Myasthenia Gravis - Classification

Classification

The most widely accepted classification of myasthenia gravis is the Myasthenia Gravis Foundation of America Clinical Classification:

• Class I: Any eye muscle weakness, possible ptosis, no other evidence of muscle weakness elsewhere
• Class II: Eye muscle weakness of any severity, mild weakness of other muscles
  • Class IIa: Predominantly limb or axial muscles
  • Class IIb: Predominantly bulbar and/or respiratory muscles
• Class III: Eye muscle weakness of any severity, moderate weakness of other muscles
  • Class IIIa: Predominantly limb or axial muscles
  • Class IIIb: Predominantly bulbar and/or respiratory muscles
• Class IV: Eye muscle weakness of any severity, severe weakness of other muscles
  • Class IVa: Predominantly limb or axial muscles
  • Class IVb: Predominantly bulbar and/or respiratory muscles (Can also include feeding tube without intubation)
• Class V: Intubation needed to maintain airway