Purpose of review: This article provides an update on classic paraneoplastic syndromes of the CNS and autoimmune encephalitis syndromes associated with antibodies against synaptic proteins, including the NMDA receptor, LGI1, and Caspr2, among others.
Recent findings: Most classic paraneoplastic syndromes are associated with antibodies against intracellular (onconeuronal) antigens, appear to be mediated by cytotoxic T-cell responses, and have limited response to treatment. The autoimmune synaptic disorders are associated with antibodies against extracellular epitopes, appear to be directly mediated by antibodies, and are responsive to immunotherapy. The syndromes associated with antibodies against intracellular antigens almost always occur in conjunction with cancer, and their clinical course is usually monophasic. In contrast, syndromes associated with antibodies against synaptic proteins may occur with or without cancer and often relapse.
Summary: The spectrum of autoimmune disorders of the CNS with distinct clinical and immunologic associations is expanding. Prompt diagnosis and treatment can result in recovery from some syndromes.