  so there are three types of strokes: hemorrhagic, thrombotic, and embolic. hemorrhagic occurs when a vessel bursts and all the downstream tissue is no longer receiving oxygen; not much you can do for it in terms of treatment. thrombotic occurs when a vessel clots off and all the downstream tissue no longer receives oxygen; embolic occurs when a piece of matter (be it a blood clot or a chunk of bacteria) breaks off from some point in the arterial system and lodges in a smaller vessel, causing blood flow to stop to that area of the brain, depriving it of oxygen.
the nice thing is that there is a treatment for thrombotic and embolic strokes. which is what i saw yesterday. a woman was in the cardiac catheterization lab getting worked up for her heart issues when we got called in after the cardiologists noticed she wasn't moving her right side at all (arm and leg were not moving, right side of her face was drooping and she wasn't able to speak) for the past five minutes after the procedure.
however, since she was under sedation for the cardiac catherization, the last time anyone saw her move her right side was before the cardiac procedure... over an hour before. so potentially she's had this difficulty for close to an hour and a half, and the one treatment we have for stroke can only be used in the first 3 hours of a stroke. so one of the other med students and i ran her down to the CT scanner to make sure she's not bleeding in her brain (we were trying to rule out a hemorrhagic stroke... if it was a hemorrhagic stroke, then we couldn't do anything for her), and we see that she's not bleeding... so we can give the tPA (i.e. tissue plasminogen activator... dissolves blood clots). we finally get her up to the ICU, by now it's been 2 hours since she was last seen normal, and we finally get the tPA injected into her (you give 10% of the dose immediately followed by the remainder infused over the next hour). about a half hour into the infusion, she starts talking and moving her arm... amazingly she recovered function right on the spot. you might be thinking, "amazing? why is this amazing? treatments always work. " BULLSHIT. head CTs and MRIs can miss 10% of head bleeds, so she could very well have had a hemorrhagic stroke but we could have been unable to see it on the scan.
and not all of the other types of strokes are caused by blood clots... if she had bacterial endocarditis (a type of heart infection), a clump of bacteria could have broken up and lodged in a vessel thus causing her symptoms. and tPA would have been pointless against it. plus the time frame... we got very lucky in terms of her time frame. most stroke patients show up to the hospital over 3 hours past the onset of symptoms. which is why tPA can only be used in 10% of stroke patients at the hospital.
besides, all medical treatments are a statistical treatment. all we know is that whatever treatment you're given, be it tPA, antibiotics, surgery, whathaveyou, that treatment worked better than placebo. and that's it... that's why not every treatment works for everyone, and the public has a hard time understanding that concept... it's also a huge reason why doctors get sued so often for unfavorable outcomes. so i'm astounded at how quickly she recovered, and i hope she's doing well today... 
