Arteriovenous Malformation (AVM)
What Is It?
An arteriovenous malformation is an abnormal tangle of blood vessels that can form in the brain or spinal cord during development. This form of cerebrovascular disease is considered congenital, meaning that they are present at birth. Most do not present clinically until childhood or early adulthood.
An arteriovenous malformation is generally comprised of arteries that carry blood into a "nidus" of tangled, abnormal blood vessels which then drain directly to a vein. Because of the high flow of blood into the abnormal bed of vessels, many of them are prone to rupture and bleeding.
What Types of Symptoms Are Typical?
The symptoms associated with an AVM vary considerably from patient to patient depending on the location of the malformation, its size and whether it bleeds or not.
Some can present with seizures. Others present with focal neurological deficits such as weakness, for example, if it is located in the motor part of the brain.
Not infrequently, an AVM can rupture and bleed. Bleeding is typically into the brain tissue itself but can also bleed into the subarachnoid space around the brain or into the ventricles, the fluid-filled spaces within the brain. Depending on the severity of bleeding, symptoms can include sudden headache, seizures, or other neurological deficits which vary depending on the location of the hemorrhage. Very severe bleeds or bleeding into the brain stem can lead to a depressed level of consciousness or coma.
How Is The Diagnosis Typically Made?
When a patient presents with symptoms suggestive of an arteriovenous malformation, following a neurological exam, an imaging study such as a CT scan
or MRI scan
are often performed. MRI can show the abnormal tangle of blood vessels in many cases. CT is good for demonstrating any bleeding which may have occurred.
However, the best study to detect most AVMs is a cerebral angiogram. An angiogram entails placing a catheter into the blood vessels that bring blood to the brain. A contrast dye is injected and x-rays are taken. This makes the blood vessels visible on the x-ray. This procedure produces excellent images of the blood vessels in and around the brain and can clearly show most AVMs as well as other cerebrovascular disease such as a brain aneurysm.
What Are Some Common Treatments?
Treatment for arteriovenous malformation varies depending on several factors. Generally, symptomatic patients with an AVM in a surgically accessible region of the brain will be recommended to have surgery. In some cases, endovascular techniques are used to occlude some of the AVM from within prior to surgery. This type of treatment is generally not curative and requires surgery to complete the job.
The goal of surgery is to completely remove the abnormal blood vessels while preserving normal brain and normal blood vessels in the area.
A newer technique which can be effective for some arteriovenous malformations is using focused radiation, called stereotactic radiation therapy, to treat the malformation. Over the subsequent years the malformation will slowly involute and become occluded in some patients.
The treatment plan for AVM cannot be generalized as there are several variables which may make one option better for an individual patient. Patients with and AVM should discuss the appropriate treatment options with their own physicians.
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This site is not intended to offer medical advice. Every patient is different, and only your personal physician can help to counsel you about what is best for your situation. What we offer is general reference information about various disorders and treatments for your education.