What is an Arteriovenous Malformation?
A brain arteriovenous malformation (AVM) is an abnormal entanglement of a blood vessels with both arteries and a veins inside of the brain. These disrupt the blood flow and oxygen supply bypassing normal tissue. They can cause damage from lack of oxygen to delicate brain tissue. They also connect the high pressure arterial blood flow to the low pressure vein blood flow which can weaken the vein walls. Brain AVMs may not produce symptoms until they enlarge, start to leak blood, or burst. This can cause bleeding into the brain, stroke or brain damage. Should they burst they are a medical emergency and you should call 911 for transportation to the hospital. Unfortunately, most brain AVMs are asymptomatic until bleeding occurs.
AVMs tend to have few or no symptoms until they bleed. If they expand and press on nerves then they may have symptoms related to those nerves. These can include droopy eyelids, headaches, a dilated pupil, blurred vision or weakness.
Ruptured AVMs are a life threatening medical emergency and you should call 911 for immediate medical care and transportation to the hospital. These will cause a subarachnoid hemorrhage which is bleeding into the space around the brain. Since the brain is in an enclosed space, the pressure inside of the head increases. Patients often describe this as “the worst headache of my life.” It can also cause headaches, progressive loss of neurological function, confusion, loss of consciousness, a stiff neck, weakness, numbness, seizures, light sensitivity, vision problems, nausea and vomiting.
A leaking brain AVM may allow a small amount of blood to escape called a “sentinel bleed”. This can also cause “the worst headache of my life” and symptoms in common with a rupture. In addition, rupture of the AVM can also follow this sentinel leak.
The causes of brain AVM are unknown but they are from abnormal development of the connections between the arteries and veins. These can have genetic causes but they are usually not inherited. Risk factors include hereditary conditions like Herideitary Hemorrhagic Telangiectasia (HHT) which is also called Osler-Weber-Rendu syndrome.
Diagnosis of AVMs may be suggested by a combination of a patient’s history and symptoms. A “whooshing sound” that the patient or doctor hear may interfere with hearing or sleep. A Computed Axial Tomography (CAT) scan is an X-ray of the head that can show bleeding inside or around the brain. MRI (Magnetic Resonance Imaging) and MRI (Magnetic Resonance Angiogram) are usually the test of choice to detect unruptured brain AVMs. These scans use strong magnetic fields and produce detailed soft tissue images of the brain. Cerebral angiography uses dye injected into an artery to show the structure of the blood vessels.
Emergency surgery is required for a leaking or ruptured brain AVM. For an unruptured AVM the size, location and symptoms will help determine the likelihood of future rupture. In addition, the potential of injury from repair of a brain AVM needs to be considered in relation to the symptoms, how safely the area of the brain can be approached, and chance of rupture. Medications can be used to manage blood pressure, seizures and headaches.
Should a brain AVM be discovered on an unrelated imaging test, and you do not have related symptoms or risk factor, your doctor may recommend watchful waiting with regular imaging tests to ensure that the AVM does not grow over time. It is also important to stop smoking and to have blood pressure well controlled. Should you develop symptoms it is important to get help immediately.
Surgery and/or endovascular treatment are the procedures to treat ruptured or unruptured AVMs.
Open surgical (microvascular) clipping
A small opening in your skull or skull base to provide access to the brain AVM. Microinstruments are used attach metal clips to seal of the base of the incoming arteries and outgoing veins. This stops blood from flowing into the AVM and will stop brain bleed or prevent future AVM rupture. Recovery time may be a few weeks for unruptured AVMs with longer times of up to a few months for ruptured AVMs. AVM surgery is considered curative although AVMs may recur. Surgery is most successful in areas of the brain that are accessible and where the risk of brain damage during surgery is low.
Highly focused radiation beams can be used to damage and shrink the blood vessels and stop the blood flow to the AVM. These can include Gamma Knife, Linear Accelerator, or Proton Beam Therapy. These can be used in combination with open surgery as well.
Sometimes it is possible to treat a brain AVM through a catheter in the arm or groin. The catheter is threaded through the vessel to the area of the AVM. Injection of a substance will close the vessels of the AVM and help decrease blood flow into the AVM.
The neurosurgeons of Norelle Health are highly trained and skilled in the diagnosis, management, and treatment of brain AVMs. Our neurosurgeons can provide the optimal treatment. As out-of-network providers, we will check your benefits for you and let you know what they are so there are no surprises. We use an individualized treatment plan for your concerns to provide a personalized holistic plan of care. If you would like assistance, please feel free to contact us (link to contact page) or call our office (link to phone number). Should you have sudden onset of symptoms, like the ones listed above, call 911 and seek immediate medical care.