Introduction
The first case report of vein of Galen aneurysmal malformation (VGAM) was published
in 1946 by Jaeger and Forbes, where the diagnosis was made by necropsy of a four and
a half years old boy who had a history of a large head at birth, recurrent nose bleeds,
dilated neck and forehead veins, and an enlarged heart.[1] VGAM is a rare congenital malformation of the cerebral blood vessels with a male
predominance and accounts for less than 1% of fetal cerebral vascular malformations.
However, they represent 30% of intracranial vascular malformations among the pediatric
age group.[2]
[3] Though ultrasound (US) imaging is crucial in the diagnosis of VGAM, prenatal diagnosis
is possible only in less than 30%, especially before the third trimester.[4]
[5] Development of cerebral vasculature occurs between 6 and 11 weeks of embryonic life
through prechoroidal and choroidal phases. In the choroidal phase, the arterial supply
to the developing brain is through choroidal arteries (CAs), and venous drainage is
through the median prosencephalic vein (MPV) of Markowski.[6] The MPV has two segments: the anterior segment regresses while the posterior segment
persists and is called the vein of Galen. Normally, there are communications between
CAs and the MPV, which should regress after 11 weeks. The formation of certain arteriovenous
(AV) shunts due to unexplained reasons leads to the persistence of abnormal communications
between the CAs and MPV, forming a dilated venous sac. Thus, as proposed by Raybaud
et al, the name “vein of Galen” is a misnomer, as the dilated venous sac is the MPV,
not the vein of Galen.[7]
[8] According to Lasjaunias, VGAM is classified into two types: viz., mural, where there
are direct arterial connections into the wall of the venous aneurysm, and choroidal,
where there is an interposition of an arterial network between the multiple feeders
and the venous aneurysm[8] ([Fig. 1A, B]). Due to these large shunts, vascular steal phenomenon occurs and according to
the degree of shunting, there is an increase in blood returning to the heart and a
decrease in perfusion of the normal brain tissue. This leads to cardiac failure and
cerebral damage, respectively. The cerebral effects are hydrocephalus, cerebral infarcts,
and leukomalacia. Most babies are symptomatic in the neonatal period itself and, if
left untreated, have very high morbidity and mortality. However, prenatal diagnosis
allows for the delivery of the baby in a tertiary care center, and early intervention
would significantly improve clinical and neurodevelopmental outcomes.[9]
[10]
Fig. 1 Types of vein of Galen aneurysmal malformation (VGAM) based on Lasjaunias classification.
(A) Mural - Characterized by direct, high-flow shunts on the wall of the venous sac.
(B) Choroidal - Characterized by multiple fistulas with interposing arterial networks
between the feeding vessels and the draining vein. Courtesy: Alfena Raj (Scientific
illustrator, University of Massachussets, USA)
In our study, we discuss three prenatally identified VGAMs, their antenatal/postnatal
course, management, and varied outcomes, along with a review of updated literature.
Case 1
Thirty-two-year-old second gravida was referred at 37 weeks of gestation for a suspected
VGAM in the routine third-trimester US. She was low risk for common aneuploidies in
first-trimester screening, and her targeted anomaly scan at 20 weeks was normal.
USG revealed a supratentorial midline, pulsatile anechoic lesion measuring 21 × 21 mm
superior to the thalamus. Multiple feeding vessels were seen entering a dilated sac,
with the draining vessel emptying into a straight, dilated vessel identified as the
straight sinus. Spectral Doppler confirmed turbulent flow with low vascular resistance.
Additional findings included bilateral moderate ventriculomegaly (14 mm) and a prominent
cisterna magna, without evidence of hemorrhage, necrosis, porencephaly, or cortical
malformations ([Figs. 2]
[3]
[4]
[5]). The features were suggestive of VGAM, and the fetal echocardiogram revealed mild
cardiomegaly with a cardiothoracic ratio (CTR) of 0.52. Head biometry (biparietal
diameter and head circumference) was more than the 99th centile, but the rest of the
fetal parameters showed normal growth. There was polyhydramnios with an Amniotic Fluid
Index (AFI) of 25 and Dopplers were normal. No other fetal anomalies were noted. Following
the diagnosis, the couple received detailed counseling. A prenatal magnetic resonance
imaging (MRI) was recommended to confirm the findings and assess for any additional
intracranial abnormalities. The limitations of genetic screening at this advanced
gestation were discussed. The need for delivery at a tertiary care center was emphasized,
along with the importance of comprehensive postnatal evaluation and close follow-up.
