What is the treatment for an acute flare of neuromyelitis optica (NMO)?

Treatment of Acute Flares in Neuromyelitis Optica Spectrum Disorder (NMOSD)

For acute flares of neuromyelitis optica, high-dose intravenous methylprednisolone followed by plasma exchange (PLEX) is the recommended treatment approach, with PLEX being particularly important if there is no improvement within 3 days of steroid therapy.

First-Line Treatment

High-Dose Intravenous Corticosteroids

• Initial therapy should be intravenous methylprednisolone 1-2 mg/kg/day
• Typically administered for 3-5 consecutive days
• Should be initiated promptly, ideally within the first few hours of symptom onset
• Early intervention is critical to minimize permanent neurological damage

Plasma Exchange (PLEX)

• Should be considered immediately if:
  • Symptoms are severe
  • No improvement after 3 days of IV corticosteroids
  • Symptoms worsen despite steroid treatment 1
• Protocol typically includes 5-7 exchanges over 7-14 days
• More effective than steroids alone for recovery from acute attacks 2
• Some experts now suggest PLEX could be considered as initial treatment in certain clinical scenarios due to higher effectiveness 2

Treatment Algorithm

1. Confirm diagnosis of NMO acute flare (MRI, AQP4-IgG testing if not previously done)
2. Start IV methylprednisolone immediately (1-2 mg/kg/day)
3. Assess response after 3 days of treatment
4. If inadequate response or worsening:
   • Initiate plasma exchange
   • Consider 5-7 exchanges over 1-2 weeks
5. For severe initial presentations (significant motor weakness, respiratory involvement, or extensive spinal cord lesions):
   • Consider early combined approach with both IV steroids and PLEX

Monitoring and Complications

Steroid-Related Adverse Events (36.7% of patients) 3

• Hyperglycemia (most common - 43.5%)
• Infections (29%)
• Monitor blood glucose levels regularly
• Consider infection prophylaxis in prolonged courses

PLEX-Related Adverse Events (61.1% of patients) 3

• Hypocalcemia (most common - 63.6%)
• Hypofibrinogenemia (42.4%)
• Hypotension (30.3%)
• Infections (21.2%)
• Monitor calcium, fibrinogen levels and blood pressure during treatment

Special Considerations

Factors Associated with Poor Prognosis

• Extensive spinal cord MRI lesions
• Reduced muscle strength or sphincter dysfunction at presentation
• Presence of antiphospholipid antibodies
• Delay (>2 weeks) in initiation of therapy 1

Optic Neuritis in NMO

• Particularly aggressive with poor visual outcomes
• Only 30% of patients maintain visual acuity better than 20/25 1
• Requires aggressive treatment with IV methylprednisolone and cyclophosphamide
• Consider anticoagulation in antiphospholipid-positive patients not responding to immunosuppressive therapy 1

Maintenance Therapy After Acute Treatment

After acute flare treatment, long-term immunosuppression should be initiated to prevent relapses, which are common (50-60%) during corticosteroid dose reduction 1. Options include:

• Rituximab (B-cell depleting therapy)
• Azathioprine
• Mycophenolate mofetil
• Low-dose oral corticosteroids

Important Caveats

1. Timing is critical - neurological response to treatment typically occurs within a few days to 3 weeks if treatment is initiated promptly 1

2. Distinguish from MS - NMO responds differently to treatment than multiple sclerosis, and MS treatments may not be suitable or could potentially worsen NMO 4

3. Consider antibody status - Treatment approach may be influenced by whether the patient is AQP4-IgG positive or MOG-IgG positive

4. Relapses cause cumulative disability - Aggressive and early treatment is essential to prevent permanent neurological damage