Understanding AE
Autoimmune encephalitis (AE) refers to a group of conditions that occur when the body’s immune system produces antibodies that mistakenly attack healthy brain cells, leading to inflammation of the brain. AE is under-reported due to its variable presentation and numerous antibodies responsible. The incidence of all types of encephalitis reported in adults varies between 0.7 to 12.6 per 100,000.
Symptoms of AE
Initially, people with AE have vague and non-specific symptoms. When symptoms are present, they are highly variable. People with autoimmune encephalitis (AE) may have various neurologic and/or psychiatric symptoms. Approximately 70% of people first have headache, fever, and other symptoms similar to a viral infection. It then progresses to symptoms such as new onset of memory loss, altered mental status, behavior changes, psychosis, or seizures, taking place over a few weeks to three months. These people may have periods of improvement and worsening.
Diagnosing AE
Diagnosing AE can be difficult because the average onset of symptoms to diagnosis often takes a few weeks to 3 months. Diagnosis requires the evaluation of the various neuropsychiatric symptoms, lab studies, neuroimaging (such as a brain magnetic resonance imaging [MRI] or computerized tomography [CT] scan, and electroencephalogram).
Treating AE
Treatment of AE commonly includes suppressing the immune system (immunotherapy). First-line immunotherapy includes corticosteroids given intravenously, immunoglobulins given intravenously, and plasmapheresis alone or combined. Plasmapheresis is a medical procedure that removes plasma, the liquid component of blood that contains the “bad” antibodies, from the body. Second-line immunotherapy for people who fail to improve on these treatments include rituximab and cyclophosphamide alone or combined in the adult population.
References:
- Autoimmune Encephalitis – StatPearls – NCBI Bookshelf. Last Update: January 2, 2023.
Last reviewed 12/16/2025
