| cerebral arteriovenous malformations | Vascular anomalies in which tangles of arteries are connected directly to veins without intervening capillaries. The resulting vessels are thin-walled owing to poorly developed elastic and muscle tissue within the media. They can be located anywhere in the brain and can produce headaches, seizures, focal neurologic deficits, or intracranial haemorrhage. Familial cases are rare, indicating that the problem reflects sporadic abnormalities in embryologic development. (12 Dec 1998) |
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| congenital pulmonary arteriovenous fistula | Abnormal congenital communication between pulmonary arteries and veins usually found in the lung parenchyma. (05 Mar 2000) |