The term “angioma” refers to a variety of vascular malformations. A cerebral arteriovenous malformation (AVM) is a vascular anomaly that occurs in the brain. Under certain circumstances, this tangle of blood vessels can rupture and cause a life-threatening brain hemorrhage. Here you will find further information as well as a selection of specialists and centers for the treatment of cerebral arteriovenous malformations.
A cerebral arteriovenous malformation is a specific type of blood vessel abnormality that falls under the category of angiomas.
An angioma is a blood vessel malformation that is either
. A specific vascular anomaly is the arteriovenous malformation (AVM), which is not actually classified as an angioma. An AVM is not a tumor!
If the AVM is located in the brain, it is referred to as a cerebral arteriovenous malformation (cAVM) or an intracranial arteriovenous malformation.
Hemangioma in a newborn © komokvm | AdobeStock
In a zAVM, the cerebral arteries are directly connected to the cerebral veins—that is, without capillaries (small blood vessels). This cluster of blood vessels is surrounded by healthy brain tissue. An angioma or cerebral arteriovenous malformation can occur in any region of the brain.
The vascular architecture—that is, the structure of a zAVM—is often complex. Due to the absence of capillaries, blood flows significantly faster. The blood vessels within the angioma are therefore subjected to high stress.
The vessel walls in a cerebral AVM are generally thinner, and for these two reasons, the blood vessels can rupture. As a result, a brain hemorrhage can occur, causing severe damage to the brain or leading directly to death.
A cerebral arteriovenous malformation is very rare. About 0.05% of the population has an angioma in the brain.
About 10% of patients with zAVM also have an aneurysm in the brain. The aneurysms usually form on the arteries that supply the angioma.
A small AVM is defined as one measuring less than 3 cm. A medium-sized AVM has a diameter of 3–6 cm, and a large AVM is larger than 6 cm.
Angiomas are generally classified into
A hemangioma is an embryonic tumor in which the cells lining the inside of the blood vessel (endothelium) proliferate. This leads to the formation of a new vascular cavity.
A lymphangioma is a benign tumor of the lymphatic vessels in which the cells of the lymphatic vessels proliferate.
An angiectasia is a dilation of a blood vessel, and a varicose vein is a knotty, dilated superficial vein.
In an arteriovenous malformation (AVM), the direct blood flow from an artery into a vein described above occurs.
Not every cerebral AVM causes symptoms. However, a cerebral angioma often leads to
Depending on the location of the cerebral AVM,
are possible. Since the natural resistance provided by the microscopic capillaries is absent, blood pressure in the surrounding brain tissue is reduced. This can lead to neurological deficits.
As mentioned, there is also an increased risk of a spontaneous cerebral hemorrhage. This can result in a life-threatening stroke.
The risk of a cerebral hemorrhage in individuals with a cAVM is 1–4% per year. The risk is higher if a cerebral hemorrhage has previously occurred as a result of a cAVM.
However, there are also studies that estimate the risk of hemorrhage from a zAVM to be higher. For example, an American study reports that it can range from 0.9% to 34.4% per year, depending on
A cerebral hemorrhage has the following symptoms:
A brain hemorrhage is life-threatening!
A cerebral angioma can lead to seizures. Possible causes of these seizures include
.
Due to the absence of a capillary bed between the artery and vein, blood flow is significantly increased. As a result, the surrounding healthy brain tissue is deprived of the blood it needs for normal brain function. This leads to chronic reduced blood flow and oxygen deprivation in the brain.
This impaired blood flow to the brain can lead to neurological deficits, such as
Neurological dysfunction, particularly of a more general nature, such as
may also be caused by increased pressure in the veins.
A cerebral arteriovenous malformation occurs in the blood vessels of the brain © peterschreiber.media | AdobeStock
Since cerebral angiomas are usually congenital, about 50% of cerebral AVMs are detected within the first 30 years of life. Cerebral AVMs that have not yet bled are often identified incidentally during an imaging examination.
However, a brain angioma may also be suspected when symptoms and signs point to a disorder in the brain. These include, for example,
If bleeding has already occurred, a cranial computed tomography (CT) scan is usually performed in the acute phase based on the symptoms. The CT scan often reveals small, atypical cerebral hemorrhages and, occasionally, blood in the subarachnoid space.
Such atypical hemorrhages are then examined in more detail using magnetic resonance imaging (MRI) to either confirm or rule out the presence of an angioma.
For the treatment of cerebral AVMs, it is important to understand the exact vascular anatomy within the angioma and the brain. This can be assessed using digital subtraction angiography.
Computed tomography (CT) of the head (cranial computed tomography, CCT) is an X-ray examination. During the procedure, the body is exposed to a low dose of radiation.
