What is a vein of Galen malformation?
Vein of Galen malformations (VOGMs) are a type of malformation of the blood vessels in the brain, where several arteries are abnormally connected to a midline brain vein causing it to enlarge under pressure. Although rare, they are the most frequent congenital malformations of the blood vessels in the brain. "Congenital" means present at birth, and the malformation develops during early pregnancy. Children with VOGMs have a malformation that directs oxygen-rich blood directly into a large deep vein in the midline instead of to the surrounding brain tissue. This causes the deep vein to swell and puts a lot of pressure on the blood vessels that lead to the heart and lungs.
With a VOGM, high-flow arterial blood enters the malformation with high pressure, causing enlargement of the involved vessels and channels, which normally return blood from the brain to the heart. This abnormal, increased flow and pressure can lead to significant problems:
- Congestive heart failure – the short-circuiting of blood through the malformation creates a relentless loop of a high volume of blood flowing into the heart and lungs. This forces the heart to work overtime to pump blood to rest of the body.
- Pulmonary hypertension – the blood pressure in the arteries from the heart to the lungs rises.
- Brain injury and loss of brain tissue – the flow of blood into the malformation and away from the normal brain, along with high pressure in the veins preventing the brain from draining properly, lead to brain injury and/or tissue loss.
- Hydrocephalus – increased blood flow in the veins affects the cerebrospinal fluid (CSF) production/absorption process, causing a build-up of fluid and pressure inside the brain.
- Multi-organ failure – the majority of the blood that should flow through the heart is instead redirected through the malformation and this prevents adequate blood flow to other organs like the liver, intestines and kidneys.
If not diagnosed and treated early, VOGMs can cause severe problems and even be life-threatening.
Types of vein of Galen malformations
There are two types of VOGMs:
- A neonatal (newborn) at-risk type that usually presents earlier (during pregnancy or in the first month of life) and causes more severe problems like heart failure and damage to the developing brain.
- An infantile type that usually presents later (in infants or toddlers), with signs like an enlarged head (macrocephaly) or poor growth/weight gain. The risk of heart failure is usually lower.
Signs and symptoms of a vein of Galen malformation
Symptoms of a VOGM may begin during development before birth, shortly after birth or during early childhood. They may include:
- congestive heart failure
- pulmonary hypertension, leading to difficulty breathing
- hydrocephalus
- prominent veins on the face or scalp
- an enlarged head (macrocephaly)
- developmental delays
- an audible whooshing sound (bruit) that can be heard over the top front soft spot (fontanelle) on the baby’s head
- poor growth/weight gain
- seizures
What are the causes of a vein of Galen malformation?
The causes of VOGMs are not fully known. There is increasing research that suggests there could be genetic mutations locally within the brain blood vessels which cause them to connect abnormally.
VOGMs are formed during early fetal development, usually during the first trimester.
Although they are the most common malformation of the blood vessels in the brain in newborns and infants (30% of all pediatric vascular malformations), they are rare and affect less than one in 25,000 deliveries.
What may happen if a vein of Galen malformation is untreated?
Infants with untreated VOGMs usually experience extremely poor outcomes, including multiorgan failure and the high likelihood of death.
A baby with a VOGM requires a multidisciplinary team of pediatric specialists including obstetricians, neonatologists, neuro-interventional radiologists, neurosurgeons, neurologists and cardiologists, who are experts in the different care needs of babies with these vascular malformations. Access to care at a highly experienced pediatric neurovascular centre is imperative and should be initiated as soon as possible. Because of the challenges associated with transporting a sick newborn, the referral for maternal care is recommended at the time of prenatal diagnosis.
Diagnostic imaging and testing
Diagnostic imaging and testing are important in identifying a VOGM. There are different types of imaging and testing that can be performed to diagnose a VOGM:
During pregnancy
- Prenatal ultrasound: A prenatal ultrasound uses high-frequency sound waves to take pictures of the fetus. VOGMs are often detected on prenatal ultrasounds, in the late second or third trimester.
