Fat embolism syndrome in patients with Duchenne muscular dystrophy

Fat embolism syndrome in Duchenne muscular dystrophy: Report on a novel case and systematic literature review

We report a non-ambulatory 13-year-old boy with Duchenne muscular dystrophy who experienced severe acute respiratory distress syndrome and cerebral fat embolism following elective soft tissue surgery. Post-surgery radiological examination revealed bilateral femoral fractures and marked osteopenia that were believed to have caused disseminated pulmonary and cerebral fat embolism. The patient had never been on glucocorticoid treatment. Five months post-surgery, he remained in a state of minimal consciousness. A literature review was performed and eleven publications included, providing case reports of a total number of 23 patients with Duchenne muscular dystrophy with fat embolism syndrome. The most common causes were falls from the wheelchair that predominantly resulted in femoral fractures. Median age at the event was around 14 years. Seven patients succumbed to complications of fat embolism. No event was described in the context of surgery. We want to raise awareness that spontaneous unnoticed fractures may occur especially in adolescents with DMD from traumatic injury of large bones and also during elective surgery with a high risk of causing fat embolism with severe sequelae.

Risk factors associated with prevalent vertebral fractures in Duchenne muscular dystrophy

Patients with Duchenne muscular dystrophy (DMD) have a high fracture burden due to progressive myopathy and steroid-induced osteoporosis. This study in males with DMD showed that markers of systemic glucocorticoid exposure including shorter stature, greater bone age delay, and lower lumbar spine bone mineral density were associated with spine fragility.

INTRODUCTION

Fragility  fractures are frequent in DMD. The purpose of this study was to identify clinical factors associated with prevalent vertebral fractures (VF) in boys, teens/young adults with Duchenne muscular dystrophy (DMD).

METHODS

This was a cross-sectional study of males aged 4-25 years with DMD. VF were evaluated using the modified Genant semi-quantitative method on T4-L4 lateral spine radiographs. Areal bone mineral density (aBMD) was measured at the lumbar spine (LS) and used to estimate volumetric BMD (vBMD). Clinical factors were analyzed for their association with the Spinal Deformity Index (SDI, the sum of the Genant grades).

RESULTS

Sixty participants were enrolled (mean age 11.5 years, range 5.4-19.5). Nineteen participants (32%) had a total of 67 VF; 23/67 VF (34%) were moderate or severe. Participants with VF were shorter (mean height Z-score ± standard deviation: - 3.1 ± 1.4 vs. - 1.8 ± 1.4, p = 0.001), had longer glucocorticoid exposure (mean duration 6.0 ± 3.3 vs. 3.9 ± 3.3 years, p = 0.027), greater bone age (BA) delay (mean BA to chronological age difference - 3.2 ± 3.4 vs. - 1.3 ± 1.2 years, p = 0.035), and lower LSaBMD Z-scores (mean - 3.0 ± 1.0 vs. - 2.2 ± 1.2, p = 0.023). There was no difference in LSvBMD Z-scores. Multivariable Poisson regression showed that every 0.1 mg/kg/day increment in average glucocorticoid daily dose was associated with a 1.4-fold SDI increase (95% confidence interval: 1.1-1.7, p = 0.013). Greater BA delay (p < 0.001), higher weight Z-score (p = 0.004), decreased height Z-score (p = 0.025), and lower LSvBMD Z-score (p = 0.025) were also associated with SDI increase.

CONCLUSION

Readily measurable clinical variables were associated with prevalent VF in males with glucocorticoid-treated DMD. These variables may be useful to identify candidates for primary osteoporosis prevention after glucocorticoid initiation.

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.

Bone Health and Osteoporosis Management of the Patient With Duchenne Muscular Dystrophy

Duchenne muscular dystrophy is associated with an increased risk of bone fragility due to the adverse effects of prolonged glucocorticoid therapy and progressive muscle weakness on bone strength. Osteoporosis manifests clinically as low-trauma long-bone and vertebral fractures (VFs), with VFs frequent, particularly in those treated with glucocorticoid therapy. It is increasingly recognized that bone pain, medical complications of osteoporosis (such as fat embolism syndrome), and the potential for permanent, fracture-induced loss of ambulation can be mitigated with timely bone health surveillance and management. This includes periodic spine radiographs for VF detection because VFs can be asymptomatic in their early phases and thereby go undetected in the absence of monitoring. With this article, we provide a comprehensive review of the following 4 phases of bone health management: (1) bone health monitoring, which is used to identify early signs of compromised bone health; (2) osteoporosis stabilization, which is aimed to mitigate back pain and interrupt the fracture-refracture cycle through bone-targeted therapy; (3) bone health maintenance, which has the goal to preserve the clinical gains realized during the stabilization phase through ongoing bone-targeted therapy; and (4) osteoporosis therapy discontinuation, which places those who are eligible for discontinuation of osteoporosis treatment back on a health monitoring program. In the course of reviewing these 4 phases of management, we will discuss the criteria for diagnosing osteoporosis, along with detailed recommendations for osteoporosis intervention including specific drugs, dose, length of therapy, contraindications, and monitoring of treatment efficacy and safety.

