National Organization for Rare Disorders, Inc.
It is possible that the main title of the report Arteriovenous Malformation is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.
Arteriovenous malformation (AVM) is a vascular lesion that is a tangle of vessels of varying sizes in which there is one or more direct connections between the arterial and venous circulations. In the lesion there is no capillary bed, which is part of normal tissue. Brain AVMs are often presumed to be congenital, but there is no direct evidence that they form in utero. The distribution of age at detection for brain AVMs is normally-distributed with the mean age in the mid-30's. Although a small number of AVMs manifest themselves at or shortly after birth, most of them present later in life, and just as likely, form and progress during the later years of life. The lack of capillaries allows blood traveling through the abnormal fistulous connections to flow rapidly. The low resistance of the direct A-V connections, termed fistulas, results in very high flow rates in the vessels leading to and within the AVM. These high flow rates can lower the pressure in the arteries leading to the AVM and to surrounding relatively normal brain tissue. Further, because of the direct A-V connections, the pressure in the arteries, even if somewhat reduced, are transmitted to the veins draining the AVM and surrounding brain, which normally operate at very low pressures. AVM can occur in many different parts of the body, but those located in the central nervous system (brain and spinal cord) can cause problems that affect the brain like other forms of stroke.
Cure HHT Foundation
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Genetic and Rare Diseases (GARD) Information Center
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NIH/National Institute of Neurological Disorders and Stroke
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National Organization of Vascular Anomalies
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Vascular Disease Foundation
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For a Complete Report
This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".
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It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report
This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.
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Last Updated: 12/7/1969
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