What is the recommended treatment approach for patients with muscular dystrophy, specifically Duchenne muscular dystrophy (DMD)?

Treatment Approach for Duchenne Muscular Dystrophy (DMD)

Glucocorticoid therapy should be initiated in all patients with DMD when they reach a functional plateau or decline phase (typically around 6 years of age) and continued even after loss of ambulation. 1

Pharmacological Management

Glucocorticoid Therapy

• First-line treatment: Prednisone 0.75 mg/kg/day (maximum 40 mg/day) or deflazacort 0.9 mg/kg/day (maximum 36 mg/day) 1, 2

• Benefits of glucocorticoids include:

  • Preservation of muscle strength and function 3, 2
  • Reduction in risk of progressive scoliosis 3, 2
  • Stabilization of pulmonary function 3, 2
  • Potential improvement in cardiac function 3, 1
  • Delay in loss of ambulation by 1.4-2.5 years (with deflazacort) 2
  • Improved survival at 5-15 years follow-up 1

• Timing considerations:

  • Not recommended for children under 2 years who are still gaining motor skills 3, 1
  • Optimal timing is when the child reaches plateau phase (no longer progressing in motor skills but before decline) 3
  • Complete immunizations and establish varicella immunity before starting 3, 1

Cardiac Management

• ACE inhibitors or ARBs should be initiated by 10 years of age (unless contraindicated) 3, 1
• β-blockers should be added after ACE inhibitor/ARB initiation, particularly with ventricular dysfunction or elevated heart rate 3
• Mineralocorticoid receptor antagonists (e.g., eplerenone) can attenuate decline in left ventricular function 3
• Regular cardiac evaluations every 6-12 months 1

Emerging Therapies

• Eteplirsen (EXONDYS 51) for patients with mutations amenable to exon 51 skipping 1, 4
• Gene transfer therapy using adeno-associated virus vectors is being investigated 4

Respiratory Management

• Regular pulmonary function testing with FVC and peak cough flow measurements 1
• Referral to respiratory specialist when:
  • Sleep disorder symptoms appear
  • Peak cough flow < 270 L/min
  • FVC ≤ 50% of predicted value 1

Rehabilitation and Supportive Care

• Physical and occupational therapy evaluations every 4 months 1, 5
• Early implementation of heel cord stretching and exercise programs 5
• Monitoring of disease progression using functional scales (e.g., Vignos lower limb scale, North Star ambulatory assessment) 1

Surgical Management

• Consider scoliosis surgery when Cobb angle is between 30-50 degrees 1
• Preoperative evaluation by pulmonologist and cardiologist at least 2 months before any surgery 1

Monitoring and Side Effect Management

• Monitor for common side effects of glucocorticoids:
  • Weight gain (more common with prednisone than deflazacort) 2
  • Hirsutism and cushingoid appearance 2
  • Cataracts (more common with deflazacort) 2
• If side effects are unmanageable, reduce dose by 25-33% 1
• Regular clinical appointments every 6 months to monitor disease progression and adjust treatment 1

Common Pitfalls and Caveats

• Despite strong evidence supporting glucocorticoid use, there is significant variation in practice regarding dosing regimens 6
• Delaying glucocorticoid initiation until after significant functional decline may limit benefits 3
• Failure to continue glucocorticoids after loss of ambulation may miss benefits for respiratory, cardiac, and orthopedic complications 3, 1
• Not providing steroid cards or similar notification of steroid use for emergency situations 3
• Inadequate monitoring of cardiac function, which requires regular assessment even in asymptomatic patients 3, 1

The evidence strongly supports early intervention with glucocorticoids as the cornerstone of DMD management, with comprehensive multidisciplinary care addressing cardiac, respiratory, orthopedic, and functional needs throughout the disease course.