Primary angiitis of the central nervous system
Primary angiitis of the central nervous system (PACNS) is a rare small- and medium-vessel vasculitis confined to the brain, spinal cord, and leptomeninges, presenting with gradually progressive headache, cognitive impairment, focal deficits, transient ischemic attacks, and strokes with normal serum laboratory tests. It is confirmed by brain biopsy (or catheter angiography) after infection, malignancy, and reversible cerebral vasoconstriction syndrome are excluded, and is treated with high-dose glucocorticoids plus cyclophosphamide.
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What this article covers
- Overview
Definition: primary angiitis of the central nervous system (PACNS) is a rare small- and medium-vessel vasculitis restricted to the central nervous system, affecting the brain parenchyma, spinal cord, and leptomeninges.
- Epidemiology
Rare: PACNS is an uncommon cause of stroke and progressive encephalopathy.
- Risk factors
No established exposure or inherited risk factor: the disease is idiopathic by definition; an identified trigger reclassifies it.
- Pathophysiology
Transmural inflammation of small and medium intracranial vessels narrows and occludes the lumen, producing infarcts in multiple territories and diffuse white and gray matter injury.
- Clinical features
Gradually progressive course over weeks to months: the hallmark that separates PACNS from the abrupt, recurrent thunderclap pattern of reversible cerebral vasoconstriction syndrome.
- Differential diagnosis
CNS infection (meningitis, encephalitis, syphilis, tuberculosis, HIV): positive CSF Gram stain, culture, PCR, or serology; immunosuppression without excluding infection is the most dangerous error.
- Diagnosis
The diagnosis is established by brain biopsy, after normal serum laboratory tests and exclusion of mimics: biopsy of brain parenchyma and leptomeninges showing granulomatous, lymphocytic, or…
- Management
First, exclude the mimics before immunosuppressing: complete CSF culture, PCR, and cytology, and confirm the history does not fit reversible cerebral vasoconstriction syndrome, because cytotoxic…
- Complications
Permanent neurologic disability from accumulated infarcts and cognitive injury, common even with treatment.
- Prognosis
Permanent disability is common, driven by the burden of infarction and cognitive injury present when treatment starts.
- Prevention
No primary prevention exists for this idiopathic vasculitis.
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