Developmental venous anomaly
A developmental venous anomaly (DVA) also known as cerebral venous angioma, is a congenital malformation of veins which drain normal brain. They were thought to be rare pre cross-sectional imaging, however are now recognised as being the most common cerebral vascular malformation, accounting for 50-63% of all such lesions 1.
A DVA is characterised by the caput medusa sign of veins draining into a single larger collecting vein, which in turn drains into either a dural sinus or into a deep ependymal vein. The appearance has also been likened to a palm tree.
The aetiology of DVAs remains uncertain, but may relate to arrested development of venous structures 2-3. Histologically they consist of a number of abnormally thickened veins with normal feeding arteries and capillaries 3.
Location and classification
The most common locations are
- frontoparietal region (36-64%) 1, usually draining towards the frontal horn of the lateral ventricle (see case 1)
- cerebellar hemisphere (14-27%) draining towards the fourth ventricle (see cases 2-3)
DVAs however can be seen anywhere, draining either superficially or deep.
- lesions are usually solitary (75%) 2, except in blue rubber bleb naevus syndrome.
- in 8-33% of cases 2 they are associated with cavernous malformations and are referred to as mixed vascular malformations
- there is an association with venous malformations of the head and neck 2.
DVAs are seen on both CT and MRI as a leash of vessels draining towards a central vein.
If large, the draining vein may be seen on non-contrast CT, and is confirmed with contrast administration.
May be visible on most sequences, but is most easily seen on post contrast T1 sequences. If there is an associated cavernous haemangioma then susceptibility weighted sequences will be most sensitive for this component.
SWI is the preferred sequence in venous anomalies and proved to have better detectability of venous structures than conventional T2*-weighted imaging. Signals on SWI are not compromised by low-velocity venous flow; therefore, SWI has successfully demonstrated low-flow vascular formations such as DVA.
DSA - angiography
Angiographically the caput medusa appearance (collection of dilated medullary veins converge in an enlarged transcortical or subependymal collector vein) is pathognomic and seen only in the venous phase. Arterial phase appears normal although late capillary blush may be present. No shunting is present.
Treatment and prognosis
If isolated, then no treatment is necessary. If part of an MVM then treatment will be predicated by the other component. Informing the surgeon of the presence of a DVA is however essential as cautery of the the collecting vein can lead to venous infarction.
When isolated, a DVA has a very low complication rate ( 0.15% per annum) mainly from spontaneous thrombosis of the collecting vein leading to venous infarction and haemorrhage. DVA's are however commonly associated (15-20%) with other vascular malformations, most commonly a cavernous malformation in which case they should be referred to as mixed vascular malformations (as in Case 1). Their risk of complication is then elevated to that of the associated lesion. There is an association with cortical dysplasia (? how strong? )
General imaging differential considerations include
- 1. Lee C, Pennington MA, Kenney CM. MR evaluation of developmental venous anomalies: medullary venous anatomy of venous angiomas. AJNR Am J Neuroradiol. 1996;17 (1): 61-70. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 2. Boukobza M, Enjolras O, Guichard JP et-al. Cerebral developmental venous anomalies associated with head and neck venous malformations. AJNR Am J Neuroradiol. 1996;17 (5): 987-94. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 3. Saba PR. The caput medusae sign. Radiology. 1998;207 (3): 599-600. Radiology (citation) - Pubmed citation
- 4. Lee BC, Vo KD, Kido DK et-al. MR high-resolution blood oxygenation level-dependent venography of occult (low-flow) vascular lesions. AJNR Am J Neuroradiol. 1999;20 (7): 1239-42. AJNR Am J Neuroradiol (full text) - Pubmed citation
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Developmental venous anomaly (DVA)||✗|
|Cerebral venous angioma||✗|
|Cerebral venous angiomas||✗|
|Developmental venous anomalies||✗|
|Developmental venous anomalies (DVA's)||✗|