Low bone density and bone metabolism alterations in Duchenne muscular dystrophy: response to calcium and vitamin D treatment

A systematic literature review and meta-analysis of the effectiveness of vitamin D supplementation for patients with Duchenne muscular dystrophy

We conducted a systematic literature review and meta-analysis on the effectiveness of vitamin D supplementation in maintaining or restoring vitamin D levels in Duchenne muscular dystrophy. Due to a lack of randomised controlled trials, cross-sectional and retrospective and prospective cohort studies were taken as the best available evidence. Inclusion criteria included reporting mean serum vitamin D levels in a supplement-taking group. After screening 102 records; 13 were included in a narrative synthesis and eight of these in a meta-analysis. We show that current dosing regimens are preventing severe deficiency but are not effective at maintaining sufficient vitamin D levels within the Duchenne population. Despite high levels of daily vitamin D supplementation (>1000 International Units), at least 20 % of people with Duchenne remain vitamin D deficient. No significant association between dose and serum vitamin D levels was found (r2 = 0.3, p = 0.237). A meta-analysis of mean serum vitamin D levels across eight studies also revealed substantial variability in response to vitamin D supplementation and high heterogeneity (I2 = 99.59 %). These data could impact on an individual's risk and severity of osteoporosis and vertebral fractures.

Metabolic assessment in children with neuromuscular disorders shows risk of liver enlargement, steatosis and fibrosis

AIM

The aim of this study was to conduct a metabolic and nutritional assessment of children with neuromuscular disorders, including the investigation of the liver and bone mineral density.

METHODS

In this observational study, we included 44 children with neuromuscular disorders. The nutritional status, bone health and liver were assessed by ultrasound, transient elastography, dual X-ray absorptiometry scan, blood samples, anthropometric measurements and 3-day diet registration.

RESULTS

Liver involvement was found in 31.0%: liver enlargement in 7.1%, steatosis in 4.8%, fibrosis in 14.3% and liver enlargement together with steatosis or fibrosis was found in 4.8%. These changes were found in 9/23 patients with Duchenne muscular dystrophy, 4/9 patients with spinal muscular atrophy type II and 0/12 patients with other neuromuscular diagnoses. Low bone mineral density was found in 44.0% of the patients, though the majority used daily vitamin D and calcium supplements. Vitamin D insufficiency or deficiency was found in 22.6%.

CONCLUSION

The metabolic assessment in children with neuromuscular disorders shows an increased risk of liver enlargement, steatosis and fibrosis. Possible causes are obesity, decreased mobility, low skeletal muscle mass and for a subgroup the use of glucocorticoids. The findings suggest that monitoring liver function should be part of the nutritional assessment in patients with neuromuscular disorders.

A Scoping Review of the Recent Clinical Practice Regarding the Evaluation of Bone Mineral Density in Children and Adolescents with Neuromuscular Diseases

Introduction: Neuromuscular Diseases (NMD) are associated with decreased bone strength due to altered muscle-bone interaction. However, the evaluation of bone quality remains a certain challenge in these patients. The purpose of this scoping review is to investigate the recent literature regarding the assessment of Bone Mineral Density (BMD) in this population. Methods: An electronic search of the PubMed and Scopus database was performed considering studies published in the English literature after 2007 that evaluated BMD in pediatric and adolescent patients with NMD. We excluded studies that evaluated patients > 20 years, studies not involving humans, and studies investigating bone mineral density in various pediatric conditions, but without specific data on NMD. Results: Overall, 19 studies were included that evaluated BMD in 1983 patients with NMD. Duchenne Muscular Dystrophy was the most widely studied disease (n = 11 studies). Dual energy X-ray absorptiometry (DEXA) was the most common diagnostic modality for BMD evaluation, while the most frequent site for BMD measurement was the lumbar spine (89.4%, n = 17 studies), followed by total body BMD (68.4%, n = 13 studies). Low BMD in children with NMD was demonstrated in all studies, especially after loss of ambulation. Moreover, a positive correlation between lower BMD and older age was shown. Conclusions: BMD evaluation in NMD remains a clinical challenge, as indicated by the high heterogeneity regarding the optimal site and technique for the evaluation of bone quality in these patients. Although DXA is currently the diagnostic modality of choice, a consensus regarding the optimal site for BMD measurement, and the adjustment method for its obtained measurements for parameters such as age and height is needed.

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.

Effectiveness of Neridronate in the Management of Bone Loss in Patients with Duchenne Muscular Dystrophy: Results from a Pilot Study

INTRODUCTION

Bone loss is a major issue in patients affected by Duchenne muscular dystrophy (DMD), a rare musculoskeletal disorder, particularly in those treated with glucocorticoids (GCs). We aimed to assess the effectiveness of neridronate in terms of bone mineral density (BMD) changes in this population.

METHODS

We retrospectively reviewed the records of patients affected by DMD receiving GCs referred to our outpatient from 2015 to 2020. All patients were treated with an intramuscular (IM) injection of neridronate (25 mg every month). Bone density was measured at the lumbar spine (LS; L1-L4 tract) using dual-energy x-ray absorptiometry (DXA) (GE Lunar), no more than 4 weeks before (T0) and after 1 year from neridronate treatment (T1).

RESULTS

Eight boys with DMD were included with a mean age at diagnosis of 4.75 ± 2.81 years. Six of them were non-ambulant and two of them had previous low-trauma fractures (a distal femur fracture and a vertebral compression fracture, respectively). All patients were receiving deflazacort [median duration of therapy 11.5 years (interquartile range 2-25)]. At the DXA evaluation (T0), the mean L1-L4 BMD value was 0.716 ± 0.164 g/cm². Six patients (75%) showed an L1-L4 Z-score height-adjusted of less than - 2. The mean age of neridronate initiation was 18.87 ± 6.81 years. All patients were supplemented with calcium carbonate and vitamin D at baseline. After 12 months of treatment (T1), the mean L1-L4 BMD value was 0.685 ± 0.190 g/cm². Seven patients (87.5%) showed an L1-L4 Z-score of less than - 2. Changes in LS BMD and Z-score were not significant between T0 and T1 in our cohort (p = 0.674 and p = 0.208, respectively) as well as among non-ambulant patients with DMD without previous fragility fractures.

CONCLUSIONS

In this study, we reported for the first time that neridronate may slow bone loss in GC-treated patients with DMD at 1-year follow-up.

Cessation of ambulation results in a dramatic loss of trabecular bone density in boys with Duchenne muscular dystrophy (DMD)

