Up to 24 hours. Tpa (alteplase) can be used by vein up to 3 hours (some patients 4.5 hours) after onset of stroke symptoms. Tpa (alteplase) in the artery can be used up to 6 hours after onset (up to 24 hours in basilar artery). See stroke. Org.
Thrombolysis. All strokes should get trombolysis within 3 hours, then the arterial system is studied to see which artery cause the stroke--- angioplasty could be done--- intraarterial clot busters could be used-- rehabilitation.