Atypical presentation of autoimmune encephalitis in a pediatric patient: Diagnostic delays and treatment responses

Autoimmune encephalitis (AE) is a rapidly progressing inflammatory brain disease often characterized by psychiatric symptoms, seizures, and cognitive impairments. This case involves a 13-year-old female who initially presented with a persistent, severe unilateral headache unresponsive to standard treatments. Despite normal imaging and neurological exams, her symptoms escalated to include neuropsychiatric issues, eventually leading to the diagnosis of AE, confirmed through the presence of NMDA receptor antibodies. Treatment with immunomodulatory therapies, including intravenous methylprednisolone and plasmapheresis, resulted in significant clinical improvement over several months. The case highlights the complexities and challenges in diagnosing AE, especially in instances where imaging findings are unremarkable or the presentation is atypical, resulting in multiple misdiagnoses.