The cause of Arteriovenous Malformation (AVM) is not known. AVMs are thought to be congenital (present at birth), and researchers believe that they may arise from developmental derangements at the embryonic stage of vessel formation (at the fetal stage). However, this theory has never been clearly established, and some researchers believe that AVMs may arise after birth. Unlike the association of head trauma, or other injuries with the development of dural arteriovenous fistulae (DAVF), there are no known environmental risk factors for AVMs. Most AVMs are termed "sporadic," which implies that they arise spontaneously without a specific gene mutation being passed on from parent to child. There is no clear familial inheritance, except in families with Heriditary Hemorrhagic Telangiectasia (HHT). HHT patients are at some 10,000 fold higher risk of developing a brain AVM than the non-HHT population.
What are pediatric AVMs?
Arteriovenous Malformations (AVMs) are abnormal tangles of arteries and veins. They can occur anywhere in the body, but our team specifically manages and treats those that are present in the brain and spinal cord. These abnormalities are typically congenital and are present at birth. They usually are not detected unless they cause seizures, weakness or have ruptured and bled in the brain. Neurologic or life threatening sequelae are associated with each hemorrhage. There is a 4% per year risk of hemorrhage once an AVM has become symptomatic. Treatment is required to reduce that risk and subsequent problems associated with additional hemorrhage. Treatment for AVMs can be quite complex and it is critical that patients with this disorder be managed and surgically treated in a center with extensive AVM experience.
Signs and Symptoms
Seizures
Nausea and vomiting
Persistent headaches
Weakness on one side of the body or stroke-like symptoms
Speech changes
Numbness or tingling of the arms or legs
Sudden loss of consciousness(with rupture)
Diagnosis
If your doctor suspects your child has an AVM, the doctor will do a complete exam and one or more of the following tests:
CT Angiogram-uses x-rays to produce multiple images of the inside of the body. This test uses X-rays to produce multiple images. These three- dimensional pictures of the brain can be used to further evaluate conditions that affect blood vessels within the brain.
MRI with Magnetic Resonance Angiography (MRA) — This procedure uses radiofrequency to create accurate two- and three-dimensional images of the arteries in the neck and brain.
Cerebral Angiogram – is a minimally invasive procedure which uses a special contrast, or dye, to observe blood flow in the brain. During the procedure, a small catheter is placed in a blood vessel in the groin, then it is used to reach the blood vessels that supply the brain. With the help of the special contrast or dye, an X-ray machine moves in different angles and takes pictures of the blood vessels. A team will care for your child throughout the procedure.
What is Hemorrhagic Telangiectasia? (HHT)
Hereditary Hemorrhagic Telangiectasia (HHT) HHT is a genetic disorder associated with small AVM (telangiectases) of the skin, nose, and GI tract, and larger AVM of the brain, lung or liver. The AVM in the lung and brain are treatable but because AVM can continue to grow/enlarge, patients need careful and continued monitoring. Once an individual with PAVM and most probably HHT is identified, the family should receive genetic counseling and screening.