What is the primary treatment for Duchenne muscular dystrophy (DMD)?

Treatment for Duchenne Muscular Dystrophy

Glucocorticoid therapy with daily prednisone (0.75 mg/kg/day) or deflazacort (0.9 mg/kg/day) is the primary treatment for Duchenne muscular dystrophy and should be offered to all patients to prolong ambulation, improve survival, and enhance quality of life. 1, 2

Pharmacological Management: Glucocorticoids

First-Line Therapy Selection

• Prednisone at 0.75 mg/kg/day (maximum 40 mg/day) is the first-line treatment unless pre-existing weight gain or behavioral issues favor deflazacort. 1, 2

• Deflazacort at 0.9 mg/kg/day should be chosen as first-line when weight or behavioral concerns exist at baseline. 1, 2

• Both agents have similar efficacy in improving muscle strength and function, but differ in side effect profiles: prednisone causes more weight gain in early treatment years, while deflazacort carries higher cataract risk. 2

Timing of Initiation

• Do not start glucocorticoids in children under 2 years who are still gaining motor skills. 3

• Initiate therapy during the plateau phase (typically age 4-8 years) when motor skills stop progressing but before clear decline begins. 3

• Starting during the decline phase is still beneficial but may provide more limited benefit compared to earlier initiation. 3

• Complete all immunizations and establish varicella immunity before starting glucocorticoids. 1

Clinical Benefits of Long-Term Therapy

Glucocorticoid therapy provides substantial benefits beyond short-term strength improvements:

• Prolongs independent ambulation by 2-5 years. 4

• Reduces risk of progressive scoliosis and need for spinal surgery. 3, 4, 2

• Stabilizes pulmonary function and delays need for noninvasive ventilation. 3, 4, 2

• Delays cardiomyopathy onset by age 18 years. 2

• Increases survival at 5-15 years of follow-up. 2

Multidisciplinary Management Components

Cardiac Management

• Initiate ACE inhibitors or ARBs by age 10 years (unless contraindicated) regardless of cardiac symptoms. 1

• Add beta-blockers after ACE inhibitor/ARB initiation, especially with ventricular dysfunction or elevated heart rate. 1

• Perform echocardiogram at diagnosis or by age 6 years, then at least every 24 months. 5

Respiratory Management

• Monitor pulmonary function regularly with spirometry and timed function tests. 1

• Assess for sleep hypoventilation using sleep studies or nocturnal oximetry. 1

• Arrange pulmonologist evaluation at least 2 months before any planned surgery. 1

Orthopedic Management

• Consider surgical intervention for scoliosis when Cobb angle reaches 30-50 degrees. 1

• No absolute pulmonary function contraindications exist for scoliosis surgery; patients with FVC as low as 20% predicted have had successful outcomes. 1

Physical and Occupational Therapy

• Schedule assessments every 4 months to maintain function and prevent contractures. 1

• Implement heel cord stretching and gentle exercise programs early in disease course. 6

Monitoring Schedule

• Routine clinic appointments every 6 months for comprehensive assessment. 1

• Perform standardized timed function tests (Gowers' time, 9-meter walk, 4-stair climb) at each visit. 5

• Screen for emotional adjustment, depression, and anxiety at every visit. 1

• Conduct comprehensive neuropsychological assessment at diagnosis. 1

Management of Glucocorticoid Side Effects

Common Side Effects

The most frequent adverse effects include:

• Excessive weight gain (most common with prednisone). 2, 7

• Cushingoid appearance and hirsutism. 2, 7

• Behavioral abnormalities. 7

• Cataracts (more common with deflazacort). 2

Proactive Management Strategy

• Do not abandon glucocorticoid therapy without first attempting dose reduction or alternative regimens. 1

• Provide families with a steroid card listing emergency considerations for acute illness, fracture, infection, or need for surgery/anesthesia. 3

• Maintain high index of suspicion for steroid-related complications at all times. 3

• Consult dietitian for all patients, particularly those on prednisone, to control weight and maintain healthy diet. 6

Critical Pitfalls to Avoid

• Delaying glucocorticoid initiation leads to faster disease progression and missed opportunities to prolong ambulation. 5

• Failing to address cardiac complications early significantly impacts mortality; prophylactic cardiac therapy by age 10 is essential. 1, 5

• Overlooking psychosocial needs reduces quality of life; designate a care coordinator and screen regularly. 5

• Supplements (coenzyme Q10, carnitine, amino acids, anti-inflammatories/anti-oxidants) lack sufficient evidence and should not replace proven glucocorticoid therapy. 1