Arteriovenous malformation (AVM) is an abnormal condition where the arteries and veins are tangled in a particular site resulting in impaired blood flow to the brain tissues around the AVM. Arteries carry oxygenated blood from the heart to different parts of the body. Veins carry de-oxygenated blood from the tissues back to the heart. Arteries and veins are interconnected to each other by several capillaries. These capillaries retard the flow of blood and helps in nourishing the cells and tissues with food, oxygen and other nutrients to the surrounding tissues.
In AVM, the arteries and veins are directly connected to each other bypassing the capillaries. The junction where these abnormal connections are developed is called a shunt. The surrounding tissue does not receive nutrients and oxygen because of lack of blood supply to the capillaries and this may cause various neurological conditions such as seizures, stroke, damage to brain and spinal cord, weakness, numbness in the limbs and headaches.
There will be increase in the flow of blood in the shunt which will weaken the wall of blood vessel and may also increase the pressure in the blood resulting in aneurysm. Aneurysm is a bulge or a sac that develops on the wall of the artery.
Conservative treatment: Certain anti-seizures medications may be prescribed for symptomatic relief in patients with unruptured AVMs or large AVMs.
Stereotactic radiosurgery: It is the site targeted radiation treatment to destroy the AVM. It involves delivering a single or high dose of radiation to the AVM blood vessels which enlarges the vessels gradually over the time. It is recommended in cases of small AVMs, less than 3cm. It may not be considered for AVM that is located deep within the organs or if the patient is not a candidate for the treatment because of various reasons.
Endovascular embolization: In this method surgeon inserts a small tube, catheter into the femoral artery in the leg and advances it into the blood vessels to the brain under the guidance of fluoroscopy. Once the catheter reaches the site of abnormality embolising agent is injected. Embolising agents include glue, gelling agents, metal coil, sclerosing agents, or a balloon which blocks the blood flow into aneurysm.
Embolisation is done before the surgery to prevent bleeding that may take place during the surgery, to reduce the size of the AVM as large AVM are impossible to be operated and it helps in redirecting the blood to flow to the normal brain tissues.
Surgical resection of AVM: The surgical resection involves removal of AVM. Your surgeon will remove a section of skull to look for AVM through a high-resolution microscope. The AVM is held by special clips and using laser or cautery instrument the AVM is removed from the surrounding tissues. Later, the skull is stitched back and the incisions are closed.
This surgery can be performed in two ways; awake brain surgery and general anesthesia. Awake brain surgery is performed under local anesthesia and is done to check the brain functioning during the procedure. Your surgeon will remove the AVM while you are awake and you may be asked few questions during the procedure. Your responses will help the surgeon to confirm no damage injury to the area of brain which control speech and movement during surgery.
In general anesthesia, your surgeon will perform an angiogram which projects images on an X-ray monitor that makes sure that AVM is completely removed.