Vein of Galen Malformation

vein of galen aneurysm ct sagittal mip

This infant presented at birth with high-output cardiac failure and multiple organ failure. The above image is a sagittal maximum-intensity projection from a CT cerebral angiogram. It shows an aneurysmal deep venous structure which drains to the vein of Galen, and then to an abnormal falcine sinus. The posterior part of the superior sagittal sinus is enlarged, as are the transverse and sigmoid sinuses. Three-dimensional reconstruction shows the malformation and draining sinuses to advantage. Feeding arteries are multiple, dilated and tortuous. They attach directly to the aneurysm without an intervening nidus. The largest arteriovenous connection is shown here. A time-of-flight magnetic resonance venogram, performed later, shows relative narrowing at the jugular foramina bilaterally.

The patient was treated by endovascular occlusion of the larger feeding vessels. An intraprocedural arterial bleed was rapidly controlled. In the immediate postprocedural period the cardiovascular status improved. Ongoing high-output state will necessitate further procedures on a staged basis.

Vein of Galen malformation is due to an arteriovenous fistula to the median prosencephalic vein at 6-11 weeks gestation. The MPV fails to regress, instead becoming aneurysmal. Drainage is to the vein of Galen. The straight sinus is absent in 50%, being replaced by a falcine vein (as in this case). Presentation is usually with high-output cardiac failure in the neonatal period, although low-flow aneurysms may remain undetected into adulthood. As much as 80% of cardiac output may shunt through the fistula. Malformations have been classified as choroidal or mural, depending on the number and origin of feeding arteries. Choroidal types have many feeders including thalamoperforating, choroidal and pericallosal arteries, and tend to present earlier with more severe shunts. Mural types have less feeders, and supply may be unilateral. There is typically associated absence or stenosis of dural sinuses, with stenosis at the level of the jugular foramen being common. Hydrocephalus may occur due to venous hypertension or aqueduct stenosis. Cerebral ischaemia occurs due to venous hypertension or a steal phenomenon.
Ideally embolisation is deferred until 6 months of age, to allow the cavernous sinus to mature. If cardiac failure is refractory to medical management, embolisation may be performed sooner. Hydrocephalus is typically not shunted, as this may exacerbate cerebral ischaemia by altering cerebral haemodynamics.

Reference: Osborn A, et al. Diagnostic Imaging: Brain Amirsys 2004

Credit: Dr Laughlin Dawes