Paraneoplastic syndromes are a group of rare degenerative disorders that are triggered by a person's immune system response to a neoplasm, or cancerous tumor. Neurologic paraneoplastic syndromes are believed to occur when cancer-fighting antibodies or white blood cells known as T cells mistakenly attack normal cells in the nervous system. These disorders typically affect middle-aged to older persons and are most common in persons with lung, ovarian, lymphatic, or breast cancer. Neurologic symptoms generally develop over a period of days to weeks and usually occur prior to tumor detection, which can complicate diagnosis. These symptoms may include difficulty in walking and/or swallowing, loss of muscle tone, loss of fine motor coordination, slurred speech, memory loss, vision problems, sleep disturbances, dementia, seizures, sensory loss in the limbs, and vertigo. Neurologic paraneoplastic syndromes include Lambert-Eaton myasthenic syndrome, stiff-person syndrome, encephalomyelitis (inflammation of the brain and spinal cord), myasthenia gravis, cerebellar degeneration, limbic and/or brainstem encephalitis, neuromyotonia, and opsoclonus (involving eye movement) and sensory neuropathy.

The cancer is treated first, followed by efforts to decrease the autoimmune response - either through steroids such as cortisone or prednisone, high-dose intravenous immunoglobulin, or irradiation. Plasmapheresis, a process that cleanses antibodies from the blood, may ease symptoms in patients with paraneoplastic disorders that affect the peripheral nervous system. Speech and physical therapy may help patients regain some functions.

There are no cures for paraneoplastic syndromes and resulting progressive neurological damage. Generally the presence of cancer determines the diagnosis.

Prepared by the National Institutes of Health