How is vasculitis diagnosed?

The diagnosis of vasculitis, including CNS vasculitis, is based on a person's medical history, symptoms, a complete physical examination, and the results of special laboratory tests. Blood abnormalities that are found in vasculitis include:

  • Anemia (a shortage of red blood cells)
  • A high white blood cell count
  • A high platelet count
  • Kidney or liver problems
  • Allergic reactions
  • Immune complexes
  • Antibodies (tools the body uses to fight off threats)
  • Elevation of inflammatory markers

(In PACNS, when the vasculitis is only confined to the brain or spinal cord, the above symptoms and signs are often lacking and patients present with symptoms of CNS vasculitis only.)

Other tests may include X-rays, tissue biopsies (taking a sample of tissue to study under a microscope), and blood vessel scans. The physician might also want to examine the spinal fluid to see what is causing the inflammation. This test is often performed in CNS vasculitis.

To help in the diagnosis of CNS vasculitis, the physician may order a magnetic resonance imaging or angiogram of the brain. An angiogram can show which blood vessels are narrowed.

Because other conditions can cause some of the same brain vessel abnormalities as CNS vasculitis, a brain biopsy is the only way to make certain of a diagnosis. A brain biopsy can distinguish between CNS vasculitis and other diseases that may have similar features.

Last reviewed by a Cleveland Clinic medical professional on 03/07/2016.


  • National Heart, Lung, and Blood Institute. What is vasculitis? Accessed 3/9/2016.
  • Hajj-Ali RA, Singhal A, Benseler S, Molloy E, Calabrese LH. Update on Primary Angiitis of the Central Nervous System. Lancet Neurol 2011 Jun;10(6):561-72.

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