Multidisciplinary consultations with neonatology, pediatric cardiology, pediatric
neurosurgery, and interventional radiology were advised.
Fig. 2 Vein of Galen aneurysmal malformation (VGAM) in two-dimensional (2D) and color Doppler
imaging.
Fig. 3 Increased head biometry and bilateral moderate ventriculomegaly.
Fig. 4 Feeder vessels and draining straight sinus of vein of Galen aneurysmal malformation
(VGAM).
Fig. 5 Spectral Doppler showing turbulent flow with low vascular resistance.
She went into spontaneous labor at 38 weeks and delivered a male baby weighing 3.82 kg,
with an Apgar score of 8. The baby was admitted to the neonatal intensive care unit
and was stabilized on continuous positive airway pressure and oxygen and was treated
for cardiac failure. Treatment with phenobarbitone and acetazolamide was instituted.
Head circumference (HC) was more than the 99th centile, and a cranial bruit was detected.
VGAM was confirmed by transfontanellar neurosonogram. Cardiac anatomy and function
were normal on echocardiography. Magnetic resonance angiography (MRA) at 1 month showed
a VGAM with a maximum diameter of 2.3 cm, dilated straight sinus and confluence of
sinuses, and obstructive moderate hydrocephalus. The feeding vessels were identified
as from bilateral CAs and venous drainage into the straight sinus and to the posterior
superior sagittal sinus ([Figs. 6]
[7]
[8]). Serial clinical surveillance was done with particular attention to head circumference
and cardiovascular performance.
Fig. 6 T1-weighted sagittal image showing flow voids in the region of the vein of Galen
aneurysmal malformation (VGAM) and straight sinus (white arrow).
Fig. 7 Magnetic resonance angiography (MRA) showing dilated vein of Galen aneurysmal malformation
(VGAM) draining into the straight sinus (white arrow).
Fig. 8 T2-weighted coronal image showing hydrocephalus and thinned out parenchyma.
At 3 months, the baby presented with an increasing head size (> 99th centile), a bulging
anterior fontanelle, and a sunset sign. Repeat MRA showed ventricular obstruction
with moderate hydrocephalus. Endovascular embolization was planned. Before the procedure,
digital subtraction angiography (DSA) was done to evaluate the VGAM angioarchitecture
and provide access to endovascular management of the lesion. A left vertebral artery
angiogram was done, which showed the VGAM with a large collector sac and feeder vessel
from bilateral posterior CAs and venous drainage into the straight sinus and posterior
superior sagittal sinus. Endovascular embolization of the collector sac was performed
with N-butyl 2-cyanoacrylate gel (80% NBCA). The post-embolization angiogram showed
a significant reduction in flow through the malformation with an extremely slow filling
of the collector vein ([Figs. 9] and [10]).
Fig. 9 Digital subtraction angiography showing early and late globular filling of vein of
Galen aneurysmal malformation (VGAM) (black arrows).
Fig. 10 Posttreatment digital subtraction angiography showing absent filling.
A ventriculoperitoneal shunt was placed 5 days after embolization in view of persistent
hydrocephalus. The child was started on antiseizure medication and has been under
regular follow-up with a pediatric neurologist, interventional radiologist, rehabilitation
therapist, and neurodevelopmental pediatrician, with neurodevelopmental assessments
conducted every 6 months.
The child is currently 3 years old, with a stable head circumference, no seizure recurrence,
and age-appropriate developmental milestones, demonstrating substantial overall improvement.
Case 2
A 31-year-old primigravida presented with a dichorionic diamniotic (DCDA) twin pregnancy
conceived through in vitro fertilization. First-trimester screening revealed a nuchal
translucency measurement at the 96th centile in fetus B, with a low-risk result for
aneuploidies. The targeted anomaly scan showed no structural abnormalities. At 35
weeks, US demonstrated a 15 × 12 mm midline cystic lesion with internal vascularity
near the thalamus in fetus B, suggestive of VGAM. No associated cardiac or cerebral
abnormalities were detected. Weekly follow-up scans documented stable cardiovascular
status without evidence of hyperdynamic circulation ([Figs. 11] and [12]). This included a search for cardiomegaly, AV valve regurgitation, and changes in
the ductus venosus flow velocity waveform.
Fig. 11 Vein of Galen aneurysmal malformation (VGAM) in gray scale (A) and color Doppler imaging (B).
