Different River

”You can never step in the same river twice.” –Heraclitus

January 5, 2006

Ariel Sharon’s Stroke

Filed under: — Different River @ 6:11 pm

When I first heard that Ariel Sharon had had a second stroke after the “mini-strokes” last month, and that the second was a hemorrhagic stroke, my first thought was that they’d put him on anticoagulants as a result of the mini-strokes, and they caused the second one.

Now, it seems that some doctors are saying the same thing. (I should have posted this two days ago; I’d have looked like a genius. But, a lot of good that would have done Sharon…)

You see, there are two kinds of strokes — and they are pretty much the opposite in terms of what happens and what causes them. An ischemic stroke is when a blood clot lodges in a artery in the brain, cutting off the supply of blood to the part of brain supplied by that artery. It’s basically the same as a heart attack, only the artery being blocked is in the brain rather than the heart. A mini-stroke is what they call a “transient ischemic attack” — a small clot that either dissolves by itself rather quickly, or blocks an artery that’s so minor the brain can sort of work around the damage. A hemorrhagic stroke — AKA, a cerebral hemorrhage — is the opposite — it’s when a blood vessel in the brain bursts and blood starts spilling all over the place, coming into contact with brain tissue it isn’t supposed be in contact with, and also causing pressure, since there’s not much room for swelling inside a hard container like the skull.

So, these two are opposites — an ischemic stroke is not enough blood where it’s supposed to be, and a hemorrhagic stroke is too much blood where it’s not supposed to be.

The main treatment for an ischemic stroke is to give anticoagulant drugs — drugs that dissolve clots, and prevent new clots from forming. If you’ve heard of that drug (tPA) that can stop a stroke, but only if is given within 3 hours of a stroke — well, that’s a drug that can dissolve blood clots. If it dissolves them fast enough, the severity of brain damage cause by the stroke can be reduced or maybe even eliminated. Someone who has an ischemic stroke — either a “mini-stroke” or a full-blown one — is normally put on milder anticoagulant drugs, such as warfarin (Coumadin®) for an extended period after the stroke, and perhaps indefinitely, to prevent a subsequent stroke. Warfarin works by inhibiting the blood from clotting.

And here’s the problem: Warfarin works on all your blood, so it slows clot formation all the time — not just when it would cause a stroke, but all the time. One of the effects of warfarin and other anticoagulants is that when you start to bleed (say, from a paper cut), you bleed longer since it takes longer for your blood to clot. And if you happen to start to bleed inside your brain, anticoagulants will prevent that bleeding from stopping, too.

In short, the same drugs that cure or prevent ischemic strokes can actually cause hemorrhagic strokes, or at least make them much, much, worse. And this isn’t really a side effect as such — anticoagulants make hemorrhagic strokes for the exact same reason that they cure, reduce, or prevent ischemic strokes.

People often wonder why people are not given tPA right away with they show up in the emergency room showing stroke symptoms. After all, could it hurt? Yes, it could — both kinds of strokes have similar or identical symptoms, so they have to do an MRI or CT scan or otherwise try to figure out whether the person is having a ischemic stroke or a hemorrhagic one — while if it’s ischemic, tPA could save the patient’s life, if it’s hemorrhagic, tPA could kill the patient or otherwise make the stoke a lot worse. And they have to do it very quickly, since tPA works much better when given sooner, and it loses its effectiveness rapidly after about three hours.

I’m not second-guessing the doctors here. I believe it’s standard practice to give anticoagulants to everyone who has an ischemic stroke unless there’s a known good reason not to, under the theory that if a person had one, they are susceptible and could have another. So, they probably did the right thing given the information they had at the time. I don’t know how common it is for the same person to be susceptible to both kinds of strokes, or if there’s any way to tell, or if it’s possible they misdiagnosed the events of last week. Perhaps a doctor reading this might be willing to leave a comment to clarify some of this.

Disclaimer: I am not a physician, and I don’t even play one on TV. Don’t take any of this as medical advice. If you think any of this applies to you, consult an actual medical doctor, not me. I do not guarantee that anything said about is true. I mean, I think it is, but I’m not a doctor so I might make a mistake, and I’m not licensed to guarantee it anyway.

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