General Child Neurology
May. 31, 2021
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This article includes discussion of vein of Galen malformations, vein of Galen aneurysm, vein of Galen aneurysmal dilation, vein of Galen arteriovenous fistula, and vein of Galen arteriovenous malformation. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Vein of Galen malformations are congenital arteriovenous malformations involving the deep venous system of the brain that were first described in 1895 by Steinheil. Vein of Galen malformations are rare lesions that present with well-defined clinical symptoms that vary with the age of the patient. They are a heterogeneous group of macroscopic or microscopic arteriovenous fistulas that can be classified according to the location of the fistula (prosencephalon vs. mesencephalic) or the angiographic architecture. Current treatment involves primarily endovascular techniques to obliterate the fistula and eliminate the arteriovenous shunting of blood and resulting symptoms. In this article, the authors provide a detailed overview of presentation, pathophysiology, and management of vein of Galen malformations.
• Vein of Galen malformations are rare congenital arteriovenous malformations involving the deep venous system of the brain and are thought to arise due to abnormal involution of primitive vascular structures during embryogenesis.
• The age of presentation and symptomatology varies and depends on the size of the shunt, venous drainage pattern, complexity of the arterial supply, and host response.
• An angiogram is the gold standard diagnostic test and will reliably help differentiate it from other vascular lesions.
• Definitive treatment consists of endovascular methods with surgical management reserved for the evacuation of associated hematomas and treatment of refractory hydrocephalus.
Galen was first to describe the vein that now bears his name in the second century AD when he characterized the deep venous anatomy of the brain in animals. Steinhill in 1895 provided the first description of vein of Galen malformation in the postmortem findings of a 49-year-old man, referring to it as a “varix aneurysm” (50). In the literature these lesions have been referred to as “aneurysms of the vein of Galen,” “arteriovenous aneurysms of the vein of Galen,” “vein of Galen aneurysmal malformations,” and “vein of Galen malformations” (22).
In 1964, Gold and colleagues described the clinical features of the disease and identified 3 characteristic syndromes associated with theses lesions (20). Amacher and Shillito defined a fourth clinical group in 1973 (03). Following that, Lasjaunias classified the malformations into 2 distinct subtypes (33). The first is a true vein of Galen malformation and occurs because of a dysembryogenic event involving the median vein of the prosencephalon (also known as the median prosencephalic vein of Markowski). Lasjaunias further subcategorized the true malformation into the mural and choroidal types. In mural type, the fistula is the wall of the vein (median vein of the prosencephalon), and in the choroidal type the drainage is into the tributary veins of the median vein of the prosencepahlon. The choroidal malformation is more common, and the arterial supply originates from the choroidal, pericallosal, and subependymal branches of the thalamoperforator arteries. The arteriovenous connection is at the anterior aspect of the persistent median vein of the prosencephalon. This subtype is most commonly associated with high-output cardiac failure (23). The arterial supply in the mural type is from the collicular vessels or the posterior choroidal branches. The fistula is located more posteriorly on the median vein of the prosencephalon. This subtype is associated with macrocephaly and failure to thrive. High-output cardiac failure is less common (23). Lasjaunias and colleagues termed the second type of malformations “vein of Galen dilatations.” These lesions are formed due to the drainage of true deep midline arteriovenous malformations that drain selectively into the vein of Galen, causing it to dilate.
Yasargil defined 4 types of vein of Galen malformations: type 1 is a simple small fistula involving branches from the pericallosal or posterior cerebral arteries; type 2 involves more feeding vessels from middle cerebral artery branches (thalamoperforating vessels); type 3 involves high-flow lesions with large numbers of fistulous connections from a wide range of feeding vessels; and type 4 is a midline arteriovenous malformation with drainage into the vein of Galen (this is analogous to the vein of Galen dilation described by Lasjaunias) (Yasargil 1988).
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