Fig. 12 Spectral Doppler showing turbulent flow with low vascular resistance.
An elective lower segment cesarean section was performed at 37 weeks' gestation, delivering
twin male infants weighing 2.8 and 2.7 kg, both with good Apgar scores. Initial transfontanelle
neurosonography in fetus B revealed a tubular, dilated anechoic area measuring 15 × 12 × 11 mm
in the posterior midline with intense color Doppler flow, consistent with VGAM. As
the baby was clinically asymptomatic and showed no signs of cardiac failure, the baby
was closely monitored for increasing head circumference and signs of cardiac failure.
A repeat neurosonogram at 1 month demonstrated a stable oval cystic midline lesion
measuring 14 × 11 × 10 mm caudal to the splenium, with internal vascularity and turbulent
flow ([Figs. 13] and [14]).
Fig. 13 Postnatal neurosonography (NSG): Vein of Galen aneurysmal malformation (VGAM) gray
scale and color Doppler showing internal vascularity.
Fig. 14 Spectral Doppler showing turbulent flow with low vascular resistance.
The baby remained clinically asymptomatic and was followed up every 3 months. Postnatal
MRI at 4 months of age demonstrated a microbleed in the basal ganglia and a chronically
thrombosed VGAM. Follow-up MRI at 1 year of age showed complete resolution, with no
evidence of VGAM. MRI images are shown in [Fig. 15A to C]. At present, the child is 2 years old, with normal neurodevelopment and ongoing
follow-up. This case illustrates the rare occurrence of spontaneous resolution of
VGAM.
Fig. 15 (A) Susceptibility-weighted imaging (SWI) showing basal ganglia microbleed (black arrow)
suggestive of chronic and thrombosed vein of Galen aneurysmal malformation (VGAM).
(B) T2-weighted axial imaging showing thrombosed VGAM (black arrow). (C) T2-weighted sagittal imaging showing a linear hypointense area with no flow void
(white arrow) suggestive of thrombosed VGAM.
Case 3
A 27-year-old primigravida at 36 weeks + 5 days of gestation was referred to our center
following the antenatal detection of VGAM. Antenatal ultrasonography revealed a supratentorial
midline cystic lesion measuring 30 × 15 mm, located superior to the thalamus. Color
Doppler demonstrated multiple feeder vessels draining into the lesion, which in turn
drained into a straight vessel identified as the straight sinus. Spectral Doppler
showed high-velocity, low-resistance flow, consistent with VGAM. Additional findings
included mild cardiomegaly (CC/CT ratio: 0.59) and increased umbilical artery resistance.
An elective lower-segment cesarean section was performed at 37 weeks, delivering a
male neonate weighing 3 kg. The infant cried at birth but exhibited poor respiratory
effort and a heart rate of 100 beats per minute. Echocardiography revealed moderate
pulmonary arterial hypertension, a small atrial septal defect, a small patent ductus
arteriosus, and normal biventricular function.
Postnatal neurosonography demonstrated a midline posterior fossa cystic structure
measuring 19 × 15 × 16 mm, with internal venous and arterial waveforms on color Doppler,
likely representing a dilated MPV. Prominent CAs were seen connecting with the venous
sac, which drained into a dilated straight sinus—features suggestive of VGAM. On the
third postnatal day, the infant underwent endovascular coil embolization, reducing
shunted flow by approximately 40 to 50%. However, the neonate succumbed on the third
day following the procedure. Prenatal and postnatal ultrasonography images are shown
in [Figs. 16] to [18].
Fig. 16 Vein of Galen aneurysmal malformation (VGAM) in gray scale (A) and three-dimensional (3D) power Doppler imaging (B).
Fig. 17 Postnatal neurosonography (NSG): Vein of Galen aneurysmal malformation (VGAM) in
gray scale and color Doppler showing internal vascularity.
Fig. 18 Spectral Doppler shows turbulent flow with low vascular resistance.
