Cerebral arteriovenous malformations (avm, cerebral vascular tangles)

What is cerebral arteriovenous malformation (AVM, Brain vein clump) and why is it important?

An AVM is an abnormal connection between an artery (artery) and a vein (vein). Normally, there is no bed between them, which we call capillaries. The transition between them is provided by abnormal and bleeding-prone diseased vessels, and they form a tangle.

The brain tissue in the center of the clump is not normal. Damaged or underdeveloped. It is especially important as it can lead to cerebral hemorrhage. The annual risk of sudden death after diagnosis is 1%, and a bleeding AVM has a very high risk of rebleeding.

What is the incidence of cerebral arteriovenous malformation (AVM, Cerebral vascular bundle)?

Cerebral AVMs are generally rare and are the most common of the vascular anomalies seen in the brain. Its incidence is about 2 per thousand. It is 5-25 times less common than brain aneurysms (bubbles). It is usually diagnosed before the age of 50.

Why do cerebral arteriovenous malformations (AVM, Cerebral vascular bundle) develop?

AVMs are usually congenital and can develop later. It is not known why the disease develops. As the brain grows, so do AVMs. There are no fully established risk factors associated with the formation, growth and bleeding of AVMs. It can occur anywhere in the brain and spinal cord.

What symptoms are seen in cerebral arteriovenous malformation (AVM, Cerebral vascular bundle)?

AVMs most often manifest themselves with cerebral hemorrhage. Sudden onset of headache, nausea, vomiting, loss of consciousness may be due to bleeding. Sudden death occurs in 10% of patients with bleeding. The mortality rate in the first hemorrhage is about 20-30%. Neurological problems develop in 30-60% of patients. The second bleeding is more dangerous than the first.

Other common symptoms are neurological findings such as epileptic seizures, loss of strength in the arms and legs, and speech disorder. There may be severe drug-resistant headaches with or without nausea-vomiting.

How can cerebral arteriovenous malformations (AVM, Cerebral vein clump) be diagnosed?

Unfortunately, most AVMs can be diagnosed after they bleed. The best diagnostic method is angiography performed by entering the artery from the groin. Since angiography is more invasive (difficult and painful) than other radiological imaging methods, a cross-sectional and angiographic diagnosis can be made with Computed Tomography (CT) and/or Magnetic Resonance Imaging (MRI) when AVM is suspected for any reason. Imaging findings are typical. It is easy to identify. After diagnosis with these methods, angiography is appropriate for determining and grading the characteristics of AVM and planning the treatment.

Should every patient with cerebral arteriovenous malformation (AVM, Cerebral vascular bundle) be treated?

The patient’s age, general condition, grade and location of the AVM are factors that affect the treatment. Elderly and patients with low bleeding risk may not be treated and only symptomatic treatment can be applied for the patient’s complaints.

How are cerebral arteriovenous malformations (AVM, Cerebral vascular bundle) treated?

Planning the treatment of AVMs should be done as a team. This team should consist of neurosurgeons, neurologists, anesthesiologists, radiotherapists and interventional neuroradiologists. Today, there are 3 options in the treatment of AVM: Surgery, radiotherapy (radiation therapy) and endovacular (through a vein) embolization by interventional neuroradiologists. There are a number of centers for all 3 treatment options. In addition to surgery and embolization treatment, all necessary equipment for radiotherapy (Gamma knife, stereotactic radiosurgery) are available in our hospital. While these treatment methods can be a separate option for any patient, a combination of them may also be required. In some cases, if the AVM is too large, no treatment may be applied.

Which treatment is more appropriate in cerebral arteriovenous malformations (AVM, Cerebral vascular bundle), in which condition and in which patient?

The aim of all treatment methods is to treat the AVM without any residual. The risk of bleeding increases 2-5 times in any treatment performed by leaving a residual.

Radiotherapy is effective in AVMs less than 2.5 cm in diameter and more centrally located. In this case, the improvement reaches 50-75% in the 1st year and 70-95% in the 2nd year. However, the healing process can take up to 2-3 years. This treatment option is especially suitable for residual AVMs that do not want surgical or endovascular treatment options and cannot be closed surgically or endovascularly. Although this treatment method can be applied in larger-sized AVMs, the chance of complete treatment decreases.

In patients presenting with bleeding, if urgent surgical intervention is required, the treatment of AVM is usually performed in a separate session, while treatment for bleeding is usually performed. The aim of surgical treatment is the complete removal of the AVM. In this method, the skull is opened and the AVM in the brain is directly accessed. Surgical option is appropriate in superficial and low grade AVMs. Surgical treatment is dangerous in large and deeply located AVMs.

How is endovascular treatment (through a vein) performed in cerebral arteriovenous malformations (AVM, Cerebral vascular bundle) and in which patients is it appropriate?

In recent years, it has been applied more frequently due to the development of imaging methods, catheter technology and more suitable embolizing (occlusive) substances. In this method, the skull is not opened, the treatment is performed under general anesthesia (as in surgical treatment) and accompanied by an angiography device. The nidus and feeder arteries of the AVM are occluded by embolizing substances (such as Onyx, cyanoacrylate) that begin to solidify when in contact with fluid and blood. Small AVMs that can be closed in a single session are fully treated, while slightly larger AVMs are combined with surgery. The embolized patient is given to the surgery without awakening and the dmar ball is removed.

The risk of bleeding increases in patients who are not fully closed in follow-up. It is also possible to partially treat AVM in patients with epilepsy, neurologic deficit (paralysis) due to stealing syndrome, or patients with concomitant aneurysm, which cannot be completely closed.

In patients presenting with emergency AVM bleeding, if it is not an aneurysm causing bleeding, it is appropriate to wait 1-6 months for endovascular treatment. If there is an accompanying aneurysm, treatment of the aneurysm can be done endovascularly without waiting, since the risk of re-bleeding is high.

How are patients treated for cerebral arteriovenous malformation (AVM, Cerebral vascular bundle) followed up?

Treated patients should be followed clinically and angiographically by whatever method. It is appropriate to control whether the AVM can be completely removed after surgery, to follow the healing process in patients receiving radiotherapy, and to follow up angiographically in terms of recanalization (recurrence) in patients treated endovascularly after 3-6 months at the beginning and then every 1-2 years.

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