Tests and diagnosis

By Mayo Clinic Staff

In a diagnostic workup for assessing neurological problems that could indicate a paraneoplastic syndrome, your doctor is trying to answer the following questions:

  • What neurological problems are present?
  • Is there evidence of cancer underlying these problems?
  • What other condition might be causing the problems?

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
  • Mental status
  • Mood

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 be given 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 fluid 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 3-D images of your body's tissue.
  • Positron emission tomography (PET) uses radioactive compounds injected into your bloodstream to produce cross-sectional or 3-D images of the body. They can be used to identify tumors, measure metabolism in tissues, show blood flow and locate brain abnormalities related to seizures.
  • PET-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 three to six months until a cause for the neurological disorder is identified.

Apr. 30, 2014

You Are ... The Campaign for Mayo Clinic

Mayo Clinic is a not-for-profit organization. Make a difference today.