What is an arteriovenous malformation (AVM)?

• A. Congenital deformity of tangled blood vessels in the brain.
• B. Acquired lesion from trauma.
• C. Benign tumor of the brain.
• D. Degenerative vascular disease of the heart.

Answer: (A)

An arteriovenous malformation is a congenital abnormality where arteries connect directly to veins in the brain, forming a tangled cluster of vessels and bypassing the normal capillary network. This direct high-flow connection makes the vessels fragile and prone to rupture, which can lead to intracranial bleeding, seizures, or neurologic deficits. AVMs are present from birth, though symptoms may appear later. The other options describe different conditions: an acquired lesion from trauma isn’t a congenital malformation; a benign brain tumor involves abnormal tissue growth rather than tangled vessels; and degenerative vascular disease of the heart affects the heart’s vessels, not the brain.