Since the examination takes only a few minutes, a CT scan can be used to quickly assess the severity of a brain hemorrhage. The blood vessels of the zAVM—and thus the angioma itself—can be visualized by administering a contrast agent (CT angiography).
Magnetic resonance imaging (MRI) takes up to one hour. However, the advantage is that the body is not exposed to radiation during an MRI. The quality of the image data obtained is also slightly better.
This allows for a more accurate visualization of complications primarily attributable to the angioma. Because it involves no radiation exposure, MRI is also the preferred method for follow-up examinations after treatment.
Magnetic resonance angiography (MRA)—which involves the targeted administration of a contrast agent—allows for better visualization of the blood vessels.
Digital subtraction angiography (DSA) provides the most reliable confirmation of a zAVM and visualization of blood flow. This medical procedure is a specialized form of angiography.
It is usually performed on an inpatient basis at specialized clinics either prior to treatment or as a follow-up examination after treatment. It is a catheter-based procedure.
The physician first punctures the femoral artery. Through the opening created, the physician guides the catheter past the heart via the aorta into the arteries supplying the brain. The target is the arteries supplying the angioma.
Under X-ray guidance, the doctor then injects a contrast agent into the vessels, making them clearly visible. The computer automatically removes bones, brain tissue, and other structures from the images.
This method can be used, for example, to determine
A cerebral AVM does not always require immediate treatment. In some cases, it is better to monitor the AVM initially. To do this, physicians must assess the risk and consequences of a potential brain hemorrhage. The lifetime risk of the cerebral AVM ever bleeding is about 50%.
After a thorough medical consultation regarding
, many patients today decide to undergo treatment. The risks also depend on the patient’s age and overall health.
Due to the relatively high risk of bleeding, doctors also usually recommend treatment.
However, some recent studies suggest a “wait-and-see” approach for asymptomatic zAVMs. Asymptomatic means that these angiomas do not cause any symptoms.
The goal of any treatment is to block the direct flow of blood from the arteries to the veins within the AVM. To achieve this, either the AVM is completely removed, or the vessels within the AVM—specifically the feeding and draining vessels—are occluded.
There are generally three treatment options available for angiomas.
In endovascular angioma treatment (embolization), the feeding and draining vessels are occluded, for example, using a special adhesive and, if necessary, small coils. The medical team inserts these into the angioma via a catheter.
In surgical angioma treatment, the angioma is completely removed, and the feeding and draining vessels are occluded.
In stereotactic radiosurgical treatment of hemangiomas (stereotactic radiation), the hemangioma is irradiated. This causes the vessels within the hemangioma to close off completely.
Since treatment is tailored specifically to the conditions within the angioma, not every procedure is suitable for every angioma. Doctors weigh the advantages and disadvantages of the individual angioma treatment procedures against their respective chances of success.
For certain zAVMs, a combination of different procedures is also necessary to occlude the angioma. It is crucial to discuss the options for angioma treatment with the patient in detail.
During embolization (endovascular angioma treatment), a catheter is advanced through an artery from the groin to the brain.
Under X-ray guidance, a special adhesive (embolic material) and, if necessary, small platinum coils are injected. This closes off the vessels from the inside.
Embolization is performed either under general anesthesia or local anesthesia. Multiple sessions may be necessary. In most cases, embolization alone cannot completely occlude a zAVM.
With embolization, there is a risk that the embolization material could enter the wrong blood vessel. This could block it, leading to damage to other areas of the brain.
Depending on the size and location of the zAVM, surgical angioma removal may be considered. Surgery is the best option for removing an angioma. However, not every patient is a candidate for this procedure.
If necessary, one or more embolizations may be performed preoperatively to reduce blood flow to the angioma. The goal is to achieve a reduction (downgrading) in the size of the angioma, which improves the chances of success for open-skull surgery.
The risks associated with surgical treatment of an angioma depend
Among other things, this can lead to
If smaller angiomas (2 to 3 cm in diameter)
making surgery impractical, radiation therapy can be performed using a Gamma Knife or a linear accelerator. Following stereotactic radiation therapy of the cerebral AVM, the cells of the blood vessels in the cerebral angioma undergo changes. They gradually enlarge and very slowly (sometimes over the course of years) occlude the blood vessels.
As long as the vessels within the angioma have not yet occluded, there remains a risk of bleeding from the cerebral angioma. If the angioma cannot be completely eliminated with radiation therapy, a second round of radiation may be necessary after several years.
About 70% of cerebral AVMs are completely occluded after 2 years; after 3 years, the figure is about 80%. Depending on
, side effects occur in about 2 to 3% of cases.
