The characteristic findings in a brain MRI, present in approximately 70% of patients, are subdural fluid collections, enhancement of the pachymeninges
, engorgement of venous structures, pituitary hyperaemia and sagging of the brain (11).
13) There is enhancement of the pachymeninges
because they have no blood-brain barrier, contrary to the leptomeninges, which have an intact blood-brain barrier and no enhancement.
Increased interstitial fluid of the pachymeninges
forms as a result of compensatory meningeal vasodilatation (1).