Doctors have clearly been worried for a while now that Sen. Edward Kennedy, 76, of Massachusetts might suffer a stroke. Last October, they operated on the carotid artery on the left side of Kennedy's neck to clear the plaque that was building up inside it. The concern: that some of that arterial plaque might break off and form a clot in the Senator's brain, interrupting the flow of blood to his cerebrum. After the operation, he was probably also given aspirin or other medications to thin his blood and decrease the risk that he would form a clot.

So when Kennedy was hospitalized this morning on Cape Cod with "stroke-like symptoms," there was no time to waste. If he has indeed suffered a stroke — which is still not clear — then every second that blood flow to the brain was interrupted, the risk of serious neurological damage increases.

Most strokes are caused by clots. But they can also occur if there is bleeding directly into the brain. This second kind of stroke, called a hemorrhagic stroke, is the most difficult kind to recover from. The risk of a hemorrhagic stroke increases a bit if you are put on blood thinners. This is apparently what happened to Israeli Prime Minister Ariel Sharon, who was given blood thinners after he suffered an earlier minor stroke and is still in a coma. News reports have not indicated whether Sen. Kennedy is on medication to thin his blood.

There are three critical junctures at which you can get a sense of someone's prognosis after a stroke — within the first hour, within the first day or two, and within the first week. This is when the extent of the damage from a stroke starts to become apparent. It is also the time when there is the greatest risk of a second, even more severe stroke.

Word that Kennedy may have suffered one or possibly two seizures does not necessarily mean that he did not have a stroke. Seizures sometimes occur immediately after a stroke. Even people who have recovered from a stroke are more likely than folks who have never had a stroke to experience a seizure at some point in the following year.

On the other hand, living past the age of 60 also increases your chances of suffering a seizure that may or may not be related to a stroke. Seizures in older adults sometimes occur as a reaction to medication, to alcohol withdrawal or because of problems with the blood supply in the brain that hasn't yet risen to the level of a stroke.

In any event, given Senator Kennedy's medical history, it made sense to examine him more closely for signs of stroke. If the doctors at Massachusetts General Hospital in Boston — where Kennedy was airlifted from the Cape Cod hospital where he was first taken — can rule out a stroke, then they will begin looking for other possible causes for his seizures.

Any time you suspect a stroke, as Sen. Kennedy or someone near him must have, speed is important, and the symptoms to look for can be best remembered with the acronym FAST — for face, arms, speech and time:

Face: Ask them to smile and see if the face looks uneven.

Arms: Do they have trouble raising both arms equally in front of them?

Speech: Are they suddenly slurring their words?

Time: Any sign of stroke is a true emergency. Call 9-1-1, if it is available, or get immediate medical assistance.

— Christine Gorman is a TIME Magazine contributor and blogs about global health issues at www.globalhealthreport.com

http://www.time.com/time/nation/article/0,8599,1807445,00.html