What is the treatment for a myasthenia crisis?

Treatment of Myasthenia Crisis

Admit the patient immediately to the ICU, initiate either IVIG (0.4 g/kg/day for 5 days, total 2 g/kg) or plasmapheresis for 5 consecutive days, secure the airway early with intubation if respiratory insufficiency is present, and avoid medications that worsen myasthenia including β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolides. 1

Immediate Recognition and ICU Admission

• ICU admission is mandatory for all patients in myasthenic crisis for close monitoring and potential respiratory support 1
• The crisis manifests as rapidly progressive weakness of respiratory and bulbar muscles leading to respiratory insufficiency and aspiration 2
• Approximately 66% of patients in crisis require intubation, and early airway protection is essential to prevent aspiration and respiratory failure 1, 3
• The median duration of mechanical ventilation is 12-14 days under appropriate treatment 2

Respiratory Assessment and Airway Management

• Perform immediate pulmonary function testing with negative inspiratory force (NIF) and vital capacity (VC) measurements 1
• Intubate early when respiratory insufficiency develops—do not delay as bulbar symptoms with aspiration can rapidly deteriorate 2
• Approximately 30% of patients develop ventilator-associated pneumonia, which is the most common complication and requires aggressive treatment 4
• About 9 out of 23 patients (39%) who require intubation subsequently need tracheostomy for prolonged ventilation 3

Acute Immunomodulatory Treatment

Choose one of the following two equally effective options: 1

Option 1: IVIG

• Dose: 0.4 g/kg/day for 5 consecutive days (total dose 2 g/kg) 1
• Time to disease stabilization: median 10 days (range 7-39 days) 4

Option 2: Plasmapheresis

• Administer for 5 consecutive days 1
• Time to disease stabilization: median 8 days (range 7-12 days) 4
• Both PE and IVIG are equally effective, with no significant difference in outcomes 4

Important caveat: IVIG should NOT be used for chronic maintenance therapy in myasthenia gravis—it is reserved only for acute exacerbations and crisis situations 5

Corticosteroid Management

• Continue corticosteroids if already prescribed (methylprednisolone 1-2 mg/kg daily) 1
• If not already on steroids, initiate immunosuppression with corticosteroids during the crisis 2
• Note that steroid administration itself can precipitate crisis in 2 out of 19 cases, so monitor closely 3

Pyridostigmine Management During Crisis

• Maintain pyridostigmine therapy and adjust dose based on improvement 1
• Typical dosing: 30 mg orally three times daily, potentially increasing to maximum 120 mg four times daily 6
• Critical warning: Distinguish myasthenic crisis from cholinergic crisis—increasing pyridostigmine during cholinergic crisis can have grave consequences including death 7
• Cholinergic crisis requires prompt withdrawal of all anticholinesterase drugs and immediate atropine administration 7

Medications to Strictly Avoid

The following medications can precipitate or worsen myasthenic crisis and must be avoided: 1, 6

• β-blockers
• IV magnesium
• Fluoroquinolone antibiotics
• Aminoglycoside antibiotics
• Macrolide antibiotics

Diagnostic Workup During Crisis

• Obtain immediate neurologic consultation 1
• Perform electrodiagnostic studies including repetitive stimulation and/or jitter studies 1
• Check anti-AChR antibodies and anti-striated muscle antibodies; if AChR negative, test for muscle-specific kinase and lipoprotein-related 4 antibodies 1
• Evaluate for concurrent myositis or myocarditis with CPK, aldolase, ESR, CRP, ECG, and TTE if respiratory insufficiency or elevated CPK/troponin T is present 1

Identify and Treat Precipitating Factors

Infection is the most common precipitant, occurring in 65% of crisis episodes 4

Other precipitants include: 4, 3

• Reduction in medication (5 cases)
• Menstruation (4 cases)
• Steroid administration (2 cases)

Aggressively treat infections and complications as they directly influence outcomes and duration of crisis 2

Long-term Immunosuppression

• Continue or initiate azathioprine or mycophenolate during crisis management 1
• After crisis resolution, continue immunosuppressive therapy and gradually taper corticosteroids based on symptom improvement 1
• For refractory cases, rituximab is an escalation option 2

Thymectomy Consideration

• Evaluate for thymectomy after stabilization in patients with thymoma, as thymoma is associated with poorer outcomes in myasthenic crisis 1
• Note that 33% of crisis episodes occur in patients with thymoma 4

Prognosis and Monitoring

• Mortality should be 5% or less with appropriate management, with elderly patients being most vulnerable 8
• The lifetime risk of recurrence is approximately 30% 2
• Most crises occur within the first 2 years of disease onset (52% of cases) 4
• Complete resolution of admission symptoms occurs in patients who survive to discharge 4
• Perform frequent pulmonary function assessment and daily neurologic review to monitor disease progression 1