BRAIN ARTERIOVENOUS MALFORMATIONS

Brain arteriovenous malformations (cerebral AVMs) are abnormal vascular masses that develop between cerebral arteries and veins. AVMs can cause neurological disorders such as brain hemorrhage, epilepsy, and weakness. AVMs can occur in one in every hundred people. While most are present at birth, they can develop later in life in some patients. They are usually diagnosed between the ages of 30 and 40. There is no significant difference in the prevalence between men and women.

How are AVMs diagnosed?

Unruptured AVMs can be detected incidentally during brain imaging studies performed for other reasons without causing any symptoms. The most common complaints in symptomatic AVMs are headache, weakness, nausea and vomiting, and neck stiffness due to the brain hemorrhage. In severe cases, coma due to the brain hemorrhage can occur. Death and disability rates are similar in 10-20% of AVM - related brain hemorrhages. Epileptic seizures are less common. 5-15% of patients complain of prolonged headaches before an AVM is detected. Scientific research has shown that the annual risk of brain hemorrhage after an AVM is detected is between 1-3%.

Patients presenting with severe headache and the symptoms mentioned above are initially subjected to a brain CT scan. If a brain hemorrhage is detected and its appearance suggests an AVM, a CT angiography (CTA) or magnetic resonance imaging angiography (MRA) may be performed. If symptoms persist in patients without a hemorrhage, a brain MRI may be performed in addition to CT scans, and AVMs can be visualized as vascular tangles within the brain tissue. As with all other cerebrovascular diseases, the most detailed evaluation and treatment planning for AVMs is achieved through cerebral angiography.

What are the treatment options for AVMs?

Different treatments are recommended for a patient diagnosed with an AVM, depending on the AVM's size, location, arterial and venous status, and whether the patient is experiencing bleeding. This treatment typically involves a combination of the following methods. For patients with small AVMs and suitable locations and vascular conditions, surgery alone, embolization, or radiosurgery may be considered.

Medical treatment: In cases where the risks of surgery and endovascular treatment outweigh the risk of bleeding from the AVM, medication may be used to address the symptoms alone. For example, in a patient presenting with epileptic seizures, anti-epileptic medications may be initiated and the AVM may be closely monitored.

Surgical treatment:

During the surgical approach, the skull is opened (craniotomy) and the AVM is excised. For the surgery to be effective, the entire AVM must be removed. Surgery almost completely eliminates the risk of bleeding if the entire AVM is removed, but depending on the characteristics of the AVM, complete removal can carry significant risks. For example, if an AVM is removed near the area of the brain that controls movement, the patient may experience weakness or paralysis on the opposite side.

Radiosurgery

In this treatment, specialized machines are used to apply focused radiation to the area of the brain where the AVM is located, sealing the vascular mass. Unlike surgical treatment, results are not immediate; depending on the characteristics of the lesion, the effects of the treatment can be seen within 1.5-2 years. Therefore, radiosurgery is generally used for small AVMs that have not yet bled or as a complement to surgery or embolization. While radiosurgery carries a low risk of late-stage bleeding and a much lower risk of developing malignant tumors.

Endovascular treatment

In an endovascular procedure, tiny microcatheters are used to access the vessels feeding the AVM in the brain from the groin veins, without open surgery, and the vessels are sealed with an adhesive liquid. While rare, this procedure, called embolization, can completely seal some AVMs. In most cases, embolization is used before surgery or radiosurgery to reduce the AVM's size and blood flow. Embolization makes cases that cannot be treated with surgery or radiosurgery alone suitable for these treatments. The main risks of endovascular treatment are stroke or brain hemorrhage due to blockage of normal blood vessels.