Paraneoplastic syndromes are rare, affecting less than 1/10,000 patients with cancer. Paraneoplastic syndromes of the nervous system are the most commonly reported paraneoplastic syndromes, but these syndromes can also affect other organ systems including hormone (endocrine), skin (dermatologic), blood (hematologic) and joints (rheumatologic). Paraneoplastic events may also in part explain some of the most common symptoms of cancer, such as fatigue, loss of appetite for food (anorexia) and weight loss. Paraneoplastic syndromes of the nervous system occur when cancer-fighting agents of the immune system also attack parts of the brain, spinal cord, peripheral nerves or muscle.
Common paraneoplastic syndromes of the nervous system include:
1. Cerebellar degeneration. This is the loss of nerve cells in the area of the brain that controls muscle functions and balance (cerebellum).
2. Limbic encephalitis. This is inflammation affecting a region of the brain known as the limbic system, which controls emotions, behaviors and certain memory functions.
3. Encephalomyelitis. Opsoclonus-myoclonus. This syndrome is due to dysfunction of the cerebellum or its connections. It can cause rapid, irregular eye movements (opsoclonus) and involuntary, chaotic muscle jerks (myoclonus) in your limbs and trunk.
4. Stiff person syndrome. Previously called stiff man syndrome, this syndrome is characterized by progressive, severe muscle stiffness or rigidity, mainly affecting your spine and legs.
5. Myelopathy. This term refers to a syndrome of injury limited to the spinal cord. It sometimes is called transverse myelitis.
Signs and symptoms of paraneoplastic syndromes of the nervous system usually develop relatively quickly, often over days to weeks. Signs and symptoms vary depending on the body part being injured, and may include: • Difficulty walking • Difficulty maintaining balance • Loss of muscle tone or weakness • Loss of fine motor skills • Difficulty swallowing • Slurred speech • Memory loss • Vision problems