Vasculitis is inflammation within the walls of blood vessels (arteries, veins, and capillaries). When this inflammation is limited to the arteries, arterioles, and capillaries of the brain or spinal cord, it is known as Central Nervous System (CNS) vasculitis or cerebral vasculitis. This inflammatory process causes vessel walls to thicken, narrow, or weaken, severely impeding the flow of oxygen and nutrients to neurological tissues. The resulting reduction in blood flow leads to tissue damage (ischemia). This damage can potentially result in stroke or hemorrhage within the brain.
The Underlying Causes and Classifications
CNS vasculitis is broadly categorized into two major types based on its origin. The first type is Primary Angiitis of the CNS (PACNS), which is a diagnosis of exclusion, meaning the inflammation is confined exclusively to the central nervous system. The cause of PACNS remains unknown (idiopathic) and it is not associated with any systemic inflammatory disease. This form is considered rare and often requires extensive testing to rule out other possible causes before a definitive diagnosis can be made.
The second category is Secondary CNS Vasculitis, which develops as a complication of an underlying systemic disorder. Many autoimmune diseases are known triggers, including systemic lupus erythematosus (Lupus), rheumatoid arthritis, and Behçet’s syndrome. Infections can also initiate this inflammatory response, such as the varicella-zoster virus (chickenpox and shingles) and various bacterial infections like syphilis and tuberculosis. In these secondary cases, managing the underlying systemic condition is the focus of treatment.
Recognizing the Signs of CNS Vasculitis
The symptoms of CNS vasculitis are highly varied, depending on which blood vessels and areas of the brain or spinal cord are deprived of blood flow. One of the most common initial complaints is a persistent, severe headache that may not respond well to typical pain relief medications. This headache often reflects the ongoing inflammatory process and changes in blood vessel structure.
Patients frequently experience episodes resembling a transient ischemic attack (TIA) or a full stroke, presenting with sudden weakness or numbness on one side of the body, difficulty speaking, or visual disturbances. Over time, individuals may show signs of progressive cognitive decline, manifesting as forgetfulness, confusion, or changes in personality and behavior. Other focal neurological deficits, such as seizures, loss of balance, or problems with coordination, can occur depending on the specific location of the affected vessels.
Confirming the Diagnosis
The diagnosis of CNS vasculitis is complex and requires a multi-step approach because no single test can definitively confirm the condition while ruling out mimics. Neuroimaging, particularly Magnetic Resonance Imaging (MRI) of the brain and spinal cord, is an initial tool used to look for signs of tissue damage, such as stroke areas or small hemorrhages. Magnetic Resonance Angiography (MRA) or Computed Tomography Angiography (CTA) visualize the blood vessels to detect abnormalities like narrowing or blockages.
A lumbar puncture (spinal tap) is often performed to analyze the cerebrospinal fluid (CSF) surrounding the brain and spinal cord. In many cases, CSF analysis shows signs of inflammation, such as elevated white blood cells or increased protein levels. This test is particularly helpful for ruling out infectious causes that mimic the condition, such as viral or bacterial infections.
Conventional catheter angiography is a more invasive procedure involving injecting a contrast dye directly into the blood vessels to obtain X-ray images. This imaging can reveal the characteristic “beading” pattern—alternating segments of narrowing and widening—often associated with the disease. However, angiography alone is not always conclusive, as this pattern can also be seen in other non-inflammatory conditions.
For ambiguous cases, a brain biopsy remains the most definitive diagnostic tool (the gold standard). A small sample of brain tissue and its vessels is surgically removed and examined under a microscope for evidence of inflammatory cells infiltrating the vessel walls. While invasive, the biopsy provides direct proof of inflammation and helps exclude other serious diseases, offering a clear basis for treatment.
Managing the Condition
The primary objective of managing CNS vasculitis is to suppress the immune system’s inflammatory attack on the blood vessels and prevent further neurological damage. Initial therapy for acute or severe cases typically involves high-dose corticosteroids, such as intravenous methylprednisolone, to quickly reduce inflammation and protect the brain tissue. This is followed by a switch to high-dose oral corticosteroids, such as prednisone, which are slowly tapered down as the patient stabilizes.
To achieve long-term control and allow for the eventual reduction of steroids, immunosuppressive agents are introduced to maintain remission. Cyclophosphamide is a potent medication used during the initial induction phase, especially in aggressive forms of the disease. Once stable, patients are transitioned to less toxic maintenance medications like azathioprine or methotrexate to sustain the suppression of the immune response. Long-term follow-up and monitoring are necessary to manage potential side effects and watch for signs of disease relapse.