A scanning electron micrograph of a blood clot. Image credit: Steve Gschmeissner/Science Photo Library (http://www.sciencephoto.com/media/203271/enlarge#)
On Monday January 1st, I overheard my dad telling my mom how his left arm was numb and that he had no strength in his left hand. I immediately ran into the medicine cabinet, grabbed two aspirin, practically shoved them down my dad’s throat, and told him to get his coat. He was going to the ER.
As it turns out, my dad was having a stroke, which is basically the cessation of blood flow to an area in the brain. Luckily, my dad only suffered a very mild stroke, and after several days of monitoring and a battery of tests, he was released from the hospital.
While we are all relieved that he dodged what could have been a fatal bullet, I came to realize that there was only a superficial understanding of what was actually happening. So, to help demystify the process for my dad (and anyone else in this situation), I’ve decided to write a mini-guide on strokes. Below you will find some handy information about strokes, including what they are, as well as a glossary of relevant terms.
Why we need blood flow in the brain
Before I get into what happens to the brain when a stroke occurs, it is important to first understand why unrestricted blood flow in blood vessels in the brain is important. The brain is a type of tissue, and like all tissues in our body, it needs a constant access to nutrients and oxygen. Furthermore, tissues produce waste, and this waste needs to be removed.
The human cardiovascular system. Image Credit: Wikipedia.
Evolution’s solution to this problem is the development of a vast network of blood vessels existing within our tissues. For instance, take a good look at your very own eyeballs. Especially when we are tired, we can see tiny blood vessels called capillaries, which help to deliver key nutrients and oxygen, keeping our organs of sight healthy and happy. Now consider that this type of blood vessel network exists in all tissues in our bodies (because it does). Depending on the needs of the tissue, these vessels vary in size and number. Sometimes the blood vessels are large, like the aorta, and sometimes they are super tiny, like the capillaries in our eyes. However, all serve the same function: to make sure that cells can breath, eat, and get rid of waste.
When blood is prevented from traveling to a specific area within a tissue, the cells in that area will not get enough fuel and oxygen and will begin to die. For instance, the restriction of blood flow to the heart leads to the death of heart tissue, causing a heart attack. Similarly, the interruption of normal blood flow within the brain causes the affected cells in the brain to essentially starve, suffocate, and die, resulting in a stroke. The medical term for a lack of oxygen delivery to tissues due to a restriction in blood flow is ischemia. In general, the heart, brain, and the kidneys are the most sensitive to ischemic events, which, when occurring in these organs, can be fatal.
So, what exactly is a stroke?
Some strokes can be categorized as being ischemic. As mentioned above, an ischemic stroke occurs when blood flow (and the associated oxygen supply) is restricted in an area within the brain, leading to tissue death. A major cause of ischemic strokes is a progressive disease called atherosclerosis, which can be translated to mean “the hardening of the arteries.”
Severe atherosclerosis of the aorta. Image Credit: Wikipedia.
Affecting the entire cardiovascular system, atherosclerosis is the result of cholesterol build-up inside of our blood vessels, causing their openings to become narrower. These cholesterol plaques can eventually burst, leading to the formation of a blood clot. Ischemic strokes occur as a result of a blood clot, medically known as a thrombus, that blocks the flow of blood to the brain, a phenomenon often related to complications from atherosclerosis. A ruptured cholesterol plaque and resulting blood clot can occur in the brain, or it can occur elsewhere in the body, such as in the carotid arteries, and then travel to the brain. Either way, the blood clot will block blood flow and oxygen delivery to sensitive brain tissue and cause a stroke.
Strokes that result from the bursting of a blood vessel in the brain can be categorized as being hemorrhagic. In this situation, there may be a pre-existing condition rendering the blood vessels in the brain defective, causing them to become weak and more susceptible to bursting. More often than not, a hemorrhagic stroke is the result of high blood pressure, which puts an awful lot of stress on the blood vessels. Hemorrhagic strokes are less common than ischemic strokes, but still just as serious.
How do you know if you’ve had a stroke?
The symptoms of a stroke can vary depending on which part of the brain is affected and can develop quite suddenly. It is common to experience a moderate to severe headache, especially if you are hemorrhaging (bleeding) in the brain. Other symptoms can include dizziness, a change in senses (hearing, seeing, tasting), muscle tingling and/or weakness, trouble communicating, and/or memory loss. If you are experiencing any of these warning signs, it is important to get to the hospital right away. This is especially important if the stroke is being caused by a blood clot since clot-busting medicationsare only effective within the first few hours hours of clot formation.
Once in the hospital, the caregiver will likely give anyone suspected of having a stroke a CT scan. From this test, doctors will be able to determine if you had a stroke, what type of stroke you had (ischemic versus hemorrhagic), or if there is some other issue. However, as was the case with my dad, a CT scan may not show evidence for a stroke. This issue can arise as a result of timing (test performed before brain injury set in) or size of affected area (too small to see). When not in an emergency situation, doctors may also or instead choose to prescribe an MRItest to look for evidence of a stroke.
