Nickolas: I don't know what I want to do after university what is topamax 100 mg used for A stroke occurs when the blood supply to the brain is interrupted, depriving it of oxygen. As a result, some of the brain cells die and others are damaged. Every year, some 10,000 people in Ireland suffer a stroke and 2,000 people die as a result. Thousands more are left with stroke-related disabilities.