Vein of Galen Malformation

The vein of Galen is located under the cerebral hemispheres and drains the anterior and central regions of the brain into the sinuses of the posterior cerebral fossa. The vein of Galen aneurysmal malformation is a choroidal type of arteriovenous malformation involving the vein of Galen forerunner and is distinct from an arteriovenous malformation with venous drainage into a dilated, but already formed, vein of Galen.

Aneurysmal malformations of the vein of Galen (VGAM) typically result in high-output congestive heart failure or may present with developmental delay, hydrocephalus, and seizures.[1]

Vein of Galen malformation (VGAM) results from an aneurysmal malformation with an arteriovenous shunting of blood. The congenital malformation develops during weeks 6-11 of fetal development as a persistent embryonic prosencephalic vein of Markowski; thus, VGAM is actually a misnomer. The vein of Markowski actually drains into the vein of Galen.

VGAM usually causes high-output heart failure in the newborn resulting from the decreased resistance and high blood flow in the lesion. Associated findings include cerebral ischemic changes such as strokes or steal phenomena that result in progressive hemiparesis. Hemorrhage from the malformation can occur, although this is not a common finding. Finally, the malformation may result in mass effects, causing progressive neurological impairment. Alternatively, the malformation may cause obstruction of the cerebrospinal fluid (CSF) outflow and result in hydrocephalus.[2]

Vein of Galen malformation has been associated with capillary malformation-arteriovenous malformation (CM-AVM), which is a newly recognized autosomal dominant disorder, caused by mutations in the RASA1 gene in 6 families. The authors report severe intracranial AVMs, including vein of Galen aneurysmal malformation, which was symptomatic at birth or during infancy, extracranial AVM of the face and extremities, and Parkes Weber syndrome, previously considered sporadic and nongenetic.[3]

Frequency

The incidence of the vein of Galen malformation is unknown.

Mortality/Morbidity

Infants often die if the high-output congestive heart failure is the presenting feature.

Macrocephaly usually improves following shunting for hydrocephalus.

Demographics

VGAM is a congenital malformation; therefore, it may present at birth or in early childhood. It occurs in all races, and boys and girls are affected equally.

 

Fetuses with prenatally diagnosed VGAM have unexpectedly poor outcomes in the presence of cardiac or cerebral anomalies, while those with strictly isolated VGAM tend to have more favorable outcomes. Of 21 cases of prenatally diagnosed VGAM, 4 (19.0%) cases were isolated and 17 (81.0%) were associated with other anomalies. There were nine terminations (42.9%) and six neonatal deaths (28.6%).[4]

Direct communication between a cerebral artery and a cerebral vein results from a congenital vascular malformation. The vein of Galen abnormality is the most frequent arteriovenous malformation in neonates.

It commonly presents in the neonatal period, although it may present later, in early childhood. Typically, in the neonatal period, VGAM presents with congestive heart failure, a cranial bruit, and marked carotid pulses.

Physical findings include heart failure and hydrocephalus.

Congestive heart failure

• Neonates may present with tachypnea, respiratory distress, and cyanosis.

• They often require ventilatory support and institution of aggressive management of heart failure.

Hydrocephalus

• Hydrocephalus may be the presenting feature in older infants.

• A cause should be sought in neonates with macrocephaly.

• Infants may have hydrocephalus, in which case prominent scalp veins or "sunset" eye findings are noted.

• Developmental delay: Signs of hydrocephalus and congestive heart failure should be looked for in infants with developmental delay.

In early childhood, symptoms include headache, convulsive seizures, hydrocephalus, and cardiac failure.

Although any vessel may be affected, the vein of Galen is the most frequently affected. Congenital malformation develops during weeks 6-11 of fetal development as a persistent embryonic prosencephalic vein of Markowski.

Cranial ultrasound

This will help to localize or identify the lesion. Doppler studies can help further to understand the hemodynamics of the lesion.

Cranial MRI and/or CT scan with and without contrast administration

These studies will help confirm the diagnosis and define the degree of involvement. Imaging studies in infants will also help determine whether the patient has accompanying hydrocephalus (see images below).

MR angiography

This can help to delineate the vascular supply (see image below).

Cranial angiography

In patients being considered for surgery or for occlusive therapy, cranial angiography is required to define the extent of aneurysmal dilatation and details for arterial feeders (see image below).

