When a stroke hits, brain cells perish at an alarming rate. The faster a patient gets treatment, the less likely it is that he or she will suffer permanent damage.

But to pick the right treatment, doctors must find the underlying cause of the stroke fast.

Most strokes occur when a clot blocks blood flow in the brain. For the best results, treatment of those strokes with clotbusting drugs should start less than 90 minutes after onset.

http://www.npr.org/blogs/health/2014/06/16/321628040/microwave-helmet-could-diagnose-strokes-as-patients-ride-to-hospital