Cerebral arteriovenous malformation

A cerebral arteriovenous malformation ( zAVM ) (including intracranial arteriovenous malformation ) is a congenital malformation of blood vessels within the brain, in which the arteries are connected directly to the veins without intervening capillaries.

• 6.1 Surgical removal
• 6.2 embolization
• 6.3 irradiation

Anatomy

→ see Arteriovenous Malformation

Frequency

Cerebral arteriovenous malformations are very rare. Data on the frequency can only be estimated because not every AVM is clinically apparent and therefore many remain undiscovered. It is believed that about 0.05 % of the population have an AVM in the brain.

According to a 2003 study, the scientists even went out of only 0.01 % of the population and reported that about one million people would need to be examined comprehensively, for example, with an MRI on an AVM back to the assumed frequency of one AVM - carriers per 10,000 population demonstrated.

Risk

The greatest risk comes from a possible cerebral hemorrhage. Within the AVM blood flow is increased, the vessel walls are stretched thinner than usual and thus more prone to rupture. The result can be a life-threatening stroke.

Since the exact number of people with cerebral AVM is unknown, the information on the average risk of bleeding are also of limited value. The risk of hemorrhage is estimated to be 2-3% per year and will increase after an initial hemorrhage.

In a study in the New York metropolitan area, it was found that the risk of bleeding varies depending on various factors. The authors therefore suggest a new evaluation system for risk assessment of cerebral AVM, which stipulates that the risk between 0.9 % and 34.4 % per year can be, depending on the location of the AVM, the blutabführenden veins and a previous cerebral hemorrhage.

Symptoms

Not all cerebral AVM is clinically apparent. Often, the AVM is discovered after a stroke, accompanied by the symptoms described therein.

Cerebral AVM, who still does not cause cerebral hemorrhage, may be visible by symptoms of TIA, such as sensory loss, paresthesia, visual or speech disorders or unilateral paralysis. Cause is a deficiency of the adjacent to the AVM brain tissue. Due to the short-circuit connections within the AVM, the blood flows unrestrained immediately through the veins from which lacks natural resistance by the microscopic capillaries. This may be reduced in the surrounding brain tissue, the blood pressure and can lead to neurological deficits. Cerebral functions which are affected depends on the location of the AVM in the brain. Also, seizures and headaches can be symptoms of a cerebral AVM.

Diagnosis

For the diagnosis of cerebral AVM come in various imaging techniques are used. With the increased use of these techniques AVM are also more frequently discovered as an incidental finding.

Computed tomography / angiography

Computed tomography ( CT) or CT angiography uses X-rays and therefore also provides a low radiation exposure to the body represents the investigation takes a few minutes allows for a brain hemorrhage a quick assessment of the situation. Through the administration of contrast agent, the blood vessels and thus the cerebral AVM can be visualized selectively.

Magnetic resonance imaging / angiography

The resolution of the images is in magnetic resonance imaging (MRI ) or magnetic resonance angiography (MRA ) is slightly higher and thus more accurate. Especially accompanying changes in the AVM can be represented better. The method works with changing magnetic fields without radiation exposure for the patient and that it is recognized as a safer method. Because there is no radiation exposure, MRI is also preferably used in regular AVM follow-up after treatment. The tests usually take longer, sometimes up to an hour. Even with the MRI blood vessels can be better illustrated by the systematic administration of contrast agent.

Digital subtraction angiography

The most accurate and clearest evidence of a cerebral AVM and blood flow is possible at present only by a so-called digital subtraction angiography (DSA). It represents a medical procedure and is mainly performed in specialist clinics stationary for planning a treatment, or the final control. Here, a catheter is introduced, for example in the area of the inguinal region in an artery and advanced through the aorta to the heart by the arteries supplying the brain. There, dye is injected selectively into individual vessels under continuous fluoroscopic control, which are then clearly visible in the high-resolution images. By computer calculations bone, brain tissue and other parts of the image can be removed from the recordings. It creates an exact three-dimensional model of the cerebral vessels, especially the AVM. The procedure is as a treatment involves risks.