Discussion
Etiopathogenesis
The underlying cause of VGAM is thought to be ischemia-induced hypoxic injury in the
CAs. This injury triggers the release of angiogenic factors, which in turn leads to
venodilatation. VGAM generally occurs sporadically and is not linked to any specific
chromosomal aneuploidy or syndrome, and familial occurrence is extremely rare. However,
recent exome sequencing studies have shown that approximately 10% of VGAM cases result
from de novo mutations in the EPH receptor B4 (EPHB4) gene and genes involved in chromatin
modification. Other genetic variants implicated in VGAM include mutations in the RAS
p21 protein activator 1 (RASA1) gene and the endoglin (ENG) gene.[11]
[12]
[13]
[14]
Classification
Several classification systems have been proposed to define VGAM based on its complexity,
type of feeder arteries, location of the fistula, or degree of venous ectasias. The
two systems that gained popularity and are being used in current practice are the
Lasjaunias and the Yasargil systems, whose morphological features are explained in
[Table 1].[15]
[16]
Table 1
Classification of VGAM (modified from refs. 15 and 16)
|
Classification
|
Morphology
|
|
Lasjaunias
|
Mural - where there are direct, high-flow shunts located within the wall of the venous
aneurysm
Choroidal - where there is an interposition of an arterial network between the feeders
and the venous aneurysm
|
|
Yasargil
|
Type 1 - Arteriovenous (AV) fistula between the posterior cerebral arteries or the
pericallosal arteries and the vein of Galen
Type II - AV fistula between the thalamoperforating arteries and the vein of Galen
Type III - A mix between types I and II
Type IV - AV fistula that drain into the vein of Galen and directly dilate it
|
Abbreviation: VGAM, vein of Galen aneurysmal malformation.
In Lasjaunias classification, VGAMs are classified based on the origin and insertion
of the feeder vessels and the clinical presentation. The choroidal type frequently
presents with high-output cardiac failure, macrocephaly with loud cranial bruits,
and dilated orbital veins due to multiple high-flow fistulas and less restricted outflow.
In the mural type of VGAM, there are fewer AV fistulas (AVFs) and more restricted
outflow, resulting in greater dilatation of the median vein of the prosencephalon
but a lesser chance of high-output cardiac failure. Choroidal type manifests prenatally
while mural-type VGAM usually manifests late in infancy as macrocephaly, hydrocephalus,
seizures, delayed developmental milestones, and failure to thrive.[16]
Yasargil classified VGAM based on the exact origin of the feeding arteries, and it
also differentiates true AVFs, which is type 1 to 3, from AV malformation (AVM), which
is type 4 and its subtypes. Based on his classification, VGAMs are a group of AVMs
with or without AVFs, and thus, the term vein of Galen aneurysm is slowly being replaced
by VGAM.[16]
There is a separate entity called the vein of Galen aneurysmal dilations (VGADs),
which represents the enlargement of the true vein of Galen. VGADs occur due to malformations
of the pial or dural shunts draining into the true vein of Galen or its tributary,
thus causing dilation of the vein of Galen. Another entity is the vein of Galen varix,
where there is dilation of the vein of Galen in the absence of an AV shunt. VGADs
and vein of Galen varix are separate entities from VGAMs and are not to be confused.[3]
Prenatal Diagnosis
Prenatal diagnosis of VGAM is possible in the late second and early third trimester
with two-dimensional ultrasonography supplemented by color Doppler and pulsed Doppler,
with a detection rate of 73%.[17] The 3D power Doppler imaging helps in better delineation of anatomic details by
removing angle dependence and aliasing irregularities. Though the defect develops
in the early first trimester, the aneurysm becomes sonologically apparent, usually
in the third trimester.[18] VGAM is a supratentorial midline translucent elongated cyst with active AV flow
within the cyst, demonstrated by the color Doppler (Comet tail /Keyhole appearance).
In 90% of cases, it is associated with high-output cardiac failure with secondary
hydrops.
