11.1 Goals

1. 
   

   Describe the embryologic origin of vein of Galen aneurysmal malformations (VGAMs).

   
   
2. 
   

   Detail the age-related presentations of symptomatic VGAMs.

   
   
3. 
   

   Review the literature on the advancement of treatments in VGAM.

   
   
4. 
   

   Review the management of VGAM based on age-related symptoms.

11.2 Case Example

11.2.3 Follow-up

The patient performed well through the various stages of transarterial embolizations. During his last transvenous embolization, the patient suffered worsening seizures secondary to an intracranial hemorrhage post coiling of the venous enlargement. He did not require any surgical intervention and went home with his parents. Interval follow-up showed good adaptation and continued achievement of appropriate developmental milestones. At the 1-year follow-up, he had a successfully treated VGAM on repeat diagnostic cerebral angiogram.

11.3 Case Summary

1. 
   

   What is the embryological origin of VGAM?

   
   
   
   
   1. 
      

      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?

   
   
   
   
   1. 
      

      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.

      
      
   2. 
      

      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}

      
      
   3. 
      

      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}

      
      
   4. 
      

      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)

   
   
   
   
   1. 
      

      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

      
      
   2. 
      

      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?

   
   
   
   
   1. 
      

      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?

   
   
   
   
   1. 
      

      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

      
      
   2. 
      

      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

      
      
   3. 
      

      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.

      
      
   4. 
      

      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?

   
   
   
   
   1. 
      

      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 cm ³ . Results showed 50% did not have filling, remainder had decreased filling, and none of the patients had nonreversible complications. ¹⁵