Arteriovenous malformations (AVMs) are rare abnormal connections between the veins and arteries that lead to the entanglement of the vessels. These abnormalities usually develop in the fetus or in a newborn baby and can form anywhere in the brain or spine.
Veins are not well equipped to be handle the pressure that come from arteries and therefore are susceptible to rupturing and bleeding. Aneurysms (“ballooning” of the vessel walls) can form as result of this increased pressure. Surrounding tissues are at a high risk for damage because the AVMs can “steal” blood flow. AVMs make up approximately 2% of hemorrhagic strokes annually.
Symptoms related to brain AVMs can often vary and they are based on their location and type. Headaches and seizures are the most common; however, majority of people with AVMs do not present with any symptoms until a bleed or rupture occurs.
Spinal AVMs usually present with sudden severe back pain, weakness or paralysis of the legs or arms.
Diagnosis:
If you or your loved one are diagnosed with an AVM, your doctor will conduct a thorough evaluation of your symptoms, current/past medical problems, medications, and family history. There are several gold standard diagnostic tests that are available to help provide more information about the aneurysm. These tests also help determine the best course of treatment.
- Computerized Tomography (CT): Non-invasive x-ray to look at the structures within the brain and to determine if the AVM ruptured or bled.
- Computerized Tomography angiography: Similar to a CT scan in which contrast is used to have a better view of the brain vessels.
- Magnetic resonance imaging (MRI): medical imaging technique that uses a magnetic field and computer generated radio waves to create detailed images of the brain
- Intracerebral angiogram: a dye test to help analyze arteries and identify the degree of narrowing or obstruction of the artery or blood vessel in the brain
Treatment:
Observation
If there is no evidence of bleeding, the doctor may decide to observe you.
You may be prescribed seizure preventive medications and/or medications to control your blood pressure.
Surgical Resection
Surgeons create an opening in the skull with computer imaging guidance (usually MRI-based). Using a high-power microscope, surgeons remove the AVM and cauterize its feeder blood vessels. Complete removal is confirmed with intracerebral angiography. This option depend on the general health of the patient and the type/location of the AVM. There is a risk of bleeding and subsequent damage to surrounding tissue, as well as stroke once the AVM is removed.
Stereotactic Radiosurgery
Computer imaging is used to guide a single high dose of radiation directly to the AVM. No incision is required. This procedure is typically used for AVMs that cannot be reached by surgery.
Endovascular embolization
This is a minimally invasive procedure that utilizes small catheters to deliver glue or other obstructive materials into the AVM in hopes that the AVM will no longer receive blood flow and will eventually die. The surgeon will place a small incision in the groin and a catheter is guided by computerized imaging to the AVM. The occluding material or glue is passed through the AVM. One advantage of this procedure is that it is less invasive than surgery and can be used for inoperable or deep AVMs. There is a risk for embolic stroke from the catheter as well as a risk for rebleeding because the AVM may not be completely gone. Multiple treatments may be indicated.