
15/07/2025
🧠 Myasthenia Gravis (MG) - Hight yield
1. Types of Myasthenia Gravis
🔹 Ocular Myasthenia Gravis
Muscles involved: Only ocular muscles.
Symptoms:
Ptosis (drooping eyelids)
Diplopia (double vision)
Weakness of orbicularis oculi
🔹 Generalized Myasthenia Gravis
Muscles involved: Ocular, bulbar, limb, and respiratory muscles.
Symptoms:
Dysphagia
Dysarthria
Limb weakness
Respiratory distress
2. Clinical Stages of MG
🟠 Stage I – Acute/Exacerbation Phase
Frequent relapses
Risk of myasthenic crisis
🟡 Stage II – Stable Phase
Persistent symptoms
Less frequent exacerbations
Crises may still occur
🟢 Stage III – Remission Phase
Minimal to no symptoms
Some patients may be medication-free
3. Key Clinical Features
Fluctuating muscle weakness with fatigability
Ocular involvement (ptosis, diplopia)
Fatigability = hallmark
Improves with rest, worsens with exertion
4. Bedside & Laboratory Tests
🧪 Diagnostic Tools:
Ice Pack Test – Improvement in ptosis
Edrophonium (Tensilon) Test – Rarely used
Repetitive Nerve Stimulation (RNS)
Single-Fiber Electromyography (SFEMG)
🔬 Serum Autoantibodies:
Anti-AChR Ab: Positive in 85–90% (generalized MG)
Anti-MuSK & Anti-LRP4 Ab: If AChR negative
📸 Imaging & Other Tests:
Chest CT/MRI: To rule out thymoma
Thyroid profile: Rule out coexisting thyroid disease
5. Indications & Timing for Thymectomy
✅ Indications:
All patients with thymoma (mandatory surgery)
Generalized MG with AChR Ab+ (especially if