Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Primary Arteritis of the CNS


KEY FACTS

Terminology

  • Primary arteritis of CNS (PACNS)

    • No evidence of secondary (systemic) vasculitis

    • May involve intracranial arteries of any size

  • 2 features essential for histopathologic diagnosis

    • Inflammation and necrosis of blood vessel wall

Imaging

  • CT

    • Look for secondary signs of vasculitis (ischemia, infarction)

    • Hypodensities on CT

    • Especially basal ganglia, subcortical white matter

  • MR (high resolution)

    • Multifocal punctate, linear hyperintensities on T2/FLAIR

    • Vessel wall imaging with thin-section, high-resolution (3T) T1 C+

      • –

        Circumferential, smooth, long segment

    • ± patchy parenchymal enhancement, restricted diffusion

    • DWI variable (may restrict)

  • DSA

    • Once considered imaging gold standard

    • “Beaded” arteries (irregular stenoses, dilatations) on DSA

      • –

        Peripheral branches > proximal (circle of Willis)

    • Less common: Long-segment stenoses, pseudoaneurysms, occlusions

Pathology

  • Brain biopsy may be required to confirm diagnosis

    • 75-80% sensitive

    • Negative biopsy does not exclude PACNS

Clinical Issues

  • Wide age range (mean: 42 years)

Diagnostic Checklist

  • Atherosclerosis is by far most common cause of vasculitis-like DSA pattern in older adults, not PACNS

Graphic depicts primary arteritis of the CNS with areas of narrowing
and dilatation
of the middle cerebral artery branches, as well as foci of patchy ischemia and microbleeds
in the basal ganglia, cortex, and subcortical white matter.

T1 C+ FS scan in a 62-year-old man with ataxia, diplopia, and confusion shows innumerable abnormal linear
and dot-like areas of enhancement
in the subcortical and deep white matter of both hemispheres. This is biopsy-proven primary arteritis of the CNS (PACNS).

Lateral DSA in a 34-year-old woman with multiple strokes shows markedly irregular posterior cerebral artery
with alternating areas of stenosis and dilatation.

Thin-section T1 C+ FS in the same patient shows enhancement in the wall of the left posterior cerebral artery
. Wall enhancement can occur in both vasculitis and atherosclerosis with chronic inflammation. Patient was a smoker with cardiovascular risk factors, but young age and clinical features were most consistent with PACNS.

TERMINOLOGY

Abbreviations

  • Primary arteritis of CNS (PACNS)

Synonyms

  • Vasculitis, vasculopathy

Definitions

  • 2 cardinal features required for histopathologic diagnosis of vasculitis

    • Inflammation and necrosis of blood vessel wall

  • PACNS: Arteritis confined to intracranial CNS without evidence for systemic vasculitis

IMAGING

General Features

  • Best diagnostic clue

    • Circumferential, smooth, long-segment vessel wall enhancement

    • “Beaded” arteries (irregular stenoses, dilatations) on DSA

      • –

        Nonspecific (intracranial atherosclerotic vascular disease (ASVD) > vasculitis)

    • Note: Imaging work-up can be normal; requires clinical/laboratory correlation

  • Location

    • Pathologically leptomeningeal arteries and veins are affected, but involves intracranial vessels of any size

    • Brain is primary site, but spinal cord can also be involved

  • Size

    • Degree of vessel narrowing may range from normal or minimally stenotic to completely occluded

  • Morphology

    • Areas of smooth or slightly irregularly shaped stenoses alternating with dilated segments

    • Nonspecific (appearance similar to other vasculitides)

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts