Paraneoplastic neurologic syndromes (PNS), also called paraneoplastic neurologic disorders, happen when the body's immune system has an abnormal response to a neoplasm, a cancerous tumor. The body's white blood cells -- antibodies the body uses to attack those cancer cells -- begin to attack normal, healthy cells in the nervous system while fighting the tumor. This accidental attack on healthy nerve cells can sometimes trigger a paraneoplastic neurologic disorder -- it's estimated that fewer than 1 percent of cancer patients are diagnosed with PNS [source: Santacroce].
Symptoms of paraneoplastic neurologic disorders vary and, to simplify things, are divided into eight categories, including: cutaneous, endocrine, gastrointestinal, hematoligic, miscellaneous (nonspecific), neuromuscular, renal and rheumatologic [source: Santacroce]. Some of the more common symptoms include difficulty walking and maintaining balance, loss of muscle coordination, muscle weakness, loss of fine motor skills, vertigo or dizziness, vision problems, memory loss, dementia, numbness or tingling in the extremities, difficulty swallowing, slurred speech and seizures [source: Mayo Clinic].