Paraneoplastic syndromes are estimated to occur in 7% to 15% of all patients with cancer. Paraneoplastic syndromes of the nervous system are a group of rare disorders that develop in some people who have 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.
Treatment of neurological paraneoplastic syndromes involves treating the cancer and, in some cases, suppressing the immune response that's causing your signs and symptoms. Your treatment will depend on the specific type of paraneoplastic syndrome you have, but it may include the following options.
Medications: In addition to drugs, such as chemotherapy, to combat your cancer, your doctor may prescribe one or more of the following drugs to stop your immune system from attacking your nervous system:
Corticosteroids, such as prednisone, inhibit inflammation. Serious long-term side effects include weakening of the bones (osteoporosis), diabetes, high blood pressure, high cholesterol and others.
Immunosuppressants slow the production of disease-fighting white blood cells. Side effects include an increased risk of infections. Drugs may include azathioprine (Imuran) and cyclophosphamide (Cytoxan). Depending on the type of neurological syndrome and symptoms, other medications may include:
Anti-seizure medications, which may help control seizures associated with syndromes that cause electrical instability in the brain.
Medications to enhance nerve to muscle transmission,which may improve symptoms of syndromes affecting muscle function. Some drugs, such as 3,4-diaminopyridine, enhance the release of a chemical messenger that transmits a signal from nerve cells to muscles. Other drugs, such as pyridostigmine (Mestinon, Regonol), prevent the breakdown of these chemical messengers.
Intravenous immunoglobulin (IVIG). Plasmapheresis