What is the primary treatment approach for a patient presenting with autoimmune hemiplegia?

Treatment of Autoimmune Hemiplegia

Initiate high-dose intravenous methylprednisolone (1-2 mg/kg/day or 1g daily for 3-5 days) immediately once infection is excluded by cerebrospinal fluid analysis, as this is the preferred first-line immunotherapy for autoimmune neurological conditions including those presenting with hemiplegia. 1, 2, 3

First-Line Immunotherapy Selection

The treatment approach depends on patient-specific factors and contraindications:

• Corticosteroids (IVMP) are the most commonly used and preferred initial agent for autoimmune neurological presentations 1, 3
• IVIG (0.4 g/kg/day for 5 days) should be chosen instead when the patient is agitated, combative, has bleeding disorders/coagulopathy, or has difficulty with central line placement 2, 3
• Plasma exchange (5-10 sessions every other day) is preferred for patients with severe hyponatremia, high thromboembolic risk, or associated brain/spinal demyelination 2, 3

For severe presentations with hemiplegia, consider combination therapy from the outset (steroids plus IVIG or steroids plus PLEX) rather than sequential monotherapy 2

Critical Diagnostic Considerations

Before initiating immunotherapy, ensure:

• CSF analysis excludes infection - this is the key gating factor for treatment initiation 1, 3
• Primary CNS lymphoma and neurosarcoidosis are not considerations 1
• Autoantibody testing is sent (though treatment should not be delayed awaiting results) 3
• Imaging (MRI brain/spine) is obtained to assess for demyelination or structural lesions 4

Escalation to Second-Line Therapy

If no meaningful clinical or radiological improvement occurs after 2-4 weeks of optimized first-line therapy, escalate immediately: 3

• Rituximab (375 mg/m² weekly for 4 weeks OR 1000 mg on days 1 and 15) is the preferred second-line agent for antibody-mediated autoimmune conditions 1, 3
• Expect improvement to begin 1-2 weeks after the first rituximab dose, though response may be slower in certain antibody-mediated conditions 1
• Cyclophosphamide should be considered if cell-mediated autoimmunity is suspected rather than antibody-mediated disease 3

Both rituximab and cyclophosphamide have demonstrated efficacy as rescue therapy, with rituximab chosen by 80% of experts for cases with unknown antibodies 3

Bridging and Maintenance Strategy

After achieving clinical improvement:

• Initiate bridging therapy with gradual oral prednisone taper, monthly IVIG, or monthly intravenous methylprednisolone to prevent relapse 1, 2
• Monitor serial antibody titers in serum and CSF to guide treatment duration 1
• Consider azathioprine or mycophenolate mofetil for long-term maintenance (typically 3-5 years) to permit steroid withdrawal 5

Refractory Cases

For patients failing both first and second-line therapies:

• Tocilizumab or bortezomib may be considered as experimental options 1, 6
• Immunoadsorption shows promise with reduction in pro-inflammatory cytokines (IL-12, IL-17, IL-6, INF-γ, TNF-α) and potentially longer therapy response compared to plasma exchange 7

Common Pitfalls to Avoid

• Do not delay treatment waiting for antibody results - initiate immunotherapy based on clinical suspicion once infection is excluded 3
• Do not use rituximab as monotherapy initially - it is a second-line agent after inadequate first-line response 1, 3
• Do not continue ineffective first-line therapy beyond 2-4 weeks - early escalation to second-line agents is associated with better long-term outcomes 6
• Avoid steroids in Guillain-Barré syndrome if that is the diagnosis, as they are not recommended; use PLEX or IVIG instead 4