Glucocorticoids are currently used to improve muscle strength and prolong ambulation in boys with DMD although the effect on bone health is still unclear. The aim of this study was to compare bone strength in healthy children and boys with DMD and investigate the interaction between diminished muscle function, loss of ambulation and high dose oral steroids, over a two year time frame. Fifty children were studied, 14 healthy boys (HB), 13 boys with DMD who remained ambulant (DMD-RA) and 23 boys with DMD who lost ambulation (DMD-LA). All boys with DMD had taken oral glucocorticoids. Peripheral quantitative computed tomography was used to measure bone geometry, density, strength and muscle mass of the non-dominant tibia and radius. Measurements were made at baseline, 12 and 24 months at the distal metaphysis and mid diaphysis sites. Differences between the three groups were evaluated using ANOVA and a repeated measures model. There were no significant differences in age between the groups: mean age was 9.4, 8.7 and 8.8 years for HB, DMD-RA and DMD-LA, respectively. There was no significant difference in steroid exposure between the DMD groups. However, boys who lost ambulation had significantly lower muscle function at baseline (North Star Ambulatory Assessment DMD-RA 23.6 vs. DMD-LA 18.8; p < 0.05). At baseline, healthy boys had significantly greater trabecular bone density at the distal radius /ulna (23%/27%) and distal tibia/fibula (30%/46%) than boys with DMD (p < 0.05). They also had significantly larger diaphyseal tibiae/fibulae (74%/36%) and radii/ulnae (49%/31%) with thicker corticies and consequently greater bone strength. In contrast, boys with DMD had greater cortical density (4%). Over time, there were small significant differences in the rate of change of both muscle and bone parameters between healthy boys and boys with DMD. For both ambulant and non-ambulant boys with DMD the greatest changes in cortical bone were evident at the tibia. After two years boys with DMD had on average, 63% less bone strength than healthy boys. However, the most strikingly significant difference was in trabecular bone density for boys who became non-ambulant. By 2 years non-ambulant DMD boys had 53% less trabecular bone density at distal tibia than their healthy age matched peers compared with boys who remained ambulant who had 27% less trabecular bone density. In conclusion, bone and muscle strength is reduced for all boys with DMD even while they remain ambulant. However, tibia trabecular bone density loss is significantly accelerated in DMD boys who lose independent ambulation compared to DMD boys who remain ambulant despite equivalent levels of corticosteroid exposure.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Bone density and bone health alteration in boys with Duchenne Muscular Dystrophy: a prospective observational study

OBJECTIVES

Boys with Duchenne Muscular Dystrophy (DMD) are at increased risk for compromised bone health, manifesting as low-impact trauma long bone fractures and vertebral compression fractures.

METHODS

In a prospective observational study, we studied bone health parameters in North Indian boys with DMD. We consecutively enrolled ambulatory boys with DMD on glucocorticoid therapy. Bone health was evaluated with X-ray spine, Dual-energy X-ray absorptiometry (DXA), serum calcium, vitamin D3 (25[OH]D), 1,25-dihyroxyvitamin D3 (1,25[OH]₂D₃), serum osteocalcin, osteopontin, and N terminal telopeptide of type 1 collagen (Ntx) levels.

RESULTS

A total of 76 boys with DMD were enrolled. The median age was 8.5 (interquartile range [IQR] 7.04-10.77) years. Among these, seven (9.2%) boys had long bone fractures, and four (5.3%) had vertebral compression fractures. Fifty-four (71%) boys underwent DXA scan, and among these 31 (57%) had low bone mineral density (BMD, ≤-2 z-score) at the lumbar spine. The mean BMD z-score at the lumbar spine was -2.3 (95% confidence interval [CI] = -1.8, -2.8), and at the femoral neck was -2.5 (95% CI = -2, -2.9). 25(OH)D levels were deficient in 68 (89.5%, n=76) boys, and 1,25(OH)₂D₃ levels were deficient in all. Mean serum osteocalcin levels were 0.68 ± 0.38 ng/mL (n=54), serum osteopontin levels were 8.6 ± 4.6 pg/mL (n=54) and serum Ntx levels were 891 ± 476 nmol/L (n=54). Boys with low BMD received glucocorticoids for longer duration, in comparison to those with normal BMD (median, IQR [16.9 (6-34) months vs. 7.8 (4.8-13.4) months]; p=0.04).

CONCLUSIONS

Bone health is compromised in North Indian boys with DMD. BMD at the lumbar spine is reduced in more than half of boys with DMD and nearly all had vitamin D deficiency on regular vitamin D supplements. Longer duration of glucocorticoid therapy is a risk factor for low BMD in our cohort.

Effects of Bisphosphonates on Osteoporosis Induced by Duchenne Muscular Dystrophy: A Prospective Study

OBJECTIVE

Duchenne muscular dystrophy (DMD) is a severe X-linked progressive neuromuscular disease that brings a significantly increased risk of osteoporosis and bone fractures. We prospectively evaluated the effects of oral and intravenous bisphosphonates on the bones of children with DMD.

METHODS

This study included a total of 52 children with DMD. They were divided into zoledronic acid (ZOL), alendronate (ALN), and control groups according to bone mineral density (BMD) and history of fragility fractures. For 2 years, all patients took calcium, vitamin D, and calcitriol. Meanwhile, 17 patients received infusions of ZOL, and 18 patients received ALN. BMD, serum levels of alkaline phosphatase (ALP) and the cross-linked C-telopeptide of type I collagen (β-CTX) were evaluated.

RESULTS

After 24 months of treatment, the percentage changes in lumbar spine BMD were 23.2 ± 9.7% and 23.6 ± 8.8% in the ZOL and ALN groups (all P<.01 vs. baseline). The increases did not differ between the ZOL and ALN groups, but were significantly larger than those of the control group (P<.01). Serum β-CTX and ALP levels, respectively, were decreased by 44.4 ± 18.0% and 31.9 ± 26.7% in the ZOL group and by 36.0 ± 20.3% and 25.8 ± 14.4% in the ALN group (all P<.01 vs. baseline).

CONCLUSION

Zoledronic acid and alendronate had similar protective effects to increase bone mineral density and reduce bone resorption in children with DMD, which were superior to treatment of calcium, vitamin D, and calcitriol.

ABBREVIATIONS

25OHD = 25 hydroxyvitamin D; ALN = alendro-nate; ALP = alkaline phosphatase; ALT = alanine aminotransferase; BMD = bone mineral density; BP = bisphosphonate; Ca = calcium; β-CTX = cross-linked C-telopeptide of type I collagen; DMD = Duchenne muscular dystrophy; FN = femoral neck; GC = glucocorticoid; LS = lumbar spine; ZOL = zoledronic acid.

Flexible intramedullary nailing for supracondylar femoral fractures in children with Duchenne muscular dystrophy

Case series

Patients: 11-year-old • 12-year-old

Final Diagnosis: Duchenne muscular dystrophy

Symptoms: Fracture

Medication: —

Clinical Procedure: —

Specialty: Orthopedics and Traumatology

Retrospective Analysis of Fractures and Factors Causing Ambulation Loss After Lower Limb Fractures in Duchenne Muscular Dystrophy

OBJECTIVE

Prevalence and characteristics of fractures and factors related to loss of ambulation after lower limb fractures were investigated.

DESIGN

Chart review included height, weight, dual-energy x-ray absorptiometry, corticosteroid use, vitamin D, fracture history, muscle strength, range of motion, and timed performance tests (10 meter walk/run, Gowers, and four steps). Patients were grouped by fracture location and ambulation loss after fracture.

RESULTS

Two hundred eighty-seven patients with Duchenne muscular dystrophy were identified, 53 of these had experienced fracture. Eighty-one percent were older than 9 yrs at first fracture and 36.4% became nonambulatory after fracture. Dorsiflexion range of motion (fracture side, P = 0.021), quadriceps strength (right side, P = 0.025), and shoulder abduction strength (right, left, and fracture side; P = 0.028, P = 0.027, and P = 0.016) were significantly different within the groups. Patients who became nonambulatory after fracture initially had less dorsiflexion (right, left, fracture side; 2.25 vs. -7.29, P = 0.004; 2.67 vs. -12, P = 0.001; and 2.41 vs. -7.42, P = 0.002) and slower 10-meter walk/run times (7.43 secs vs. 14.7 secs, P = 0.005).

CONCLUSIONS

Fracture represents a significant risk in patients with Duchenne muscular dystrophy; both slower walking speed and ankle contracture confer an increased risk of ambulation loss after fracture.

TO CLAIM CME CREDITS

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Identify the main factors that are associated with ambulation loss after fracture in patients with Duchenne muscular dystrophy; (2) Identify the risk of fracture in the Duchenne muscular dystrophy population; and (3) Articulate the characteristics associated with fracture in patients with Duchenne muscular dystrophy.

