What is the management plan for a young male patient with a history of progressive muscle weakness and diagnosed with Duchene muscular dystrophy?

Management of Duchenne Muscular Dystrophy

Initiate corticosteroid therapy (deflazacort 0.9 mg/kg/day) starting at age 5 years or older, combined with comprehensive multidisciplinary care focused on respiratory monitoring, cardiac surveillance, and physical therapy to reduce morbidity and mortality. 1

Pharmacological Management

Corticosteroid Therapy

• Deflazacort is FDA-approved for DMD treatment in patients ≥5 years of age at a dose of approximately 0.9 mg/kg/day administered orally once daily. 1
• Corticosteroids slow the rate of decline in muscle function, prolong ambulation, delay respiratory decline, and help preserve ventilatory function longer. 2
• When discontinuing after more than a few days of use, taper gradually to avoid adrenal suppression. 1

Monitoring for Corticosteroid Adverse Effects

• Monitor for Cushingoid appearance, weight gain, hyperglycemia, hypertension, decreased bone mineral density, cataracts, glaucoma, behavioral changes, and increased infection risk. 1
• Check blood pressure, serum sodium, potassium levels, and bone mineral density regularly with chronic use. 1
• Avoid live or live-attenuated vaccines during immunosuppressive corticosteroid therapy; administer such vaccines 4-6 weeks before starting treatment if possible. 1

Respiratory Management

Surveillance and Monitoring

• Respiratory complications are the second most frequent cause of death in DMD (after cardiac failure) and a major cause of morbidity and unplanned hospital admissions. 2
• Respiratory muscle weakness typically becomes noticeable after loss of ambulation in adolescence, though onset varies significantly. 2
• Monitor for inspiratory muscle weakness causing nocturnal hypoventilation and sleep-disordered breathing. 2
• Assess for expiratory muscle weakness leading to poor cough and inability to manage respiratory secretions effectively. 2

Ventilatory Support

• Initiate ventilatory support when respiratory muscle weakness progresses—initially overnight, but may require 24-hour support as disease advances. 2
• The 2024 British Thoracic Society-endorsed UK respiratory care guidelines provide specific algorithms for assessment, monitoring, and emergency management. 2

Cardiac Management

Cardiac Surveillance

• DMD causes progressive dilated cardiomyopathy, which is the leading cause of death in this population. 2
• The cardiomyopathy presents with unique characteristics: less left ventricular dilation at diagnosis, only 30% symptomatic at diagnosis, and higher mortality compared to other dilated cardiomyopathies. 3
• Early introduction of cardiac medication delays onset and/or slows progression of cardiomyopathy. 2

Cardiac-Respiratory Interaction

• Cardiac involvement impacts respiratory function, and respiratory failure can trigger cardiac arrhythmias or exacerbate cardiac failure. 2
• Perform ECG, echocardiogram, or cardiac MRI for cardiac monitoring. 4
• Measure troponin to evaluate myocardial involvement. 4

Multidisciplinary Follow-Up

Frequency of Monitoring

• Schedule clinical visits every 6 months. 3
• Conduct specialized physical and occupational therapy evaluations every 4 months. 3

Disease Progression Assessment

• Perform strength tests, range of motion assessments, timed function tests, and activities of daily living evaluations at regular intervals. 3

Prognosis and Expectations

• With current standard of care in the UK, median life expectancy is 29-30 years. 2
• Without supportive care, death typically occurs in late teens to early twenties. 3
• With improved respiratory support, cardiomyopathy has become an increasingly important source of morbidity and mortality. 3

Common Pitfalls to Avoid

• Do not delay corticosteroid initiation—early treatment improves outcomes and slows disease progression. 2, 5
• Do not overlook respiratory monitoring after loss of ambulation—this is when respiratory complications typically emerge and require proactive management. 2
• Do not neglect cardiac surveillance—cardiomyopathy is often asymptomatic initially but is the leading cause of death. 2, 3
• Do not abruptly discontinue corticosteroids—gradual tapering is essential to prevent adrenal crisis. 1