What is a Vein of Galen Malformation?
A vein of Galen malformation starts during early prenatal development, as early as the first trimester. In normal prenatal development, a large vein forms at the base of the brain and is eventually replaced by a true vein of Galen. When a child has a vein of Galen malformation, high-pressure, oxygen-rich blood from the arteries flows directly into the initial vein, preventing development of the actual vein of Galen.
Without the vein of Galen, oxygen-rich blood is unable to flow slowly through capillaries that deliver this blood to surrounding tissues. Since there is also no slowing of the blood flow, it rushes quickly away through the vein, causing a constant rush of blood to the heart and lungs. The heart and lungs have to work extra hard to keep up with the volume of blood, which may result in congestive heart failure or pulmonary hypertension. These conditions are often life-threatening.
What Causes Vein of Galen Malformations?
Vein of Galen malformations are not inherited. There is currently no known cause of these malformations, but children with VOGMs are more likely to suffer from other types of arteriovenous malformations (AVMs)
, or blood vessel malformations.
How Common are Vein of Galen Malformations?
These malformations are extremely rare, making them difficult to diagnose right away. VOGMs account for approximately 1 in 3 cases of all arteriovenous malformations (AVMs) in children.
VOGMs are slightly more common in males than in females.
In the more severe cases, the blood overload goes almost directly from the vein to the heart and rapidly overwhelms it, leading to congestive heart failure. In rare cases, bleeding in the brain may occur.
Some children will not experience life-threatening symptoms. For these children, the severity of the malformation will affect the type of symptoms they have.
- Abnormally enlarging head, resulting from hydrocephalus, retention of fluid in the brain
- Enlarged or prominent veins in the head/scalp
In older children:
- Persistent headaches
- Seizures or strokes
- Failure to meet developmental milestone
VOGMs are often diagnosed via magnetic resonance imaging (MRI), which shows detailed images of the brain. In prenatal diagnosis, the condition is often noted during an ultrasound. If your child is diagnosed in the womb, it is important to locate a pediatric hospital with VOGM specialists as medical treatment may start prior to delivery. It is often recommended that the delivery occur near the pediatric hospital so that the VOGM team is ready to take immediate action as needed after birth.
Treatment and Surgery
In the majority of cases, repair of a vein of Galen malformation will occur after a child is born.
Upon birth, the best treatment for VOGM is embolization. This is a minimally-invasive procedure performed under general anesthesia. The endovascular surgeon threads a small, soft tube (catheter) into an artery up to the site of the malformation. The surgeon then sends a substance through the tube that creates a clot to contain the blood flow. In some cases, more than one procedure may be required to close off the malformation gradually.
There are complications associated with embolization which include failure of the clot to completely block the flow of blood or failure of the clotting substance to remain in place. It is recommended that VOGM patients be treated by those specialists at multidisciplinary centers. Whether children receive single or multiple treatments, they tend to do very well.
Your surgeon will provide specific instructions during your child’s recovery period. Most children are able to leave the hospital within a few days of the embolization procedure. Doctors will continue to monitor your child’s condition in the following weeks to ensure that the treatment was fully successful.
Approximately half of children suffer from a malformation that cannot be corrected. If the malformation cannot be corrected, the child may not survive beyond the first few days after birth.
For children with treatable malformations, long-term outlook is good following successful embolization. They typically go on to live normal lives.