LEVEL

Advanced.

ACCREDITATION

The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Guidelines for the management of children at risk of secondary bone fragility: Expert opinion of a French working group

The current French national guidelines were elaborated by a working group consisting of experts in the field of pediatric endocrinology, rheumatology, hepatogastroenterology, nephrology, and pneumology. A systematic search was undertaken of the literature published between 2008 and 2018 and indexed in PubMed. The recommendations developed were then validated by an external evaluation group comprising representatives from the various highly specialized fields in pediatrics, representatives of the societies and groups supporting the development of the guidelines, and representatives of different healthcare professions. The objective of these guidelines was to detail the current optimal management of children at risk of secondary bone fragility.

Safety issues and harmful pharmacological interactions of nutritional supplements in Duchenne muscular dystrophy: considerations for Standard of Care and emerging virus outbreaks

At the moment, little treatment options are available for Duchenne muscular dystrophy (DMD). The absence of the dystrophin protein leads to a complex cascade of pathogenic events in myofibres, including chronic inflammation and oxidative stress as well as altered metabolism. The attention towards dietary supplements in DMD is rapidly increasing, with the aim to counteract pathology-related alteration in nutrient intake, the consequences of catabolic distress or to enhance the immunological response of patients as nowadays for the COVID-19 pandemic emergency. By definition, supplements do not exert therapeutic actions, although a great confusion may arise in daily life by the improper distinction between supplements and therapeutic compounds. For most supplements, little research has been done and little evidence is available concerning their effects in DMD as well as their preventing actions against infections. Often these are not prescribed by clinicians and patients/caregivers do not discuss the use with their clinical team. Then, little is known about the real extent of supplement use in DMD patients. It is mistakenly assumed that, since compounds are of natural origin, if a supplement is not effective, it will also do no harm. However, supplements can have serious side effects and also have harmful interactions, in terms of reducing efficacy or leading to toxicity, with other therapies. It is therefore pivotal to shed light on this unclear scenario for the sake of patients. This review discusses the supplements mostly used by DMD patients, focusing on their potential toxicity, due to a variety of mechanisms including pharmacodynamic or pharmacokinetic interactions and contaminations, as well as on reports of adverse events. This overview underlines the need for caution in uncontrolled use of dietary supplements in fragile populations such as DMD patients. A culture of appropriate use has to be implemented between clinicians and patients' groups.

Flexible Femoral Nailing of an Awake Adult Muscular Dystrophy Patient

Femoral fractures can be common in nonambulatory patients with myopathies because they present with notable osteoporosis. From the orthopaedic perspective, this can be complicated by a pre-existing knee flexion contracture and small femoral shaft size. The goals of treatment are to reduce external immobilization, maximize comfort for transfers, prevent functional loss, and preclude refracture. The purpose of our work is to describe the anesthetic and orthopaedic considerations in treating a bed-bound adult patient with nemaline dystrophy and a midshaft femur fracture. The authors have obtained the patient's informed written consent for print and electronic publication of the case report.

The role of delayed bone age in the evaluation of stature and bone health in glucocorticoid treated patients with Duchenne muscular dystrophy

Background

Low bone mineral density and an increased risk of appendicular and vertebral fractures are well-established consequences of Duchenne muscular dystrophy (DMD) and the risk of fractures is exacerbated by long-term glucocorticoid treatment. Monitoring of endocrine and skeletal health and timely intervention in at-risk patients is important in the management of children with DMD.

Methods

As part of the Norwegian Duchenne muscular dystrophy cohort study, we examined the skeletal maturation of 62 boys less than 18 years old, both currently glucocorticoid treated (n = 44), previously treated (n = 6) and naïve (n = 12). The relationship between bone age, height and bone mineral density (BMD) Z-scores was explored.

Results

The participants in the glucocorticoid treated group were short in stature and puberty was delayed. Bone age was significantly delayed, and the delay increased with age and duration of treatment. The difference in height between glucocorticoid treated and naïve boys was no longer significant when height was corrected for delayed skeletal maturation. Mean BMD Z-scores fell below − 2 before 12 years of age in the glucocorticoid treated group, with scores significantly correlated with age, duration of treatment and pubertal development. When BMD Z-scores were corrected for by retarded bone age, the increase in BMD Z-scores was significant for all age groups.

Conclusion

Our results suggest that skeletal maturation should be assessed in the evaluation of short stature and bone health in GC treated boys with DMD, as failing to consider delayed bone age leads to underestimation of BMD Z-scores and potentially overestimation of fracture risk.

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.

The relationship of bone mineral density and vitamin D levels with steroid use and ambulation in patients with Duchenne muscular dystrophy

Objectives

This study aims to assess the bone mineral density (BMD) and serum levels of 25(OH)-vitamin D and their relationship with steroid use and ambulation in patients with Duchenne muscular dystrophy (DMD).

Patients and methods

Between January 2017 and May 2018, medical records of a total of 67 male patients (mean age, 13.9±4.3 years; range, 8 to 25 years) who were diagnosed with definite DMD were retrospectively analyzed. Demographic data, functional activity level, steroid use, fracture history and location, serum levels vitamin D, and lumbar and hip Z-scores in BMD at the time of the initial admission were recorded.

Results

The mean level of vitamin D was 13.4±7.5 ng/mL. In terms of serum levels of vitamin D, 28 patients (41.8%) had severe deficiency, 31 (46.3%) had insufficiency, and five patients (7.5%) had deficiency. Only three (4.5%) of the patients had sufficient levels of vitamin D. The hip Z-scores were significantly lower than lumbar Z scores. There was no significant difference in the lumbar and hip BMD measurements between the patients with and without steroid use. Lumbar Z-scores were significantly lower in non-ambulatory patients than ambulatory patients.

Conclusion

It is of utmost importance to evaluate the initial serum vitamin D levels in terms of bone health and prescribe replacement in case of deficiency/insufficiency in DMD patients. Since the decrease in the BMD is evident in this patient population, maintaining the mobilization as long as possible, providing loading on the bone for a long time, may be beneficial.

Duchenne muscular dystrophy: an historical treatment review

In this review, we discuss the therapies used in the treatment of patients with Duchenne muscular dystrophy since the first description of the disease. A short description is given of the various theories based on disease pathogenesis, which give the substrates for the many therapeutic interventions. A brief review of the methods of evaluation used in therapeutic trials is made. Of all the treatments, the only drugs that are still considered able to modify the course of the disease are the corticosteroids (prednisone/prednisolone/deflazacort). Other drugs (coenzyme Q10 and creatine) have had a little effect in a few functions without adverse reactions. Idebenone seems to improve the respiratory function in the long term. The trials with mRNA transcription, through nonsense mutations or exon 51 skipping, show some beneficial results in a few functional tests, but they are limited to a small set of DMD patients.

Renal involvement in the pathogenesis of mineral and bone disorder in dystrophin-deficient mdx mouse

Duchenne muscular dystrophy is a severe muscular disorder, often complicated with osteoporosis, and impaired renal function has recently been featured. We aimed to clarify the involvement of renal function in the pathogenesis of mineral and bone disorder in mdx mice, a murine model of the disease. We clearly revealed renal dysfunction in adult mdx mice, in which dehydration and hypercalcemia were contributed. We also examined the effects of dietary phosphorus (P) overload on phosphate metabolism. Serum phosphate and parathyroid hormone (PTH) levels were significantly increased in mdx mice by dietary P in a dose-dependent manner; however, bone alkaline phosphatase levels were significantly lower in mdx mice. Additionally, bone mineral density in mdx mice were even worsened by increased dietary P in a dose-dependent manner. These results suggested that the uncoupling of bone formation and resorption was enhanced by skeletal resistance to PTH due to renal failure in mdx mice.

