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Tumefactive Perivascular Spaces

Summary

  • Tumefactive perivascular spaces (TPVS) are abnormally enlarged perivascular spaces that can mimic cystic neoplasms
  • Typically found in the basal ganglia, centrum semiovale, and midbrain
  • Characterised by well-defined, round or oval cystic lesions following CSF signal on all sequences

Pathophysiology

  • Perivascular spaces (PVS) are extensions of the subarachnoid space that surround penetrating arteries
  • TPVS occur when these spaces become abnormally enlarged, potentially due to:
    • Obstruction of CSF flow
    • Increased permeability of vessel walls
    • Impaired drainage of interstitial fluid

Demographics

  • More common in elderly patients
  • No significant gender predilection
  • Associated with:
    • Hypertension
    • Dementia
    • Small vessel disease
    • Mucopolysaccharidoses

Diagnosis

  • Often an incidental finding on neuroimaging
  • Clinical presentation:
    • Usually asymptomatic
    • Rarely, may cause mass effect leading to headaches or focal neurological deficits
  • Differential diagnosis:
    • Cystic neoplasms
    • Lacunar infarcts
    • Cryptococcosis
    • Neurocysticercosis

Imaging

  • CT:
    • Well-defined, round or oval hypodense lesions
    • No enhancement with contrast
  • MRI:
    • T1: Hypointense
    • T2/FLAIR: Hyperintense, following CSF signal
    • DWI: No restricted diffusion
    • No enhancement on post-contrast T1
  • Key features:
    • Cluster of cystic lesions
    • No surrounding oedema
    • No mass effect
    • Typically bilateral and symmetrical

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  • 40-year-old patient presenting with headache.
  • There was chronic ventriculomegaly although the periventricular oedema had increased since imaging 1 year prior.
  • CSF outflow through the sylvian aqueduct was impaired by cystic lesions in the right paramedian thalamus and in the midbrain.
  • The cysts had not changed in 1 year and there was no soft tissue component or pathological enhancement to indicate a neoplasm.

Treatment

  • No specific treatment required for asymptomatic TPVS
  • Management focuses on underlying conditions (e.g., hypertension, small vessel disease)
  • In rare cases of symptomatic TPVS:
    • Surgical decompression may be considered
    • CSF diversion procedures (e.g., ventriculoperitoneal shunt) for hydrocephalus
  • Follow-up imaging to monitor for stability and exclude neoplastic processes

Differential diagnosis

Differential Diagnosis Differentiating Feature
Low-grade glioma Enhances with contrast, shows mass effect
Multiple sclerosis Ovoid lesions, periventricular distribution
Lacunar infarcts Irregular borders, restricted diffusion on DWI
Cryptococcosis Gelatinous pseudocysts in basal ganglia showing T2 hyperintensity with restricted diffusion; may show enhancement
Neurocysticercosis Cystic lesions with enhancing scolex; calcifications in chronic stage on CT
Metastases Multiple lesions with ring or nodular enhancement and surrounding vasogenic oedema
Mucopolysaccharidosis Diffuse white matter T2 changes; enlarged perivascular spaces similar in appearance but more diffuse
Small vessel disease Irregular borders, associated white matter hyperintensities
Virchow-Robin spaces Smaller size, typically <3mm
Arachnoid cysts Extra-axial location, CSF signal on all sequences