Central nervous system vasculitis

Last revised by Rohit Sharma on 21 Jan 2024

Central nervous system (CNS) vasculitides represent a heterogeneous group of inflammatory diseases (vasculitis or cerebral angiitis) affecting the walls of blood vessels in the brain, spinal cord, and meninges.

Please refer to the article on vasculitis for a general discussion of that entity. 

The aim of this article will be to discuss primary angiitis of the CNS (PACNS) (also known as primary CNS vasculitis (PCNSV)) since the other vasculitides are already discussed in specific articles. 

CNS vasculitides are classified as 1,2:

  • primary: confined to the CNS with no involvement of other systems - referred to as primary angiitis of the CNS

  • secondary: occurs in the context of a systemic inflammatory or infectious process

Please, note that this classification is different from the one used when discussing systemic vasculitides.

Primary angiitis of the CNS remains a rare disorder with an estimated average annual incidence rate of 2.4 cases per million 12. It affects patients of all ages, but peaks at around 50 years of age, with males affected more commonly than females 1.

Secondary causes of CNS vasculitis far exceed the number of cases of primary angiitis of the CNS 2. Please refer to each specific vasculitis for further details.  

Clinical features of primary angiitis of the CNS are non-specific. The diagnosis is made based on Calabrese’s criteria 4, including:

  • the presence of an acquired otherwise unexplained neurological or psychiatric deficit

  • the presence of either classic angiographic or histopathological features of angiitis within the CNS (biopsy remains the standard of reference for diagnosis 3)

  • no evidence of systemic vasculitis or any disorder that could cause or mimic the angiographic or pathological features of the disease

Common clinical features include headache (thunderclap headaches are rare), cognitive impairment, focal neurological deficits from stroke (weakness, visual deficit, aphasia), and seizures 11,12.

When part of a systemic disorder, the diagnosis may be easier, unless the cerebral symptoms are the first to manifest. Please refer to a specific vasculitis for further details on clinical manifestation. 

For almost all forms of vasculitis, including primary angiitis of the CNS, the triggering factor is unknown 3

CNS secondary vasculitides:

High erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), anemia, or increased cell count in cerebrospinal fluid (CSF) may raise the suspicion of cerebral vasculitis 8.

Imaging findings for primary angiitis of the CNS are usually variable and non-specific, with ischemic infarctions the most common lesions, occurring in approximately 60% of cases 5,11

CT may show areas of hypoattenuation reflecting infarction. CT angiography may show multifocal intracranial arterial narrowing and/or beading of both small and medium-sized blood vessels 8.

Digital subtraction angiography typically shows focal or multifocal segmental narrowing and/or beading of both small and medium-sized blood vessels 11. Vessel occlusions may also rarely be present 11. The same findings can be demonstrated in both CT angiography and MR angiography 8. The middle cerebral artery is the most commonly affected artery, followed by the anterior and posterior cerebral arteries, and less commonly (<15%) internal carotid, vertebral and basilar arteries 11.

It is important to note that a normal digital subtraction angiogram does not exclude CNS vasculitis 12.

MRI is nearly always abnormal 11,12, and is more specific in demonstrating multiple infarctions, which are typically bilateral, affecting different vascular territories, are of variable size, and are in various stages of healing. Unilateral cases have only been very rarely reported 9.

T2/FLAIR high intensity lesions in the white matter are seen in almost half of cases 11, but are non-specific. GRE/SWI may reveal hemorrhagic lesions such as cerebral microhemorrhages, intracranial hemorrhage and rarely, subarachnoid hemorrhage 10,11Meningeal enhancement and/or parenchymal enhancement may be seen in up to approximately 40% of cases 11,12.

MR angiography may show multifocal intracranial arterial narrowing and/or beading of both small and medium-sized blood vessels 11. Vessel wall MRI (VW-MRI) may be a useful adjunct to conventional MRI, allowing differentiation between vasculitis, where there is contrast enhancement of the affected arterial wall, and other causes of vascular narrowing, such as intracranial atherosclerotic disease (ICAD) plaque, reversible cerebral vasoconstriction syndrome, dissection, and moyamoya disease 7

Primary angiitis of the CNS is managed with high-dose corticosteroids and other immunosuppressive agents such as cyclophosphamide or rituximab 3,12.

Primary angiitis of the CNS was initially reported in 1959 by Humberto Cravioto and Irwin Feigin 6.

  • remember that despite being composed of non-specific findings, MRI is almost 100% sensitive for primary angiitis of the CNS and a normal MRI practically excludes this diagnosis 1,11,12

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