Neuro Arteriovenous Malformation
Arteriovenous malformations (AVMs) are malformed blood vessels that cause direct and irregular connections between arteries and veins. This results in an absence of capillaries—a network of small blood vessels that delivers oxygen to cells. In most cases, AVMs cause damage by reducing the amount of oxygen reaching brain tissue and by compressing or displacing parts of the brain. Over time, the increased blood flow through the arteries into the veins can cause some AVMs to grow progressively larger, weaken, and rupture, causing a hemorrhagic stroke.
Dural arteriovenous fistulas (dAVF) and Vein of Galen malformations are two types of AVMs that affect specific parts of the brain.
- dAVFs occur within the dura (outermost membrane) between the brain and the skull. The most serious problem associated with dAVFs is the transfer of arterial blood directly into the veins or venous sinuses. This results in an increase in the pressure of the venous system around the brain, potentially causing irreversible damage.
- A Vein of Galen malformation is a rare form of AVM that can occur during early brain development. The Vein of Galen is a large vein at the base of the brain that returns blood to the heart. If a Vein of Galen malformation develops, then it causes an overload of blood flowing to the heart. This can lead to rapid heart failure, hydrocephalus (or water on the brain), commonly prominent veins on the face and scalp, developmental delay, persistent headache, and neurological problems.
People with AVMs experience few, if any, significant symptoms. Symptoms of dAVFs and Vein of Galen aneurysms can be present at birth or can go undetected until later in childhood. If symptoms are present, they typically include:
- problems with speech, vision, or movement
- pulsing sound
- physical vibrations
- increased pressure on the brain
Vein of Galen
- prominent veins on face or scalp
- increased head size
- developmental delay
- heart failure
Your doctor may:
- conduct a physical examination
- ask about signs and symptoms
Your doctor may order one or more of the following imaging tests:
- Cerebral angiography, also called cerebral arteriography, provides the most accurate pictures of blood vessel structure. A special water-soluble dye, called a contrast agent, is injected into an artery so that blood vessels can be more easily seen on X-rays.
- Computed axial tomography (CT scan) uses X-rays to create an image of the head, brain, or spinal cord and are especially useful in revealing the presence of hemorrhage.
- Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to create detailed images that can show subtle changes in neurological tissues.
- Magnetic resonance angiography (MRA) can record the pattern and speed of blood flow through vascular lesions as well as the flow of cerebrospinal fluid throughout the brain and spinal cord.
Transcranial Doppler ultrasound can detect medium and large AVMs, as well as the presence and amount of hemorrhage. It evaluates blood flow through the brain by directing high-frequency sound waves through the skull at particular arteries. Sound wave signals that bounce back from blood cells are interpreted by a computer to create an image of the velocity of blood flow.
Treatment for this condition must always be discussed with your doctor
for a full discussion of options, risks, benefits, and other information.
Medication can relieve general AVM symptoms.
Endovascular embolization, a minimally-invasive treatment that blocks blood flow to problem areas, may be the appropriate treatment in some cases. To reach an AVM, a catheter (tube) is inserted through an incision in the femoral artery at the groin and threaded towards the brain. Your doctor will use fluoroscopy (a type of X-ray) to track the catheter through the arteries, up to the affected site. Once in position, a substance (such as balloons, coils or a fast-drying, glue-like material) is pushed through the tube and released into the enlarged space