Enlarged Perivascular Spaces

Karen L. Salzman, MD

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Perivascular spaces (PVS) are pial-lined interstitial fluid-filled structures that accompany penetrating arteries
Most commonly seen as a normal variant

Helpful Clues for Common Diagnoses

Normal Variant
- Round/oval fluid-filled spaces that have CSF density/intensity, no enhancement
- Rare mass effect (giant PVS)
- Most commonly seen at anterior commissure, inferior basal ganglia (BG)
- Common: Midbrain, deep white matter (WM), subinsular cortex, extreme capsule
- Rare: Thalami, dentate nuclei, corpus callosum (CC), cingulate gyrus
Aging Brain, Normal
- PVS are commonly seen as the brain loses volume as part of normal aging

Helpful Clues for Less Common Diagnoses

Cryptococcosis
- Enlarged PVS in BG & superior brainstem
- May see DWI hyperintense rim

Helpful Clues for Rare Diagnoses

Mucopolysaccharidoses
- Enzyme deficiency & inability to break down glycosaminoglycan (GAG)
- PVS dilated by accumulated GAG
- CC & periatrial WM most common sites
- Surrounding T2 hyperintensity common ± additional patchy WM signal
Tumor-Associated Cysts, Nonneoplastic
- “Cysts” caused by enlarged/obstructed PVS reported with pituitary adenomas
CADASIL
- Subcortical lacunar infarcts & leukoencephalopathy in young adults
- Dilated PVS are frequent in CADASIL, involving temporal WM & BG
- PVS dilation in CADASIL increases with age (may be related to aging or vascular wall alterations)
Megalencephaly with Dilated Perivascular Spaces
- Enlarged WM PVS with surrounding T2 hyperintensity
Hypomelanosis of Ito
- Large PVS with periventricular T2 hyperintensity