[Paraneoplastic limbic encephalitis]

Paraneoplastic limbic encephalitis (PLE) is a condition characterized by nervous system damage or dysfunction without indication that the nervous system is directly affected by tumor cells. Since it is clinically presented with an array of neuropsychiatric symptoms that usually precede the occurrence of malignant disease, and because of mimicking a psychiatric disease, it can sometimes make the diagnosis difficult and can be overlooked. Typical presentations consist of progressive confusion and deficits in short-term memory, which worsen over days to weeks. The current hypothesis on the pathogenesis of PLE implicates an autoimmune process involving antigens shared by tumor cells and neuronal cells in limbic structures. It has been considered that the autoantibodies cross-react with antigens on normal cells such as the neurons, resulting in cytotoxicity, or they can form complexes with a circulating antigen to induce organ damage through immune complex deposition. The treatment of PLE involves underlying cancer removal by surgery, chemotherapy, radiotherapy or hormonal treatment, and immunosuppressive therapy. Unfortunately, this therapy combination is still generally unsatisfactory. Although PLE is a relatively rare neurologic disorder, because of its association with malignancies and difficulty in diagnosing, this article gives a brief review of the literature and summarizes current knowledge of this syndrome.