Tests and diagnosisBy 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 general questions:
- What neurological problems are present?
- Is there evidence of cancer underlying these problems?
- What other condition might be causing the problems?
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 relatively simple tests in the office to judge:
- Muscle strength
- Muscle tone
- Sense of touch
- Vision and hearing
- Mental status
Laboratory tests will likely include:
- Blood tests. A nurse or technician may draw a blood sample for laboratory tests. These tests may identify antibodies commonly associated with paraneoplastic syndromes. However, a person may carry suspect antibodies without having a paraneoplastic syndrome, and a person with the disorder may not carry the suspect antibodies. Lab tests may also identify an infection, a hormone disorder or a disorder in nutrient processing (metabolic disorder) that could be causing symptoms.
- Spinal tap (lumbar puncture). During a lumbar puncture, a neurologist or nurse inserts a needle into your lower spine to extract a small amount of cerebrospinal fluid (CSF) — the fluid that cushions your brain and spinal cord — for laboratory analysis. Sometimes, paraneoplastic antibodies may be present in CSF fluid when they're not detectable in your blood.
Imaging tests are used to locate a cancerous tumor that may be the underlying problem or to identify other factors causing the 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-section 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 those with paraneoplastic neurological disorders.
If no malignant tumor is located or no other cause identified, the problem may be a tumor that's still too small to find. You'll likely have follow-up imaging tests every three to six months for a few years or until a cause is identified.
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