Paraneoplastic syndromes of the nervous system are a group of uncommon disorders that develop in some people who have cancer. Paraneoplastic syndromes can also affect other organ systems including hormone (endocrine), skin (dermatologic), blood (hematologic) and joints (rheumatologic).
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.
Depending on where the nervous system is affected, paraneoplastic syndromes can cause problems with muscle movement or coordination, sensory perception, memory or thinking skills, or even sleep.
Sometimes the injury to the nervous system is reversible with therapy directed toward the cancer and the immune system. However, these diseases can also rapidly result in severe damage to the nervous system that can't be reversed.
Regardless, treatment of the underlying cancer and other interventions may prevent further damage, improve symptoms and give you a better quality of life.
Signs and symptoms of paraneoplastic syndromes of the nervous system can develop relatively quickly, often over days to weeks. Signs and symptoms of paraneoplastic syndromes of the nervous system often begin even before a cancer is diagnosed.
Signs and symptoms vary depending on the body part being injured, and may include:
Examples of paraneoplastic syndromes of the nervous system include:
Lambert-Eaton myasthenic syndrome. This is a syndrome caused by disrupted communication between nerves and muscles. Signs and symptoms include pelvic and lower extremity muscle weakness, fatigue, difficulty swallowing, difficulty speaking, irregular eye movement, and double vision. Autonomic nervous system problems can include dry mouth and impotence.
When it occurs as a paraneoplastic syndrome, Lambert-Eaton myasthenic syndrome is typically associated with lung cancer.
Myasthenia gravis. Myasthenia gravis is also related to disrupted communication between nerves and muscles and also characterized by weakness and rapid fatigue of any of the muscles that are under voluntary control, including muscles in your face, eyes, arms and legs. The muscles involved in chewing, swallowing, talking and breathing may be affected as well.
When myasthenia gravis occurs as a paraneoplastic syndrome, it is typically associated with cancer of the thymus gland (thymoma).
The signs and symptoms of paraneoplastic syndromes of the nervous system are similar to those of many conditions, including cancer, cancer complications and even some cancer treatments.
But if you have any signs or symptoms suggesting a paraneoplastic syndrome, see your doctor as soon as possible. Early diagnosis and appropriate care can be extremely important.
Paraneoplastic syndromes are not caused by cancer cells directly disrupting nerve function, by the cancer spreading (metastasis), or by other complications such as infections or treatment side effects. Instead, they occur alongside the cancer as a result of the activation of your immune system.
Researchers believe that paraneoplastic syndromes are caused by cancer-fighting abilities of the immune system, particularly antibodies and certain white blood cells, known as T cells. Instead of attacking only the cancer cells, these immune system agents also attack the normal cells of the nervous system and cause neurological disorders.
Any cancer may be associated with a paraneoplastic syndrome of the nervous system. However, the disorders occur more often in people with cancers of the lung, ovary, breast, testis or lymphatic system.
To diagnose paraneoplastic syndrome of the nervous system, your doctor will need to conduct a physical exam and order blood tests. He or she may also need to request a spinal tap or imaging tests.
Because paraneoplastic syndromes of the nervous system are associated with cancer, your doctor may also perform certain cancer screening tests based on your age.
Your doctor or a neurologist will conduct a general physical, as well as a neurological exam. He or she will ask you questions and conduct simple tests in the office to judge:
Laboratory tests will likely include:
Spinal tap (lumbar puncture). You may undergo a lumbar puncture to obtain a sample of cerebrospinal fluid (CSF) — the fluid that cushions your brain and spinal cord. A neurologist or specially trained nurse inserts a needle into your lower spine to remove a small amount of CSF for laboratory analysis.
Sometimes, paraneoplastic antibodies may be found in CSF when they can't be seen in your blood. If these antibodies are found in both your CSF and your blood, it provides strong evidence that your nervous system symptoms are caused by a specific form of activation of the immune system.
Imaging tests are used to find a tumor that may be the underlying problem or to identify other factors causing your neurological symptoms. One or more of the following tests may be used:
If no malignant tumor is located or no other cause identified, the problem may still be related to a tumor that is too small to find. The tumor may be causing a powerful response from the immune system that is keeping it very small. You'll likely have follow-up imaging tests every three to six months until a cause for the neurological disorder is identified.
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.
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:
Depending on the type of neurological syndrome and symptoms, other medications may include:
Other treatments that may improve symptoms include:
Other therapies may be helpful if a paraneoplastic syndrome has caused significant disability:
Many people with cancer benefit from education and resources designed to improve coping skills. If you have questions or would like guidance, talk with a member of your health care team. The more you know about your condition, the better you're able to participate in decisions about your care.
Support groups can put you in touch with others who have faced the same challenges you're facing. If you can't find an appropriate support group where you live, you might find one on the internet.
Most people with paraneoplastic syndrome experience neurological problems before having any indication of cancer or receiving a cancer diagnosis. Therefore, you're likely to start by seeing your primary care doctor about your symptoms. You may then be referred to a specialist in nervous system disorders (neurologist) or a cancer specialist (oncologist).
Your time with your doctor may be limited, so preparing a list of questions can help you make the most of your time together. List your questions from most important to least important in case time runs out. Some basic questions to ask your doctor include:
Your doctor may ask the following questions: