What is the treatment for bulbar onset Motor Neuron Disease (MND)?

Treatment of Bulbar Onset Motor Neuron Disease (MND)

Non-invasive ventilation (NIV) is the cornerstone treatment for respiratory complications in bulbar onset MND, though its effectiveness may be limited by the severity of bulbar dysfunction. 1

Understanding Bulbar Onset MND

Bulbar onset MND is characterized by:

• Initial symptoms affecting speech, swallowing, and breathing
• Progressive weakness of muscles controlled by cranial nerves
• High risk of respiratory complications due to:
  • Inability to clear secretions effectively
  • Risk of aspiration
  • Upper airway obstruction
  • Abnormal respiratory patterns during swallowing 2

Respiratory Management

Non-Invasive Ventilation (NIV)

• First-line intervention for respiratory insufficiency
• Benefits:
  • Improves quality of life in all patients with respiratory insufficiency
  • Prolongs median survival in patients with normal to moderately impaired bulbar function
  • Less effective for survival in patients with severe bulbar dysfunction 1

Ventilation Settings for Bulbar Onset MND

• Lower levels of pressure support are typically required
• PEEP in range of 5-10 cm H₂O is commonly needed to:
  • Increase residual volume
  • Reduce oxygen dependency 1
• I:E ratio of 1:1 is recommended due to high impedance 1

Monitoring and Progression

• Watch for warning signs:
  • Difficulty achieving adequate oxygenation
  • Rapid desaturation during breaks from NIV
  • Deterioration may be sudden and requires prompt intervention 1

Secretion Management

Pharmacological Approaches

• For sialorrhea (excessive saliva):
  • First-line: Hyoscine, amitriptyline, glycopyrrolate, or atropine 3
  • Second-line: Botulinum toxin type B injections to parotid and submandibular glands
    • Provides improvement for up to 4 weeks 1

Non-Pharmacological Approaches

• Specialized physiotherapy for sputum clearance
• Cough assistance techniques
• Mini-tracheostomy may be considered in severe cases 1

Nutritional Support

Enteral Feeding

• Consider early when:
  • Dysphagia affects adequate nutrition
  • Weight loss occurs
  • Aspiration risk increases
• Timing is critical - malnutrition is a poor prognostic factor 4
• PEG (percutaneous endoscopic gastrostomy) placement should be considered before respiratory function significantly declines 1

Decision-Making for Invasive Ventilation

Factors to Consider

• Senior staff should be involved in decision-making about invasive mechanical ventilation (IMV) 1
• Consult with home mechanical ventilation specialists when considering IMV 1
• Important considerations:
  • Severe bulbar dysfunction makes tracheostomy decannulation more difficult 1
  • Planned elective domiciliary NIV is preferable to crisis management 1

Multidisciplinary Care Approach

• Coordinated care involving:
  • Respiratory specialists
  • Neurologists
  • Speech and language therapists
  • Dietitians
  • Physiotherapists
  • Occupational therapists 5

Pitfalls and Caveats

1. Delayed Intervention: Early implementation of NIV is crucial before respiratory crisis develops
2. Inadequate Secretion Management: Bulbar dysfunction with abundant secretions increases aspiration risk and makes NIV more difficult 2
3. Overlooking Nutritional Status: Malnutrition worsens respiratory muscle function and reduces survival 2
4. Inaccurate Assessment: Standard respiratory function tests like forced vital capacity may be inaccurate in patients with bulbofacial weakness 2
5. Inappropriate Ventilation Settings: Patients with bulbar onset MND require specific ventilation parameters different from other neuromuscular conditions 1

Disease-Modifying Treatment

Currently, riluzole is the only medication that modestly prolongs survival (by 3-4 months) in ALS, the most common form of MND 4. However, its effect is limited, emphasizing the importance of symptomatic management and quality of life measures.