Autoimmune Encephalitis: A Case Series from a Tertiary Care Center in South India.

Autoimmune encephalitis (AE) is a heterogeneous group of immune-mediated disorders of the central nervous system characterized by neuropsychiatric symptoms, seizures, cognitive decline, and movement abnormalities. Timely recognition and initiation of immunotherapy are critical to improving outcomes. We report three cases of AE presenting with varied clinical phenotypes from the Neurology department of Madras Medical College. The first, a 44-year-old male, presented with altered sensorium, action tremor, and myokymia, and was diagnosed with LGI1 and CASPR2 antibody-positive AE. The second, a 16-year-old girl, presented with seizures, progressive cognitive decline, behavioral disturbance, and focal weakness, confirmed as anti-NMDAR encephalitis. The third, a 14-year-old boy, developed seizures and behavioral changes following herpes simplex encephalitis and was later confirmed to have anti-NMDAR antibody-positive AE with features of Kluver-Bucy syndrome. All patients received first-line immunotherapy (steroids, IVIg), with escalation to rituximab in resistant cases.