Subcortical laminar heterotopia
Nov. 01, 2023
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Vein of Galen malformations are a rare and congenital vascular abnormality consisting of one or more arteriovenous shunts draining into the median vein of the prosencephalon, the embryonic precursor of the vein of Galen. It is a rare condition, and the vast majority of cases are seen in the pediatric population. Management is best performed in large centers by a multidisciplinary team familiar with the entity. Advances in endovascular technique as well as critical care have helped improve the treatment and outcomes in what was once a condition with a uniformly poor prognosis. This article provides an overview of the condition and will be of interest to diverse medical fields, including neonatology, pediatrics, obstetrics, neurology, neurosurgery, and both diagnostic and interventional neurology.
• The term vein of Galen malformation is actually a misnomer as the actual abnormality consists of one or more arteriovenous shunts that drain into the median prosencephalic vein of Markowski, an embryonic precursor to the vein of Galen that normally involutes.
• Neonates commonly present with high output heart failure due to arteriovenous shunting. Children more commonly present with macrocephaly, hydrocephalus, and seizures due to venous hypertension.
• The decision of when and if to treat patients through endovascular embolization is complex; factors to be considered include age of the patient, the presence of established cerebral damage, cardiorespiratory function, hepatic function, and renal function.
• If possible, endovascular treatment of neonates is delayed until at least 5 to 6 months of age. During this time, patients are treated medically for heart failure, but there are cases of severe heart failure or other end organ dysfunction that necessitate early endovascular intervention.
• Endovascular treatment may be staged and is most commonly performed via embolization with cyanoacrylate glue. Transvenous approaches may be used in combination or when an arterial route is not feasible or successful. Open neurosurgical treatment has little role in the modern day aside from ventricular shunting for hydrocephalus or, rarely, evacuation of intraparenchymal hemorrhage.
• Infants and neonates presenting with severe cardiorespiratory function have the worst prognosis, and untreated malformations are almost always fatal. In appropriately selected patients without significant brain damage, the majority have good outcome and normal neurologic function.
Many of the entities reported in past literature may not have been true vein of Galen malformations due to the complexity of the lesion and later developments in understanding embryology and pertinent anatomy. The first mention of a possible vein of Galen malformation by Steinhel in 1895, cited by the eminent neurosurgeon Walter Dandy, was in fact an arteriovenous malformation draining into an already formed vein of Galen, a distinct entity with greater risk of hemorrhage (07). There are later papers describing treatment via arterial ligation of arteriovenous communications into a vein of Galen that encounter the same problem and may or may not have been true vein of Galen malformations (04). Landmark work by Raybaud and others provided an improved understanding of cerebral venous anatomy and embryology and laid the groundwork for the current understanding of vein of Galen malformations. It was recognized that the abnormally dilated vein is actually a persistent embryonic precursor to the vein of Galen called the median prosencephalic vein, also called the median prosencephalic vein of Markowski (23).
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