What is the treatment for autoimmune encephalitis with myocarditis?

Treatment of Autoimmune Encephalitis with Myocarditis

The treatment for autoimmune encephalitis with myocarditis should begin with high-dose corticosteroids, followed by sequential or combination therapy with intravenous immunoglobulin (IVIG) or plasma exchange (PLEX) depending on clinical severity and response to initial treatment. 1

Diagnostic Approach Before Treatment

Before initiating treatment, confirm the diagnosis with:

• Brain MRI to look for focal or multifocal brain abnormalities
• Lumbar puncture to evaluate for inflammatory markers and rule out infectious causes
• Serum and CSF testing for neuronal autoantibodies
• Cardiac evaluation including:
  • ECG and cardiac biomarkers (troponin, BNP)
  • Echocardiogram to assess ventricular function
  • Consider cardiac MRI if available

Treatment Algorithm

First-Line Therapy

1. High-dose corticosteroids:

   • Intravenous methylprednisolone 1g daily for 3-5 days 1
   • For myocarditis component: Consider methylprednisolone pulse dosing (1g/day for 3-5 days) 1

2. If no improvement after initial corticosteroid treatment:

   • Add IVIG (0.4 g/kg/day for 5 days) OR
   • Add PLEX (5-10 sessions every other day) 1

3. Selection between IVIG and PLEX:

   • IVIG preferred for:
     • Agitated patients
     • Patients with bleeding disorders
   • PLEX preferred for:
     • Severe hyponatremia
     • High thromboembolic risk
     • Associated brain or spinal demyelination 1

Severe Initial Presentation

For severe initial presentation (severe encephalopathy, refractory status epilepticus, severe dysautonomia):

• Consider combination therapy with steroids plus IVIG or steroids plus PLEX from the beginning 1
• This is particularly important when both encephalitis and myocarditis are severe

Second-Line Therapy

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

1. For antibody-mediated autoimmunity:

   • Rituximab (anti-CD20 monoclonal antibody) 1

2. For cell-mediated autoimmunity:

   • Cyclophosphamide 1

Refractory Cases

For patients not responding to first and second-line therapies:

• Consider novel approaches such as tocilizumab or bortezomib 1

Special Considerations for Myocarditis Component

1. Cardiac monitoring:

   • Continuous telemetry monitoring
   • Regular assessment of cardiac biomarkers (troponin, BNP)
   • Serial echocardiograms to monitor ventricular function 1

2. For severe myocarditis (Grade 3-4):

   • Permanently discontinue any immune checkpoint inhibitors if that was the cause
   • Consider cardiology consultation and intensive care monitoring
   • Provide supportive treatment for heart failure if present 1

3. Additional immunosuppressive agents:

   • For severe refractory myocarditis, consider additional immunosuppressive agents beyond corticosteroids 1
   • IVIG has shown particular benefit in myocarditis with encephalitis, with improved ejection fraction and reduced mortality 2

Bridging and Maintenance Therapy

After acute treatment:

• Gradual oral prednisone taper
• Consider monthly IVIG or IV methylprednisolone for maintenance 1

Evidence for Combined Encephalitis-Myocarditis Treatment

Research specifically on autoimmune encephalitis with myocarditis is limited, but case reports suggest that immunomodulatory therapy targeting both conditions can be effective 3. In one case report, IVIG therapy improved both neurological status and cardiac dysfunction in a patient with concurrent autoimmune encephalitis and myocarditis 3.

Pitfalls and Caveats

1. Do not delay immunotherapy while waiting for antibody results if clinical suspicion is high
2. Rule out infectious causes before starting immunosuppression
3. Monitor for complications of treatment:
   • Corticosteroids: hyperglycemia, hypertension, psychiatric effects
   • PLEX: bleeding risk, volume shifts (problematic in dysautonomic patients)
   • IVIG: thromboembolic events, aseptic meningitis, renal dysfunction
4. Cardiac function may worsen during initial treatment phase - maintain close monitoring
5. Consider cancer screening as paraneoplastic syndromes may present with both encephalitis and myocarditis

The combination of autoimmune encephalitis with myocarditis represents a severe presentation requiring prompt and aggressive immunotherapy to improve outcomes for both neurological and cardiac function.