Vein of Galen Aneurysmal Malformation (VGAM)

Your child has been diagnosed with VGAM — what does this mean?

A diagnosis of Vein of Galen aneurysmal malformation means that your baby has a congenital vascular abnormality deep within the brain, where multiple arteries connect directly to a large vein, bypassing the normal capillary network.

This creates very high blood flow from the heart to the brain and back to the heart, placing major strain on the cardiovascular system (neonatal heart failure) and on the brain’s venous circulation (venous hypertension, hydrocephalus, and risk of injury to brain tissue).

Our goals are to:

• stabilize cardiac function and breathing,
• protect the brain from permanent injury,
• reduce flow through the malformation gradually using safe, endovascular techniques.

What exactly is Vein of Galen aneurysmal malformation?

In reality, the term “Vein of Galen malformation” can be somewhat misleading. In true VGAM, the dilated venous structure is an embryonic vein that persists (the median prosencephalic vein), which normally regresses. Instead, it remains patent in the neonatal period and receives large volumes of arterial inflow.

Key features:

• It forms in utero, typically around 8–11 weeks of gestation.
• It is supplied by multiple arteries, including choroidal arteries (anterior/posterior), periventricular branches, and others.
• Blood drains into a large, dilated vein (the median prosencephalic vein), which empties into abnormally developed venous sinuses.
• Several angiographic subtypes exist (mural, choroidal; Yasargil/Lasjaunias types I–IV), which matter mainly for endovascular planning rather than for parents.

For families, the critical questions are: how high the flow is, at what age the condition presented, and the functional status of the brain on imaging (MRI/ultrasound).

When & why does it occur — can anything be done to prevent it?

VGAM is a congenital anomaly that develops during fetal life. It is not linked to a particular maternal behavior during pregnancy and, in most cases, could not have been prevented.

It may:

• be detected prenatally on specialized second- or third-trimester ultrasound,
• be diagnosed immediately after birth in a newborn with heart failure,
• be identified later in infancy due to macrocephaly and/or developmental delay.

There is no well-established simple hereditary factor as seen in some genetic syndromes. If there is a family history of other vascular malformations, individualized genetic counseling/testing can be discussed.

How does it present at different ages?

Neonatal period

• Significant high-output cardiac failure
• Rapid breathing, feeding difficulty, cyanosis
• Edema, enlarged liver (hepatic congestion)
• Sometimes the need for mechanical ventilation & intensive care

Infancy & early childhood

• Macrocephaly (progressively increasing head circumference)
• Delayed developmental milestones
• Visible, dilated scalp veins
• Possible irritability, lethargy, signs of raised intracranial pressure
• Possible seizures if there is parenchymal brain injury

Older children & rarely adults

• Headaches, seizures, signs of intracranial hypertension
• Intracerebral or intraventricular hemorrhage
• Neurologic deficits depending on the affected region

Neonatal heart failure — what does it mean, and what do we do?

In severe VGAM, a newborn’s heart is forced to pump extremely large volumes of blood through the malformation. This leads to high-output cardiac failure and often pulmonary hypertension.

Priorities:

• Stabilize breathing (oxygenation, possible intubation)
• Medical cardiac support (inotropes, diuretics, etc.)
• Continuous monitoring in a NICU/PICU setting
• Early brain MRI/ultrasound to assess injury & hydrocephalus

The decision regarding when to perform the first endovascular intervention is based on a combination of:

• clinical scoring (e.g., Bicêtre score),
• cardiac and end-organ status,
• brain imaging findings (especially whether severe parenchymal injury is already present).

Hydrocephalus, macrocephaly & development

In infants and young children, VGAM causes intracranial venous hypertension. This disrupts normal cerebrospinal fluid (CSF) absorption and leads to hydrocephalus.

What do we see clinically?

• Rapid head circumference growth beyond expected percentiles
• Tense anterior fontanelle, prominent scalp venous congestion
• Delayed developmental milestones
• Possible lethargy, vomiting, irritability

The key principle is to first reduce venous hypertension by embolization and often avoid early placement of a ventriculoperitoneal (VP) shunt. Experience from major centers suggests worse outcomes when a shunt is placed before the VGAM is controlled, due to adverse shifts in pressure between the CSF and venous systems.

How is the diagnosis made? Ultrasound, MRI, angiography

Depending on age and clinical severity, evaluation may include:

• Prenatal ultrasound & fetal Doppler — may reveal a large midline venous structure with high-flow signals.
• Neonatal/infant cranial ultrasound through the fontanelle — rapid assessment of venous dilation, hydrocephalus, and intraventricular flow.
• Brain MRI/MRA — detailed imaging of the brain, ventricles, malformation anatomy, and any parenchymal injury.
• Digital subtraction angiography (DSA) — the gold standard for precise angiographic characterization and endovascular treatment planning.

At every stage, the goal is not only to “identify the lesion,” but to understand:

• how high the flow is,
• how the brain has been affected,
• how urgent invasive therapy is.

When is treatment needed? Is there an “ideal” time window?

VGAM management is not an “all-or-nothing” single-session procedure. It is a staged, strategy-driven treatment plan guided by age and clinical presentation:

• Newborns with severe heart failure and reassuring brain imaging — often require urgent endovascular intervention to reduce shunt flow.
• Infants/toddlers with macrocephaly and venous hypertension, without profound developmental delay — embolization is pursued before permanent injury becomes established.
• Children/adolescents — treated similarly to deep brain AVMs, using endovascular therapy ± radiosurgery in selected low-flow residual lesions.

Endovascular embolization — what does it involve in practice?

Endovascular therapy is currently the primary treatment modality for VGAM. It is performed in a specialized angiography suite under general anesthesia by an experienced neuroendovascular team.

General steps:

• Insertion of a small catheter via the femoral artery (less commonly via a vein).
• Navigation into the abnormal feeding arteries under continuous fluoroscopic guidance.
• Controlled delivery of liquid embolic material (NBCA, Onyx, etc.) near the shunt point to reduce or eliminate flow.

More than one session is often required to gradually reduce flow without abruptly altering cerebral perfusion or provoking sudden increases in venous pressure.

Recovery & long-term outlook

Outcomes in VGAM have improved dramatically over recent decades due to advances in intensive care and endovascular neurosurgery. Prognosis, however, depends on:

• the brain’s baseline condition (pre-treatment MRI),
• the severity of heart failure and end-organ involvement,
• age and timing of treatment initiation,
• whether multiple procedures or hydrocephalus diversion were needed.

In many children, with appropriately staged embolization, it is possible to achieve:

• stabilization of head circumference & hydrocephalus,
• a favorable neurodevelopmental trajectory,
• good quality of life with early intervention and structured follow-up.

Long-term follow-up is essential and may include:

• pediatric neurology & neurosurgery care,
• interval imaging (MRI/MRA),
• speech/physical/occupational therapy as needed,
• cardiology follow-up, especially during the early years.

When should I seek urgent medical attention?

Urgent evaluation is required for:

• A newborn with shortness of breath, rapid breathing, cyanosis, poor feeding, or marked lethargy.
• An infant with sudden deterioration: excessive sleepiness, inconsolable crying, vomiting, rapid head enlargement, or a bulging fontanelle.
• New-onset seizures.
• Any sign of acute worsening in a known VGAM case, such as behavioral change, loss of skills, or new neurologic deficits.