The Effect of Vitamin D Supplementation on Skeletal Muscle in the mdx Mouse Model of Duchenne Muscular Dystrophy

Vitamin D (VitD) has shown to be beneficial in reversing muscle weakness and atrophy associated with VitD deficiency. Duchenne muscular dystrophy is characterized by worsening muscle weakness and muscle atrophy, with VitD deficiency commonly observed. This study aimed to investigate the effect of VitD supplementation on dystrophic skeletal muscle. Eight-week old female control (C57BL/10; n = 29) and dystrophic (C57BL/mdx; n = 23) mice were randomly supplemented with one of three VitD enriched diets (1000, 8000 & 20,000 IU/kg chow). Following a four-week feeding period, the extensor digitorum longus (EDL) and soleus muscles contractile and fatigue properties were tested ex vivo, followed by histological analysis. As expected, mdx muscles displayed higher mass yet lower specific forces and a rightward shift in their force frequency relationship consistent with dystrophic pathology. There was a trend for mdx muscle mass to be larger following the 20,000 IU/kg diet, but this did not result in improved force production. Fiber area in the EDL was larger in mdx compared to controls, and there were higher amounts of damage in both muscles, with VitD supplementation having no effect. Four weeks of VitD supplementation did not appear to have any impact upon dystrophic skeletal muscle pathology at this age.

Intermittent PTH treatment improves bone and muscle in glucocorticoid treated Mdx mice: A model of Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy (DMD) is a progressive muscle disorder caused by genetic mutations of the dystrophin encoding gene. In the absence of functional dystrophin, DMD patients suffer from muscle inflammation and wasting, as well as compromised bone health with increased risk of fracture. The use of high dose glucocorticoids (GC) as the standard therapy also contributes to bone fragility. This study examined the effects of intermittent, daily administered parathyroid hormone (iPTH), an approved bone anabolic therapy, on growing bone and dystrophic muscle in the presence and absence of prednisone treatment using the Mdx mouse model of DMD. Five-weeks of prednisone treatment in Mdx mice decreased cortical bone thickness and area (p < 0.001), with a large increase in endocortical osteoclasts that were significantly improved by PTH treatment (p < 0.001). GC-induced decreases in cortical bone toughness and modulus were improved with iPTH therapy (p < 0.05). Mdx mice showed significantly less bone mass in trabecular compartments of lumbar vertebrae and iPTH treatment, with or without glucocorticoids, significantly improved structural and material properties of this bone. Prednisone improved grip strength and endurance of treadmill running, which were maintained and further improved, respectively, in co-treated Mdx mice. Altogether, our study demonstrates that iPTH therapy significantly ameliorated GC-induced bone loss and maintained or further enhanced the positive effects of GCs on dystrophic muscle function. These findings give insight into the potential for use of teriparatide to treat growing bone in children with DMD.

Increased Rates of Vitamin D Insufficiency in Boys With Duchenne Muscular Dystrophy Despite Higher Vitamin D3 Supplementation

Vitamin D supplementation is important for many chronic pediatric conditions to help maintain bone health; however, there is little evidence about how disease-related factors affect vitamin D status. The objective was to compare 25-hydroxyvitamin D (25(OH)D) concentrations in 3 pediatric cohorts (Duchenne muscular dystrophy [DMD], systemic lupus erythematosus [SLE], and osteogenesis imperfecta [OI]). In a retrospective study of 367 subjects, children with DMD had increased prevalence of vitamin D insufficiency (25% vs 14% [SLE] and 10% [OI], P = .002), despite higher vitamin D₃ supplementation doses. Boys with DMD also had higher weight, fat mass, and lower lean mass percentage Z scores. DMD was associated with having higher rates of vitamin D insufficiency than other comparable pediatric chronic disease cohorts, the effect of which may be modulated by clinical factors such as increased adiposity. While corroboration of these results is needed given baseline differences between the patient groups, greater vitamin D supplementation doses may be required to achieve optimal serum 25(OH)D concentrations in boys with DMD.

Growth, bone health & ambulatory status of boys with DMD treated with daily vs. intermittent oral glucocorticoid regimen

Oral glucocorticoids (GC) preserve muscle strength and prolong walking in boys with Duchenne muscular dystrophy (DMD). Although vertebral fractures have been reported in boys taking GC, fracture rates for different GC regimes have not been investigated. The aim of this pragmatic longitudinal study was to compare growth, body mass, bone mineral density (BMD), vertebral fractures (VF) and ambulatory status in boys with DMD on daily (DAILY) or intermittent (INTERMITTENT), oral GC regimens. A convenience sample of 50 DMD boys from two centres was included in the study; 25 boys each were on the DAILY or INTERMITTENT regimen. Size adjusted lumbar spine BMD (LS BMAD), total body less head BMD (TBLH), by DXA and distal forearm bone densities by pQCT, GC exposure, VF assessment and ambulatory status were analysed at three time points; baseline, 1 and 2 years. At baseline, there were no differences in age, GC duration or any bone parameters. However, DAILY boys were shorter (height SDS DAILY = -1.4(0.9); INTERMITTENT = -0.8(1.0), p = 0.04) with higher BMI (BMI SDS DAILY = 1.5(0.9); INTERMITTENT = 0.8(1.0), p = 0.01). Over 2 years, DAILY boys got progressively shorter (delta height SDS DAILY = -0.9(1.1); INTERMITTENT = +0.1(0.6), p < 0.001). At their 2 year assessment, 5 DAILY and 10 INTERMITTENT boys were non-ambulant. DAILY boys had more VFs than INTERMITTENT boys (10 versus 2; χ² p = 0.008). BMAD SDS remained unchanged between groups. TBLH and radius BMD declined significantly but the rate of loss was not different. In conclusion, there was a trend for more boys on daily GCs to remain ambulant but at the cost of more VFs, greater adiposity and markedly diminished growth. In contrast, boys on intermittent GCs had fewer vertebral fractures but there was a trend for more boys to loose independent ambulation.

Primary Care and Emergency Department Management of the Patient With Duchenne Muscular Dystrophy

Primary care providers (PCPs) are usually the first point of contact with the health care system for patients with Duchenne muscular dystrophy (DMD), and patients often present to emergency departments in which providers have little experience in dealing with this condition. With this article, we give primary care and emergency medicine providers a background in the common issues that affect people with DMD. By acquiring some specialized knowledge about the multisystem medical complications of DMD and by applying general principles of primary care, such as timely immunization, anticipatory safety counseling, behavioral screening, and routine nutritional and developmental assessments, the PCP can be a valued and effective medical provider to patients with DMD. The PCP can provide access to and effective coordination among the patient's specialty caregivers. Moreover, the PCP can become a trusted advisor to the patient and his family about important medical decisions, as well as issues in the psychosocial, behavioral, and educational domains. This article also contains a "pocket guide" used to assess and manage common urgent medical problems that cause patients with DMD to seek care in the emergency department. With the background information discussed in this article, both PCPs and emergency medicine physicians can skillfully care for patients with DMD in their respective settings, optimizing patient outcomes.

