THE ROLE OF VASCULAR ABNORMALITIES IN THE DEVELOPMENT OF ARTERIOVENOUS MALFORMATIONS

Arteriovenous malformation (AVM) is a congenital abnormality of the blood vessels in the brain, consisting of clusters of various shapes and sizes formed by the disorderly interweaving of pathological vessels. Typical AVMs have three main components: feeding arteries (AVM afferents), a cluster of altered vessels (the core of the malformation), and draining veins (AVM efferents). AVMs usually lack a capillary network, resulting in direct shunting of blood from arterial vessels into the superficial and deep veins of the brain. This vascular abnormality of the brain occurs in 0.01% of the population, more commonly in men, with peak manifestation occurring between the ages of 20 and 40. AVMs are diagnosed based on magnetic resonance imaging (MRI), but selective cerebral angiography is considered the gold standard. Vascular development occurs in two stages: vasculogenesis (the formation of blood vessels de novo in embryogenesis) and angiogenesis. Most genes and genetic risk factors play a role in the development of vasculogenesis, angiogenesis, and vascular remodeling.