Vasculitis is inflammation of blood vessels (veins, arteries, and capillaries) that carry blood through the body. Vasculitis can affect blood vessels of any type, size, or location, including those in the central and peripheral nervous systems, where it affects the blood vessels that nourish the brain, spinal cord, and peripheral nerves. A vasculitis syndrome may begin suddenly or develop over time.

Inflammation from vasculitis can cause the walls of blood vessels to weaken, stretch, thicken, and swell or develop scarring, which can narrow the vessel and slow or completely stop the normal flow of blood. In the brain and elsewhere, the weakened vessel can burst, causing bleeding into surrounding tissues.

An inflammatory process involving the wall of the vessels (large, medium, or small-sized vessels). The inflammatory process may cause necrosis or formation of granulomas in the vascular wall. It may be the result of an autoimmune disorder, infection, or malignancy. Representative examples include polyarteritis nodosa, temporal arteritis, Wegener granulomatosis, Kawasaki disease, Takayasu arteritis, and Henoch-Schonlein purpura.

Many forms of vasculitis can affect the brain, spinal cord, and nerves, including:

Giant cell arteritis (also known as temporal arteritis or cranial arteritis)

Giant cell arteritis affects the aorta, which brings blood to every branch of the body, including the arms, legs, and head. The temporal artery (found on both sides of the head and running across the temple) and the ophthalmic artery that supplies the eyes are often affected. Giant cell arteritis typically occurs in people age 50 years and older. Untreated temporal arteritis can cause strokes and even death. Symptoms include:

• New, severe headache
• Visual problems, including blurred or double vision, or sudden vision loss
• Pain in the jaw or tongue when chewing or swallowing
• Tenderness in the temporal arteries or the scalp

Primary angiitis of the central nervous system (also known as granulomatous angiitis)

This rare disorder, which is confined to the brain and spinal cord, typically develops slowly and includes headache, dementia, behavioral changes, pain, sensory abnormalities, and tremor. Stroke, transient ischemic attack, multiple mini-strokes, and seizures can occur. The disorder can affect anyone of any age but peaks about age 50 and is most often seen in males. It is fatal if left untreated.

Takayasu's arteritis

This disease affects large arteries such as the aorta. It may cause strokes, headaches, dizziness, a feeling of cold or numbness in the limbs, problems with memory and thinking, and visual disturbances. It also may cause heart attacks and damage to the intestines. The disorder can cause partial to complete disability and can be fatal if left untreated. Most individuals with the disorder are female, with disease onset between the ages 15 and 40.

Polyarteritis nodosa

The onset of this rare disease can occur at any age but most often appears between the ages of 40 and 60. Men are affected more often than women.  Damage to the peripheral nerves with neuropathy is more common than damage to the brain and spinal cord tissue. As the disease progresses the kidneys may fail and high blood pressure may develop rapidly. In some instances, the disease can recur after a few years. If untreated, the disorder is often fatal, ending in failure of vital organs.

Deficiency of adenosine deaminase 2 (also known as DADA2)

DADA2 is a rare, genetic form of vasculitis that is caused by a mutation in the CECR1 gene and can occur in more than one family member. Most individuals with DADA2 experience strokes in infancy or early childhood. DADA2 was discovered by researchers at the National Institutes of Health (NIH).

Kawasaki disease is a rare form of vasculitis that can cause stroke or brain damage in children. It primarily affects children age 5 or younger. Inflammation of the walls of blood vessels in the coronary arteries may cause aneurysms.

Giant cell arteritis (GCA) is a form of vasculitis, a group of disorders that cause inflammation of blood vessels. GCA most commonly affects the arteries of the head (especially the temporal arteries, located on each side of the head), but arteries in other areas of the body can also become inflamed. The inflammation causes the arteries to narrow, resulting in poor blood flow. Signs and symptoms when arteries in the head are involved may include a throbbing headache on one side or the back of the head, tenderness of the scalp, flu-like symptoms, and/or problems with eyesight. Symptoms when other arteries are involved depend on the location of those arteries.

The cause of GCA is still being studied, but it is thought to involve the immune system mistakenly attacking the artery walls. Several genetic and environmental factors may increase a person's risk to develop GCA. Complications of GCA may include permanent vision loss or a stroke, so treating the condition is important. Treatment may include corticosteroids and/or other medications that suppress the immune system.

GCA may develop with or after another inflammatory disorder known as polymyalgia rheumatica, which occurs in about 40% to 50% of people with GCA.

Vasculitis can cause strokes, blood clots, swelling, and other conditions that affect the brain and nervous system and other organs.

How vasculitis in the brain leads to stroke:

• Cerebral aneurysms (weak spots on a blood vessel in the brain that balloon out) can burst and spill blood into surrounding tissue (hemorrhagic stroke)
• Blood in the inflamed blood vessel can clot (thrombosis), blocking blood flow and causing ischemic stroke

Nervous system symptoms may include:

• Transient ischemic attack (TIA, sometimes also called a “mini-stroke”)
• Headaches, especially a headache that doesn't go away
• Swelling of the brain
• Confusion or forgetfulness leading to dementia
• Paralysis or numbness, usually in the arms or legs
• Seizures or convulsions
• Abnormal sensations or loss of sensation
• Trouble speaking or understanding
• Visual disturbances, such as double vision, blurred vision, or blindness

 General symptoms may include:

• Fever
• Malaise (feeling restless and sad)
• Rapid weight loss
• Aches and pains in the joints and muscles
• Pain while chewing or swallowing
• Unusual rashes or skin discoloration
• Problems with the kidneys or other organs

Diagnosing vasculitis that affects the nervous system can be difficult, as some diseases have similar symptoms. Diagnosis depends on the number of blood vessels involved, their size, and their location as well as the types of other organs involved.

A doctor will review the person's medical history, perform a physical exam to confirm signs and symptoms, and order diagnostic tests and procedures, including:

• Blood and urine tests to look for signs of inflammation (such as abnormal levels of certain proteins, antibodies, and blood cells)
• Analysis of the fluid that surrounds the brain and spinal cord (cerebrospinal fluid) to check for infection and signs of inflammation
• Biopsy of brain or nerve tissue (involving removal of a small piece of tissue that is studied under a microscope)
• Diagnostic imaging such as computed tomography (CT) and magnetic resonance imaging (MRI) to provide images of the brain, nerves and other organs, and tissues, and detect weakened or blocked vessels.
• Angiogram (x-ray imaging using a special dye that is released into the bloodstream) to detect the degree of narrowing of blood vessels in the brain, head, or neck
• Ultrasound to produce high-resolution images of the blood vessel walls and organs to look for inflammation

Treatment for vasculitis is aimed at reducing inflammation, controlling the anti-inflammatory response, and suppressing the abnormal immune system activity.

Medications to treat vasculitis include:

• Corticosteroid drugs such as prednisone to reduce blood vessel inflammation
• Immunosuppressive drugs such as cyclosporine to suppress or weaken the immune system
• Monoclonal antibodies that attach to certain abnormally functioning immune cells (B cells) and kill them
• Blood thinners and anti-clotting medications
• Immunoglobulin therapy, which involves intravenous injections of antibodies (protein produced by a blood cell to make a specific immune response) that are collected from a pool of healthy volunteers to lessen the infectious attack on the immune system

Other procedures to treat vasculitis include:

• Plasma exchange, or plasmapheresis, which involves taking blood out of the body and removing components in the blood's plasma that are thought to be harmful and then transfusing the blood plus replacement plasma back into the body 
• Surgery to bypass blocked vessels or treat aneurysms (although this is rare)