In a prenatally diagnosed VGAM, a detailed neurosonography should be done including
measurement of the orthogonal diameters of VGAM (craniocaudal, anteroposterior, and
mediolateral), volume of VGAM (using the ellipsoid formula), noting the presence/absence
of other brain abnormalities like straight sinus dilatation, ventriculomegaly, secondary
brain lesions like ischemia, leukomalacia, porencephaly, schizencephaly, or cortical
malformations. A detailed fetal echocardiography is also warranted to look for evidence
of cardiac overload: cardiomegaly, CTR, presence of tricuspid regurgitation, or reversal
of blood flow across the aortic isthmus. The presence of tricuspid regurgitation,
supraventricular extrasystoles, and tachycardia are associated with adverse outcomes.[19] Differential diagnosis for midline cystic lesions behind the third ventricle includes
arachnoid cyst, cavum vergae, porencephalic cyst, choroid papillomas, intracerebral
hematomas, and tumors. However, color Doppler would help differentiate VGAM from these
lesions. Prenatal MRI is considered the gold standard in diagnosing VGAM and is superior
to the conventional Doppler assessment. It helps assess the number and type of arterial
pseudo feeders, the exact fistula position, evaluate venous drainage, and identify
venous thrombosis. Additionally, fetal MRI can identify significant complications
like cardiac failure, fetal hydrops, and brain injury secondary to the hemodynamic
alterations of VGAM, thus helping in the prognostication and planning of intervention.[20]
Postnatal diagnosis is typically made using transfontanellar ultrasonography, supplemented
by MRA. DSA offers a more detailed assessment of the VGAM angioarchitecture and plays
a key role in planning the endovascular management of the malformation.[21]
Prenatal Prognostic Predictors
Prenatal US and MRI parameters have been extensively evaluated to predict adverse
outcomes in infants with VGAM. Key US predictors include VGAM volume calculated by
the ellipsoid method, dilation of the straight sinus, ventriculomegaly > 10 mm, and
cerebral lesions such as porencephalic cysts, leukomalacia, or other signs of ischemic
brain injury. Cardiac variables assessed include CTR, presence of tricuspid regurgitation,
and reversal of blood flow through the aortic isthmus. In a two-center series of 49
cases, Paladini et al concluded that three prenatal variables were most strongly associated
with poor outcomes—major brain lesions leading to neonatal death or late termination,
tricuspid regurgitation, and VGAM volume ≥ 20,000 mm3.[22]
Arko et al[23] stratified neonates with VGAM into two prognostic groups:
-
Neonates at high risk (NAR): at significant risk for neonatal death or requiring emergency
intervention.
-
Infantile treatment (IT) group: lower risk, suitable for planned intervention after
1 month of age.
Among several vascular MR imaging parameters assessed—including maximal diameters
of the prosencephalic varix, basilar artery, internal carotid arteries (bilaterally),
sigmoid sinuses (bilaterally), and the maximal mediolateral diameter of the straight
or falcine sinus—the most robust predictor of adverse outcome was the mediolateral
width and cross-sectional area of the straight or falcine sinus at its narrowest craniocaudal
point. A measurement > 8 mm at this constricted segment reliably distinguished high-
from low-risk neonates. Deloison et al, in a retrospective study on the “hidden mortality”
of prenatally diagnosed VGAM, reported that the presence of associated cardiac or
cerebral anomalies significantly increased the risk of adverse outcomes.[24]
Postnatal Management
A systematic review and meta-analysis (2022) evaluating the outcome of neonates diagnosed
with VGAM concluded that, though the incidence of Intra Uterine Demise (IUD) is relatively
low (1.5%), approximately 24% succumb during the neonatal period, 29.7% were free
from neurological impairment after birth, and 61% had abnormal brain findings on postnatal
imaging.[25] This should be considered while counseling the parents regarding the short- and
long-term prognosis. High mortality rates were encountered prior to the endovascular
treatment era, and morbidity and mortality have reduced significantly with the introduction
of surgical and endovascular treatment methods, even with their innate risks.[26] The initial goal is to stabilize the infant's cardiac status, followed by definitive
treatment. The commonly followed mode of evaluation of the newborn with VGAM is based
on the Bicêtre score developed by Lasjaunias, Ĥopital de Bic ̂etre in France, to
decide on the prospective treatment options.[27]
[28] This 21-point scale assigns points based on the severity of symptoms and signs related
to five systems: cardiac, pulmonary, neurological, hepatic, and renal.
Treatment
Medical management in the neonates is mainly directed toward stabilization of the
cardiac status till a definitive surgery is performed. In neonates with acyanotic
cardiac failure, medications used are diuretics and/or inotrope therapy, and if pulmonary
hypertension is noted, additional treatment with β-agonists, phosphodiesterase inhibitors,
digoxin, and prostaglandin infusions is advocated.[29] Historically used treatment methods like open surgery and bilateral internal carotid
artery ligation by transtorcular approach have met with adverse outcomes and thus
are considered unsafe treatment options. The advent of endovascular embolization essentially
changed the outcomes of children diagnosed with VGAM and is the most preferred option
today. This treatment method, along with advanced neonatal critical care, has reduced
the mortality from 100 to 50%.[30] Though this procedure had been developed in the 1980s, literature is limited to
case reports and case series due to its rarity. The preferred treatment time is between
4 and 6 months when the child is considered stable for intervention, thereby ensuring
optimal outcomes.
