11 Vein of Galen Malformations

11.1 Goals

11.2 Case Example

11.2.1History of Present Illness

Imaging studies: Cranial ultrasound. See ▶ Fig. 11.1.

11.2.2 Treatment Plan

With the patient’s symptomatic VGAM, he was taken to have a transarterial diagnostic cerebral angiogram for VGAM classification. Subsequently, a staged approach for a transarterial Onyx embolization of the various anterior and posterior circulation feeders was planned. After successful embolization of the various arterial feeders, the venous enlargement was treated with coils and Onyx (▶ Fig. 11.2).

11.2.3 Follow-up

Fig. 11.1 Magnetic resonance angiography (MRA) of the brain (a,b) and angiogram (c) of the vein of Galen aneurysmal malformation (VGAM). VGAM is receiving supply from the pericallosal artery and bilateral posterior cerebral artery (PCA).

Fig. 11.2 Angiography (a) and magnetic resonance imaging (MRI) (b) after the endovascular transarterial and transvenous treatment of the vein of Galen aneurysmal malformation (VGAM) with Onyx and coils. The patient underwent six stepwise treatments ranging from age 10 to 15 months, (c) Unsubtracted angiogram demonstrating the coil mass and Onyx cast following treatment.

11.3 Case Summary

a) VGAMs are congenital vascular malformations that form during the generation of primitive vasculature of the brain parenchyma. Though commonly called a vein of Galen malformation, it is actually a failed regression of the medial prosencephalic vein of Markowski (mProV of Mar-kowski).¹ Between weeks 10 and 11 of development, the primary arterial flow shifts from the choroidal arteries to the cortical arteries; this results in the formation of the paired internal cerebral veins that connect to the posterior mProV of Markowski. With decreased flow, the anterior portion involutes. A residual arterial shunt, usually from the anterior choroidal, posterior choroidal, and anterior cerebral arteries, causes the failed involution of the anterior mProV of Markowski and the subsequent dilation into a VGAM.^2,3

2. What are the different symptomatic presentations of VGAM?

a) The symptoms for a VGAM patient are largely determined by age and the severity of the VGAM. The presentations are divided into neonates, infants, and older children/ adults.

b) Neonates

1. Neonates already have a disproportionate distribution of blood flow to the brain, but the additional high-flow, low-resistance VGAM sequesters as much as 80% of the cardiac output.⁴ Quiet and initially controlled by the presence of the placenta, another low-resistance system, the VGAM presents postpartum and is worsened by a patent ductus arteriosus and/or patent foramen ovale.⁵ The increased venous return causes pulmonary hypertension, and arterial steal with increased cardiac demand causes myocardial infarctions.^6,7

c)Infants

1. The presenting signs in an infant are hydrocephalus and macrocephaly. The robust deep cerebral venous drainage can keep primitive occipital and marginal sinuses patent and cause hypoplastic galenic veins.⁸ This causes venous hypertension and subsequently intracranial hypertension. Though the dilated vein of Galen may cause communicating hydrocephalus, the hydrocephalus associated with VGAM is typically a non-communicating hydrocephalus, secondary by the decreased hydrovenous equilibrium. The intracranial hypertension and venous hypertension can cause impaired cortical development, calcifications, and epilepsy.^1,9

d) Older children/Adults

1. Quiescent VGAMs may present out of infancy with seizures, headaches, or intracranial hemorrhages.⁸ These are usually smaller and less severe, but could be associated with flow-related microaneurysms.⁵