Effect of 25-HydroxyVitamin D Deficiency and Its Interaction with Prednisone Treatment on Musculoskeletal Health in Growing Mdx Mice

Duchenne muscular dystrophy (DMD) results from genetic mutations of the gene encoding dystrophin, leading to muscle inflammation and degeneration that is typically treated with glucocorticoids. DMD and its treatment with glucocorticoids result in poor bone health and high risk of fractures. Insufficient levels of 25-hydroxyvitamin D (25-hydroxy D) that may contribute to weakened bone are routinely found in DMD patients. To determine the effect of 25-hydroxy D deficiency, this study examined the effects of low vitamin D dietary intake with and without glucocorticoids on the musculoskeletal system of the Mdx mouse model of DMD. At 10 weeks of age, Mdx mice on control diet had low trabecular bone mineral density of distal femurs and lumbar vertebrae with increased osteoclast numbers compared to wild-type mice. Low vitamin D intake resulted in 25-hydroxy D deficiency but had no effect on trabecular or cortical bone. Cortical bone loss and bone weakness were induced by glucocorticoids while they improved muscle grip strength in Mdx mice. 25-hydroxy D deficiency did not result in any significant effects on growing bone or muscle in the Mdx mice. In combination with glucocorticoid treatment, low 25-hydroxy D resulted in no change in cortical bone mineral density but bone ductility was significantly increased suggesting lower bone mineralization.

Basics of bone metabolism and osteoporosis in common pediatric neuromuscular disabilities

Bone modeling is a process that starts with fetal life and continues during adolescence. Complex factors such as hormones, nutritional and environmental factors affect this process. In addition to these factors, physical conditioning and medications that have toxic effects on bony tissue should be carefully considered in patient follow-up. Osteoporosis is a significant problem in pediatric population because of ongoing growth and development of skeletal system. Two types of osteoporosis are primary and secondary types and children with neuromuscular disabilities constitute a major group with secondary osteoporosis. Low bone mass in patients with cerebral palsy, spina bifida, and Duchenne muscular dystrophy cause increased bone fragility in even slight traumas. Maximizing peak bone mass and prevention of bone loss are very important to reduce the fracture risk in neuromuscular diseases. This article aims to review the determinants of bone physiology and bone loss in children with cerebral palsy, spina bifida, and Duchenne muscular dystrophy.

Nutritional Challenges in Duchenne Muscular Dystrophy

Neuromuscular diseases (NMDs) represent a heterogeneous group of acquired or inherited conditions. Nutritional complications are frequent in NMDs, but they are sometimes underestimated. With the prolongation of survival in patients with NMDs, there are several nutritional aspects that are important to consider, including the deleterious effects of overnutrition on glucose metabolism, mobility, and respiratory and cardiologic functions; the impact of hyponutrition on muscle and ventilatory function; constipation and other gastrointestinal complications; chewing/swallowing difficulties with an increased risk of aspiration that predisposes to infectious diseases and respiratory complications; as well as osteoporosis with an associated increased risk of fractures. The aim of this review is to provide a comprehensive analysis of the nutritional aspects and complications that can start in children with Duchenne muscular dystrophy (DMD) and increase with ageing. These aspects should be considered in the transition from paediatric clinics to adult services. It is shown that appropriate nutritional care can help to improve the quality of life of DMD patients, and a multidisciplinary team is needed to support nutrition challenges in DMD patients. However, studies on the prevalence of overnutrition and undernutrition, gastrointestinal complications, infectious diseases, dysphagia, and reduced bone mass in the different types of NMDs are needed, and appropriate percentiles of weight, height, body mass index, and body composition appear to be extremely important to improve the management of patients with NMD.

Bone Density in the Obese Child: Clinical Considerations and Diagnostic Challenges

The prevalence of obesity in children has reached epidemic proportions. Concern about bone health in obese children, in part, derives from the potentially increased fracture risk associated with obesity. Additional risk factors that affect bone mineral accretion, may also contribute to obesity, such as low physical activity and nutritional factors. Consequences of obesity, such as inflammation, insulin resistance, and non-alcoholic fatty liver disease, may also affect bone mineral acquisition, especially during the adolescent years when rapid increases in bone contribute to attaining peak bone mass. Further, numerous pediatric health conditions are associated with excess adiposity, altered body composition, or endocrine disturbances that can affect bone accretion. Thus, there is a multitude of reasons for considering clinical assessment of bone health in an obese child. Multiple diagnostic challenges affect the measurement of bone density and its interpretation. These include greater precision error, difficulty in positioning, and the effects of increased lean and fat tissue on bone health outcomes. Future research is required to address these issues to improve bone health assessment in obese children.

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

BACKGROUND

Corticosteroid treatment is considered the 'gold standard' for Duchenne muscular dystrophy (DMD); however, it is also known to induce osteoporosis and thus increase the risk of vertebral fragility fractures. Good practice in the care of those with DMD requires prevention of these adverse effects. Treatments to increase bone mineral density include bisphosphonates and vitamin D and calcium supplements, and in adolescents with pubertal delay, testosterone. Bone health management is an important part of lifelong care for patients with DMD.

OBJECTIVES

To assess the effects of interventions to prevent or treat osteoporosis in children and adults with DMD taking long-term corticosteroids; to assess the effects of these interventions on the frequency of vertebral fragility fractures and long-bone fractures, and on quality of life; and to assess adverse events.

SEARCH METHODS

On 12 September 2016, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL Plus to identify potentially eligible trials. We also searched the Web of Science ISI Proceedings (2001 to September 2016) and three clinical trials registries to identify unpublished studies and ongoing trials. We contacted correspondence authors of the included studies in the review to obtain information on unpublished studies or work in progress.

SELECTION CRITERIA

We considered for inclusion in the review randomised controlled trials (RCTs) and quasi-RCTs involving any bone health intervention for corticosteroid-induced osteoporosis and fragility fractures in children, adolescents, and adults with a confirmed diagnosis of DMD. The interventions might have included oral and intravenous bisphosphonates, vitamin D supplements, calcium supplements, dietary calcium, testosterone, and weight-bearing activity.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed reports and selected potential studies for inclusion, following standard Cochrane methodology. We contacted study authors to obtain further information for clarification on published work, unpublished studies, and work in progress.

MAIN RESULTS

We identified 18 potential studies, of which two, currently reported only as abstracts, met the inclusion criteria for this review. Too little information was available for us to present full results or adequately assess risk of bias. The participants were children aged five to 15 years with DMD, ambulant and non-ambulant. The interventions were risedronate versus no treatment in one trial (13 participants) and whole-body vibration versus a placebo device in the second (21 participants). Both studies reported improved bone mineral density with the active treatments, with no improvement in the control groups, but the abstracts did not compare treatment and control conditions. All children tolerated whole-body vibration treatment. No study provided information on adverse events. Two studies are ongoing: one investigating whole-body vibration, the other investigating zoledronic acid.

AUTHORS' CONCLUSIONS

We know of no high-quality evidence from RCTs to guide use of treatments to prevent or treat corticosteroid-induced osteoporosis and reduce the risk of fragility fractures in children and adults with DMD; only limited results from two trials reported in abstracts were available. We await formal trial reports. Findings from two ongoing relevant studies and two trials, for which only abstracts are available, will be important in future updates of this review.

Body composition of patients with Duchenne muscular dystrophy: the Greek experience

Greece ranks among the first countries suffering from the obesity epidemic globally. The aim of the study was to evaluate body composition in Greek patients with Duchenne muscular dystrophy (DMD). We hypothesized that able-bodied patients would not differ from controls, in terms of adiposity, based on clinical observations during everyday practice.

