Arterio-Venous Malformation Surgery and Embolization Arterio-venous malformation or AVMs are abnormal connections in the vessels of the brain that directly divert blood from the arteries to the veins. They occur in less than 1% of the population, but it is unknown why they occur. They may result in bleeding in the brain, seizures, headache or difficulty with movement, speech and vision. Therapy for AVM depends on its location, size, and the symptoms it map be causing. Surgical removal of AVM is recommended if it is accessible. Placing a small catheter inside the blood vessels and blocking off blood supply to the AVM with variety of materials can also be used to treat part/all of the AVM - a procedure called Embolization.