Transependymal edema, also known as interstitial cerebral edema, is a type of cerebral edema 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 periventricular ischemic disease
- 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 edema from a commonly seen variant of a slight increase in signal anterior to the frontal horns, and posterior to the occipital horns, which is known as ependymitis granularis 3.
- 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
- 3. Sze G, De armond SJ, Brant-zawadzki M et-al. Foci of MRI signal (pseudo lesions) anterior to the frontal horns: histologic correlations of a normal finding. AJR Am J Roentgenol. 1986;147 (2): 331-7. AJR Am J Roentgenol (abstract) - Pubmed citation