An article review from "Embryological background of truncular venous malformation in the extracranial venous pathways as the cause of chronic cerebrospinal venous insufficiency" by B.B. Lee, J.Laredo, R. Neville. International Angiology, 29(2), pp.95-108. Congential Vascular Malformations (CVM) are described in this article as part of a group of birth defects occurring in the developing fetus during the embryonic phase (0-8 weeks gestation). Many different types of venous and arterial malformationa are described. Two specific malformations involve defective veins occurring wither early in fetal development (called extratruncular) or at a later stage of fetal development (called truncular). Extratruncular malformations of the veins, because of embryonic tissue remnants, have the ability to re-occur when stimulated by trauma, pregnancy, surgery, other hormones, menarche, etc. Truncular malformations involved the already formed venous "trunk" and include underdeveloped or overdeveloped abnormalities which cause obstructions or dilated areas (such as internal jugular vein aneurysms or azygous vein stenosis). Sometimes, defects can occur inside the veins (called intraluminal)  such as webs or membranes resulting in stenosis or or obstruction. Infrequently, truncular malformations occur as persistent pieces of fetal vein alongside mature veins. In persons with truncular defects (or lesions) serious issues can occur within the stability of the cardiovascular system due to the vessel size and location. Extreme variations in blood pressure cause hypertension and venous congestion  due to truncular lesions and their resulting venous reflux or occlusions. An example of such membranous stenosis is with an area of the inferior vena cava and is called "Primary Budd-Chiari Syndrome". This membranous venous defect causes portal (liver area) hypertension from the hepatic venous outlet obstruction. This obstruction and hyypertension of the liver cause chronic venous insufficiency of the lower extremities. In the same manner, cerebrospinal venous malformations cause hypertension of the brain resulting in chronic cerebrospinal venous insufficiency and/or hypertension. The article continues to review the detailed anatomy of the cardiovascular system from conception to maturity. The author describes how embryonic veins give way to the jugular veins, azygous veins, superior vena cava, as well as othe rimportant veins. From this discussion, the concept of anomalous (abnormal) veins is explained. When anomalous veins develop, the usual course, as attributed by vein name, is explained as well. The author stresses the profound impace of "simple" truncular venous malformations and their role in CCSVI and possibly, MS development or exacerbation. Please contact me for further info at www.worldmedassist.com or read more at www.msandccsvi.com