An arteriovenous malformation is a direct connection between an artery and a vein without passing through capilliaries. Depending on the location of the malformation, it can cause a variety of symptoms but in the vast majority of cases, the malformation is completely asymptomatic. The most likely symptom is hypoxia in the area fed by the artery resulting in muscle weakness or even paralysis. They can also cause vertigo, aphasia, peripheral neuropathy and even dementia and other neurological problems. Arteriovenous malformations are a common diagnosis on House, M.D.