures. LS BMD Z-scores were positively correlated with FVC (r = 0.50; p = 0.01), but not with glucocorticoid use, and FVC was positively associated with BGP (r = 0.55; p = 0.02). In non-ambulant subjects, LS BMD Z-scores were associated with BMI (r = 0.54; p = 0.02) and sclerostin was associated with age (r = 0.44; p = 0.05). Age, BMI, FVC and sclerostin were independently associated with LS BMD Z-score in a stepwise multiple regression analysis. Older age, lower BMI, FVC and sclerostin were associated with lower LS BMD Z-scores.

CONCLUSION

In a cohort of DMD patients, our data confirm low LS BMD Z-scores, mainly in non-ambulant subjects and irrespective of the glucocorticoid use, and suggest that FVC and sclerostin are independently associated with LS BMD Z-scores.

Outcomes of Zoledronic Acid Use in Paediatric Conditions

INTRODUCTION

Limited evidence is available concerning experience with use of zoledronic acid (ZA) and treatment for conditions other than primary bone fragility.

MATERIALS AND METHODS

A retrospective review of all Royal Children Hospital patients who had been administered at least 1 dose of intravenous ZA from 2002 to 2015 was undertaken.

RESULTS

The audit included 309 children with 228 being treated for bone fragility conditions. Of the 228, 68 had height-adjusted lumbar spine bone mineral density Z-scores available over up to a 5-year period, and median increases were +2.0 SD (median absolute deviation = 0.9) (N = 36, p value for median increase of at least 0.5 in Z-score <0.001), for patients with osteogenesis imperfecta or other primary bone fragility disorders, +1.0 SD (0.9) (N = 14, p = 0.029), for immobility conditions, +0.5 SD (0.7) (N = 10, p = 0.399), and for glucocorticoid-induced secondary osteoporosis, +0.7 SD (0.6) (N = 8, p = 0.015). 81/309 children were treated for bone abnormality indications (e.g., avascular necrosis [AVN], fibrous dysplasia, and bone cysts). Of 39 with AVN, outcome data were available for 33, with joint integrity maintained for 24/33 from 6 to 24 months after last ZA, subjective reports (22/28) of reduced pain. Reduction in bone lesion size was seen in 2/4 patients with bone cysts within 12 months of ZA commencement.

DISCUSSION/CONCLUSION

This is the largest cohort of reported outcomes of ZA use in a paediatric population. Results demonstrate a good efficacy profile and associated improved bone density for osteoporotic conditions and stabilization of non-traumatic AVN with a low rate of joint collapse.

Becker muscular dystrophy: case report, review of the literature, and analysis of differentially expressed hub genes

INTRODUCTION

Becker muscular dystrophy (BMD) is a genetic and progressive neuromuscular disease caused by mutations in the dystrophin gene with no available cure. A case report and comprehensive review of BMD cases aim to provide important clues for early diagnosis and implications for clinical practice. Genes and pathways identified from microarray data of muscle samples from patients with BMD help uncover the potential mechanism and provide novel therapeutic targets for dystrophin-deficient muscular dystrophies.

METHODS

We describe a BMD family with a 10-year-old boy as the proband and reviewed BMD cases from PubMed. Datasets from the Gene Expression Omnibus database were downloaded and integrated with the online software.

RESULTS

The systematic review revealed the clinical manifestations and mutation points of the dystrophin gene. Gene ontology analysis showed that extracellular matrix organization and extracellular structure organization with enrichment of upregulated genes coexist in three datasets. We present the first report of TUBA1A involvement in the development of BMD/Duchenne muscular dystrophy (DMD).

DISCUSSION

This study provides important implications for clinical practice, uncovering the potential mechanism of the progress of BMD/DMD, and provided new therapeutic targets.

Bone microarchitectural alterations in boys with Duchenne muscular dystrophy on long-term glucocorticoid treatment

INTRODUCTION

Osteoporosis is a major health issue in boys with Duchenne muscular dystrophy (DMD). Data on the specific bone deficits and microarchitectural alterations in children with DMD were limited. This study aimed to assess the bone microarchitectural alterations in boys with DMD on long-term glucocorticoid using high-resolution peripheral quantitative computed tomography (HR-pQCT).

MATERIALS AND METHODS

This was a cross-sectional, case-control study. Boys with DMD older than 5 years with no prior history of symptomatic fracture and had been on long-term glucocorticoid treatment were recruited from a single tertiary centre. For each participant, three gender- and age-matched controls were selected randomly from an existing HR-pQCT database of healthy individuals.

