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.

Clinical exam

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:

  • Reflexes
  • Muscle strength
  • Muscle tone
  • Sense of touch
  • Vision and hearing
  • Coordination
  • Balance
  • Mood
  • Memory

Laboratory tests

Laboratory tests will likely include:

  • Blood tests. You may have blood drawn for a number of laboratory tests, including tests to identify antibodies commonly associated with paraneoplastic syndromes. Other tests may attempt to identify an infection, a hormone disorder or a disorder in processing nutrients (metabolic disorder) that could be causing your symptoms.
  • 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

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:

  • Computerized tomography (CT) is a specialized X-ray technology that produces thin, cross-sectional images of tissues.
  • Magnetic resonance imaging (MRI) uses a magnetic field and radio waves to create detailed cross-sectional or 3D images of your body's tissue.
  • Positron emission tomography (PET) uses radioactive compounds injected into your bloodstream to produce cross-sectional or 3D images of the body. PET scans can be used to identify tumors, measure metabolism in tissues, show blood flow and locate brain abnormalities related to seizures.
  • PET plus CT, a combination of PET and CT, may increase the detection rate of small cancers, common in people who have paraneoplastic neurological disorders.

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 3 to 6 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:

  • Corticosteroids, such as prednisone, inhibit inflammation. Serious long-term side effects include weakening of the bones (osteoporosis), type 2 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, Azasan), mycophenolate (CellCept), rituximab (Rituxan) 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 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.

Other medical treatments

Other treatments that may improve symptoms include:

  • Plasmapheresis. This process separates the fluid part of the blood, called plasma, from your blood cells with a device known as a cell separator. Technicians return your red and white blood cells, along with your platelets, to your body, while discarding the plasma, which contains unwanted antibodies, and replacing it with other fluids.
  • Intravenous immunoglobulin (IVIg). Immunoglobulin contains healthy antibodies from blood donors. High doses of immunoglobulin speed up the destruction of the damaging antibodies in your blood.

Other therapies

Other therapies may be helpful if a paraneoplastic syndrome has caused significant disability:

  • Physical therapy. Specific exercises may help you regain some muscle function that has been damaged.
  • Speech therapy. If you are having trouble speaking or swallowing, a speech therapist can help you relearn the necessary muscle control.

Coping and support

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.

Preparing for your appointment

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).

What you can do

  • Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet.
  • Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
  • Write down key personal information, including any major stresses or recent life changes.
  • Make a list of all medications, vitamins or supplements that you're taking.
  • Consider taking a family member or friend along. Sometimes it can be difficult to remember all the information provided during an appointment. Someone who accompanies you may remember something that you missed or forgot.
  • Write down questions to ask your doctor.

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:

  • What's the most likely cause of my symptoms?
  • What diagnostic tests will you order? Do I need to prepare for these tests?
  • Which specialists will I need to see?
  • How soon am I likely to complete the tests and get results?
  • What are you looking for in the tests?
  • What conditions are you trying to rule out?

What to expect from your doctor

Your doctor may ask the following questions:

  • Have you had any muscle weakness or lack of coordination?
  • Have you had any unusual or involuntary muscle movements?
  • Have you had any vision problems?
  • Do you have any problems chewing, swallowing or speaking?
  • Do you have any difficulty breathing?
  • Have you had any seizures? How long have they lasted?
  • Have you experienced dizziness or nausea?
  • Do you have trouble sleeping, or have your sleep patterns changed?
  • Are you having difficulty performing everyday tasks with your hands?
  • Have you had any numbness or tingling in your limbs?
  • Have you had a significant change in mood?
  • Have you been seeing or hearing things that others are not aware of?
  • Have you had any memory problems?
  • When did your symptoms begin?
  • Have your symptoms become worse?
  • Have you been diagnosed with cancer?
  • What medications do you take, including over-the-counter drugs and dietary supplements? What are the daily dosages?
  • Have any close relatives had cancer? If so, what types of cancer?
  • Have you ever smoked?
  • Do you or does anyone in your family have some form of autoimmune disease?

Paraneoplastic syndromes of the nervous system care at Mayo Clinic

March 26, 2022
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