The paraneoplastic neurological syndromes are all side effects that occur in the body from cancer but are not caused directly by the disease or by treatments to alleviate it. These are side effects of cancer, most notably the Lambert-Eaton syndrome, considered a rare disease that weakens the nervous system and causes weakness in the limbs, especially the legs. This kind of weakness, predominantly in the morning, may be accompanied by dry mouth, muscle pain and diarrhea. It also tends to occur more frequently in patients already suffering from other ailments before, as encephalomyelitis, subacute sensory neuropathy and limbic encephalitis, among others.