The American Stroke Association has made a major change to its recommendations for a first-line stroke therapy. The group's new guidelines, published online Jan. 24, 2018, by Stroke, say that instead of having just six hours from the onset of stroke symptoms to reach into a blood vessel, grab the clot, and pull it out, doctors now have up to 24 hours to perform the procedure (depending on the circumstances). The new recommendation will be helpful for people who suffer a stroke while sleeping and therefore don't know at what time the symptoms began. A thrombectomy may be combined with the other first-line treatment for stroke caused by a blood clot: a clot-busting drug called tissue plasminogen activator, or tPA. The treatment window to use tPA is just three to four hours, so it's imperative that you call 911 at the first sign of stroke symptoms. Those include the sudden onset of confusion, difficulty talking, weakness or numbness on one side of the body, or difficulty walking.