"Fibromuscular Dysplasia, commonly called FMD, is a disease that causes one or more arteries in the body to have abnormal cell development in the artery wall. As a result, areas of narrowing (called stenosis), aneurysms, or tears (called dissections) may occur. If narrowing or a tear causes a decrease in blood flow through the artery, symptoms may result. Many people with FMD do not have any symptoms or signs on physical examination and are diagnosed by accident during a radiology scan for another problem.
FMD is most commonly found in the arteries that supply the kidneys with blood (renal arteries) and the arteries called the carotid and vertebral arteries which are found in the neck and supply the brain with blood. Less commonly, FMD affects the arteries in the abdomen (supplying the liver, spleen and intestines) and extremities (legs and arms). In more than one-half of people with this disease, there will be evidence of FMD in more than one artery.
What causes FMD?
The cause of FMD is not yet known, but several theories have been suggested. A number of case reports in the literature have identified the disease in multiple members of the same family including twins. As a result, it is felt that there may be a genetic cause. However, a relative may have different artery involvement, different disease severity, or not develop FMD at all. In fact, most individuals with FMD do not have a family member who also has the disease. Among some individuals with FMD, there is a family history of other vascular problems, such as blood vessel aneurysms.
FMD is far more commonly seen in women than in men, resulting in the theory that hormones may play an important role in disease development. However, in small population studies, one's reproductive history (number of pregnancies and when they occurred) as well as the use of birth control pills did not correlate with the development of FMD.
Other possible causes of FMD include abnormal development of the arteries that supply the vessel wall with blood, resulting in inadequate oxygen supply; the anatomic position or movement of the artery within the body, certain medications, and tobacco use. It is possible that many factors contribute to the development of FMD. This area requires further research and is under investigation by many researchers around the world."-FMDSA.org
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