3. What are the different classifications of VGAM? (▶ Fig. 11.3)

a) Lasjaunias grouped VGAMs in three forms. Mural and choroidal are the true VGAMs: Mural type has distinct direct arterial connections to the wall of the mProV of Markowski while choroidal type has many choroidal arteries forming a nidus that drains into the mProV of Markowski. The secondary VGAM is from high flow of a deep arteriovenous malformation (AVM).¹⁰

b) Yasargil categorized VGAMs by the arterial feeder pattern. Type 1 are direct fistulas from the pericallosal or posterior cerebral arteries. Type 2 is supplied by the thalamoperfo-rator arteries. Type 3 has multiple fistulas from Type 1 and 2 supplying the VGAM. Type 4 is a flow-related false VGAM formed by a deep AVM. Similar to Lasjaunias, Yasargil distinguishes Type 1 to 3 as the true VGAMs.¹¹

4. What is the gold standard for neuroimaging of the VGAM? What other tests should be ordered?

Fig. 11.3 The right side shows the four-group Yasargil classification, while the left side shows the three-group Lasjaunias classification.

a) The gold standard is a diagnostic cerebral angiogram. However, a transfontanelle ultrasound, computed tomography angiography (CTA), and magnetic resonance angiography/ venography (MRA/MRV) are all part of the initial work-up to diagnose a VGAM.¹² In addition, an electroencephalogram, echocardiogram, and liver and renal function tests should be checked for seizures, myocardial infarction, and liver and renal perfusion injuries, respectively.¹³

5. What is the current management algorithm for VGAMs?

a) Neonates—Symptomatic

1. The goal of intervention is to stabilize high-output cardiac failure and other end-organ damage until infancy for more definitive intervention. Diuretics, inotropic agents, and vasodilators are used for symptomatic control.¹⁵ If unsuccessful, emergent embolization is carried out just enough to control the cardiac failure and attain organ equilibrium.¹² Unfortunately, neonates with severe cardiogenic shock, end-organ damage, or significant brain damage are not offered intervention. The Bicetre neonatal evaluation score is to direct management; a score of below 8 is deemed futile, 8 to 12 will get emergent embolization of physiological stability, and above 12 will get medical management until 4 to 5 months of age.¹²

b) Infancy—Symptomatic

1. The endovascular treatments are limited until 6 months of age, until the infant is old enough to withstand the endovascular procedure. The goal of intervention is to normalize the hydrovenous equilibrium to physiological levels. A combination of n-butyl cyanoacrylate and Onyx is used in a stepwise fashion. Zerah et al discovered that hydrocephalus is reversed in VGAMs once hydrovenous equilibrium is achieved. Sixty-six percent of nonshunt VGAMs as opposed to 33% of shunt VGAMs were neurologically normal.⁹

c)Older children/Adults—Symptomatic

1. When discovered later in life, VGAMs can be treated immediately. Except for mild headaches, which could be asymptomatic, patients presenting with a hemorrhage or neurological deficits need treatment to minimize the vascular steal.

d) Asymptomatic

1. Neurological delays can occur in asymptomatic and incidentally found VGAMs. Patients should be carefully monitored for deficits through neurocognitive assessments.

6.What is the mortality and morbidity of the different treatment modalities?

a) Initially, treatment was done through microsurgery, which had poor outcomes, with Gold et al experiencing 100% mortality in nine neonates. Until endovascular techniques became available, mortality was commonly close to 100%. Early embolization treatment had 50% mortality, but with the advent of better embolic material and improved medical care, Lasjaunias et al’s series in 2006 of 233 patients had a morality of 10.6% and normal neurological development in 74% of survivors.^12,14 Payne et al published an eight-patient series in 2000 for VGAMs treated with gamma knife radiosurgery. His treatment dosage ranged from 17 to 50 Gy, with a maximum size of 8.0 cm³. Results showed 50% did not have filling, remainder had decreased filling, and none of the patients had nonreversible complications.¹⁵

11.4 Level of Evidence¹⁶

Microsurgical treatment: Microsurgical treatment of VGAMs is associated with excess of morbidity and mortality compared to endovascular treatment (Class III, Level of Evidence B—nonrandomized).

Endovascular treatment: Endovascular treatment should be initiated at 5 months of age, unless deemed emergent in neonates, in a stepwise fashion to achieve hydrovenous equilibrium (Class I, Level of Evidence B—nonrandomized).