RESULTS

Nine boys with DMD at a median age of 9.3 years were included. Three were found to have asymptomatic vertebral compression fracture. The HR-pQCT findings of these nine boys were compared with 27 healthy controls. Trabecular microstructure indices at the distal radius were significantly lower but the cortical vBMD was significantly higher in the DMD boys when compared with healthy controls.

CONCLUSION

Lower microarchitectural measurement of trabecular bones, but higher cortical vBMD, was observed in DMD boys on long-term oral glucocorticoid. The results from this study provide preliminary, yet important insights into the bone microarchitecture of this group of patients.

The Positive Impact of Vitamin D on Glucocorticoid-Dependent Skeletal Muscle Atrophy

(1) The study aimed to investigate whether vitamin D₃ supplementation would positively affect rats with glucocorticoids-induced muscle atrophy as measured by skeletal muscle mass in two experimental conditions: chronic dexamethasone (DEX) administration and a model of the chronic stress response. (2) The study lasted 28 consecutive days and was performed on 45 male Wistar rats randomly divided into six groups. These included two groups treated by abdominal injection of DEX at a dose of 2 mg/kg/day supplemented with vegetable oil (DEX PL; n = 7) or with vitamin D₃ 600 IU/kg/day (DEX SUP; n = 8), respectively, and a control group treated with an abdominal injection of saline (CON; n = 6). In addition, there were two groups of rats chronically stressed by cold water immersion (1 hour/day in a glass box with 1-cm-deep ice/water mixture; temperature ~4 °C), which were supplemented with vegetable oil as a placebo (STR PL; n = 9) or vitamin D₃ at 600 IU/kg/day (STR SUP; n = 9). The last group was of sham-stressed rats (SHM; n = 6). Blood, soleus, extensor digitorum longus, gastrocnemius, tibialis anterior, and quadriceps femoris muscles were collected and weighed. The heart, liver, spleen, and thymus were removed and weighed immediately after sacrifice. The plasma corticosterone (CORT) and vitamin D₃ metabolites were measured. (3) We found elevated CORT levels in both cold water-immersed groups; however, they did not alter body and muscle weight. Body weight and muscle loss occurred in groups with exogenously administered DEX, with the exception of the soleus muscle in rats supplemented with vitamin D₃. Decreased serum 25(OH)D₃ concentrations in DEX-treated rats were observed, and the cold water immersion did not affect vitamin D₃ levels. (4) Our results indicate that DEX-induced muscle loss was abolished in rats supplemented with vitamin D₃, especially in the soleus muscle.

Aberrant RhoA activation in macrophages increases senescence-associated secretory phenotypes and ectopic calcification in muscular dystrophic mice

Duchenne Muscular Dystrophy (DMD) patients often suffer from both muscle wasting and osteoporosis. Our previous studies have revealed reduced regeneration potential in skeletal muscle and bone, concomitant with ectopic calcification of soft tissues in double knockout (dKO, dystrophin-/-; utrophin-/-) mice, a severe murine model for DMD. We found significant involvement of RhoA/ROCK (Rho-Associated Protein Kinase) signaling in mediating ectopic calcification of muscles in dKO mice. However, the cellular identity of these RhoA+ cells, and the role that RhoA plays in the chronic inflammation-associated pathologies has not been elucidated. Here, we report that CD68+ macrophages are highly prevalent at the sites of ectopic calcification of dKO mice, and that these macrophages highly express RhoA. Macrophages from dKO mice feature a shift towards a more pro-inflammatory M1 polarization and an increased expression of various senescence-associated secretory phenotype (SASP) factors that was reduced with the RhoA/ROCK inhibitor Y-27632. Further, systemic inhibition of RhoA activity in dKO mice led to reduced number of RhoA+/CD68+ cells, as well as a reduction in fibrosis and ectopic calcification. Together, these data revealed that RhoA signaling may be a key regulator of imbalanced mineralization in the dystrophic musculoskeletal system and consequently a therapeutic target for the treatment of DMD or other related muscle dystrophies.

