Tag: Anatomy

Stroke Symptoms, Part 2 – BE FAST

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I recently wrote a piece about the common symptoms of stroke, and how public awareness campaigns, as effective as they are, can leave a gap in the number of strokes they help to detect.

I’ve been doing more reading on this subject, and turning up some interesting results.

For years, the mnemonic F-A-S-T has been used to trigger us to recognize when someone may be having a stroke. Using this word, we should check the Face (is it drooping?), Arms (can you raise both?), and Speech (is it slurred?). “T” is for Time, as in don’t waste any before getting help.

Sounds good. But is it?

I mentioned in my previous piece that there’s more to the story. Why? Because F-A-S-T refers to ischemic strokes that occur in the carotid arteries. (There are two types of stroke: ischemic strokes, which occur when blood clots block flow in the arteries; and hemorrhagic strokes, which are associated with a rupture in a blood vessel.)

As a reminder, the carotids are the large arteries at the front of the neck. They account for about 80 percent of the total blood flow to the brain. In neurological terms, the carotids are the workhorses. And these are the arteries that, if they get blocked or damaged, can result in the symptoms noted above.

The balance of the blood flow to the brain is delivered in the vertebral/basilar artery system at the back of the neck. These arteries are smaller and they deliver blood to different parts of the brain. Not surprisingly, blockages in this network of arteries produce different symptoms. When vertebral blood flow is restricted, problems with balance and coordination of the eyes and the limbs can occur.

It has been recognized that a modified mnemonic would help detect strokes that occur in the vertebral arteries. BE FAST is already being recommended by some healthcare agencies as a more comprehensive trigger. Here, “B” is for Balance, and “E” is for Eyes (or ears). That makes sense to me, especially as I was having precisely those symptoms for weeks before I acted on it.

A study done by the University of Kentucky Stroke Center suggested that 14 percent of stroke patients were not identified using FAST. When BE FAST was applied, the proportion of identified strokes that were missed dropped to 4 percent.

In other words, more strokes could be caught if a wider screen were in use. Coincidentally, but maybe not, the number of strokes missed by FAST more or less matches the proportion of blood flow to the brain that originates in the smaller, but still important, vertebral arteries.

Another article I read recently on CNN Health addressed the different presentation of strokes between men and women. Interestingly, women may experience other stroke symptoms, beyond the parameters of even the broader, BE FAST, mnemonic.

Research summarized in the CNN article has shown that women may present with atypical stroke symptoms or symptoms that are more subtle and vague. In some cases, symptoms such as severe headache, generalized weakness, generalized fatigue, shortness of breath and chest pains, nausea and vomiting, brain fog, and even hiccups, may occur instead of or in addition to the symptoms noted above.

As to the reason why men and women experience stroke differently, scientists have come up with different theories. First, it’s about hormones. Age is another factor. There are other possible explanations too. I recommend reading the article to get the whole story.

It goes without saying that any symptoms that suggest a neurological problem should be acted upon immediately. No one ever needs to apologize for flagging a problem that may turn out to be nothing. It really is a case of being better safe than sorry.

As a final point, I’ve been spreading the word about stroke symptom cues when I speak to my running friends. There’s something appropriate about advising runners to BE FAST. After all, this should be an easy phrase for them to remember… it’s what they’re trying to do already!

A Brief Introduction to an Amazing System

Two main sets of arteries feed blood to the human brain. At the front of the neck are the left and right common carotid arteries. The common carotids divide into the external and internal carotids. The carotid arteries are big, as far as arteries go, at about six millimetres in diameter for the average adult, and they account for about eighty percent of the total blood supply to our brains.

At the back of the neck, we find the left and right vertebral arteries—the verts. These major arteries run from a point behind the collarbones, up and through the vertebrae in our neck, and into the back of the brain. The verts originate from a junction with the subclavian arteries, another pair of large arteries that deliver blood into the arms. The verts are smaller than the subclavians, at about three millimetres in most adults.

As I’ve mentioned before, I look at medical subjects from a strictly layman’s perspective. One aspect of the arterial system feeding the brain that I find fascinating is the amount of redundancy that is built into it. In most people, the left and right vertebrals do the same job. The two separate arteries meet up in the back of the skull to form the larger basilar artery. It is the basilar artery that supplies the remainder of the blood to the brain, about twenty percent of the total.

Redundancy extends further than just between the left and right vertebrals. It also includes connectivity between the two sets of arteries feeding the brain, the carotids and the vertebrals. At the base of the brain, where the various arteries come together, there is a circle of connections between the carotid and vertebral arteries. This arrangement of communicating arteries is called the Circle of Willis, named for Thomas Willis, an English doctor who discovered it in the seventeenth century. Several other arteries meet up in the Circle of Willis and then take blood away to other parts of the brain.

The reason for the Circle of Willis is quite simple and elegant. If any of the main arteries is blocked, or occluded, then the parts of the brain that depend on the blocked artery can still get blood supply. In other words, blood can flow around the circle to get to its destination by another route.

Not the Circle of Willis

There can be differences in each person’s arterial connections, and many people have an arrangement other than a textbook Circle of Willis. This is what a neurologist would refer to as an “incomplete Circle of Willis”. It doesn’t seem that having an incomplete Circle of Willis is necessarily a problem. Besides, there is no option to fix it, given the complexities involved. In other words, an incomplete Circle of Willis is likely something that would only ever be discovered in an autopsy.

So, why am I even writing about this?

I know from personal experience that having an incomplete Circle of Willis can lead to higher risks of stroke or other neurological problems.

Even if that weren’t the case, I look at this system from a chemical engineer’s perspective. And when I do, I can’t help but be fascinated by the perfection of the design for this most essential system.

Mine just doesn’t happen to be perfect.