Cardiac ultrasound

This study may be indicated to assess left ventricular function.

Recently, 9 children aged from newborn to 18 years were examined and it was demonstrated that the arterialized blood flow in the vein of Galen or its tributaries when these showed abnormal signal hyperintensity from arteriovenous shunting using susceptibility-weighted imaging was found to accurately differentiate between high- and low-flow vessels identified by time-of-flight studies and helped in planning for intervention.[5]

An ECG may be used to look for evidence of congestive heart failure.

Lesion shows thin capillaries or veins connecting directly to the arteries.

Cardiac management of high-output heart failure is essential. A pediatric cardiologist should be consulted to manage high-output failure, if present. Often patients need to be intubated.

Seizures should be managed with antiepileptic medications. Usually, neonate patients are given phenobarbital and phenytoin. Please see the articles Complex Partial Seizures and Neonatal Seizures.

Head circumference measurements should be obtained regularly and monitored carefully to detect hydrocephalus.

Assessment of the child's development is an important part of medical care.

Reversible diencephalic syndrome can be seen in some patients, mainly in adults.[6, 7]

Endovascular embolization

Endovascular embolization is the first option for treatment. A systematic review of 34 studies, in which neonates accounted for 44% of the sample, infants accounted for 41%, and children and adults accounted for 12%, found that endovascular embolization for VGAM can result in an acceptable mortality rate, complications, and good clinical outcomes. The meta-analysis revealed that complete occlusion was performed in 57% of cases, with partial occlusion in 43%. The pooled proportion of patients showing a good outcome was 68%, while 31% showed a poor outcome.[8]

Embolic glue to occlude the arteriovenous fistula on the arterial side is N -butyl-cyanoacrylate. Detachable microcoils can also be used, although their application may take longer and they may have a higher risk of vessel rupture.[9, 6]

Other procedures

Neurosurgical procedures to relieve hydrocephalus are important.[10] A ventriculoperitoneal shunt may be required in some infants.[11, 12, 13, 14]

Vaso-occlusive therapy, including selective catheterization and therapeutic embolization of feeding arteries in the vein of Galen malformation, can be performed (see image below).

Only a small number of patients with arteriovenous aneurysm have been reported.

Death usually results from cardiac failure or cerebral decompression.

A few patients have been cured by surgical ligation of the arterial feeders from the posterior and middle cerebral arteries and plication of the aneurysm.

Some malformations thrombose spontaneously.

In some patients, malformation can be associated with subarachnoid bleeding.[15]

A study of 21 neonates demonstrated that poor outcomes included neurological manifestations at birth, focal cerebral parenchymal changes, calcification of cerebral tissue, tonsillar herniation, and two or more arterial feeders.[16] In infants with these features, consideration could be given to withholding aggressive intervention.

Optimal intervention is at age 4-5 months if clinical condition allows for deferral until that age.

The issue of progressive brain parenchymal loss was addressed in a recent study.[17]  Review of an assembled database of vein of Galen aneurysmal malformations between 2000 and 2014 found 251 patients. Of these patients, 83 were diagnosed prenatally. This study demonstrated that middle cerebral artery pseudofeeders were associated with impaired cerebral blood flow and were particularly at risk for further brain "melting" at birth. This factor was considered a negative prognostic indicator, particularly if associated with hydrocephalus. In the latter instance patients had congestive heart failure more frequently.[17]

Neurosurgical evaluation should be obtained urgently to assess the extent and location of the VGAM and to treat hydrocephalus.

A cardiologist should evaluate the patient for congestive heart failure.

A neonatologist should help coordinate care and decide whether intubation and ventilatory support are required.

The infant should be assessed in a facility where interventional neuroradiologist expertise is available; should embolization be an option, this specialist can help with specific care.

No specific medical therapy is available for VGAM.

Patient should be monitored for the development of hydrocephalus.

Infants who undergo surgical ligation or selective embolization should be reimaged to assess results of the therapeutic intervention.

Head circumference measurements should be obtained in patients who undergo ventriculoperitoneal shunt to treat hydrocephalus.

Patients diagnosed with VGAM should be transferred to a tertiary neonatal intensive care unit where a pediatric neurologist, an interventional neuroradiologist, and a neurosurgeon are available for management of the infant.

More than half of patients with VGAM have a malformation that cannot be corrected. Patients frequently die in the neonatal period or in early infancy.