Effects of Bisphosphonate Therapy on Bone Mineral Density in Boys with Duchenne Muscular Dystrophy

The objective of this study was to estimate the comparative effectiveness of bisphosphonate therapy on bone mineral density (BMD) in patients with corticosteroid-treated Duchenne muscular dystrophy (DMD). A retrospective, comparative effectiveness study evaluating changes in BMD and fragility fractures in patients with DMD presenting to British Columbia Children's Hospital from 1989 to 2017 was conducted. Marginal structural generalized estimating equation models weighted by stabilized inverse-probability of treatment weights were used to estimate the comparative effectiveness of therapy on BMD. Of those treated with bisphosphonates (N = 38), 7 (18.4%), 17 (44.7%), and 14 (36.8%) cases were treated with pamidronate, zoledronic acid, or a combination of both, respectively, while 36 cases of DMD were untreated. Mean age of bisphosphonate initiation was 9.2 (SD 2.7) years. Mean fragility fractures declined from 3.5 to 1.0 following bisphosphonate therapy. Compared to the treated group, the untreated group had an additional 0.63-SD decrease (95% confidence interval [CI]: -1.18, -0.08, P = .026) in total BMD and an additional 1.04-SD decrease (95% CI: -1.74, -0.34; P = .004) in the left hip BMD, but the change in lumbar spine BMD (0.15, 95% CI: -0.36, 0.66; P = .57) was not significant. Bisphosphonate therapy may slow the decline in BMD in boys with corticosteroid-treated DMD compared to untreated counterparts. Total number of fragility fractures decreased following bisphosphonate therapy.

Effects of Neurological Disorders on Bone Health

Neurological diseases, particularly in the context of aging, have serious impacts on quality of life and can negatively affect bone health. The brain-bone axis is critically important for skeletal metabolism, sensory innervation, and endocrine cross-talk between these organs. This review discusses current evidence for the cellular and molecular mechanisms by which various neurological disease categories, including autoimmune, developmental, dementia-related, movement, neuromuscular, stroke, trauma, and psychological, impart changes in bone homeostasis and mass, as well as fracture risk. Likewise, how bone may affect neurological function is discussed. Gaining a better understanding of brain-bone interactions, particularly in patients with underlying neurological disorders, may lead to development of novel therapies and discovery of shared risk factors, as well as highlight the need for broad, whole-health clinical approaches toward treatment.

Management of primary and secondary osteoporosis in children

Osteoporosis in children differs from adults in terms of definition, diagnosis, monitoring and treatment options. Primary osteoporosis comprises primarily of osteogenesis imperfecta (OI), but there are significant other causes of bone fragility in children that require treatment. Secondary osteoporosis can be a result of muscle disuse, iatrogenic causes, such as steroids, chronic inflammation, delayed or arrested puberty and thalassaemia major. Investigations involve bone biochemistry, dual-energy X-ray absorptiometry scan for bone densitometry and vertebral fracture assessment, radiographic assessment of the spine and, in some cases, quantitative computed tomography (QCT) or peripheral QCT. It is important that bone mineral density (BMD) results are adjusted based on age, gender and height, in order to reflect size corrections in children. Genetics are being used increasingly for the diagnosis and classification of various cases of primary osteoporosis. Bone turnover markers are used less frequently in children, but can be helpful in monitoring treatment and transiliac bone biopsy can assist in the diagnosis of atypical cases of osteoporosis. The management of children with osteoporosis requires a multidisciplinary team of health professionals with expertise in paediatric bone disease. The prevention and treatment of fragility fractures and improvement of the quality of life of patients are important aims of a specialised service. The drugs used most commonly in children are bisphosphonates, that, with timely treatment, can give good results in improving BMD and reshaping vertebral fractures. The data regarding their effect on reducing long bone fractures are equivocal. Denosumab is being used increasingly for various conditions with mixed results. There are more drugs trialled in adults, but these are not yet licenced for children. Increasing awareness of risk factors for paediatric osteoporosis, screening and referral to a specialist team for appropriate management can lead to early detection and treatment of asymptomatic fractures and prevention of further bone damage.

Does Whole-Body Vibration Treatment Make Children's Bones Stronger?

PURPOSE OF REVIEW

To summarize the last 10 years of literature regarding the effects of whole-body vibration (WBV) on bone in children, and if WBV results in increased bone acquisition.

RECENT FINDINGS

WBV intervention appears to be a safe intervention with beneficial effects on bone mass in some diseases and syndromes, but there is still low evidence for WBV in clinical practice. The positive effects on muscle strength, balance, and walking speed are more conclusive. One of the takeaways of this review is that well-trained individuals may not further improve bone mass with WBV; thus, interventions are more beneficial in pediatric individuals with Down syndrome or severe motor disabilities with low bone mass and reduced activity levels. WBV appears to be a safe non-pharmacological anabolic approach to increase bone mass in some pediatric populations; however, longer (> 6 months) and larger prospective studies are needed to elucidate the efficacy of WBV on bone health in young individuals.

