The ABCs of stroke

It happens quickly. First there’s a sudden loss of vision in one eye. You find yourself unable to speak, you feel weak, or maybe experience a numbness or tingling in the face or limbs. Perhaps it’ll make its presence felt with a severe headache, accompanied by dizziness and a sensation of faintness.

Whatever the symptoms, chances are anyone encountering any of the above are in the midst of having a stroke.

Ranked fourth among the “killer” illnesses plaguing our society — and the leading cause of neurological disability — stroke claims the lives of an estimated 10,000 Canadians each year, permanently scarring the lives of a further 40,000. In fact, Canada’s more than 300,000 stroke survivors face a variety of problems ranging from extreme disabilities — severe brain damage amongst them — to minor defects such as slurred speech or partially frozen facial muscles. That’s not all: these survivors also risk a second potentially fatal stroke later in life. The disease also exacts a heavy toll from Canada’s already overburdened healthcare system. It’s estimated the average stroke patient requiring acute care costs taxpayers about $27,000 for hospital stays lasting up to 40 day But the spending doesn’t end there: toss into the mix the added expense of rehabilitation services, possible institutionalization, medications and lost wages and the bill for stroke soars. In fact, in Ontario alone, it’s estimated stroke is responsible for direct and indirect costs of close to $1 billion.

But it’s not all doom and gloom. According to the Heart and Stroke Foundation, Canada has in recent years witnessed an astonishing improvement in the mortality rates of stroke victims since the 1950s and 1960s. In the past 30 years, in fact, deaths from stroke have fallen by 50 per cent, a dramatic drop credited to improvements in treatment and increased awareness of preventative techniques.

What is stroke?

A stroke (also known as a cerebral infarct) is most often caused when a blood clot forms in an artery in or around the brain. Referred to as a thromboembolic stroke, these represent 70 per cent of all cases. A potentially lethal clot can also form elsewhere and be carried to the brain as blood circulates through the body, in which case it’s called an embolus. Equally devastating is a stroke caused by bleeding from an artery in the brain, known as an hemorrhagic stroke.

Often, brain tissue is injured or dies due to inadequate blood supply or because bleeding from a vessel destroys the surrounding cells. Starved of oxygen, nerve cells can’t work properly and so the body functions they control — memory, speech, vision and movement — become impaired. In the most severe cases, the entire flow of blood to the brain is cut off — similar to the effects of strangulation, drowning or cardiac arrest. With this type of stroke, if blood flow isn’t restored in a matter of minutes, death will occur.

Struck by stroke

According to Dr. Alastair Buchan, a neurologist at Calgary’s Foothills Hospital and Professor of Stroke Research with the Heart and Stroke Foundation of Alberta, the effect of a stroke could more aptly be referred to as a “brain attack.”

“The hallmark of a stroke is that it happens instantly,” says Dr. Buchan. “Its sudden appearance lead to its originally being referred to as ‘struck’ — one was struck by the associated symptoms quickly, without warning. There are even suggestions people were aware of it in biblical times. And in early literature, it was referred to as an apoplexy, which it’s still known as in French.”

While an awareness of stroke has been with us for centuries, it wasn’t until more recent times, says Dr. Buchan, that physicians developed an understanding of the condition.

“They were aware of hemorrhages in the brain through autopsy 120 years ago,” he says. “And they were aware of ischemic stroke at the turn of the century. We’ve learnt about blood clots in the brain far more recently, in the 1940s, and we’ve learnt how to prevent stroke in 1970s and 1980s.”

And the 1990s? “Now we’re really learning how to treat stroke,” says Dr. Buchan

Time of the essence

Today, the Heart and Stroke Foundation — along with specialists in the cardiovascular field — have adopted a motto they hope will help instil in the public a sense of the urgency necessary to successfully treat a stroke.

“One of the expressions we use is ‘time is brain’,” says Dr. Buchan. “A stroke is interrupted blood flow, and the brain’s a greedy organ requiring a lot of energy. Problem is, it doesn’t have any reserve. Therefore you lose consciousness within a second or two, and brain damage can occur within minutes — four or five at most — if the flow isn’t returned. If it’s just partial, a clot that goes to part of the brain, it takes about an hour to an hour-and-a-half before you start to get damage. But that damage continues to evolve.”

One of the worst case scenarios for stroke victims is when a transient ischemic attack (TIA), or mini-stroke, occurs. This happens when a blood clot lodges in the brain momentarily, then breaks up. During a TIA, the regular symptoms of a stroke will be experienced for periods of between 15 minutes and an hour before passing. Trouble is, if the clot doesn’t clear, the ischemia becomes extremely damaging and valuable time is lost.

“That’s why we want to get people into hospital immediately,” continues Dr. Buchan. “Those people experiencing a TIA that we treat most successfully get here within an hour, but we have good results with treatment when a patient gets to us within three hours. Generally, these are the people that recognize the symptoms, and who consequently stand the best chance of surviving with limited brain damage.”

Failure to receive treatment within these crucial first hours causes “the left side of the brain to basically whither and die,” says Dr. Buchan. “While young people can recover well — the other side of brain takes on some of its function — the older we get the harder it is for the brain to adapt. As a result, a damaged left side of the brain may leave a patient unable to speak and paralyzed.”

But as Dr. Buchan says, the key to reducing the likelihood of such devastating ocurrences rests not just with the speed with which patients are treated. Over the next few decades, millions more Canadians, young and old, will be touched by stroke. Many will die, and many lives will be permanently, distressingly altered. Yet many more will find that their greater awareness of stroke through education and understanding will prove a life saver, if not a brain saver.

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Dr. Ken Walker practises medicine in Toronto and also writes under the pen name of Gifford-Jones.—>