RESUMO
Most patients with autoimmune encephalitis do not present with well-described symptoms. Demographic data and information regarding co-morbidities could help in diagnosing the underlying disorder, but a definitive diagnosis is made by the result of autoimmune antibodies. Limbic encephalitis (LE), a variant of autoimmune encephalitis, is the inflammation of the limbic system of the brain. The disorder presents with the rapid development of confusion, working memory impairment, mood changes, and often seizures. LE could have paraneoplastic or non-paraneoplastic etiology. We present the case of a 15-year-old girl with seronegative LE, who presented with cognitive decline and seizures. This condition is rare, and therefore poses a great challenge in diagnosis at an early stage.