Expert panel consensus recommendations for diagnosis and treatment of secondary osteoporosis in children

BACKGROUND

Osteoporosis incidence in children is increasing due to the increased survival rate of patients suffering from chronic diseases and the increased use of drugs that can damage bones. Recent changes made to the definition of childhood osteoporosis, along with the lack of guidelines or national consensuses regarding its diagnosis and treatment, have resulted in a wide variability in the approaches used to treat this disease. For these reasons, the Osteogenesis Imperfecta and Childhood Osteoporosis Working Group of the Spanish Society of Pediatric Rheumatology has sounded the need for developing guidelines to standardize clinical practice with regard to this pathology.

METHODS

An expert panel comprised of 6 pediatricians and 5 rheumatologists carried out a qualitative literature review and provided recommendations based on evidence, when that was available, or on their own experience. The level of evidence was determined for each section using the Oxford Centre for Evidence-based Medicine (CEBM) system. A Delphi survey was conducted for those recommendations with an evidence level of IV or V. This survey was sent to all members of the SERPE. All recommendations that had a level of agreement higher or equal to 70% were included.

RESULTS

Fifty-one recommendations, categorized into eight sections, were obtained. Twenty-four of them presented an evidence level 4 or 5, and therefore a Delphi survey was conducted. This was submitted electronically and received a response rate of 40%. All recommendations submitted to the Delphi round obtained a level of agreement of 70% or higher and were therefore accepted.

CONCLUSION

In summary, we present herein guidelines for the prevention, diagnosis and treatment of secondary childhood osteoporosis based on the available evidence and expert clinical experience. We believe it can serve as a useful tool that will contribute to the standardization of clinical practice for this pathology. Prophylactic measures, early diagnosis and a proper therapeutic approach are essential to improving bone health, not only in children and adolescents, but also in the adults they will become in the future.

Fractures and Linear Growth in a Nationwide Cohort of Boys With Duchenne Muscular Dystrophy With and Without Glucocorticoid Treatment: Results From the UK NorthStar Database

Importance

Based on studies with relatively small sample size, fragility fractures are commonly reported in glucocorticoid (GC)-treated boys with Duchenne muscular dystrophy (DMD).

Objective

To determine the fracture burden and growth impairment in a large contemporary cohort of boys with DMD in the United Kingdom and in relation to GC regimen.

Design, Setting, and Participants

A retrospective review of fracture morbidity and growth from 832 boys with DMD in the UK NorthStar database (2006-2015), which systematically captures information from 23 participating centers. A total of 564 boys had more than 1 visit. No numbers of boys who refused were collected, but informal data from 2 centers in London and from Scotland show that refusal is very low. Data were analyzed between October 2006 and October 2015.

Main Outcomes and Measures

Fracture incidence rate per 10 000 person-years was determined. Cox regression analysis was used to identify factors associated with first fracture.

Results

Median age at baseline was 6.9 years (interquartile range, 4.9-7.2 years). At baseline, new fractures were reported in 7 of 564 participants (1.2%). During a median follow-up of 4 years (interquartile range, 2.0-6.0 years), incident fractures were reported in 156 of 564 participants (27.7%), corresponding to an overall fracture incidence rate of 682 per 10 000 person-years (95% CI, 579-798). The highest fracture incidence rate was observed in those treated with daily deflazacort at 1367 per 10 000 person-years (95% CI, 796-2188). After adjusting for age at last visit, mean hydrocortisone equivalent dose, mobility status, and bisphosphonate use prior to first fracture, boys treated with daily deflazacort had a 16.0-fold increased risk for first fracture (95% CI, 1.4-180.8; P = .03). Using adjusted regression models, change in height standard deviation scores was -1.6 SD lower (95% CI, -3.0 to -0.1; P = .03) in those treated with daily deflazacort compared with GC-naive boys, whereas there were no statistical differences in the other GC regimen.

Conclusions and Relevance

In this large group of boys with DMD with longitudinal data, we document a high fracture burden. Boys treated with daily deflazacort had the highest fracture incidence rate and the greatest degree of linear growth failure. Clinical trials of primary bone protective therapies and strategies to improve growth in boys with DMD are urgently needed, but stratification based on GC regimen may be necessary.