If a stroke has been confirmed, the next steps will be to try and figure out the underlying cause. For ischemic strokes, it is important to find out if there is a blood clot and where it originated. Because my dad had an ischemic stroke, he had to undergo a series of tests that searched for a blood clot in his carotid arteries though ultrasound, as well as in the heart, using both an electrocardiogram(EKG) and an echocardiogram(ultrasound of the heart). The patient might also be asked to wear a Holter Monitor, which is a device worn for at least 24 hours and can detect potential heart abnormalities that may not be obvious from short-term observations, like those obtained via an EKG. If a stroke is due to a hemorrhagic event, an angiogramwould be performed to try an pinpoint the compromised blood vessel.
A stroke you did have. Now what?
Once a stroke has been confirmed and categorized, the patient will most likely be transferred to the stroke unit of the hospital for both treatment and further observation. If a clot has been detected, a patient will receive clot-busting medications (assuming this detection occurs within several hours of clot formation). Alternatively, a clot can be mechanically removed with surgery (animation of clot removal, also known as a thrombectomy). Patients might also be given blood-thinning medications to either ensure that clots do not increase in size or to prevent new clots from forming. As for secondary prevention, meaning preventing another stroke from happening, patients might be given blood pressure and cholesterol lowering medications.
If a disability arises due to stroke, a patient might need to undergo rehabilitation. The type and duration of stroke rehabilitation is dependent on the area of brain that was affected, as well as the severity of the injury.
Major risk factors and predictors of stroke
There are many situations that could predispose one to having a stroke, and many of these conditions are treatable. The absolute greatest predictor of a stroke is blood pressure. High blood pressure, also known as hypertension, will significantly raise your risk of having a stroke. Other modifiable stroke risk factors include blood cholesterol levels, smoking, type 2 diabetes, diet, alcohol/drug use, and a sedentary life style. However, there are also risk factors that you cannot change including family history of stroke, age, race, and gender. But that shouldn’t stop one from practicing a healthy lifestyle!
In conclusion, strokes are no joke. I am glad that my dad is still here (yes, dad, if you are reading this, we are in fact friends) and that he escaped with relatively no real consequences. Let’s just not do this again, ok?
Anti-coagulants:These are medications that help to reduce the incidence of blood clotting. The repertoire includes aspirin, Plavix, Warfarin, and Coumadin. Also called blood thinners.
Atherosclerosis:Literally translated as “hardening of the arteries,” this condition is hallmarked by the build-up of cholesterol inside of blood vessels. Atherosclerosis can lead to many complications including heart disease and stroke.
Cardiovascular System: The network of blood vessels and heart that works to distribute blood throughout the body.
Carotid Arteries: Arteries that carry blood away from the heart toward the head, neck, and brain.
CT Scan: Cross sectional pictures of the brain using X-rays.
Echocardiogram:An ultrasound of the heart. In stroke vicitms, electrocardiography is used to detect the presence of a blood clot in the heart.
Electrocardiogram (EKG or ECG): The measurement of the electrical activity of the heart. It is performed by attaching electrodes to a patient at numerous locations on the body, which function to measure electrical output of the heart.
Embolic Stroke: A type of ischemic stroke, an embolic stroke occurs when a blood clot forms (usually in the heart) and then travels to the brain, blocking blood flow and oxygen delivery to brain tissue.
Hemorrhagic Stroke: A type of stroke that results form the bursting of a blood vessel in the brain.
Hypertension:High blood pressure, defined as having 140/90 mmHg or above.
It’s not easy being green. First, you have decide which green to be. (Source)
[We at Double X Science had been considering a "toxins" post but then found the following post by Jennifer Mo, a happily childfree vegetarian who lives in California with a cat named Brie but variously nicknamed Walnut "for her brain capacity" or Toxokitty for her history of toxoplasmosis--which, as it turns out, turns up in Jennifer's guest post, below. This post first appeared at Jennifer's blog, It's Not Easy to Be Green, where she writes about environmental issues as a "rationalist and a pragmatist." You can also follow Jennifer on Twitter @noteasy2begreen. We appreciated the pragmatics of this particular post quite a bit and thank Jennifer for allowing us to host it at Double X Science. We are particularly taken with the fact that she asks if we'd ever wanted to call our own brain a troglodyte.]
It’s a common demand from the public to scientists: prove to us something is safe before unleashing your monster on the world. And on one hand, it’s a totally fair, reasonable request to not be treated as lab rats. I get that. I hate the idea of having big chemical corporations profiting off their creations that create long term problems for ordinary people and the environment. On the other, whether you’re talking about GMOs or synthetic chemicals, it’s a problematic request for a couple of key reasons:
It assumes a binary between safe and unsafe without regard to exposure level or other circumstances. Just about everything can be harmful under the right (or perhaps I should say wrong?) conditions. Take water, for example.TonsContinue reading →
Stayin’ Alive. The heart is a muscle that must beat in good timefor you to remain alive.
