[Paraneoplastic neurological syndromes in 2008]

Paraneoplastic neurological syndromes (PNS) can be defined as remote effects of cancer that are not caused by the tumor and its metastasis, or by infection, ischemia or metabolic disruptions. PNS can affect any part of the central and peripheral nervous system, the neuromuscular junction, and muscle. In most patients, the neurological disorder develops before the cancer becomes clinically overt and the patient is referred to the neurologist who has the charge of identifying the neurological disorder as paraneoplastic. PNS are caused by autoimmune processes triggered by the cancer and directed against antigens common to both the cancer and the nervous system, designated as onconeural antigens. Well-characterized anti-onconeural antibodies have been identified in the patient's serum and CSF and these antibodies, due to their high specificity (>90 %) are the best way to diagnose a neurological disorder as paraneoplastic. In addition, as these antibodies are associated with a restricted range of cancers, they can guide the search for the underlying tumour at a stage when it is frequently not clinically overt. In the last months, novel antibodies against neuronal surface antigens have been described in paraneoplastic limbic encephalitis. Interestingly, the likelihood of improvement is significantly higher in patients with these antibodies against neuronal surface antigens than in those with classical anti-onconeural antibodies or without antibodies.