Plain language
What is a Vein of Galen Malformation?
It is a tangle of blood vessels in a baby’s brain, in a place where a fine mesh should be.
In a healthy brain, blood travels from the arteries into a mesh of tiny vessels, and only then into the veins. The mesh slows the blood down.
In a Vein of Galen Malformation, that mesh never formed. Arteries drain straight into a large vein deep in the middle of the brain, at full pressure. The vein swells, and the heart has to work extremely hard to keep up.
It happens very early in pregnancy, long before anyone knows. You will also see it written as VGAM, VGM, or “aneurysm of the vein of Galen”. These are all the same condition.
About this information. We have written this in plain language from published medical sources, and we link to every one. For anything specific to your child, your own doctors are the authority.
Nothing you did caused this
From Great Ormond Street Hospital: a Vein of Galen Malformation is not caused by anything a mother did or did not do during pregnancy. Most cases have no identified cause at all.
It can be treated
The treatment is embolisation. A doctor passes a very fine tube through a blood vessel, up into the brain, and blocks the abnormal connections from the inside. The skull is not opened. It is usually done in stages, over more than one procedure.
It is done by an interventional neuroradiologist. There are not many of them, and experience matters enormously — which is why asking for a second opinion is a normal and sensible thing to do here.
What the numbers actually say
You will find frightening statistics online, and reassuring ones. Both are real. They describe different groups of children — and almost nobody tells you which. So here they are, with their groups attached.
- About 6% died; about 89% had a good outcome — pooled analysis of treated patients of all ages, 2022–2024 (participant-level meta-analysis)
- About 40% died — every newborn who presented in the UK over ten years — the sickest group, treated or not (UK national cohort)
Newborns already in heart failure are the hardest group. Babies found before birth, or later in infancy, generally do better. Where your child sits is a question only your own doctors can answer.
What every one of those numbers agrees on: treatment works, and children with this condition grow up.
Words you are going to hear
- Embolisation
- Closing off the abnormal blood vessels from the inside, through a fine tube. The treatment.
- Interventional neuroradiologist
- The specialist who does it. Also called a neuro-endovascular surgeon.
- Hydrocephalus
- A build-up of fluid inside the brain.
- Fontanelle
- The soft spot on a baby’s head.
- Shunt
- A tube that drains fluid from the brain. In this condition it is usually not the first step.
- VGAM / VGM
- Other names for exactly the same thing.
Where to read more
These are the institutions we trust. We link to them rather than rewrite them.