- Fetal echocardiography: Fetal echocardiography uses sound waves to take pictures of the fetus’ heart. The images show the structure of the heart and how well it is working
- Fetal magnetic resonance imaging (MRI): – A fetal MRI uses a strong magnet to take pictures of the fetus. It is used to evaluate abnormalities that may have developed in the brain, spine and body. It may also be used to confirm the prenatal ultrasound findings or add further information in complex cases.
After delivery
- MRI: An MRI uses a strong magnet to take a picture of the brain. The images of the arteries in the brain are called MRI–Angiograms (MRAs), and the images of the veins in the brain are called MRI–Venograms (MRVs). Sometimes, further MRI imaging is done with contrast dye to take additional pictures of the vessels of the brain.
- Cerebral angiogram: A cerebral angiogram is a procedure performed using a catheter inside the blood vessels and contrast dye injected to create a map of the arteries so they can be seen by X-rays. It is the standard test for understanding all the unique details of normal and abnormal brain vessels.
- Echocardiogram: An echocardiogram is an imaging test that uses sound waves to take pictures of the heart. The images show the structure of the heart and how well it is working.
Termination
If a severe VOGM with brain injury is detected during pregnancy, termination of the pregnancy may be an option. The health-care team will discuss all the options for treatment with you before any decisions need to be made.
In utero endovascular treatment
Early intervention during pregnancy may improve outcomes in very severe cases of VOGM. Newborns with high-risk VOGMs are likely to medically decline soon after birth, so the goal of in utero endovascular treatment would be to try to reduce blood flow through the complex malformation before birth. The health-care team will discuss whether this is an option.
Endovascular embolization
After delivery, endovascular embolization is a treatment option. Your child’s interventional neuroradiologist will insert a catheter into an artery in your child’s leg or umbilical cord (if accessed immediately after delivery), which is threaded through the blood vessels to the brain. Once the VOGM is located, an embolizing agent is injected to block the arteries and reduce blood flow to the malformation. This is often performed once your newborn has been medically stabilized.
The goal of treatment is to decrease as much blood flow through the VOGM while maximizing the blood supply to the brain. If the malformation is complex, your child may require more than one endovascular embolization. This may happen over days or weeks.
Complications
The high-pressure blood flow in the vein of Galen can lead to significant problems:
- Congestive heart failure
- Pulmonary hypertension
- Brain injury and loss of brain tissue
- Hydrocephalus
- Failure of other organs in the body
- Seizures
- Developmental delays
A newborn with a VOGM may be quite medically unstable and require a prolonged hospital stay in either a neonatal intensive care unit (NICU) or specialized care environment. They may require several different medical teams to be involved in managing their complex medical needs, including medical treatment for heart failure and ventilation to support lung function. They will require continuous monitoring, frequent echocardiograms and brain imaging.
Helping yourself and your child
Receiving the diagnosis of a VOGM can be very stressful and emotional. The health-care team can suggest resources that may be available for you and/or your child to help to with coping.
For more information on coping, see:
- Pregnancy and infant loss
- Living with a chronic condition: Overview
- Living with a chronic condition: Helping your child manage their health
- Living with a chronic condition: Maintaining your child's everyday routines
- Living with a chronic condition: Supporting yourself as a caregiver
- Mental health learning hub
- Guided audio meditations
Follow-up care
Your child will require years of follow-up care and serial imaging to continue to follow their development and the treatment of the VOGM. Further interventions may be required depending on the complexity of the malformation.
At SickKids
SickKids Neurosurgery Clinic – SickKids Neurosurgery offers the highest level of care to children with all types of neurosurgical disorders.
Paediatric Neurovascular Program – The Paediatric Neurovascular Program is made up of a team of specialists dedicated to providing care to children with neurovascular diseases.
Resources
Ontario Fetal Centre – Canada’s first centre to provide improved access for patients and their families to cutting-edge in utero medical and surgical interventions for sick babies.
Vein of Galen Malformation Support Network – a non-profit organization started by parents that provides information and emotional and financial support to other parents whose children have been diagnosed with VOGM.
References
Clarke NE, Shekhawat J, Popat H, Lord DJE, Abdel-Latif ME. Vein of Galen Aneurysmal Malformation: A Case Report. Healthcare (Basel). 2024 Mar 25;12(7):716. Retreived from https://pmc.ncbi.nlm.nih.gov/articles/PMC11011842/.