11.5 Landmark Papers

In 1948, Boldrey and Miller were the first to surgically treat two patients with aneurysms of the vein of Galen.¹⁷ In case one, a 16-month-old patient with progressive head enlargement and papilledema was discovered to have a large vein of Galen aneurysm with enlarged right posterior communicating and posterior cerebral arteries. The patient was treated with right common carotid artery ligation. The result was resolution of papilledema and normalized head circumference. A postligation angiogram showed no filling of the fistula and once confirmed, the posterior cerebral artery was clipped. Three years postinter-vention, the patient’s development was normal. In case two, a 15-year old presented with right eye exophthalmos and an audible bruit. Angiogram showed a fistulous connection between dilated posterior communicating and posterior cerebral arteries with a bulbous great vein. The right internal and external arteries were ligated, the venous engorgement disappeared, and bruit was reduced without neurological deficits.

Boldrey and Miller were the first to publish the diagnosis using carotid angiography and treatment of vein of Galen dilation. Prior to this, vein of Galen dilations were only described in cadavers and incidental intraoperative discovery. They attributed to the findings to cerebral AVMs and argued bruits, macro-cephaly, and pineal gland calcification should be examined for AVMs. Recent reviews note that only one of the cases was likely a true VGAM; nonetheless, they were the first to intervene on VGAMs and more importantly, show restoration of normal cerebrovascular physiology with treatment.

Gold A, RansohoffJ, Carter S. Vein of Galen aneurysm malformation. Acta Neurol Scand Suppl 1964;40(Suppl 11):1.

In 1964, Gold et al presented a review of literature with 8 patients from the Columbia-Presbyterian Medical Center in New York and 35 previously published cases.¹⁸ They defined that an AVM of the vein of Galen occurs when “one or more branches of the carotid or vertebral circulation communicates directly with this vein.” The authors acknowledged it as a unique entity with congenital end-to-end anastomosis and a network of poorly differentiated noncapillary vessels between the artery and vein.

Reviewing the available literature, Gold et al found three major subsets of symptomatic VGAMs. Early neonates presented with marked deficits in cardiovascular function, often with cyanosis and respiratory distress. Gold and his colleagues suggested that in neonates, the shunt is of such severe magnitude that it elicited peripheral congestion and congestive heart failure; none of the neonates survived. In contrast to neonates, infants presented primarily with hydrocephalus, convulsions, and distension of scalp veins. In infants, the shunt is of lesser magnitude than in neonates, such that it resulted in marked dilation of the vein of Galen and cerebral compression. Cerebral compression resulted in a diversity of clinical presentations, but included hydrocephalus, convulsions, psychomotor retardation, cardiome-galy, papilledema, and harsh intracranial bruits. In late childhood or adulthood, the patients typically presented with headaches and central nervous system (CNS) dysfunction. These include convulsions, paresis, ataxia, aphasia, cranial nerve palsies, ocular disturbances, and subarachnoid hemorrhage. Finally, X-rays of the skull in the oldest group showed concentric calcification in the wall of the VGAM.

Gold and his colleagues established a consistent definition for VGAMs and related their functional hemodynamics, rather than anatomic similarities, to the clinical presentations. In addition, these symptoms correlated with three major age groups and started invaluable evaluation of VGAMs through age-associated severity and clinical findings.

Hoffman HJ, Chuang S, Hendrick EB, Humphreys RP. Aneurysms of the vein of Galen. Experience at The Hospital for Sick Children, Toronto. J Neurosurg 1982;57(3):316-322.