Neuromuscular Diseases and Bone

Neuromuscular diseases (NMDs) are inherited or acquired conditions affecting skeletal muscles, motor nerves, or neuromuscular junctions. Most of them are characterized by a progressive damage of muscle fibers with reduced muscle strength, disability, and poor health-related quality of life of affected patients. In this scenario, skeletal health is usually compromised as a consequence of modified bone-muscle cross-talk including biomechanical and bio-humoral issues, resulting in increased risk of bone fragility and fractures. In addition, NMD patients frequently face nutritional issues, including malnutrition due to feeding disorders and swallowing problems that might affect bone health. Moreover, in these patients, low levels of physical activity or immobility are common and might lead to overweight or obesity that can also interfere with bone strength features. Also, vitamin D deficiency could play a critical role both in the pathogenesis and in the clinical scenario of many NMDs, suggesting that its correction could be useful in maintaining or enhancing bone health, especially in the early phases of NMDs. Last but not least, specific disease-modifying drugs, available for some NMDs, are frequently burdened with adverse effects on bone tissue. For example, glucocorticoid therapy, standard of care for many muscular dystrophies, prolongs long-term survival in treated patients; nevertheless, high dose and/or chronic use of these drugs are a common cause of secondary osteoporosis. This review addresses the current state of knowledge about the factors that play a role in determining bone alterations reported in NMDs, how these factors can modify the biological pathways underlying bone health, and which are the available interventions to manage bone involvement in patients affected by NMDs. Considering the complexity of care of these patients, an interdisciplinary and multimodal management strategy based on both pharmacological and non-pharmacological interventions is recommended, particularly targeting musculoskeletal issues that are closely related to functional independence as well as social implications.

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.

Distrofia muscular de Becker con duplicación en el exón 5del gen DMD

Las distrofinopatías son un grupo de enfermedades ligadas al cromosoma X que abarcan diferentes entidades, siendo las más importantes la distrofia muscular de Duchenne (DMD) y la de Becker (DMB). Están causadas por mutaciones en el gen de la distrofina (gen DMD) localizado en el cromosoma X, locus Xp21.1. En relación con el tipo de mutaciones reportadas en el gen DMD, las delecciones  y las mutaciones puntuales son las más comunes,  mientras que las duplicaciones corresponden a 10-12%. Aunque las duplicaciones que abarcan el exón 5 ya han sido reportadas en la literatura, a la fecha no existen informes de casos que establezcan una relación genotipo fenotipo clara.  Presentamos el caso de un paciente con distrofia muscular de Becker con un fenotipo no tan severo, en quien se encontró una duplicación en el exón 5.  Con este caso pretendemos profundizar en la relación genotipo-fenotipo de la DMB, reportando las características clínicas en relación con la duplicación del exón 5 encontrada.

Growth, pubertal development, and skeletal health in boys with Duchenne Muscular Dystrophy

PURPOSE OF REVIEW

Glucocorticoid therapy is currently the most widely used treatment for Duchenne muscular dystrophy (DMD), having consistently shown to prolong ambulation by 2 years, reduce the frequency of scoliosis, and improve cardiorespiratory function. Among the most frequent side effects of glucocorticoids are fractures due to osteoporosis, linear growth retardation or arrest, and pubertal delay, the subjects of this review.

RECENT FINDINGS

The diagnosis of osteoporosis has shifted in recent years away from a bone mineral density-centric to a fracture-focused approach, with particular emphasis on early vertebral fracture identification (one of the key triggers for osteoporosis intervention). Delayed puberty should be addressed in an age-appropriate manner, with numerous options available for sex steroid replacement. Growth impairment, however, is a more challenging complication of glucocorticoid-treated DMD, one that is most likely best addressed through growth-sparing therapies that target the dystrophinopathy.

SUMMARY

With glucocorticoid prescription an increasingly prevalent component of DMD care, early attention to management of osteoporosis and delayed puberty are important components of multidisciplinary and anticipatory care. The treatment of short stature remains controversial, with no accepted therapy currently available to over-ride the toxic effects of glucocorticoids on the growth axis.

Clinical management of Duchenne muscular dystrophy: the state of the art

INTRODUCTION

Duchenne muscular dystrophy (DMD) is a devastating, progressive neuromuscular disorder for which there is no cure. As the dystrophin gene is located on the X chromosome, DMD occurs predominately in males. DMD is caused by a lack of functional dystrophin protein resulting from mutations in the 2.2-Mb DMD gene, whichdisrupts the reading frame. Care considerations for DMD advocate a coordinated, multidisciplinary approach to the management of DMD in order to optimize management of the primary manifestations of DMD as well as any secondary complications that may arise.

