Arteriovenous Malformation

Understanding Brain AVMs

In a normally developed brain, arteries deliver oxygenated blood through progressively smaller vessels — arterioles and capillaries — before reaching the venous system. In an AVM, this capillary network is absent; high-pressure arterial blood flows directly into thin-walled veins that are not designed to withstand such pressure. Over time, the abnormal vessels dilate, the nidus may enlarge, and the risk of rupture increases. Each haemorrhage carries a 10–15 per cent mortality rate and a 30–50 per cent risk of permanent neurological deficit.

Even unruptured AVMs produce symptoms through a mechanism called vascular steal, where the high-flow shunt diverts blood away from surrounding healthy brain tissue, causing progressive neurological deficits and seizures. Treatment aims to completely obliterate the nidus, eliminating both the rupture risk and the steal phenomenon. Istanbul offers access to expert multidisciplinary AVM management, combining Gamma Knife radiosurgery with advanced endovascular techniques at a fraction of Western costs.

Symptoms of Brain AVM

Approximately 50 per cent of AVMs first present with intracranial haemorrhage, producing sudden severe headache, nausea, vomiting, and focal neurological deficits corresponding to the haemorrhage location. Seizures are the presenting symptom in 20–25 per cent of patients, particularly with superficial frontal or temporal AVMs. Chronic headaches, progressive neurological deficits from vascular steal, and pulsatile tinnitus are common in unruptured AVMs. An audible bruit over the skull or eye may be detected on auscultation in high-flow lesions.

Diagnostic Pathways

CT angiography (CTA) is the first-line imaging for suspected acute haemorrhage and can identify the AVM nidus and its arterial supply. MRI/MRA provides detailed anatomical localisation of the nidus and its relationship to eloquent brain regions. Digital subtraction angiography (DSA) remains the gold standard for AVM grading — the Spetzler-Martin classification (Size × Eloquence × Venous Drainage) determines the treatment strategy and surgical risk. DSA provides dynamic visualisation of arterial feeders, the nidus, and draining veins essential for treatment planning.

Advanced Treatment Options at Vellum Select

Vellum Select provides comprehensive AVM management through Prof. Dr. Türker Kılıç, integrating Gamma Knife radiosurgery, microsurgical resection, and endovascular techniques.

Gamma Knife Radiosurgery

For small to medium-sized AVMs (under 3 cm) located in deep or eloquent brain regions, Gamma Knife Radiosurgery in Turkey is the preferred modality. The treatment delivers precisely focused radiation to the nidus, inducing progressive endothelial proliferation and vessel wall thickening that leads to complete obliteration over 2–3 years. Obliteration rates reach 80 per cent at three years for AVMs under 3 cm. During the latency period, the rupture risk is not eliminated but is reduced, and patients undergo serial MRI surveillance. The procedure is outpatient, non-invasive, and international patients typically return home within 48 hours.

Microsurgical Resection

For superficial AVMs in non-eloquent areas — Spetzler-Martin grades I and II — microsurgical resection offers immediate cure. Combined approaches using pre-operative embolisation followed by Gamma Knife are employed for complex, large, or high-grade AVMs where single-modality treatment is insufficient.

To discuss your AVM diagnosis with Prof. Dr. Türker Kılıç, view his profile or contact Vellum Select to arrange a consultation.