AVM stands for arteriovenous malformation, which is an abnormal tangle of blood vessels in the brain or spinal cord. Normally, arteries carry oxygen-rich blood away from the heart to various parts of the body, while veins return oxygen-depleted blood back to the heart. Capillaries are tiny blood vessels that connect arteries to veins.
In an AVM, arteries and veins are connected directly without the usual intervening capillaries. This abnormal connection disrupts normal blood flow patterns and can lead to serious complications such as bleeding (hemorrhage), seizures, headaches, or neurological deficits, depending on the size and location of the AVM.