STUDY DESIGN

Cross-sectional study of steroid-dependent DMD subjects, who underwent dual-energy X-ray absorptiometry and laboratory metabolic bone profile evaluation. Forty-two patients and thirty-one controls were studied. Overall, DMD subjects were shorter (height Z-score = -1.4, p = 0.01). Their bone mineral density (BMD) was low (lumbar spine BMD Z-score = -1.2, p < 0.01, subcranial total body BMD Z-score = -1.8, p < 0.01). Lean tissue mass (LTM) was also decreased (LTM Z-score = -2.2, p < 0.01). The above findings were more pronounced in adolescence. Regarding adiposity, increased fat mass (FM) was found only in pubertal DMD patients (FM Z-score = 1.4, p < 0.01), whereas prepubertal, able-bodied patients did not differ from controls, thus confirming the initial hypothesis. Finally, 65 % of DMD subjects had increased bone resorption markers and 57 % had suboptimal vitamin D levels. The importance of using native population as controls for body composition analysis is highlighted. In Greece, abnormal body composition in DMD patients is more striking when loss of ambulation occurs and not during the prepubertal period, due to the concurrent presence of obesity in the pediatric population. Thus, adolescents with this neuromuscular disorder should be targeted toward prompt lifestyle interventions.

Effects of teriparatide on bone mineral density and quality of life in Duchenne muscular dystrophy related osteoporosis: a case report

Duchenne muscular dystrophy (DMD) is an X-linked recessive muscle disease characterized by secondary osteoporosis and increased fractures. We describe the case of a 20-year-old boy with DMD suffering from back pain due to multiple vertebral fractures who was treated with teriparatide. Improvement of bone density, pain, and quality of life was achieved. DMD is an X-linked recessive muscle disease with secondary osteoporosis and related frequently occurring fractures. To date, only bisphosphonates have been used to treat osteoporosis in DMD. Black bear parathyroid hormone has been previously reported to enhance bone mass in the dystrophin-deficient mouse. This study reports the positive effect of osteoanabolic treatment with once-daily recombinant human parathyroid hormone 1-34 (rhPTH 1-34, teriparatide) in a 20-year-old DMD boy suffering from multiple vertebral fractures causing back pain. Bone formation and resorption markers (osteocalcin and C-telopeptide of type I collagen, respectively), as expected, increased within 6 months and intensity of back pain early decreased, with no pain reported after 6 months at visual analog scale. Over a 18-month period of treatment with teriparatide, bone mineral density and quality of life, assessed by the 36-item short-form questionnaire, considerably improved and no side effects were reported. Further studies on large cohorts are warranted to test the efficacy of this promising treatment for DMD related osteoporosis.

Nutraceuticals and Their Potential to Treat Duchenne Muscular Dystrophy: Separating the Credible from the Conjecture

In recent years, complementary and alternative medicine has become increasingly popular. This trend has not escaped the Duchenne Muscular Dystrophy community with one study showing that 80% of caregivers have provided their Duchenne patients with complementary and alternative medicine in conjunction with their traditional treatments. These statistics are concerning given that many supplements are taken based on purely "anecdotal" evidence. Many nutraceuticals are thought to have anti-inflammatory or anti-oxidant effects. Given that dystrophic pathology is exacerbated by inflammation and oxidative stress these nutraceuticals could have some therapeutic benefit for Duchenne Muscular Dystrophy (DMD). This review gathers and evaluates the peer-reviewed scientific studies that have used nutraceuticals in clinical or pre-clinical trials for DMD and thus separates the credible from the conjecture.

Vitamin D in corticosteroid-naïve and corticosteroid-treated Duchenne muscular dystrophy: what dose achieves optimal 25(OH) vitamin D levels?

AIM

Assessment of the efficacy of vitamin D replenishment and maintenance doses required to attain optimal levels in boys with Duchenne muscular dystrophy (DMD).

METHOD

25(OH)-vitamin D levels and concurrent vitamin D dosage were collected from retrospective case-note review of boys with DMD at the Dubowitz Neuromuscular Centre. Vitamin D levels were stratified as deficient at <25 nmol/L, insufficient at 25-49 nmol/L, adequate at 50-75 nmol/L and optimal at >75 nmol/L.

RESULT

617 vitamin D samples were available from 197 boys (range 2-18 years)-69% from individuals on corticosteroids. Vitamin D-naïve boys (154 samples) showed deficiency in 28%, insufficiency in 42%, adequate levels in 24% and optimal levels in 6%. The vitamin D-supplemented group (463 samples) was tested while on different maintenance/replenishment doses. Three-month replenishment of daily 3000 IU (23 samples) or 6000 IU (37 samples) achieved optimal levels in 52% and 84%, respectively. 182 samples taken on 400 IU revealed deficiency in 19 (10%), insufficiency in 84 (47%), adequate levels in 67 (37%) and optimal levels in 11 (6%). 97 samples taken on 800 IU showed deficiency in 2 (2%), insufficiency in 17 (17%), adequate levels in 56 (58%) and optimal levels in 22 (23%). 81 samples were on 1000 IU and 14 samples on 1500 IU, with optimal levels in 35 (43%) and 9 (64%), respectively. No toxic level was seen (highest level 230 nmol/L).

CONCLUSIONS

The prevalence of vitamin D deficiency and insufficiency in DMD is high. A 2-month replenishment regimen of 6000 IU and maintenance regimen of 1000-1500 IU/day was associated with optimal vitamin D levels. These data have important implications for optimising vitamin D dosing in DMD.

Prophylactic pamidronate partially protects from glucocorticoid-induced bone loss in the mdx mouse model of Duchenne muscular dystrophy

Glucocorticoids are extensively used to treat patients with Duchenne muscular dystrophy because of their ability to delay muscle damage, prolong ambulation and extend life. However, use of glucocorticoids significantly increases bone loss, fragility and fractures. To determine if antiresorptive bisphosphonates could prevent the effects of glucocorticoids on bone quality, we used dystrophic mdx mice treated with the glucocorticoid prednisone during 8weeks of rapid bone growth from 5 to 13weeks of age and treated some mice with the bisphosphonate pamidronate during the first two weeks of prednisone administration. Prednisone reduced long bone growth, decreased cortical bone thickness and area and decreased the strength of the femurs. Pamidronate treatment protected mice from cortical bone loss but did not increase bone strength. The combination of prednisone and pamidronate inhibited remodeling of metaphyseal trabecular bone with large numbers of trabeculae containing remnants of calcified cartilage. Prednisone improved muscle strength in the mdx mice and decreased serum creatine kinase with evidence of improved muscle histology and these effects were maintained in mice treated with pamidronate.

Fracture in Duchenne Muscular Dystrophy: Natural History and Vitamin D Deficiency

The present study examined the natural history of fracture and vitamin D levels in Duchenne muscular dystrophy patients, who are vulnerable to osteoporosis and fractures. Retrospective analysis of a cohort of 48 Duchenne muscular dystrophy patients revealed that 43% of patients experienced ≥1 fracture. Fracture probabilities at ages 6, 9, 12, and 15 years were 4%, 9%, 31%, and 60% respectively, accelerating around the time of ambulation loss (mean age 11.8 ± 2.7 years). Chronic corticosteroid therapy was utilized in 69% of patients and was associated with all vertebral fractures. A history of vitamin D deficiency occurred in 84%, and 35% were currently deficient. Despite chronic vitamin D supplementation, 38% remained deficient. These results demonstrate that osteoporosis and fracture remain major concerns in Duchenne muscular dystrophy. Bone health should be optimized well before loss of ambulation, however current levels of vitamin D supplementation may be inadequate given high levels of deficiency.

Practice guideline update summary: Corticosteroid treatment of Duchenne muscular dystrophy: Report of the Guideline Development Subcommittee of the American Academy of Neurology

OBJECTIVE

To update the 2005 American Academy of Neurology (AAN) guideline on corticosteroid treatment of Duchenne muscular dystrophy (DMD).

