Transependymal oedema, also known as interstitial cerebral oedema, is a type of cerebral oedema that occurs with increased pressure within the cerebral ventricles. FLAIR is the most sensitive MRI sequence for detection.
The ventricular ependymal lining is eventually disrupted, allowing for the transependymal migration of cerebrospinal fluid into the brain parenchyma around the cerebral ventricles. This is usually seen surrounding the lateral ventricles in the setting of an acute obstructive hydrocephalus.
- low attenuation periventricular changes around the lateral ventricles
- effacement of adjacent cerebral sulci may be seen, which is helpful to distinguish the condition from age related cerebral atrophy with small vessel peri-ventricular ischaemic changes
- other corresponding features of obstructive hydrocephalus may be noted
- halo of high T2 or FLAIR signal around the lateral ventricles
It is important to distinguish interstitial oedema from the normal slight increase in signal anterior to the frontal horns, and posterior to the occipital horns, which is known as ependymitis granularis.
- 1. Segev Y, Metser U, Beni-adani L et-al. Morphometric study of the midsagittal MR imaging plane in cases of hydrocephalus and atrophy and in normal brains. AJNR Am J Neuroradiol. 2001;22 (9): 1674-9. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 2. Ho ML, Rojas R, Eisenberg RL. Cerebral edema. AJR Am J Roentgenol. 2012;199 (3): W258-73. doi:10.2214/AJR.11.8081 - Pubmed citation