|
|
Arteriovenous malformation - cerebralDefinition A cerebral arteriovenous malformation is a congenital disorder (present at birth) of the brain's blood vessels. It is characterized by an abnormal connection between the arteries and the veins in the brain. Causes, incidence, and risk factors The cause of cerebral arteriovenous malformation (AVM) is unknown. The condition occurs when, in the brain, one or more blood vessels develop in which the arteries connect directly to the veins, without having the normal capillaries between them. Arteriovenous malformations vary in their size and location within the brain. There are often no symptoms until complications occur, which involve rupture of the AVM and a resulting sudden bleed in the brain. Sudden bleeding in the brain is known as a hemorrhagic stroke, which is essentially what occurs when an AVM breaks. In more than half of patients with AVM, hemorrhage from the malformation is the first symptom. Depending on the location and the severity of the bleed, the hemorrhage can be profoundly disabling or fatal. The risk of bleeding from an AVM is approximately 2-4% per year. The first symptoms often include headache, seizure, or other sudden problems, such as vision problems, weakness, inability to move a limb or a side of the body, lack of sensation in part of the body, or abnormal sensations. Symptoms are the same as for stroke. After a hemorrhage, there is a risk of developing epilepsy. If an AVM bleeds once, the risk might be greater that it will bleed again. Intracerebral (in the brain) or subarachnoid (around the brain) hemorrhages are common with cerebral arteriovenous malformation. In some cases, symptoms may also occur because of lack of blood flow to an area of the brain (ischemia), compression or distortion of brain tissue by large AVMs, or abnormal brain development in the area of the malformation. There may be a progressive loss of nerve cells in the brain caused by mechanical (pressure) and ischemic (lack of blood supply) factors. Cerebral arteriovenous malformations occurs in less than 1% of people. Although the condition is present at birth, symptoms may occur at any age. Hemorrhages occur most often in people aged 15-20, but can also occur later in life. Some patients harboring an AVM also have a cerebral aneurysm. Symptoms
Additional symptoms that may be associated with this disease:
Signs and tests A complete physical examination and neurologic examination are required to detect abnormal flow in vessels and any focal neurologic signs (weakness, numbness, language problems, visual problems). Tests that may be used to diagnose AVM include:
An EEG (electroencephalogram) may be performed if symptoms include seizures, but it will not identify the specific area of the lesion. On the MRI, it is important to rule out that the blood clot is not due to a tumor that has bled. Treatment A bleeding arteriovenous malformation is a medical emergency and requires immediate hospitalization. The goal of treatment is to prevent further complications by limiting bleeding, controlling seizures and, if possible, removing the AVM. Treatment is usually required. Open brain surgery, endovascular treatment, and radiosurgery are some of the treatments used. Often these treatment options will be used in combination. Very large AVMs may short-circuit blood flow enough to cause cardiac decompensation in which the heart is unable to pump enough blood to compensate for bleeding in the brain. In this case, the condition is usually identified in infants and young children. The risks of surgery depend on the accessibility and size of the malformation and the status of the patient at the time of surgery. Open brain surgery is the actual removal of the malformation in the brain through an opening made in the skull. It must be done by a highly skilled vascular neurosurgeon. Possible complications include brain swelling, hemorrhage, stroke, or seizure. Embolization (injecting a glue-like substance into the abnormal vessels to stop abherent blood flow into the AVM) may be an alternative if surgery is not feasible because of size or location of the lesion. Stereotactic radiosurgery may be another alternative treatment for inoperable arteriovenous malformations. It is particularly useful for small deep lesions which are difficult to remove by surgery. Diagnosis of a cerebral AVM may be made prior to a catastrophic hemorrhage because of recurrent headaches. Early diagnosis is preferable to diagnosis following a catastrophic hemorrhage, which can be fatal or severely disabling. However, since treatment can also be risky, treatment decisions must be made with great care for AVM. Anti-convulsant medications, such as phenytoin, are usually prescribed if seizures occur. Expectations (prognosis) The expected outcome varies. Approximately 10% of cases which have hemorrhage as the first symptom are fatal. Seizures and neurologic changes may be permanent or may resolve with treatment. Complications
Calling your health care provider Go to the emergency room or call the local emergency number (such as 911) if severe headache, vomiting, seizures, weakness or numbness of parts of the body, or other symptoms suggestive of ruptured arteriovenous malformation occur. Illustrations
Page Content: AVM - cerebral |
   |
