Brain arteriovenous malformations – AVM
Cavernous angiomas of the brain
A cerebral angioma or venous angioma is a congenital anomaly of the cerebral blood vessels. Venous angioma refers to an arteriovenous malformation - AVM, which can occur in any part of the brain.
Symptoms of brain angioma
The symptoms of a brain angioma depends on the location and size of the angioma, but the characteristic signs of a venous angioma are:
- Bleeding - 50%
- Epileptic attacks and convulsions - 30%
- Neurological disorders such as limb weakness, nausea and vomiting, dizziness, taste, visual or speech disorders - 15%
- Non-specific symptoms such as headache and migraine are seen in about 3-5% of cases
Most often, brain angioma does not manifest itself in any way and remains undetected for a long time. Typically, a brain AVM is discovered accidentally when a magnetic resonance imaging (MRI) or computed tomography (CT) scan of the head is performed for other reasons.
The first symptoms of angioma appear in teenagers and young adults and about 50% of angiomas are diagnosed by the time the patient is 30 years old, most often after a bleeding episode.
The incidence is about 1.5-1.8 cases per 100,000 people. The risk of cerebral bleeding for patients with arteriovenous malformation is 1-3% in each year. If the angioma has already caused bleeding several times, the risk of hemorrhage increases significantly. Approximately 10% of patients are found to have a combination of angioma and aneurysm. These aneurysms are almost always located on the arteries that feed the angioma with blood (feeder).
Classification of arteriovenous malformations
Since 1986, angiomas have been classified according to the Spetzler-Martin scale, which categorizes brain AVMs into 5 stages. The classification takes into account size, localization, and type of venous drainage. Angiomas smaller than 3 cm are considered small, medium-sized angiomas are 3-6 cm in diameter, and large angiomas are larger than 6 cm.
The next evaluation criteria are the location of the lesion in relation to functionally significant (eloquent) brain areas and the type of drainage (deep or only superficial veins).
According to the Spetzler-Martin scale, angiomas less than 3 cm in size, located not in the eloquent zone, with superficial veins, belong to stage 1.
Angiomas larger than 6 cm, located in the eloquent zone, with deep veins, are stage 5.
How is angioma diagnosed?
If bleeding has already occurred, it is usually diagnosed with a computed tomography (CT) scan. It is not uncommon to see small hemorrhages in the brain and surrounding subarachnoid space. Often, pathologic vascular structures may be seen in the area of hemorrhage (on CT with contrast). In any case with hemorrhage, a control MRI examination should be performed to exclude the presence of an angioma.
Once an angioma is diagnosed in the brain, digital subtractive angiography (DSA) is the most effective diagnostic method for choosing further treatment tactics. This method allows a detailed analysis of the vascular status, detection of related vascular pathologies and a detailed examination of the angioma.
Digital subtractive angiography is performed using a special angiographic catheter that is passed through the blood vessels into the area of the suspected angioma. Upon reaching this area, a contrast agent is injected. The obtained images provide comprehensive information about the shape and location of the angioma, help to find the artery feeding it (feeder). Only after the exact location, feeding vessels and draining veins of the malformation have been identified, the optimal treatment can be planned.
How do you treat a angioma?
Whatever type of cerebral angioma you have, treatment is to stop the blood supply completely (complete occlusion). There are three ways to achieve this goal:
- Surgical Treatment
- Embolization (a combination of several methods)
- Radiation Therapy
Treatment of cerebral venous angioma requires an exact analysis of the vessels feeding it, the size and location of the malformation. When choosing a treatment method, it is also necessary to consider the patient's age and previous symptoms (hemorrhages, seizures or asymptomatic course of the disease).
In each case, a treatment will be proposed that considers the patient's current situation and is the one with the lowest risk. It is important to understand that partially removed or partially embolized brain AVMs usually retain the same risk of bleeding.
Surgery
If an angioma that is located on the surface or even deep in the brain can be completely removed by surgery, surgical treatment should be preferred.
Surgery to remove an arteriovenous malformation should be performed in certified neurosurgery centers. Contact us for an appointment:
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Vascular embolization
When the blood supply to a tumor can be reduced or completely cut down by catheter embolization, this is attempted prior to surgery. Vascular embolization is a procedure that uses the insertion of a small vascular catheter to block a vein or artery that supplies blood to an angioma. This sometimes requires several procedures at intervals. Embolization can achieve a reduction in the size of the angioma, which makes surgery easier.
Radiation therapy
For small angiomas with a diameter of 2 to 3 cm located, for example, in the basal ganglia, thalamus or brainstem, radiation therapy is suggested as the main treatment method.
Cavernoma of the brain
A cerebral cavernoma or cavernous angioma is the term used to describe small, usually solitary vascular malformations. A cavernoma looks like the fruit of a mulberry tree. Typically, these small vascular nodules range in diameter from a few mm to 2 cm.
Larger cavernomas are quite rare. They begin to manifest themselves with small hemorrhages or cramps, but also often do not cause any clinical symptoms and are found incidentally during MRI diagnostics.
Approximately 30-40% of these vascular nodules are located in the medial structures of the brainstem. The risk of bleeding is about 1% per year.
Cavernomas belong to diseases with genetic predisposition. There have been cases of several family members with one or more cavernomas. However, it has been shown that cavernomas can occur in regions of the brain in which they have not been found before.
Cavernoma diagnosis
The most effective method of examining cavernomas is magnetic resonance imaging (MRI). Special MRI protocols can detect bleeding caused by a cavernoma even without any clinical signs of hemorrhage.
On screening, it is often possible to detect a embryonic vein that is close to the cavernoma but not related to it. Such a vein should be preserved during surgery when the cavernoma is removed. If even cavernomas cannot be visualized by angiography, it is helpful to get images of the cerebral vessels preoperatively, as smaller angiomas are often located near cavernomas.
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Treatment of cavernoma
Treatment methods for cavernoma are selected depending on the localization, symptoms and age of the patient and include two options:
- Surgical removal of the cavernoma - if it can be performed without serious neurologic consequences
- Observation - if the formation is located in an inaccessible region of the brain or the disease is asymptomatic
Radiation therapy for cavernomas is not recommended.
Blocking blood flow through the vessels, as is done with angiomas, is not possible because cavernomas are not visualized by angiography.
Surgical resection of cavernous angiomas is performed microsurgically using neuronavigation or stereotactic targeting. This method allows safe removal of venous malformations as small as a few millimeters.