The neurologic outcome of patients with paraneoplastic syndromes varies considerably among different disorders. Some patients have major neurologic improvement solely with treatment of the associated neoplasm; this possibility places an obvious premium on prompt recognition of the paraneoplastic syndrome. Unfortunately, many patients are left with severe and permanent neurologic disability despite remission of the associated tumor. The success of tumor therapy or immunotherapy spans a spectrum: patients with Lambert-Eaton myasthenic syndrome generally have a gratifying response (Tim et al 2000), whereas the great majority of patients with paraneoplastic encephalomyelitis or cerebellar degeneration are left with severe permanent neurologic disability despite aggressive treatment. The outcome for patients with paraneoplastic opsoclonus, limbic encephalopathy, or stiff-person syndrome usually lies somewhere between these extremes.