AT A GLANCE BY SHELLEY FLANNERY 3 HOURS Stroke patients who get to the emergency room in less than three hours from symptom onset are less likely to have stroke-related disability three months later, compared with patients who waited to seek treatment. Call 911 right away. ISCHEMIC STROKE Blood unable to pass clot HEMORRHAGIC STROKE Blood leaks into the brain through a burst blood vessel INSIDE A STROKE Time is of the essence when it comes to stroke. But that doesn't mean these so-called "brain attacks" come out of nowhere. The disease process leading up to a stroke takes months, years or sometimes even decades to transpire. 44 W IN TER 2016 ILLUSTRATION BY THINKSTOCK Knowing what happens before, during and after a brain attack could help save your life