What is the management approach for Becker and Duchenne muscular dystrophy?

Management of Becker and Duchenne Muscular Dystrophy

The management of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) requires a comprehensive multidisciplinary approach focused on anticipatory care, with glucocorticoid therapy as the pharmacological cornerstone for DMD patients and careful monitoring of cardiac, respiratory, and musculoskeletal function for both conditions. 1

Diagnostic Approach

• Genetic testing: Precise genetic diagnosis is the gold standard and should be actively sought in all cases

  • Essential for:
    • Confirming diagnosis
    • Genetic counseling
    • Potential eligibility for mutation-specific therapies 1

• Clinical presentation differences:

  • DMD: Symptoms typically appear by age 3-5, loss of ambulation by early teens
  • BMD: Milder phenotype with later onset, variable progression, and dystrophin levels >40% of normal 2

Neuromuscular Management

Pharmacological Interventions

• Glucocorticoids (for DMD):

  • Recommended regimens:
    • Prednisone: 0.75 mg/kg/day
    • Deflazacort: 0.9 mg/kg/day
  • Benefits:
    • Increased muscle mass
    • Delayed disease progression
    • Preserved pulmonary function
    • Extended ambulation 1
  • Side effects requiring monitoring:
    • Weight gain
    • Growth retardation
    • Osteoporosis
    • Behavioral changes
    • Adrenal insufficiency 1

• BMD-specific considerations:

  • Glucocorticoids less commonly used due to milder phenotype
  • Treatment individualized based on symptom severity 2

Rehabilitation Management

• Physical therapy:

  • Regular assessments every 4-6 months
  • Stretching to prevent contractures
  • Passive stretching of ankles, knees, and hips
  • Night splints and standing frames 1

• Occupational therapy:

  • Adaptive equipment for activities of daily living
  • Wheelchair and seating assessments
  • Environmental modifications 3

• Orthopedic interventions:

  • Monitor for scoliosis development after loss of ambulation
  • Surgical intervention when Cobb angle reaches 30-50 degrees 1
  • Achilles tendon contractures may require intervention 1

Respiratory Management

• Regular monitoring:

  • Pulmonary function tests (FVC, PCF)
  • Sleep studies to detect nocturnal hypoventilation 1

• Interventions:

  • Airway clearance techniques
  • Assisted coughing when peak cough flow <270 L/min
  • Non-invasive ventilation when signs of nocturnal hypoventilation present
  • Consider mechanical insufflation-exsufflation for secretion management 1

• Perioperative considerations:

  • Preoperative pulmonary evaluation at least 2 months before surgery
  • Assess for sleep hypoventilation
  • Aggressive postoperative airway clearance 1

Cardiac Management

• Regular monitoring:

  • Echocardiogram at diagnosis or by age 6 years for DMD
  • Maximum 24 months between investigations
  • ECG and Holter monitoring as needed 1

• Interventions:

  • ACE inhibitors at first sign of cardiac dysfunction
  • Beta blockers as adjunctive therapy
  • Consider early intervention even with normal function in DMD 1

Psychosocial Management

• Regular assessments:

  • Emotional adjustment and coping
  • Neurocognitive functioning
  • Speech and language development
  • Screen for autism spectrum disorders 1

• Interventions:

  • Designate a care coordinator
  • Develop individualized education plan
  • Psychotherapy for behavioral issues
  • Pharmacological interventions for psychiatric symptoms when needed 1

Transition of Care

• Anticipatory planning:

  • Encourage self-advocacy in medical care
  • Facilitate transfer to adult medical care team
  • Develop educational and vocational opportunities 1, 4

• Palliative care considerations:

  • Pain management
  • Emotional and spiritual support
  • Guidance for treatment decisions 1

Special Considerations

BMD-Specific Management

• Generally milder course than DMD
• Higher dystrophin levels (>40% of control) correlate with milder phenotype
• Patients with deletions ending at exon 51 show higher dystrophin levels than those ending at exon 53 2

Emerging Therapies

• Exon-skipping therapies aim to transform DMD phenotype to milder BMD phenotype
• Gene therapy approaches under investigation 2, 5

Common Pitfalls and Caveats

• Delayed diagnosis: Failure to perform genetic testing can delay appropriate management
• Inadequate monitoring: Cardiac and respiratory complications can develop silently
• Steroid management: Side effects must be actively monitored and managed
• Surgical timing: Optimal timing for scoliosis surgery is while lung function is satisfactory but before severe cardiomyopathy develops 1
• Respiratory failure: Failure to anticipate respiratory decline can lead to emergency situations
• Psychosocial neglect: Cognitive and behavioral issues are often overlooked but significantly impact quality of life 1

The multidisciplinary management of DMD and BMD requires coordination between neurology, pulmonology, cardiology, orthopedics, rehabilitation, and psychosocial services to optimize outcomes and quality of life.