Treatment options

Due to the relatively high risk of bleeding is advised to treatment according to current medical knowledge in most cases. In assessing whether a treatment is appropriate, but also the age and condition of the patient play a role, for example. Goal of any treatment is basically the complete elimination of short-circuit connection, either by complete removal of the affected blood vessels, or by the closure of the blood vessels, as only then the risk of ( re ) cerebral hemorrhage can be ruled out. However, each treatment also brings great risks, which are weighed against the natural bleeding risk of cerebral AVM due to the delicate situation in the brain. The appropriate treatment method must be found individually in an interdisciplinary team of surgeons, neurologists, radiologists, etc. for each patient, with combinations of treatment methods are possible.

Controversial is currently the need for treatment at a cerebral AVM, which has caused no hemorrhage. The long-term clinical study ARUBA ( A Randomized Trial of Brain Arteriovenous malformations Unrupted ) to help identify the best approach here. Also, several German clinics involved for several years in the international survey. An interim analysis of the ARUBA study suggests that the risk of a first stroke for patients with non -treated AVM is less than in patients whose AVM was prophylactically by means of embolization, surgery or radiation treated. Due to the clearly increased risk of mortality and stroke risk in the group of treated patients, the study now had to be stopped prematurely. Thus, this study suggests the non-treatment of asymptomatic cerebral arteriovenous malformations.

Surgical removal

Whether a surgical removal of the question, is highly dependent on the size and location of the AVM. If necessary. can open skull surgery preceded by embolization. The Spetzler -Martin scale is to assist in the assessment of risk and the chances of success of an intervention surgeons.

Embolization

For embolization, known endovascular treatment, a catheter, similar to the DSA, such as the femoral artery, starting out into the brain. There is under continuous fluoroscopic control a kind of glue that " embolizate ", and occasionally small platinum spirals, injected, which cover the containers inside. The embolizate can consist for example of ethylene-vinyl alcohol copolymer. Complete obstruction of the cerebral AVM is often not possible by a sole embolization. Risky the procedure is, for example, because the embolizate can fall into the wrong blood vessels feeding the important areas of the brain. Embolization can be done either under general anesthesia or under local anesthesia, in one or more sessions.

Radiotherapy

The third treatment, the stereotactic irradiating the AVM, for example, with the gamma knife, or with a linear accelerator. It usually is a one-time irradiation. By irradiating the cells of the blood vessels mutate into the AVM. Enlarge gradually, which leads to the fact that close the blood vessels. This process is very slow and can take several years. During this time the natural AVM bleeding risk persists. The possible side effects of radiation also require regular follow-up examinations. Should not the AVM by the irradiation completely closed, a second irradiation may be necessary after several years, however, brings a higher risk of side effects.

Society and Culture

• The Musical Nervensache ( Oritinaltitel: A New Brain ) William Finn has processed his experiences as a patient and AVM - staged staged. German premiere was in 2008 at the Theater für Niedersachsen.
• In the American television series Six Feet Under - Died always (2001-2005) suffers from the series character Nate Fisher from a cerebral AVM. The series focuses on multiple psychological distress after diagnosis. The series character suffers in the final season due to the AVM a stroke and died a short time later.
• Cerebral AVM form the framework of individual episodes of various medical series Grey's Anatomy ( Episode 8), Hawthorne (TV series ) ( Episode 5 ) Royal Pains ( Episode 6 )
• In the English science fiction novel " Mind Scan" by Robert J. Sawyer of 2005, the main character suffers from an AVM, which moved him to one of the first test the patient to copy his consciousness into an artificial body and to assign all his personal rights to the copy.
• The American brain researcher Jill Bolte Taylor suffered a stroke in 1996 due to a cerebral AVM. Her autobiography All of a sudden (AKA My Stroke of Insight) is being filmed currently directed by Ron Howard. Taylor reported at the TED conference about your experiences during the stroke, the lecture is one of the most-watched TED talks.