Abnormally dilated arteries that drain directly into veins, also abnormal, there are no capillaries.
They may be chance finding or symptomatic: Cerebral bleeding, generally in the form of an intraparenchymatous haematoma, or intraventricular haemorrhage, but onset may also include epileptic seizures.
Possible treatments: Embolisation (onyx, bioglu), surgery or radiosurgery.
They may be one, two or three treatments in the same patient.
Bleeding in young people, mortality of 10%, with 30-50% of morbidity.
Risk of bleeding: 3% per year.
7% of patients with AVM have aneurysms (flow aneurysms).