What is the treatment for Neuromyelitis Optica (NMO)?

Treatment of Neuromyelitis Optica (NMO)

Rituximab is the most effective treatment for neuromyelitis optica spectrum disorder (NMOSD), demonstrating superior reduction in relapse rates compared to other immunosuppressants. 1

Acute Attack Management

• High-dose intravenous methylprednisolone (IVMP) at 1000 mg/day for 3-5 days is the initial recommended treatment for acute NMOSD attacks and should be initiated promptly, as delay beyond 2 weeks is associated with poorer outcomes 1
• Plasma exchange (PLEX) should be initiated early in severe attacks or when response to steroids is inadequate, with clinical improvement in 79.2% of patients 1, 2
• Some experts suggest that PLEX could be considered as an initial treatment approach in certain clinical scenarios due to its higher effectiveness compared to IVMP alone 2
• Common adverse events with IVMP include hyperglycemia (43.5%) and infection (29%), while PLEX can cause hypocalcemia (63.6%), hypofibrinogenemia (42.4%), and hypotension (30.3%) 3

Long-Term Disease-Modifying Therapy

• Rituximab (RTX) is the preferred first-line maintenance therapy with recommended dosing of either 375 mg/m² weekly for 4 weeks or 1000 mg × 2 weeks apart 1
• Mycophenolate mofetil (MMF) is an effective alternative at doses of 1-3 g/day, demonstrating significant decreases in disability scores 1
• Azathioprine (AZA) at 2-3 mg/kg/day can be effective but has higher rates of side effects and discontinuation compared to other immunosuppressants 1, 4
• Low-dose oral corticosteroids are often used in combination with these immunosuppressants for maintenance therapy 4

Treatment Algorithm

1. For acute attacks:

   • Start with IVMP 1000 mg/day for 3-5 days immediately upon diagnosis 1, 5
   • If severe attack or inadequate response to steroids within 3-5 days, initiate PLEX 1, 2
   • For Grade 3-4 severity (as per immune-related adverse events grading): Consider ICU admission for severe cases 6

2. For long-term prevention:

   • First-line: Rituximab 1
   • Second-line options: Mycophenolate mofetil or azathioprine 1, 5
   • Maintain therapy long-term as relapses are common (50-60%) during immunosuppressive dose reduction 1

Monitoring and Follow-up

• Regular ophthalmological evaluations including visual acuity, visual fields, and funduscopy are necessary to monitor treatment response 1, 7
• Visual-evoked potentials may detect bilateral optic nerve damage before it becomes clinically apparent 1, 7
• MRI of brain and spinal cord should be performed periodically to assess disease activity 7
• Evaluate for urinary retention and constipation, which are common complications 6

Important Considerations and Pitfalls

• Risk factors for poor outcomes include extensive spinal cord lesions, reduced muscle strength, sphincter dysfunction at presentation, presence of antiphospholipid antibodies, and delay in therapy initiation 1
• Common treatment pitfalls include inadequate duration of acute treatment, failure to initiate PLEX early in severe cases, and discontinuing maintenance therapy prematurely 1
• NMO is distinct from multiple sclerosis (MS), and MS treatments may not be suitable or could potentially worsen NMO 5, 4
• Emerging treatments under investigation include bevacizumab, ublituximab, and HBM9161, but these are still in clinical trials 2