METHODS

We systematically reviewed the literature from January 2004 to July 2014 using the AAN classification scheme for therapeutic articles and predicated recommendations on the strength of the evidence.

RESULTS

Thirty-four studies met inclusion criteria.

RECOMMENDATIONS

In children with DMD, prednisone should be offered for improving strength (Level B) and pulmonary function (Level B). Prednisone may be offered for improving timed motor function (Level C), reducing the need for scoliosis surgery (Level C), and delaying cardiomyopathy onset by 18 years of age (Level C). Deflazacort may be offered for improving strength and timed motor function and delaying age at loss of ambulation by 1.4-2.5 years (Level C). Deflazacort may be offered for improving pulmonary function, reducing the need for scoliosis surgery, delaying cardiomyopathy onset, and increasing survival at 5-15 years of follow-up (Level C for each). Deflazacort and prednisone may be equivalent in improving motor function (Level C). Prednisone may be associated with greater weight gain in the first years of treatment than deflazacort (Level C). Deflazacort may be associated with a greater risk of cataracts than prednisone (Level C). The preferred dosing regimen of prednisone is 0.75 mg/kg/d (Level B). Over 12 months, prednisone 10 mg/kg/weekend is equally effective (Level B), with no long-term data available. Prednisone 0.75 mg/kg/d is associated with significant risk of weight gain, hirsutism, and cushingoid appearance (Level B).

Bone and Spinal Muscular Atrophy

Spinal Muscular Atrophy (SMA) is an autosomal recessive neuromuscular disease, leading to progressive denervation atrophy in the involved skeletal muscles. Bone status has been poorly studied. We assessed bone metabolism, bone mineral density (BMD) and fractures in 30 children (age range 15-171 months) affected by SMA types 2 and 3. Eighteen children (60%) had higher than normal levels of CTx (bone resorption marker); 25-OH vitamin D was in the lower range of normal (below 20 ng/ml in 9 children and below 12 ng/ml in 2). Lumbar spine BMAD (bone mineral apparent density) Z-score was below -1.5 in 50% of children. According to clinical records, four children had sustained four peripheral fractures; on spine X-rays, we observed 9 previously undiagnosed vertebral fractures in 7 children. There was a significant inverse regression between PTH and 25-OH D levels, and a significant regression between BMC and BMAD values and the scores of motor-functional tests. Even if this study could not establish the pathogenesis of bone derangements in SMA, its main findings - reduced bone density, low 25OH vitamin D levels, increased bone resorption markers and asymptomatic vertebral fractures also in very young patients - strongly suggest that even young subjects affected by SMA should be considered at risk of osteopenia and even osteoporosis and fractures.

Risk Factors for First Fractures Among Males With Duchenne or Becker Muscular Dystrophy

BACKGROUND

Fractures are a significant concern for individuals with Duchenne/Becker muscular dystrophy with 21% to 44% of males experiencing a fracture. Factors that increase or decrease the risk for fracture have been suggested in past research, although statistical risk has not been determined.

METHODS

In this retrospective cohort study, we used the Muscular Dystrophy Surveillance, Tracking and Research Network cohort, a large, population-based sample to identify risk factors associated with first fractures in patients with Duchenne or Becker muscular dystrophy. Our study cohort included males with Duchenne or Becker muscular dystrophy born between 1982 and 2006 who resided in Arizona, Colorado, Georgia, Iowa, and Western New York, retrospectively identified and followed through 2010. We utilized a multivariate Cox proportional hazard model to determine hazard ratios for relevant factors associated with first fracture risk including race/ethnicity, surveillance site, ambulation status, calcium/vitamin D use and duration, bisphosphonate use and duration, and corticosteroid use and duration.

RESULTS

Of 747 cases, 249 had at least 1 fracture (33.3%). Full-time wheelchair use increased the risk of first fracture by 75% for every 3 months of use (hazard ratio=1.75, 95% confidence interval, 1.14, 2.68), but corticosteroid use, bisphosphonate use, and calcium/vitamin D use did not significantly affect risk in the final adjusted model.

CONCLUSIONS

In this cohort, first fractures were common and full-time wheelchair use, but not corticosteroid use, was identified as a risk factor. The impact of prevention measures should be more thoroughly assessed.

CLINICAL RELEVANCE

Fractures are a significant concern for individuals with dystrophinopathies, but the contribution of various risk factors has not been consistently demonstrated.

Optimizing Bone Health in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder characterized by progressive muscle weakness, with eventual loss of ambulation and premature death. The approved therapy with corticosteroids improves muscle strength, prolongs ambulation, and maintains pulmonary function. However, the osteoporotic impact of chronic corticosteroid use further impairs the underlying reduced bone mass seen in DMD, leading to increased fragility fractures of long bones and vertebrae. These serious sequelae adversely affect quality of life and can impact survival. The current clinical issues relating to bone health and bone health screening methods in DMD are presented in this review. Diagnostic studies, including biochemical markers of bone turnover and bone mineral density by dual energy X-ray absorptiometry (DXA), as well as spinal imaging using densitometric lateral spinal imaging, and treatment to optimize bone health in patients with DMD are discussed. Treatment with bisphosphonates offers a method to increase bone mass in these children; oral and intravenous bisphosphonates have been used successfully although treatment is typically reserved for children with fractures and/or bone pain with low bone mass by DXA.

Dietary phosphorus overload aggravates the phenotype of the dystrophin-deficient mdx mouse

Duchenne muscular dystrophy is a lethal X-linked disease with no effective treatment. Progressive muscle degeneration, increased macrophage infiltration, and ectopic calcification are characteristic features of the mdx mouse, a murine model of Duchenne muscular dystrophy. Because dietary phosphorus/phosphate consumption is increasing and adverse effects of phosphate overloading have been reported in several disease conditions, we examined the effects of dietary phosphorus intake in mdx mice phenotypes. On weaning, control and mdx mice were fed diets containing 0.7, 1.0, or 2.0 g phosphorus per 100 g until they were 90 days old. Dystrophic phenotypes were evaluated in cryosections of quadriceps and tibialis anterior muscles, and maximal forces and voluntary activity were measured. Ectopic calcification was analyzed by electron microscopy to determine the cells initially responsible for calcium deposition in skeletal muscle. Dietary phosphorus overload dramatically exacerbated the dystrophic phenotypes of mdx mice by increasing inflammation associated with infiltration of M1 macrophages. In contrast, minimal muscle necrosis and inflammation were observed in exercised mdx mice fed a low-phosphorus diet, suggesting potential beneficial therapeutic effects of lowering dietary phosphorus intake on disease progression. To our knowledge, this is the first report showing that dietary phosphorus intake directly affects muscle pathological characteristics of mdx mice. Dietary phosphorus overloading promoted dystrophic disease progression in mdx mice, whereas restricting dietary phosphorus intake improved muscle pathological characteristics and function.

Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy is one of the most severe muscle diseases to affect children. In the last twenty years, treatments have been established that have significantly improved patients' quality of life and life expectancy. The purpose of this article is to outline the main features of the disease and its treatment, and to examine possible future treatment options.

METHOD

The article is based on a literature search in PubMed, current international guidelines and our own clinical experience.

RESULTS

Close monitoring by an interdisciplinary rehabilitation team forms the basis of treatment. Treatment with glucocorticoids can slow disease progression and improve motor function in the short term. The treatment may cause side effects, which must be monitored and which may require intervention. A not insignificant proportion of patients have cognitive and neuropsychiatric problems that must be addressed. Active intervention in response to signs of respiratory or cardiac failure is important. More causal treatment of Duchenne muscular dystrophy is under testing and offers cautious hope for future patients.