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.

Diagnosis and management of Duchenne muscular dystrophy, part 2: respiratory, cardiac, bone health, and orthopaedic management

A coordinated, multidisciplinary approach to care is essential for optimum management of the primary manifestations and secondary complications of Duchenne muscular dystrophy (DMD). Contemporary care has been shaped by the availability of more sensitive diagnostic techniques and the earlier use of therapeutic interventions, which have the potential to improve patients' duration and quality of life. In part 2 of this update of the DMD care considerations, we present the latest recommendations for respiratory, cardiac, bone health and osteoporosis, and orthopaedic and surgical management for boys and men with DMD. Additionally, we provide guidance on cardiac management for female carriers of a disease-causing mutation. The new care considerations acknowledge the effects of long-term glucocorticoid use on the natural history of DMD, and the need for care guidance across the lifespan as patients live longer. The management of DMD looks set to change substantially as new genetic and molecular therapies become available.

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.

Fat embolism after fractures in Duchenne muscular dystrophy: an underdiagnosed complication? A systematic review

Duchenne muscular dystrophy is the most frequent lethal genetic disease. Several clinical trials have established both the beneficial effect of steroids in Duchenne muscular dystrophy and the well-known risk of side effects associated with their daily use. For many years it has been known that steroids associated with ambulation loss lead to obesity and also damage the bone structure resulting in the bone density reduction and increased incidence of bone fractures and fat embolism syndrome, an underdiagnosed complication after fractures. Fat embolism syndrome is characterized by consciousness disturbance, respiratory failure and skin rashes. The use of steroids in Duchenne muscular dystrophy may result in vertebral fractures, even without previous trauma. Approximately 25% of patients with Duchenne muscular dystrophy have a long bone fracture, and 1% to 22% of fractures have a chance to develop fat embolism syndrome. As the patients with Duchenne muscular dystrophy have progressive cardiac and respiratory muscle dysfunction, the fat embolism may be unnoticed clinically and may result in increased risk of death and major complications. Different treatments and prevention measures of fat embolism have been proposed; however, so far, there is no efficient therapy. The prevention, early diagnosis and adequate symptomatic treatment are of paramount importance. The fat embolism syndrome should always be considered in patients with Duchenne muscular dystrophy presenting with fractures, or an unexplained and sudden worsening of respiratory and cardiac symptoms.

The PJ Nicholoff Steroid Protocol for Duchenne and Becker Muscular Dystrophy and Adrenal Suppression

Duchenne muscular dystrophy (DMD or Duchenne) is a progressive, life-limiting muscle-wasting disease that requires comprehensive, multidisciplinary care. This care, at minimum, should include neuromuscular, respiratory, cardiac, orthopedic, endocrine and rehabilitative interventions that address both the primary and secondary manifestations of the disease. The care needs of patients evolve over the cdourse of the disease and as they transition from childhood into young adulthood. In the past two decades, life expectancy has increased significantly by the use of corticosteroids and enhanced clinical management. Nevertheless, each year, patients with Duchenne muscular dystrophy are admitted to emergency departments and intensive care units where medical expertise thrives, but where expertise in rare diseases, such as Duchenne, may not. Emergency care for patients with Duchenne can be as complex as the disease process itself. While any illness or injury may occur in a person with Duchenne, some acute scenarios are much more common in the context of the disease. Making decisions about the clinical care of a person with Duchenne who presents with an acute illness can be quite difficult — in part, because of the extensive use of corticosteroids, which can lead to adrenal suppression. The life of a person with Duchenne needing emergency care may therefore depend upon the ability of the clinician on duty in the emergency department to recognize and mitigate adrenal suppression resulting from corticosteroid dependence. With this in mind, and drawing from expertise and experience with other steroid-dependent diseases, the ‘PJ Nicholoff Steroid Protocol’ was developed. The purpose of this protocol is to provide clinicians information regarding the safe management of corticosteroid during emergency situations in patients who may have accompanying adrenal suppression. The protocol explains how to recognize the signs and symptoms of acute adrenal crisis, how to prevent it with supplemental stress doses of corticosteroids, and how to taper doses after emergency care in order to prevent corticosteroid withdrawal.

