Once you start to have symptoms of stroke there's only a tiny window of time for  you to get life-saving treatment. Now, research from Stanford School of Medicine has cracked that window open a little bit wider.

 If a patient arrive at the emergency room more than three hours after experiencing  stroke symptoms current  guidelines say  a potent clot-busting medication that could save brain tissue should not  be used.

But Stanford's new study suggests the traditional three-hour time window is too short. By combining data from  several clinical trials researchers showed that treatment can benfiti patients up to four anf a half hours after they experience their first symptoms . You can read more about the findings in the Journal Stroke.

In addition Stanford is using a specially developed software program called RAPID that can immediately determine the best course of  treatment and whether a patient would be a good candidate to receive treatment after the traditional three hour window.

Experts estimate that roughly 15 percent of patients at Stanford come in during the three- to 4.5-hour time window. Nationwide 680,000 stroke victims a year  arrive at the hospital  three hours after first symptoms.