Paraneoplastic sensory neuronopathy is a rare but potentially devastating complication of small cell lung carcinoma or, less often, other systemic neoplasms. In most patients the sensory neuronopathy is part of a multifocal encephalomyeloneuritis. The disorder is believed to arise from an autoimmune response directed against onconeural antigen(s) shared by tumor cells and primary sensory neurons in the dorsal root ganglia. Early identification of this syndrome and treatment of the underlying tumor can improve the likelihood of neurologic recovery, although most patients are severely and permanently disabled. Dr. Dropcho, from the Indiana University Medical Center, summarizes the clinical presentation, autoimmune features, and treatment options for patients with paraneoplastic sensory neuronopathy.