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Vascular malformations, also called congenital vascular malformations (CVMs), are abnormalities in the formation of blood vessels. Though they are almost always congenital, or present at birth, there have been rare instances when vascular malformations have been caused by trauma or linked with a neurological disorder. Several types of CVMs exist, including arteriovenous malformations, capillary malformations, lymphatic malformations, venous malformations, and combined vascular malformations. These usually take the form of blood vessel clusters and can cause aberrations in blood flow. Vascular malformations are subdivided into two groups, fast flow and slow flow, based on the rate of blood flow through the lesion.
Arterio-venous malformations (AVMs) are one of the more common and dangerous CVMs. These vascular malfunctions occur when blood vessels cluster across a capillary bed to provide an abnormal direct connection between arteries and veins. Normally, the artery would carry oxygenated blood to the capillaries, which would distribute blood into the body’s tissue and then return deoxygenated blood to the veins. The direct connection between veins and arteries in an AVM causes blood to pool in the veins.
AVM is particularly dangerous because it is delicate and prone to bleeding. If the lesion occurs in the brain, bleeding may cause a fatal stroke. These vascular malformations usually present few symptoms, or possibly none at all, and are often diagnosed after the lesion has ruptured and caused damage, such as paralysis or death, to the body. Less severe symptoms may include headaches, neurological disorders, and seizures. Doctors may treat an AVM by removing the offending cluster of blood vessels with surgery, excluding it from the rest of the circulatory system through embolization, or intentionally damaging the blood vessels around the lesion with radiosurgery to cause the blood vessels to close and cut off the AVM.
A capillary malformation, or port wine stain, can be diagnosed by sight, appearing as a red or pink birthmark that may appear in small or large patches. This is caused by the presence of abnormally large capillaries in a given area. If present on the forehead or eyelid, portwine stains are associated with Sturge-Weber syndrome, and marks over the spine are linked with Cobb syndrome. Lesions may grow and darken over time, eventually creating lumpiness on the skin, others may fade by the age of one year. Laser therapy is used for more superficial vascular malformations, and surgery is required for outgrowths and deeper tissue capillary malformations.
A venous malformation may also exhibit visible symptoms, usually of soft, red or blue, lumpy skin. This is caused by a lack of smooth muscle in the veins that makes them abnormally dilated. Besides cosmetics, venous malformations can clot or abruptly bleed, causing serious complications. These vascular malformations may be treated with surgical removal, laser therapy, compression garments, or sclerotherapy, wherein an irritant is injected in an attempt to shrink the affected veins.
Lymphatic malformations are also physically visible, presenting an enlarged structure, such as a toe or lip, or a bubble on the skin. This is caused by the slowing of fluid through the lymphatic system into the veins, producing an accumulation of fluid in the lymphatic vessels. Complications may include difficulty breathing if located in the trachea, infection due to the leaking of lymph, or Gorham syndrome if located near a bone, which can cause bone loss. Treatments are similar to those for venous malformations.
Combined vascular malformations include more than one type of vessel abnormalities. These usually affect the limbs, but may be present in any part of the body. Complications and treatment vary depending on the location of the abnormality and the types of malformations present. Combined vascular malformations are diagnosed through magnetic resonance imaging (MRI), computed tomography (CT) scans, X-rays, and sonograms.