AVM in brain
Very small, less than 1 in 1, 000, but it happens.
In most of the people who have them, they don't know it because they're not having any symptoms. These are the kinds of things the mris discover when they are performed for some other reason like headaches, or skull injury. If they're not causing any symptoms, don't worry about them. Treatmen(surgery) can be worse than the condition.