Hoffman et al reviewed the clinical course and management of 128 patients from 1937 to 1981 with an aneurysm of the vein of Galen.¹⁹ Utilizing Gold’s findings, Hoffman’s 128 patients were divided into 45 neonates, 36 infants, and 47 older children and adults; moreover, 43 of 45 neonates presented with heart failure, 33 of 36 infants with hydrocephalus, and 18 of 47 adults with subarachnoid hemorrhage. Fifty-four of these patients were treated surgically. More importantly, Hoffman et al published the largest series of patients with 29 from 1950 to 1980 at The Hospital for Sick Children. Of this series, 16 were neonates, 8 were infants, and 5 were older children.

Overall, untreated patients did very poorly and none were reported as normal. Of those treated, most were through carotid ligation; 26 of the 54 treated patients were considered normal. In the single site series, 5 of 16 treated patients were considered normal and only 10 of 29 total patients survived. Notably, treatment was morbid in the neonate population with only 1 of 16 surviving on follow-up.

In Hoffman et al’s review, neonates had the worst prognosis. Therefore, the authors suggest they require early treatment to avoid aneurysmal stealing of blood and subsequent cerebral infarction. In addition, early treatment was crucial to eliminate the hemodynamic abnormalities contributing to myocardial ischemia and infarction. Hoffman claimed that, instead of excision, like in AVMS, simple occlusion was sufficient to convert a malformed vein of Galen into a physiologically normal vein. Hoffman et al were the first to suggest favorable outcomes from the treatment of VGAMs for a significant part of the population.

Lasjaunias P, Rodesch G, Pruvost P, Laroche FG, Landrieu P. Treatment of vein of Galen aneurysmal malformation. J Neurosurg 1989;70(5):746-750.

In 1989, Lasjaunias reported the treatment of a VGAM in a 1-year-old baby with macrocephaly and divergent strabismus with the first endovascular treatment for VGAMs.¹⁰ Initially with normal birth and cardiovascular and neurological development, the infant was found to have an intracranial bruit. Plan skull X-ray revealed craniofacial dysmorphism, without signs of intracranial hypertension, pathological calcification, or posterior fossa abnormalities. The VGAM was found on follow-up CT and magnetic resonance imaging (MRI) and confirmed on subsequent cerebral angiography.

One week after the diagnosis, the VGAM was completely em-bolized through a left femoral approach, with occlusion of the artery and a reduction of VGAM flow. At 4-month follow-up, angiography confirmed the resolution of the AV fistula and demonstrated shrinkage of the torcular dilation. Clinically, the patient was neurologically normal. The authors argue that VGAMs are a therapeutic challenge due to their deep location and severe symptoms and urged the clinicians to consider arterial embolization as the primary treatment choice.

Lasjaunias et al reported a series of 36 VGAM patients managed between 1982 and 1988 at Bicetre Hospital.²⁰ These VGAMs ranged a variety of symptoms including systemic manifestations (36%), neurological symptoms (22%), hydrocephaly (17%), and intracranial hemorrhage (11%). In addition, the authors evaluated the angioarchitecture and natural or post-therapeutic history of the VGAMs.

VGAM was more commonly symptomatic in the pediatric population. However, isolated neurological signs and hemorrhage correlate more closely with adult symptomatology as no patient older than 15 years presented with systemic symptoms. Of the 36 patients, 30 angioarchitectural analyses were obtained. The authors classified VGAMs into five different subtypes. Mural arteriovenous fistulas (AVFs) (20% of total) and choroidal fissure AVFs (30% of total) were more common in neonates and infants, whereas parenchymal (44% of total), dural AVFs (3% of total), and vein of Galen varices (7% of total) were usually associated with late childhood or even adulthood. Patients were treated surgically, endovascularly, or not at all. Among the 36 patients, 6 passed away; of these, two were treated surgically, two were treated endovascularly, and two were too futile for any treatment. This represents a 13% mortality rate for embolized patient, significantly better than historical surgical prognosis (91% mortality in neonates, 38% in infants).

