Management of Anti-NMDA Receptor Encephalitis Secondary to Ovarian Mass
Surgical removal of the ovarian mass (left salpingo-oophorectomy) is the first-line treatment for anti-NMDA receptor encephalitis associated with an ovarian teratoma, followed by immunotherapy with corticosteroids and either plasma exchange or intravenous immunoglobulin.
Diagnostic Approach
Anti-NMDA receptor encephalitis is an autoimmune disorder that often presents with:
- Psychiatric symptoms (confusion, psychosis)
- Seizures
- Altered mental status/encephalopathy
- Involuntary movements (choreoathetosis, orofacial dyskinesia)
- Autonomic instability
- Central hypoventilation (in severe cases)
Key Diagnostic Tests
- MRI brain (may be normal in up to 90% of cases initially) 1
- CSF analysis (lymphocytosis and NMDA receptor antibodies)
- EEG (epileptiform activity early, generalized slowing later)
- Comprehensive tumor screening (particularly ovarian imaging)
Treatment Algorithm
Step 1: Tumor Removal
- Surgical excision of the ovarian mass should be performed as soon as possible 1, 2, 3
- In women with anti-NMDA receptor encephalitis, 30-60% have an associated ovarian teratoma 4
- Tumor removal is crucial for neurological recovery and has been shown to improve outcomes 2, 5
Step 2: First-line Immunotherapy
- High-dose corticosteroids (methylprednisolone 1g IV daily for 3-5 days) 1
- PLUS one of the following:
- Plasma exchange (especially if poor response to steroids)
- Intravenous immunoglobulin (IVIg)
Step 3: Second-line Immunotherapy (if inadequate response)
- Consider rituximab or cyclophosphamide 1
- These may be necessary in approximately 30% of cases, particularly those without tumors or with delayed tumor removal
Step 4: Supportive Care
- Seizure management with antiepileptic drugs
- ICU care for patients with decreased level of consciousness
- Airway protection and ventilatory support if needed 1
- Management of autonomic instability
- DVT prophylaxis
Monitoring and Follow-up
- Continuous EEG monitoring during acute phase
- Regular neurological assessments
- CSF analysis to monitor antibody titers
- Long-term immunosuppression may be needed in patients who relapse (approximately 30% of cases) 1
- Annual tumor screening for several years, particularly if treatment response is poor or relapses occur 1
Prognosis
With prompt tumor removal and immunotherapy, most patients experience gradual neurological recovery, though this may take weeks to months 2, 3. The median hospital stay can be prolonged (median 160 days in some series) 1.
Important Considerations
- Early recognition and treatment are critical - delays in diagnosis and treatment are associated with poorer outcomes
- The clinical presentation often has a characteristic biphasic pattern:
- Initial phase: seizures, confusion, amnesia, psychosis
- Later phase: involuntary movements, fluctuating consciousness, dysautonomia
- Young women with new-onset psychiatric symptoms, seizures, and movement disorders should always be screened for ovarian tumors 4
- Even microscopic ovarian neoplasms can trigger anti-NMDA receptor encephalitis 2
- Patients may require prolonged rehabilitation due to persistent cognitive and behavioral symptoms
Pitfalls to Avoid
- Delaying tumor removal while waiting for immunotherapy response
- Failing to screen for ovarian tumors in young women with encephalitis
- Discontinuing immunotherapy too early (may need prolonged course)
- Missing subtle ovarian lesions (comprehensive imaging is essential)
- Overlooking the need for long-term monitoring due to relapse risk
By following this treatment approach with prompt tumor removal and aggressive immunotherapy, most patients with anti-NMDA receptor encephalitis associated with ovarian teratomas can achieve substantial neurological recovery.