What is the recommended management plan for muscular dystrophy, including corticosteroid therapy, physiotherapy, cardiac and pulmonary monitoring, and genetic counseling?

Management of Muscular Dystrophy (Duchenne)

Glucocorticoid therapy is the cornerstone of treatment and should be initiated when the child reaches a functional plateau or begins declining, typically around age 6 years, using prednisone 0.75 mg/kg/day or deflazacort 0.9 mg/kg/day on a daily schedule 1.

Corticosteroid Therapy: The Primary Disease-Modifying Treatment

When to Start Glucocorticoids

The timing depends on functional status, not just age 1:

Age ≥6 years:

• Plateau or decline in function: Initiate glucocorticoids immediately (highly recommended)
• Still improving: Consider Becker muscular dystrophy as alternative diagnosis

Age <6 years:

• Improving (typical): Do NOT initiate glucocorticoids
• Plateau (uncommon): Monitor closely every 3-4 months
• Decline (atypical): Investigate alternative diagnoses or concomitant pathology

Critical prerequisite: Complete all immunizations and establish varicella immunity before starting steroids 1.

Dosing Regimens

First-line daily therapy 1:

• Prednisone: 0.75 mg/kg/day (first-line unless weight/behavioral issues exist)
• Deflazacort: 0.9 mg/kg/day (consider first-line if pre-existing weight gain or behavioral problems)

Increase dose incrementally as child grows up to maximum weight of 40 kg (prednisone cap: 30-40 mg/day; deflazacort cap: 36-39 mg/day) 1.

Continue glucocorticoids even after loss of ambulation - this reduces scoliosis progression, stabilizes pulmonary function, and may slow cardiac decline 1.

Managing Intolerable Side Effects

If side effects become unmanageable 1:

1. First step: Reduce daily dose by 25-33%, reassess in 1 month
2. If still intolerable:
   • For weight gain/behavior issues: Switch from prednisone to deflazacort
   • Consider alternative dosing: high-dose weekend (5 mg/kg Friday/Saturday)
3. Last resort before discontinuation: Intermittent 10/10 or 10/20 schedule (less effective but better tolerated)

Minimum effective dose: Prednisone 0.3 mg/kg/day shows some benefit, though not maximal 1.

Mandatory Side Effect Monitoring

Monitor at every clinic visit (every 6 months) 1:

• Weight and BMI: Most common issue; reduce salt intake, refer dietitian
• Blood pressure: Check as percentile for height/sex; if >99%, reduce salt and consider ACE inhibitor
• Bone health: Annual DEXA scan; monitor vitamin D levels (supplement if <32 nmol/L); consider bisphosphonates for fractures
• Glucose: Urine dipstick at each visit; if positive, check fasting/post-prandial glucose
• Cataracts: Annual ophthalmology exam (especially with deflazacort)
• Behavioral changes: ADHD symptoms, emotional lability
• Growth: Height velocity (expect some suppression)

Provide families with a steroid emergency card listing considerations for acute illness, surgery, or trauma 1.

Multidisciplinary Monitoring and Interventions

Cardiac Management

• Baseline cardiac evaluation at diagnosis or by age 6 years 2
• Echocardiogram and ECG every 2 years until age 10, then annually thereafter
• Initiate ACE inhibitors or beta-blockers prophylactically when cardiac dysfunction detected
• Female carriers also require cardiac screening

Pulmonary Management

• Pulmonary function tests (FVC) every 6 months starting when child can cooperate (typically age 5-6) 2
• Initiate noninvasive positive pressure ventilation when FVC <50% predicted or symptoms of nocturnal hypoventilation
• Assisted cough devices when peak cough flow declines
• Annual influenza vaccination; pneumococcal vaccination

Physical Therapy and Orthopedic Care

Physical/occupational therapy assessments every 4 months 1:

• Stretching exercises: Focus on heel cords, iliotibial bands, hip flexors, knee flexors
• Avoid excessive eccentric exercise (descending stairs, squatting, trampolining) - risk of myoglobinuria 1
• Standing frames to maintain bone density and reduce contractures
• Ankle-foot orthoses (AFOs) for nighttime use to prevent contractures

Orthopedic monitoring:

• Scoliosis screening every 6 months once non-ambulatory
• Spinal fusion surgery if curve progresses to 20-30 degrees (glucocorticoids delay but don't eliminate need)

Bone Health

Beyond steroid monitoring 1:

• Calcium and vitamin D supplementation (dietitian assessment)
• Annual vitamin D levels (target >32 nmol/L)
• Bisphosphonates (e.g., pamidronate) for recurrent fractures or severe osteoporosis

Genetic Counseling

• Confirm specific DMD mutation via genetic testing for family planning
• Carrier testing for female relatives
• Prenatal/preimplantation genetic diagnosis options for future pregnancies
• Discuss emerging mutation-specific therapies (exon skipping, gene therapy) based on patient's specific mutation 3, 4

Emerging Therapies (Context for Discussions)

While glucocorticoids remain standard of care, newer options exist 3, 5:

• Exon-skipping therapies (FDA-approved for specific mutations: exon 51,45,53)
• Gene replacement therapy (AAV-based microdystrophin; recently FDA-approved)
• Nonsense suppression (ataluren for nonsense mutations)

These are mutation-specific and require precise genetic characterization. They complement but do not replace glucocorticoids and multidisciplinary care.

Common Pitfalls to Avoid

1. Delaying glucocorticoid initiation until significant functional decline - start at plateau phase around age 6
2. Stopping steroids when non-ambulatory - continue for cardiac, pulmonary, and scoliosis benefits
3. Abandoning steroids at first side effect - adjust dose/regimen before discontinuing
4. Inadequate bone health monitoring - fractures significantly impact quality of life
5. Missing cardiac surveillance - cardiomyopathy is leading cause of death in modern era
6. Neglecting pulmonary function monitoring - early intervention with NIV improves survival