Management and Follow-Up for Myasthenia Gravis
The recommended treatment plan for myasthenia gravis (MG) should begin with pyridostigmine for symptom control, followed by immunosuppressive therapy with corticosteroids and steroid-sparing agents, with regular neurological assessments to monitor response and adjust medications accordingly. 1
Initial Treatment Approach
First-Line Therapy
- Pyridostigmine (Acetylcholinesterase Inhibitor)
Immunosuppressive Therapy
Corticosteroids
- Add prednisone 0.5-1.5 mg/kg orally daily for Grade 2 symptoms (mild generalized weakness)
- 66-85% of patients show positive response 1
Steroid-Sparing Agents (initiate concurrently with corticosteroids)
- Methotrexate: 15 mg weekly
- Azathioprine: 2 mg/kg of ideal body weight in divided doses
- Mycophenolate mofetil: 500 mg twice daily, increasing to 1000 mg twice daily 1
Management of Severe Cases
Acute Exacerbations and Crisis
- IVIG: 2 g/kg over 5 days
- Plasmapheresis: Daily for 5 days
- Indicated for myasthenic crisis, severe exacerbations, or when refractory to immunosuppressive therapy 1, 3
Refractory Cases
Thymectomy
- Indicated for all patients with thymoma
- Recommended for non-thymoma AChR-positive patients up to age 50-65 years who don't achieve remission with symptomatic treatment 1, 4
Monitoring and Follow-Up
Regular Assessment
- Neurological evaluations when starting or adjusting medications
- Monitor for signs of respiratory compromise (crucial for early detection of myasthenic crisis)
- Assessment of improvement in muscle strength and endurance 1
Respiratory Function
- Regular pulmonary function testing (NIF and vital capacity)
- Early intervention for respiratory infections
- Consider non-invasive ventilation for respiratory insufficiency 1, 3
Medication Monitoring
- Watch for signs of cholinergic crisis (overdosage of pyridostigmine) vs. myasthenic crisis (worsening disease) 2
- Differentiation is critical as management differs radically:
Long-Term Management
Medication Adjustments
- Aim to reduce corticosteroid dose to minimize side effects
- Long-term immunosuppression with azathioprine has shown marked clinical improvement, allowing reduction in pyridostigmine and prednisolone doses 5
- Regular follow-up with a neuromuscular specialist for medication adjustments based on clinical response 1
Medication Precautions
- Avoid medications that can exacerbate symptoms:
- Beta-blockers
- IV magnesium
- Fluoroquinolones
- Aminoglycosides
- Macrolide antibiotics 1
- Safer antibiotic alternatives: penicillins, cephalosporins, and tetracyclines 1
Special Considerations
- Elderly patients: Start at lower doses and titrate more slowly due to increased sensitivity to side effects 1
- Surgical patients: Continue pyridostigmine until surgery; increased sensitivity to neuromuscular blocking agents 1
- Pregnancy planning: Requires careful medication management due to potential teratogenicity of immunosuppressants 6
Additional Evaluations
- Consider MRI of brain/spine to rule out other conditions
- Chest imaging to evaluate for thymoma (present in 10-20% of AChR-positive patients) 1
- Cardiac evaluation with troponin, ECG, and consider TTE/cardiac MRI to rule out myocarditis 1
Prognosis and Outcomes
- Most patients with myasthenic crisis can be weaned from mechanical ventilation within 1 month
- Mortality rate in US cohorts is less than 5%, primarily driven by age and medical comorbidities
- Myasthenic crisis does not appear to affect long-term prognosis 3
- With appropriate treatment, most patients achieve good disease control 4
Common Pitfalls to Avoid
- Failure to distinguish between cholinergic crisis (pyridostigmine overdose) and myasthenic crisis (disease exacerbation)
- Overlooking respiratory function monitoring, which can lead to delayed recognition of impending crisis
- Using medications known to exacerbate MG symptoms
- Inadequate immunosuppression or premature tapering of immunosuppressants
- Failing to initiate steroid-sparing agents early, leading to prolonged high-dose steroid exposure