Arteriovenous malformation is an abnormal connection between arteries and veins, bypassing the capillary system. This vascular anomaly is widely known because of its occurrence in the central nervous system (usually cerebral AVM), but can appear in any location. Although many AVMs are asymptomatic, they can cause intense pain or bleeding or lead to other serious medical problems.AVMs are usually congenital and belong to the RASopathies. The genetic transmission patterns of AVMs are incomplete, but there are known genetic mutations (for instance in the epithelial line, tumor suppressor PTEN gene) which can lead to an increased occurrence throughout the body. Signs and symptoms
Symptoms of AVM vary according to the location of the malformation. Roughly 88% of people with an AVM are asymptomatic; often the malformation is discovered as part of an autopsy or during treatment of an unrelated disorder (called in medicine an "incidental finding"); in rare cases, its expansion or a micro-bleed from an AVM in the brain can cause epilepsy, neurological deficit, or pain.The most general symptoms of a cerebral AVM include headaches and epileptic seizures, with more specific symptoms occurring that normally depend on the location of the malformation and the individual. Such possible symptoms include:
Difficulties with movement coordination, including muscle weakness and even paralysis;
Vertigo (dizziness);
Difficulties of speech (dysarthria) and communication, such as aphasia;
Difficulties with everyday activities, such as apraxia;
Abnormal sensations (numbness, tingling, or spontaneous pain);
Memory and thought-related problems, such as confusion, dementia or hallucinations.Cerebral AVMs may present themselves in a number of different ways:

Bleeding (45% of cases)
Acute onset of severe headache.
Cultural Depictions
In the HBO series Six Feet Under (TV series), main character Nate Fisher discovers he has an AVM after being in a car accident and getting a precautionary cat scan at the hospital during Season 1. His AVM becomes a key focus during Season 2 and again in Season 5. Research
Despite many years of research, the central question of whether to treat AVMs has not been answered. All treatments, whether involving surgery, radiation, or drugs, have risks and side-effects. Therefore, it might be better in some cases to avoid treatment altogether and simply accept a small risk of coming to harm from the AVM itself. This question is currently being addressed in clinical trials. See also
Foix–Alajouanine syndrome
Haemangioma
Klippel–Trénaunay syndrome
Parkes Weber syndrome


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