A 16-year-old girl in California was referred to an emergency department after experiencing hallucinations, including a flying green dinosaur and voices telling her to harm others. She also felt that someone was following her. Trembling, sweating, a racing pulse and rapid, shallow breathing prompted doctors to investigate a physical cause for her psychiatric symptoms. A head CT scan revealed neither swelling nor bleeding, while a test of the brain's electrical activity offered no explanation.
Although initial testing of her cerebrospinal fluid appeared normal, subsequent analysis detected autoantibodies targeting neuronal intermediate filament, a protein that provides structural support to nerve cells. She was diagnosed with autoimmune encephalitis, a rare disorder in which antibodies attack nervous tissue, producing inflammation that can cause psychiatric symptoms. MRI and PET scans found no tumors, a recognized trigger of the condition. On her second hospital day, she also developed catatonia, a disruption of responsiveness that subsided within days after treatment with lorazepam.
Her immune treatment included intravenous steroids, immunoglobulin from healthy donors and rituximab, which kills antibody-producing B cells. Over the next month, she underwent five sessions of plasmapheresis, a procedure that replaces blood plasma to help remove harmful antibodies. She was discharged after almost two months, continuing psychiatric medicines alongside immune-directed treatment. As her symptoms improved over the following year, she stopped the psychiatric drugs but remained on immunotherapy. Most pediatric evidence on autoimmune encephalitis concerns antibodies against NMDA receptors rather than the structural protein targeted in her case.