METHODS

This review provides an overview of the multidisciplinary clinical management of DMD with regard to the respiratory, cardiology, orthopedic, and nutritional needs of patients with DMD. Recent advances in novel disease-modifying treatments for DMD are also discussed with specific reference to exon skipping and suppression of premature stop codons as promising genetic therapies.

RESULTS

The combination of multidisciplinary clinical management alongside novel gene therapiesoffers physicians a powerful armamentarium for the treatment of DMD.

Phase 1 trial of vamorolone, a first-in-class steroid, shows improvements in side effects via biomarkers bridged to clinical outcomes

BACKGROUND

Glucocorticoid drugs are highly effective anti-inflammatory agents, but chronic use is associated with extensive pharmacodynamic safety concerns that have a considerable negative impact on patient quality of life.

PURPOSE

Vamorolone (VBP15) is a first-in-class steroidal multi-functional drug that shows potent inhibition of pro-inflammatory NFkB pathways via high-affinity binding to the glucocorticoid receptor, high affinity antagonism for the mineralocorticoid receptor, and membrane stabilization properties. Pre-clinical data in multiple mouse models of inflammation showed retention of anti-inflammatory efficacy, but loss of most or all side effects.

EXPERIMENTAL APPROACH

We report first-in-human Phase 1 clinical trials (86 healthy adult males), with single ascending doses (0.1-20.0 mg/kg), and multiple ascending doses (1.0-20 mg/kg/day; 14 days treatment).

KEY RESULTS

Vamorolone was well-tolerated at all dose levels. Vamorolone showed pharmacokinetic and metabolism profiles similar to prednisone. Biomarker studies showed loss of side effects of traditional glucocorticoid drugs (bone fragility, metabolic disturbance, immune suppression). Suppression of the adrenal axis was 10-fold less than prednisone. The crystallographic structure of vamorolone was solved, and compared to prednisone and dexamethasone. There was overlap in structure, but differences in conformation at the C-ring where glucocorticoids interact with Asn564 of the glucocorticoid receptor. The predicted loss of Asn564 binding to vamorolone may underlie the loss of gene transcriptional activity.

CONCLUSIONS AND INTERPRETATIONS

Vamorolone is a dissociative steroid that retains high affinity binding and nuclear translocation of both glucocorticoid (agonist) and mineralocorticoid (antagonist) receptors, but does not show pharmacodynamic safety concerns of existing glucocorticoid drugs at up to 20 mg/kg/day.

Bone Health and Endocrine Care of Boys with Duchenne Muscular Dystrophy: Data from the MD STARnet

BACKGROUND

Patients with Duchenne muscular dystrophy (DMD) are at high risk of endocrine and bone health complications resulting from the high glucocorticoid (GC) doses used to treat this condition. There are limited data characterizing the clinical management of these complications.

OBJECTIVE

To determine the frequency of bone health screening, endocrinologist evaluation, and use of endocrine and bone health pharmacotherapy in the clinical care of males with DMD.

METHODS

A population based cohort study using data from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) was conducted. Clinical data was abstracted from the medical records of 683 males with DMD at five surveillance sites across the US.

RESULTS

A DXA scan had been documented in 24% of cases; the percentage of cases with DXA varied across surveillance sites from 13% to 43%, p < 0.001. History of fracture and greater disease duration were associated with greater odds of having a DXA. Only 4.7% of cases had documentation of an endocrinologist evaluation. The frequency of documented endocrine and bone health pharmacotherapy use included calcium (42.8%), vitamin D (36.6%), bisphosphonates (13.3%), growth hormone (1.9%), testosterone (1.7%), insulin (1.2%), and metformin (0.3%)Conclusions:A low percentage of DMD males had record of DXA scan, endocrinologist evaluation, or treatment with endocrine or bone health pharmacotherapy. Endocrine and bone health care may represent an unmet need in the DMD population.

Zoledronic acid in pediatric metabolic bone disorders

Zoledronic acid (ZA), a highly potent intravenous bisphosphonate (BP), has been increasingly used in children with primary and secondary osteoporosis due to its convenience of shorter infusion time and less frequent dosing compared to pamidronate. Many studies have also demonstrated beneficial effects of ZA in other conditions such as hypercalcemia of malignancy, fibrous dysplasia (FD), chemotherapy-related osteonecrosis (ON) and metastatic bone disease. This review summarizes pharmacologic properties, mechanism of action, dosing regimen, and therapeutic outcomes of ZA in a variety of metabolic bone disorders in children. Several potential novel uses of ZA are also discussed. Safety concerns and adverse effects are also highlighted.