Recurrent Fat Embolic Strokes in a Patient With Duchenne Muscular Dystrophy With Long Bone Fractures and a Patent Foramen Ovale

BACKGROUND

Individuals with Duchenne muscular dystrophy have an increased risk of long bone fractures. Such fractures are sometimes associated with brain dysfunction due to fat embolism syndrome, although this syndrome has seldom been documented in muscular dystrophy patients.

PATIENT DESCRIPTION

We describe a child with Duchenne muscular dystrophy who developed fat embolism syndrome with neurological dysfunction following multiple long bone fractures. He experienced recurrent cerebral infarctions that probably resulted from embolization through a patent foramen ovale. The patent foramen ovale was closed by an occluder device in the cardiac catheterization laboratory, and he did not experience further infarctions.

CONCLUSIONS

Fat embolism with ischemic cerebral infarction can occur in individuals with Duchenne muscular dystrophy following long bone fractures. In this setting it is important to identify and close atrial level shunts in order to prevent additional infarctions.

Fat Emboli Syndrome in a Child with Duchenne Muscular Dystrophy After Minor Trauma

BACKGROUND

Fat embolism syndrome is the result of systemic manifestations of fat emboli in the microcirculation. Duchenne muscular dystrophy is a condition that increases the risk of fracture resulting in fat emboli.

CASE REPORT

We describe a patient with Duchenne muscular dystrophy who exhibited cardiopulmonary, neurologic, and ophthalmologic sequelae consistent with fat emboli syndrome after minor trauma. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Fat embolism syndrome is a rare but important consideration with significant morbidity and risk of mortality in patients with Duchenne muscular dystrophy after even minor trauma. Early recognition and aggressive resuscitation are crucial to positive clinical outcomes.

Eplerenone for early cardiomyopathy in Duchenne muscular dystrophy: a randomised, double-blind, placebo-controlled trial

BACKGROUND

Cardiomyopathy is a leading cause of death in patients with Duchenne muscular dystrophy and myocardial damage precedes decline in left ventricular systolic function. We tested the efficacy of eplerenone on top of background therapy in patients with Duchenne muscular dystrophy with early myocardial disease.

METHODS

In this randomised, double-blind, placebo-controlled trial, boys from three centres in the USA aged 7 years or older with Duchenne muscular dystrophy, myocardial damage by late gadolinium enhancement cardiac MRI and preserved ejection fraction received either eplerenone 25 mg or placebo orally, every other day for the first month and once daily thereafter, in addition to background clinician-directed therapy with either angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB). Computer-generated randomisation was done centrally using block sizes of four and six, and only the study statistician and the investigational pharmacy had the preset randomisation assignments. The primary outcome was change in left ventricular circumferential strain (Ecc) at 12 months, a measure of contractile dysfunction. Safety was established through serial serum potassium levels and measurement of cystatin C, a non-creatinine measure of kidney function. This trial is registered with ClinicalTrials.gov, number NCT01521546.

FINDINGS

Between Jan 26, 2012, and July 3, 2013, 188 boys were screened and 42 were enrolled. 20 were randomly assigned to receive eplerenone and 22 to receive placebo, of whom 20 in the eplerenone group and 20 in the placebo group completed baseline, 6-month, and 12-month visits. After 12 months, decline in left ventricular circumferential strain was less in those who received eplerenone than in those who received placebo (median ΔEcc 1·0 [IQR 0·3-2·2] vs 2·2 [1·3-3·1]; p=0·020). Cystatin C concentrations remained normal in both groups, and all non-haemolysed blood samples showed normal potassium concentrations. One 23-year-old patient in the placebo group died of fat embolism, and another patient in the placebo group withdrew from the trial to address long-standing digestive issues. All other adverse events were mild: short-lived headaches coincident with seasonal allergies occurred in one patient given eplerenone, flushing occurred in one patient given placebo, and anxiety occurred in another patient given placebo.

INTERPRETATION

In boys with Duchenne muscular dystrophy and preserved ejection fraction, addition of eplerenone to background ACEI or ARB therapy attenuates the progressive decline in left ventricular systolic function. Early use of available drugs warrants consideration in this population at high risk of cardiac death, but further studies are needed to determine the effect of combination cardioprotective therapy on event-free survival in Duchenne muscular dystrophy.

FUNDING

BallouSkies, Parent Project for Muscular Dystrophy, US National Center for Advancing Translational Sciences, and US National Institutes of Health.