Vein of Galen aneurysmal malformation (ORPHA:1053)
A rare intracranial congenital high-flow vascular malformation characterized by arteriovenous shunts draining into the median prosencephalic vein of Markowski, embryonic precursor of the vein of Galen, typically presenting in neonates or infants.
Epidemiology
Although its prevalence is unknown, vein of Galen aneurysmal malformation (VGAM) is thought to account for 30% of all pediatric intracranial arteriovenous malformations.
Clinical description
Clinical presentation differs according to age group. Neonates typically present with congestive heart or multi-organ failure and, in more severe cases, melting brain syndrome. Infants tend to present with hydrovenous disorders (hydrocephalus, macrocrania), collateral maxilla-facial venous circulation, neurodevelopmental delays; children (and exceptionally young adults) commonly present with neurological symptoms (seizures, deficit, headaches or intracranial hemorrhage). Pulsatile bruit can be heard at auscultation of the skull. VGAM can be classified into mural or choroidal types based on their angioarchitecture. The mural type occurs when the fistula is in the wall of the dilated vein itself. The choroidal type consists of multiple shunts into choroidal tributaries draining into the prosencephalic vein of Markowski. Mixed forms combining direct shunts and arterial networks may also occur.
Etiology
VGAM is created between the 8th and 11th weeks of gestation. Recent data suggest that genetic dysregulation of RAS signaling pathway is an important driver of VGAM pathogenesis.
Diagnostic methods
Imaging is essential for diagnosis and include trans-fontanel ultrasonography, magnetic resonance imaging/angiography (MRI/MRA) or computed tomography scan, and digital subtraction angiography (usually coupled with embolization).
Differential diagnosis
It is important to differentiate VGAM from dilatation of the vein of Galen draining cerebral arteriovenous malformation (AVMs); venous dilatation without arteriovenous shunt can also be observed in developmental venous anomalies or in rare neonatal cases with congenital cardiopathy. In the assessment of neonatal heart failure, VGAM has to be excluded from congenital cardiopathy.
Antenatal diagnosis
Diagnosis is most often made during the third trimester of pregnancy with ultrasound and fetal MRI.
Genetic counseling
VGAM can occur in the context of capillary malformations AVMs and more rarely in hereditary haemorrhagic telangiectasia. Genetic screening can therefore be proposed to patients depending on the clinical and familial context.
Management and treatment
If the diagnosis is established antenatally, delivery at a tertiary care center is recommended. The timing of endovascular management depends on the clinical presentation. Ideally, the first intervention should be performed at 5-6 months of age; however, early embolization may be required if there is congestive heart failure refractory to medical management or if cerebral development is impaired. In such cases, partial, rather than complete, obliteration of the shunt is the goal in order to improve hemodynamic situation and allow proper maturation of the brain. A residual shunt will be occluded at later times in sequential procedures. Hydrocephalus may require ventriculocisternostomy (preferred to ventricular shunt which is associated with neurological complications) in association with endovascular treatment of the VGAM.
Prognosis
The neurological prognosis can be satisfactory with early proper treatment; however, the prognosis is poorer for patients with severe neonatal presentation or with cerebral defects or cardiac dysfunction detected prenatally. Patients presenting later in life have better post-operative outcomes.

                            Last update: 
                            July 2024


                            - Expert reviewer(s): 
                            Dr Julien COULIE  - Dr Georges RODESCH | VASCERN* - Dr Stanislas SMAJDA | VASCERN*


                                * European Reference Network