What is the treatment approach for autoimmune encephalitis with stroke and Central Nervous System (CNS) vasculitis?

Treatment Approach for Autoimmune Encephalitis with Stroke and CNS Vasculitis

For autoimmune encephalitis complicated by stroke and CNS vasculitis, immediate initiation of high-dose corticosteroids followed by appropriate immunosuppressive therapy is the recommended treatment approach to reduce mortality and improve neurological outcomes. 1

Initial Assessment and Diagnosis

Before initiating treatment, confirm the diagnosis through:

• Brain MRI to identify focal or multifocal brain abnormalities
• Lumbar puncture to confirm inflammatory etiology and rule out infectious causes
• Serum and CSF testing for neuronal autoantibodies
• Consider brain FDG-PET if other studies are uninformative
• Appropriate cancer screening in relevant cases 1

Treatment Algorithm

First-Line Therapy

1. Immediate immunotherapy once infection is ruled out:

   • High-dose intravenous methylprednisolone (1g daily for 3-5 days) 1
   • For patients with severe presentation (stroke with CNS vasculitis), initiate combination therapy rather than sequential therapy:
     • Corticosteroids PLUS either IVIG or plasma exchange 1

2. Selection of adjunctive first-line therapy:

   • IVIG (preferred in agitated patients and those with bleeding disorders)
   • Plasma exchange (preferred in patients with high thromboembolic risk, severe hyponatremia, or associated brain demyelination) 1

Second-Line Therapy

If no clinical or radiological improvement 2-4 weeks after completion of first-line therapy:

1. For antibody-mediated autoimmunity:

   • Rituximab (anti-CD20 monoclonal antibody) 1

2. For cell-mediated autoimmunity or primary CNS vasculitis:

   • Cyclophosphamide 1
   • Alternative steroid-sparing agents include:
     • Mycophenolate mofetil
     • Azathioprine
     • Methotrexate 1

3. For giant cell arteritis specifically:

   • Methotrexate or tocilizumab as adjunctive therapy to steroids 1

Maintenance Therapy

• Bridging therapy with gradual oral prednisone taper
• For CNS vasculitis: slow tapering of steroids to target ≤5 mg/d after 1 year 1
• Consider monthly IVIG or IV methylprednisolone pulses 1

Special Considerations

• For CNS vasculitis: Long-term maintenance with steroid-sparing immunosuppressants is preferred over steroid monotherapy due to higher relapse rates and poorer outcomes with steroids alone 1

• Avoid infliximab in patients with giant cell arteritis as it is associated with recurrent symptoms and increased disease activity 1

• For infectious vasculitis: Treat the underlying infectious etiology alongside immunosuppression 1

Monitoring Response

• Follow clinical neurological status
• Serial MRI to assess for radiological improvement
• EEG to monitor for electrophysiological improvement
• Regular assessment of inflammatory markers 1

Common Pitfalls and Caveats

1. Delayed treatment: Early aggressive immunotherapy is crucial to prevent permanent neurological damage and reduce mortality. Do not wait for all antibody results before initiating treatment if clinical suspicion is high 1, 2

2. Inadequate immunosuppression: Monotherapy with steroids may be insufficient for cases with stroke and vasculitis; combination therapy should be considered from the outset 1

3. Premature discontinuation: Autoimmune encephalitis with vasculitis requires prolonged immunosuppression with careful tapering to prevent relapse 1

4. Overlooking infectious causes: Always rule out infectious etiologies before starting immunosuppression 1

5. Failure to screen for malignancy: Paraneoplastic autoimmune encephalitis requires tumor treatment alongside immunotherapy 1

The combination of prompt diagnosis and aggressive immunotherapy is essential for preventing catastrophic stroke and improving outcomes in patients with autoimmune encephalitis complicated by CNS vasculitis 3, 4.