Endovascular embolization aims to occlude the AVF and can be done by two approaches:
the transarterial and the transvenous. The transarterial approach is done through
the femoral artery, and the transvenous is done through the femoral vein or jugular
venous approach. NBCA glue is the embolic material of choice.[28]
[31] Detachable microcoils are also an acceptable alternative, though they carry an increased
risk of vessel rupture and longer procedure duration. Generally, transarterial embolization
is preferred, with the best outcomes seen when there are fewer arterial feeders. However,
in cases of multipedicular vein of Galen aneurysms, a transvenous approach is often
more effective. When numerous small arterial pedicles are present, a transvenous technique
or a combined transvenous–transarterial approach (kissing microcatheter technique)
is considered more appropriate.[31]
[32] If hydrocephalus is present, it is usually addressed after embolization with ventriculoperitoneal
shunting. Surgical intervention is reserved for cases where endovascular treatment
fails or in the event of intracranial hemorrhage.
Complications and Outcomes
Overall, post-embolization mortality and complication rates for VGAM are approximately
12% and 35%, respectively.[33] Reported complications include cerebral hemorrhage (37%), cerebral ischemia (6%),
hydrocephalus, and nontarget embolization. Over time, clinical outcomes have improved
significantly.[34] In 2006, Lasjaunias reported treating 216 children with endovascular glue embolization.
Despite or because of the procedure, 23 patients (10.6%) died. Of the 193 survivors,
20 (10.4%) had severe developmental delay, 30 (15.6%) had moderate delay, and 143
(74%) had normal neurological development at follow-up. He concluded that most treated
children survive with normal neurodevelopment, emphasizing the importance of careful
patient selection and timing.[28] Savage et al, in a systematic review of 35 studies including 307 participants, found
that good clinical outcomes were achieved in 68% of cases. They noted that incomplete
embolization or early neonatal embolization was associated with higher mortality and
poorer outcomes, with an overall all-cause mortality of 16%.[35] Progressive fetal cardiac dysfunction is considered a grave prognostic sign, often
indicating that the high-flow lesion may not respond to any treatment.
Spontaneous Resolution of VGAM
There have been reports of thrombosis of VGAM in literature resulting in spontaneous
resolution and thus deferring postnatal treatment.[36]
[37]
[38] This has been identified as more common in mural type and is attributed to the ongoing
myointimal proliferation of the VGAM due to turbulent blood flow and increased venous
pressure. Other possible mechanisms postulated to lead to spontaneous thrombosis are
compression from adjacent hematoma/intra-aneurysmal clot, posthemorrhagic edema, arteriosclerosis
of the vessel walls, vascular spasm, and gliosis resulting from microbleeding.[39] Our study also witnessed the spontaneous complete resolution of VGAM in one of the
DCDA twins without any postnatal treatment. Research is warranted to understand the
complex mechanisms leading to spontaneous thrombosis so that this subgroup is identified
to prevent unnecessary interventions with their associated risks.
Role of Prenatal Endovascular Treatment
Though postnatal VGAM management has advanced by strides due to the efficient perinatal
intensive care and endovascular treatment methods, there exists a considerable risk
for mortality and neurological morbidity associated with postnatal treatment due to
the irreversible cardiac and cerebral changes and hence the need for evaluating the
role of prenatal endovascular treatment. Orbach et al proposed that performing fetal
intervention before the onset of acute postnatal cardiovascular and cerebrovascular
stress could reduce both mortality and morbidity. They introduced a novel ultrasound
guided transuterine fetal cerebral embolization of VGAM using microcoils, resulting
in a normal postnatal outcome without cardiac support and postnatal embolization.[40] Subsequently, Naggara et al successfully managed a case of VGAM through prenatal
embolization, using a transuterine transfontanellar approach to insert microcoils
into the large AVM. However, this baby needed a postnatal endovascular treatment procedure
to occlude the feeder vessels. Postnatally, at 11 months of age, the baby is said
to have achieved typical milestones.[41] The common feature in both these cases that prompted the authors to perform the
prenatal intervention procedure was the increased width of the fetal falcine sinus > 8 mm,
which predicted a very high risk for neonatal decompensation. There have been few
anecdotal reports which have been unsuccessful in prenatal endovascular embolization.[42] As there is a lack of standardized protocol regarding the optimal patient selection
criteria, the choice of method of endovascular treatment, and their safety profiles,
Samaha et al have proposed a global registry where physicians can share their knowledge,
techniques, and patient specifics, which will open the doors for an optimal, patient-friendly
treatment for VGAM.[43]
