What is a cerebrovascular malformation? Patients and families are often confused after receiving such a diagnosis. In fact, we can make a common analogy: the arteries of the normal brain need to be connected to the veins through capillaries, which is like the current starting from the fire wire and then need to pass through the fluorescent lamp and then connect to the ground wire. If there is no fluorescent light, connecting the fire wire and the ground wire directly will cause a short circuit and cause problems. Simply put, a cerebrovascular malformation is a short circuit between artery and vein when the capillaries are missing and the artery and vein are directly connected to each other, that is, there are many ground fistulas between artery and vein. So, what are the dangers of cerebrovascular malformation? First of all, when the artery and vein are short-circuited, the blood flows away from the fistula due to the low resistance of the fistula, which is called “blood theft” in medical science, so that the normal brain tissue does not get enough blood supply and becomes ischemic and malnourished. Secondly, the artery is directly connected to the vein, so the pressure in the vein is raised, and as a result, the blood flow is not able to flow smoothly into the vein after it has nourished the brain tissue, causing the brain tissue to stagnate, which also causes the actual blood flow to the brain tissue to drop and the brain tissue to become undernourished. Worse, sometimes the high blood flow and pressure in the vein behind the fistula can cause backflow in the vein. Since the vein wall is very thin, this can very easily cause the vessel to rupture and bleed. Finally, when the malformation occurs, the intravascular pressure and flow are very high. Long-term high pressure and flow can also cause aging and degeneration of the vessel, resulting in dilatation and stenosis, and eventually the vessel becomes overloaded and bleeding occurs. Common symptoms of cerebrovascular malformation include headache, numbness and lack of strength in hands and feet, cramps, and in serious cases, cerebral hemorrhage. Therefore, after cramps or cerebral hemorrhage occur in young people, it is important to check the cause, otherwise, it will cause missed diagnosis.