Cerebral arteriovenous malformations: neurosurgeon explains the risks, diagnosis, and treatment options

Cerebral arteriovenous malformation (AVM) is a vascular anomaly characterized by abnormal connections between arteries and veins, bypassing the normal capillary network. This abnormal vascular architecture allows blood to flow directly from arteries into veins, exposing the venous system to increased blood flow and hemodynamic stress. Over time, these changes may contribute to vascular complications, including intracranial hemorrhage.

In addition to bleeding, which can be fatal in severe cases, an AVM can cause persistent headaches, seizures, weakness or loss of sensation in specific parts of the body, vision changes, and cognitive impairment. “The clinical manifestations depend on several factors, particularly the location of the malformation, its vascular characteristics, and whether bleeding has occurred. Some patients remain asymptomatic for decades, while others may develop seizures, neurological deficits, or intracranial hemorrhage.” Explains neurosurgeon Feres Chaddad, Associate Professor with a habilitation in the Department of Neurology and Neurosurgery at the Paulista School of Medicine – Federal University of São Paulo (UNIFESP); Head of the Vascular Neurosurgery Division at Hospital São Paulo / UNIFESP; and Head of the Neurosurgery Division at BP – Beneficência Portuguesa de São Paulo.

Diagnosis is usually made through imaging tests, either after the appearance of symptoms, such as seizures and hemorrhages, or from incidental findings during routine consultations. Among the main methods are computed tomography (CT), magnetic resonance imaging (MRI), and cerebral angiography. “Digital subtraction angiography remains the gold standard for evaluating cerebral AVMs because it provides detailed information about their vascular architecture, including feeding arteries, the nidus, venous drainage, and associated vascular abnormalities. These findings are essential for treatment planning,” explains the specialist.

With these results, it is possible to assess the risk of bleeding and define the best treatment strategy, which depends on the characteristics of the lesion, since there is no medication capable of curing an AVM. “Treatment strategies include clinical observation, microsurgical resection, endovascular embolization, and stereotactic radiosurgery. The decision depends on the patient's clinical condition and the anatomical and hemodynamic characteristics of the malformation,” Chaddad says.

“Microsurgery may provide immediate and definitive treatment when complete resection is feasible. Embolization involves introducing a catheter into the cerebral circulation to deliver materials that occlude abnormal vessels and may be used alone in selected cases or in combination with other treatments. Radiosurgery delivers focused radiation to induce gradual closure of the malformation, particularly in selected small or surgically challenging AVMs,” details the neurosurgeon.

The choice between treating or simply monitoring an AVM depends on several factors: the patient’s age, the location of the malformation, history of bleeding, and the risks associated with each approach. “Cerebral AVMs are not tumors, and many patients may live for decades without symptoms. However, the risk of hemorrhage varies considerably depending on the characteristics of the malformation and the patient's clinical history. The most important decision is not simply whether to treat an AVM, but whether the expected benefits of intervention outweigh its potential risks. For this reason, every patient should undergo an individualized evaluation by a specialized cerebrovascular team,” Feres Chaddad concludes.