Vein of Galen aneurysm: A congenital malformation of blood vessels of the brain. Specifically, an arteriovenous (AV) malformation in which blood shunts from cerebral arteries into a dilated vein of Galen (an internal cerebral vein).
In newborns this shunt can cause high cardiac output and heart failure. In infants this AV malformation can obstruct the Aqueduct of Sylvius, a necessary channel for the flow of cerebrospinal fluid, and cause hydrocephalus. In older children it can seizures (epileptic fits), a stroke, or learning difficulties.
Treatment is catheterization to deposit a glue in the shunt to shut it off. Several of these embolizations procedures may be needed to shut off all the vascular communications. This is usually done over a period of months before the child is two years old.