Cardiac deaths reach their peak during December and January, the experts say, and it’s important for anyone to know what to do in the event of either experiencing a heart attack or witnessing one. Below is a post that initially appeared at The Biology Files, but given the season, we think it’s important information to have front and center.
Last spring, a man who had come to our house to deliver a box for storage/moving died of a either a heart attack or sudden cardiac arrest in the street in front of our home. The story of what happened with him and our response is available here. What I’d like to blog here is simply a health warning of sorts, an alert for anyone who reads this in the hope that maybe that one person can avoid an early, sudden death like this one.
The man who died was only 56. But from what we experienced, he had at least three of the risk factorsfor having heart disease:
·he was male
·he was over age 45
·he had central obesity
I’d infer from his physical condition that he likely also had another risk factor, a sedentary lifestyle. Even though his work had been for many years delivering these boxes–with a smile and a lovely friendliness, I add–it was not necessarily physically demanding work, as it primarily involved using a forklift to load and unload the crates.
The thing is, I learned from one of his co-workers that he had come in the previous day complaining about feeling unwell in an odd, indescribable way and of unusual fatigue. I wish–I’m sure everyone who knew him wishes–that he’d taken that as a sign to get checked out. With his risk factors, it would have been a reasonable thing to have done.
Complicating his situation was the fact that he had asthma. The symptoms of an asthma attack and of a heart attack can seem very similar and difficult to tease apart. The key distinction seems to be that asthma doesn’t involve a feeling of chest pressure, and a heart attack does not respond to the use of inhaled asthma medication.
Add to that that his asthma may also have been a risk factor for heart disease, and you’ve got someone who had four or five risk factors for a heart attack. He was certainly a good candidate for a full health workup had he presented the previous day with his symptoms of “not feeling quite right” and “fatigue” and his risk factors.
His death was a terrible loss for his family. It’s also terrible to think that recognition of some of the risk factors compounded by what may have been some warning signs went unheeded and ended in this loss. These issues aren’t close to my heart only because this man died at our home. My grandfather also died at a relatively young age and without warning, lying in bed, reading a news magazine. He also had a number of risk factors for heart disease, including a family history, smoking, and other lifestyle factors. His visits to the doctor were few and far between, and he likely had never had a workup for heart disease. The night before he died in his bed, he’d complained about not feeling quite right, an upset feeling in his stomach. And then he…just died.
Everyone is going to die. Obviously, we can’t get away from that. But an awareness of risk factors and of lifestyle factors you can modify can mean the difference between dying suddenly and all too young or dying in your sleep at a grand old age with your life in order and some expectation that Death is on its way.
·Discomfort in the torso/upper body (this is what my grandfather had)
·Shortness of breath
Because this is Double X Science, we note that heart attack symptoms in women can differ from those in men. There is some overlap, including feeling strangely fatigued, something like indigestion, anxiety, dizziness, shortness of breath, and weakness. Women may also experience sleep disturbance, arm weakness, and indigestion more than men do, while not showing what have been considered the classic chest-gripping signs of a heart attack.
Another form of sudden death related to heart problems can be sudden cardiac arrest. We were told that the man who died did so of a heart attack, but I’m not sure if that was a term arising from a layperson’s understanding or because that was the final medical determination. A sudden cardiac arrest results from electrical misfiring in the heart muscle. It differs from a heart attack, which results from blockage of blood flow to the heart so that the heart tissue dies. Either can cause sudden death. The fact that he may have been having some sort of prodrome the previous day could have indicated either. If he was fibrillating, he also would have felt “odd” and “fatigued.”
Some things about what happened make me think that the man who died may have experienced sudden cardiac arrest. He was unresponsive and not breathing when we found him, and after the EMTs arrived, they continued the CPR we’d begun and tried de-fib on him three times. Given these factors, it sounds to me as though he’d had sudden cardiac arrest, rather than a heart attack. The risk factors for the two are similar. And the outcome in this case, regardless, was death.
Finally, there is the matter of what a bystander can do who finds themselves in our position. Call 911. Push hard and fast. Someone had already called 911, so we immediately began chest compressions. No mouth-to-mouth is necessary. Further, the compressions really need to be deep enough. In essence, you are trying to be the heart for the victim, to imitate what the heart, a powerful, muscular pump, would be doing.
So, the current response to a sudden cardiac death is pretty simple: Chest compressions only, 100 times a minute. Count them out loud as you go. It’s a fast clip. Some people recommend doing it to the beat of the Bee Gees’ song, Stayin’ Alive, if you’re familiar with that. For more information on what you can do in an emergency situation like this one, see the Red Cross guidelines (pdf). Learning these may someday help you save a life, in any season.
On using the Stayin’ Alive technique (amidst many other story threads and information), from RadioLab:
Here’s a video of comedian Ken Jeong demonstrating the hands-only Stayin’ Alive technique. The basics: Call 911. Push hard and fast.