Central nervous system (CNS) vasculitides represent a heterogeneous group of inflammatory diseases affecting the walls of blood vessels in the brain, spinal cord, and the meninges.
Please refer to the article on vasculitis for a general discussion of that entity.
The aim of this article will be to discuss the primary angiitis of the CNS (PACNS) 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 as PACNS
- secondary: occurs in the context of a systemic inflammatory or infectious process
Please, note that this classification is different from that one used when discussing systemic vasculitides.
PACNS remains a rare disorder: an estimated average annual incidence rate of 2.4 cases per million. 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 in number PACNS 2. Please refer to each specific vasculitis for further details.
Clinical features of PACNS 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
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 PACNS, the triggering factor is unknown 3.
CNS secondary vasculitides:
- affecting large blood vessels
- affecting medium blood vessels
- affecting small blood vessels
- variable vessels sizes
- associated with systemic disease
- associated with a known aetiology
- infection-induced vasculitis
Imaging findings for PACNS are usually variable and nonspecific, with ischemic infarctions the most common lesions, occurring in 53% of cases 5.
May show areas of hypoattenuation.
Digital subtraction angiography shows focal or multifocal segmental narrowing of both small and medium-sized blood vessels, occlusions are also present. The same findings could be demonstrated in both CTA and MRA.
More specific to show multiple infarctions: usually bilateral, affecting different vascular territories of variable size, and in various stages of healing.
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 plaque, reversible cerebral vasoconstriction syndrome, dissection, and moyamoya disease 7.
Treatment and prognosis
PACNS is managed with high dose steroids and cytotoxic agents 3.
History and etymology
PACNS was initially reported in 1959 by Humberto Cravioto and Irwin Feigin 6.
Remember that despite being composed by nonspecific findings, MRI is almost 100% sensitive for PACNS and a normal exam practically excludes this diagnosis 1.
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- 2. Fieschi C, Rasura M, Anzini A et-al. Central nervous system vasculitis. J. Neurol. Sci. 1998;153 (2): 159-71. Pubmed citation
- 3. Abdel Razek AA, Alvarez H, Bagg S et-al. Imaging spectrum of CNS vasculitis. Radiographics. 2014;34 (4): 873-94. doi:10.1148/rg.344135028 - Pubmed citation
- 4. Calabrese LH, Mallek JA. Primary angiitis of the central nervous system. Report of 8 new cases, review of the literature, and proposal for diagnostic criteria. Medicine (Baltimore). 1988;67 (1): 20-39. Pubmed citation
- 5. Salvarani C, Brown RD, Calamia KT et-al. Primary central nervous system vasculitis: analysis of 101 patients. Ann. Neurol. 2007;62 (5): 442-51. doi:10.1002/ana.21226 - Pubmed citation
- 6. Cravioto H, Feigin I. Noninfectious granulomatous angiitis with a predilection for the nervous system. Neurology. 1998;9: 599-609. Pubmed citation
- 7. Mandell DM, Mossa-Basha M, Qiao Y, Hess CP, Hui F, Matouk C, Johnson MH, Daemen MJ, Vossough A, Edjlali M, Saloner D, Ansari SA, Wasserman BA, Mikulis DJ. Intracranial Vessel Wall MRI: Principles and Expert Consensus Recommendations of the American Society of Neuroradiology. (2017) AJNR. American journal of neuroradiology. 38 (2): 218-229. doi:10.3174/ajnr.A4893 - Pubmed