INTERPRETATION

With improved treatment and increased life expectancy come new challenges for patients with Duchenne muscular dystrophy and their families, as well as new demands on the support services. This patient group requires close and comprehensive follow-up, also in the transition from child to adult.

Vibration therapy tolerated in children with Duchenne muscular dystrophy: a pilot study

BACKGROUND

Duchenne muscular dystrophy is an X-linked recessive muscular dystrophy. Clinical management primarily involves rehabilitation strategies aimed at preserving functional mobility as long as possible. Side-alternating vibration therapy is a rehabilitation intervention that has shown promise in a number of different neuromuscular disorders, and has the potential to preserve strength, functional mobility, and bone mass. There has been little research regarding the tolerance to side-alternating vibration therapy in muscle diseases such as Duchenne muscular dystrophy.

METHODS

Four patients were recruited for a pilot study assessing the safety and tolerance of side-alternating vibration therapy in individuals with Duchenne muscular dystrophy. All patients participated in a 4-week training period involving side-alternating vibration therapy sessions three times per week. Serum creatine kinase was measured, and adverse effects reviewed at each session with functional mobility assessed before and after the training period.

RESULTS

All patients tolerated the training protocol well, and there were no major changes in functional mobility. One patient had a transient increase in creatine kinase during the study; however, levels of this enzyme were stable overall when comparing the pretraining and posttraining values. Some patients reported subjective improvement during the training period.

CONCLUSIONS

Side-alternating vibration therapy is well tolerated in children with Duchenne muscular dystrophy and may have potential to improve or maintain functional mobility and strength in these patients.

Balloon Kyphoplasty for Refractory Vertebral Compression Fractures in a Growing Child With Duchenne Muscular Dystrophy With Five-Year Follow-Up: Case Report and Review of Literature

OBJECTIVE

Presentation of previously unreported results and 5-year follow-up of balloon kyphoplasty used to treat an 8-year-old patient with refractory vertebral compression fractures resulting from 3 years of corticosteroid treatment for Duchenne muscular dystrophy.

SUMMARY OF BACKGROUND DATA

Long-term corticosteroid treatment in patients with DMD has been used to try and improve muscle strength, prolong ambulation, and lower the prevalence of scoliosis. However, these patients have an increased risk of osteoporosis and vertebral fractures.

METHODS

The patient was an 8-year-old boy with Duchenne muscular dystrophy who had received corticosteroid treatment for 3 years, with refractory vertebral compression fractures at T11, L1, and L3. Balloon kyphoplasty was performed at the 3 vertebral bodies using careful technique.

RESULTS

The patient achieved immediate pain relief after the procedure. The height of the treated vertebrae remained stable without further collapse over a 5-year follow-up period. At 5-year follow-up, the patient developed 2 new vertebral compression fractures at T12 and L2 adjacent to the treated vertebrae. The treatment also did not affect the growth of the treated vertebrae or the patient's overall growth.

CONCLUSIONS

Because the procedure resulted in rapid stabilization of the treated vertebrae, effective analgesia, and no effect on the growth of the treated vertebrae over a 5-year follow-up period, balloon kyphoplasty was a good therapeutic option for this pediatric patient.

Delayed bone regeneration is linked to chronic inflammation in murine muscular dystrophy

Duchenne muscular dystrophy (DMD) patients exhibit skeletal muscle weakness with continuous cycles of muscle fiber degeneration/regeneration, chronic inflammation, low bone mineral density, and increased risks of fracture. Fragility fractures and associated complications are considered as a consequence of the osteoporotic condition in these patients. Here, we aimed to establish the relationship between muscular dystrophy and fracture healing by assessing bone regeneration in mdx mice, a model of DMD with absence of osteoporosis. Our results illustrate that muscle defects in mdx mice impact the process of bone regeneration at various levels. In mdx fracture calluses, both cartilage and bone deposition were delayed followed by a delay in cartilage and bone remodeling. Vascularization of mdx fracture calluses was also decreased during the early stages of repair. Dystrophic muscles are known to contain elevated numbers of macrophages contributing to muscle degeneration. Accordingly, we observed increased macrophage recruitment in the mdx fracture calluses and abnormal macrophage accumulation throughout the process of bone regeneration. These changes in the inflammatory environment subsequently had an impact on the recruitment of osteoclasts and the remodeling phase of repair. Further damage to the mdx muscles, using a novel model of muscle trauma, amplified both the chronic inflammatory response and the delay in bone regeneration. In addition, PLX3397 treatment of mdx mice, a cFMS (colony stimulating factor receptor 1) inhibitor in monocytes, partially rescued the bone repair defect through increasing cartilage deposition and decreasing the number of macrophages. In conclusion, chronic inflammation in mdx mice contributes to the fracture healing delay and is associated with a decrease in angiogenesis and a transient delay in osteoclast recruitment. By revealing the role of dystrophic muscle in regulating the inflammatory response during bone repair, our results emphasize the implication of muscle in the normal bone repair process and may lead to improved treatment of fragility fractures in DMD patients.

Muscular dystrophy: new challenges and review of the current clinical trials

PURPOSE OF REVIEW

We provide a review of recent standards of care and therapeutic development in different forms of muscular dystrophies. This topic is relevant as the improved understanding of these disorders has not only led to a better definition of clinical course and to the development of standards of care for individual types of muscular dystrophies, but also culminated in different therapeutic approaches.

RECENT FINDINGS

Recent natural history studies have demonstrated the impact of new standards of care in different forms of muscular dystrophies, and identified areas of clinical management in which further developments are needed. The majority of the experimental studies are focused on Duchenne muscular dystrophy. Some of them target patients with specific mutations, such as antisense oligonucleotides, to induce exon skipping of specific mutations or drugs developed to allow read-through of nonsense mutations, whereas other therapies deal with secondary aspects of muscle degeneration, aiming, for example, at reducing inflammation or apoptosis, and may also be suitable for other forms of muscular dystrophies.

SUMMARY

The advances in the field of muscular dystrophy have resulted in improved clinical course and survival. The encouraging results of early experimental studies could further improve these outcomes in the future.

Vitamin D deficiency in patients with neuromuscular diseases with chronic respiratory failure

BACKGROUND

The prevalence and clinical implications of vitamin D deficiency have never been studied in patients with underlying neuromuscular diseases complicated with chronic respiratory failure. The aim of this study is to demonstrate the prevalence of vitamin D deficiency, its relationship with other bone markers, and mode of nutrition.

MATERIALS AND METHODS

Serum 25-hydroxyvitamin D (25[OH]D) levels along with calcium, serum albumin, and phosphorus levels were obtained from 57 patients with chronic respiratory failure due to underlying neuromuscular diseases. These levels were obtained during their first visit to a chronic respiratory diseases clinic. Data with regard to nutrition, respiratory muscle function, and level of mobility were also obtained at the same time.

RESULTS

Seventy-five percent of patients had serum 25(OH)D levels ≤ 30 ng/mL. There is a negative correlation between parathyroid hormone and 25(OH)D levels (P = .006) and corrected calcium levels (P = .066). Serum 25(OH)D levels varied with the mode of nutrition. Patients on enteral nutrition had the highest serum levels of 25(OH)D, whereas combined oral and tube feeds had the lowest 25(OH)D levels (P = .006).

CONCLUSION

Low serum 25(OH)D levels are highly prevalent in patients with neuromuscular disease and chronic respiratory failure. The route of nutrition has an impact on these levels.