Autoimmune encephalitis
Autoimmune encephalitis is antibody-mediated brain inflammation, most often N-methyl-D-aspartate (NMDA) receptor antibody disease, that classically opens with a psychiatric prodrome and psychosis in a young patient before progressing to seizures, abnormal movements, and autonomic instability. Diagnosis requires antibody testing of blood and cerebrospinal fluid plus a tumor search; treatment is tumor removal plus immunotherapy, intravenous methylprednisolone and immune globulin first, escalating to rituximab or cyclophosphamide.
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What this article covers
- Overview
Definition: autoimmune encephalitis is brain inflammation driven by antibodies against neuronal antigens rather than direct infection; N-methyl-D-aspartate (NMDA) receptor antibody disease is the…
- Epidemiology
NMDA receptor antibody disease is the most common autoimmune encephalitis and presents with a subacute onset, evolving over days to a few weeks rather than the months required for a primary psychotic disorder.
- Risk factors
Ovarian teratoma: the dominant risk factor for NMDA receptor antibody disease, present in about half of affected patients.
- Pathophysiology
Antibody-mediated neuronal dysfunction, not direct infection: autoimmune neurologic syndromes are driven by circulating antibodies (onconeural antibodies in the paraneoplastic form) against neuronal…
- Clinical features
Psychiatric prodrome (the presentation that reaches psychiatry first): a young patient, classically a woman under 35 years old, develops behavioral change, headache, and fever after a viral-like…
- Differential diagnosis
Schizophrenia: requires symptoms present for more than 6 months, without the seizures, movement disorder, or autonomic instability seen here.
- Diagnosis
Antibody testing, not the psychiatric picture alone, confirms the diagnosis: a serum and CSF antibody panel for the specific neural antibody (most often the NMDA receptor antibody) establishes…
- Management
First, stabilize evolving seizures, autonomic instability, or a declining level of consciousness: give lorazepam 0.1 mg/kg IV (maximum 4 mg per dose), repeated once in 10 to 15 minutes if needed…
- Complications
Refractory status epilepticus from ongoing antibody-mediated cortical irritability, resistant to first-line abortive therapy.
- Prognosis
Acute immunotherapy is often helpful, particularly IVIG or methylprednisolone combined with tumor removal.
- Prevention
There is no primary prevention for autoimmune encephalitis itself; the lever is early recognition.
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