In this landmark series, Lasjaunias et al concluded that endo-vascular treatment of VGAM results in superior outcomes. Also, they differentiated VGAMs into five subtypes and associated them with different age groups. Historically, VGAMs carried high morbidity and mortality; however, Lasjaunias et al claimed that certain subtypes (mural or choroidal AVF) can probably be cured with appropriate diagnosis and treatment. Contrary to the leading practice of the time, Lasjuanias et al found cerebral tissue damage or uncontrollable systemic failure to be contraindications to treatment. Therefore, they assert that treatment is only indicated when there is a possibility to compensate for systemic failure that previously responded to maximal medical treatment.

Zerah M, Garcia-Monaco R, Rodesch G, et al. Hydrodynamics in vein of Galen malformations. Childs Nerv Syst 1992;8(3):111-117.

In 1992, Zerah et al published a series of 43 patients with VGAM seen between 1985 and 1990 and reviewed an additional 335 cases in literature.⁹ These cases were reviewed with particular attention paid to the hydrodynamics associated with shunting. Similar to other literature, the patients in this series were categorized by age (prenatal [12%], newborn [50%], infant [19%], and child [16%]), and presenting symptoms (heart failure [26%], hydrocephalus/macrocephaly [15%], hemorrhage [1%], and clinical deterioration [1%]).

In addition to reviewing the cases, the authors explored several theories that could explain the development of hydrocephalus in VGAM. Zerah et al supported the hypothesis that increased venous pressure is the primary cause of VGAM hydrocephalus. They hypothesized that increased venous pressure inhibits cerebrospinal fluid (CSF) flow from the subarachnoid space into the venous system. Fifty percent of VGAM patients presented with macrocrania. In their experience, ventricular drainage of CSF through shunting worsened the complications associated with increased venous pressure. After shrinking the ventricles, the venous malformation enlarges to fill the potential space. Zerah et al considered embolization to be the best method of reducing the venous pressure and restoring the hydrovenous equilibrium and that VP shunting be avoided in order to prevent clinical deterioration.

Lasjaunias PL, Chng SM, Sachet M, Alvarez H, Rodesch G, Garcia-Monaco R. The management of vein of Galen aneurysmal malformations. Neurosurgery 2006; 59(5, Suppl3)S184-S194.

In 2006, Lasjaunias et al presented a 20-year review of 317 patients with VGAM at the Hopital de Bicetre.¹² Of these, 233 (74%) were treated with endovascular embolization, 67 (21%) were deferred for treatment for a variety of reasons, and 17 (5%) were lost to follow-up. As a first-line treatment, the authors chose transarterial embolization using n-butylcyanoa-crylate glue as the embolic agent with a goal to preserving normal development and avoiding neurologic deficits. A total or near total (90-100%) occlusion of the VGAM was obtained in 55% of the patients; only 6.2% of patients had an obliteration rate of less than 50%. Patients were followed up with clinical examination every year and MRI every 2 years. In their series, 74% of surviving patients were neurologically normal. Only 2% experienced permanent neurological disability.

With the largest series of VGAMs, Lasjaunias was able to provide multiple important observations. First, the angioarchitecture of an individual patient should direct the treatment decision. Fistulas involving the choroidal arteries and an interposed vascular network before opening into the vein of Galen tend to be more severe and correlate with poorer outcomes, thus lending themselves to earlier treatment. On the contrary, mural fistulas are direct AV fistulas and tend to be better tolerated. Second, there exists a “therapeutic window” in which endovascular treatment is optimized based on the evolution of clinical manifestations as outlined in the literature. Third, treatment should be stratified based on age and specific medical complications. Treatment should focus on restoration of physiological flow. Finally, contrary to the previous thought, a majority of children treated endovascularly survive and maintain normal neurological development.

Lasjaunias was among the first to combine clinical, anatomical, and pathophysiological aspects of VGAM to predict disease evolution and guide management decisions. From the series, the Bicetre Neonatal Evaluation Score ( Table 11.1) was created to lead best management of neonatal VGAMs. Their data showed that patient selection and therapeutic timing are keys to successful outcomes.

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