[Paraneoplastic neurological syndrome and autoantibodies]

Paraneoplastic neurological syndrome (PNS) is a rare disorder caused by the remote effects of cancer is considered as caused by humoral or cell-mediated immunity. Several autoantibodies related to PNS have been discovered since the 1980s. These antibodies were classified into 2 categories based on the PNS diagnostic criteria recommended by PNS Euronetwork in 2004: well-characterized onconeural antibodies and partially characterized onconeural antibodies. Recently, techniques for the detection of these antibodies have been developed. Additional autoantibodies have been shown for neural surface antigens related to autoimmune-mediated encephalitis in patients with and without cancer. Because the PNS neurological symptoms often precede tumor diagnosis, the antibodies are useful diagnostic markers for PNS and occult tumors. Anti-tumor therapies are essential for PNS, and successful immunotherapies depend on the location of antigens, whether intracellular or on the surface of membranes. Generally, the latter cases are responsive to therapy. Only a limited numbers of cases with intracellular antigens have been improved by early and aggressive immunotherapies. Neurologists should be alert for PNS and check the presence of autoantibodies at the start of therapies when encountering rapidly progressive neurological symptoms of unknown origin. Here, we describe the relationship between onconeural antibodies, clinical features, tumor types, and response to immunotherapies.