damage today from bechtolsheim also owns hundreds of hectares of forest nearby and regularly invites business acquaintances for hunts that'll say many of the trophies are mine but several also come from my father some from my great grand uncle leopard down there I didn't shoot him that was my great grand uncle and then my dogs chewed off his ears so he no longer has his former


beauty but he's too precious not to keep as we're sharpen a recurring topic in the special issues of the manager magazine are the super-wealthy snit works this gift goes alongside there are larger and smaller networks and there are a lot of them and most even we journalists don't know about in high society there are certain typical hobbies horse racing hockey okay a bit

Germany: The discreet lives of the super rich | DW Documentary


of tennis though that's almost old-school he'll meet in the boxes at major football stadiums because of course they're all football fans and football is huge of that a lot of networking happens there that's like their marketplace they mingle and meet there more than its so-called parties for the rich as of zuga nantan i [Applause] Dork oh yeah good we always have a lot of employees here


we have a lot of friends in the box because Jim Pfeifer is here today Germany's most famous criminologist sometimes you live for someone from politics comes by Christian Wulff and Bettina are part of my close circle of friends so there's always lots going on here [Applause] in villain avinash allah is opening a new club a new branch of his fitness empire shallow also has become a member


in the network of important people from the sports business and entertainment industries true it's a closed circle that's hard to get into sure money attracts success and success attracts money I do believe that I've experienced myself how you can suddenly connect with people previously out of reach I am in a different position the hot scene at Bouchon field for independence


[Applause] Derk horseman is ready to leave his box he wants to celebrate the victory with his friend the Berlin air and hearing aid company owner Martin Kent Kent is also co-owner and president of Hannover 96 his box is located on the other end of the exclusive VIP area I told you we'd win today I told him that if we didn't win he'd pay 10 million that was the bet


right - halfway decent many networks are important for business but do the rich also have political clout can political influence be bought in Germany bingo is life lost in the best way available for rich or super rich people in Germany to exert influence is the number of employees working in their companies someone who owns a company with a hundred thousand employees or let's say


less maybe fifteen thousand employees can go to business associations and say finally go ahead and pass that law but that will cost me or an even better argument is that will cost you two thousand jobs in that area but there are no super rich people who regularly call up the ministers or ms merkel and say what needs to happen next which tax laws they'd like and so on


that's not how things work here in Germany the deadline for the special issue is approaching the heart of it is the ranking of the 1001 richest Germans what do the rich think of this ranking is a ranking suit those rankings are for entertainment all their scraped together sometimes using stock market quotations but they aren't reliable in any real way and five Gunson fontana giving and visit


roughly and also craft as each house I don't think much of these rankings and I didn't want to be included because it creates this impression of rich people being like Scrooge McDuck that they have these money bins in which they wallow in their coins the fact that I'm at the top of the rankings including of the wealthiest Germans does make me feel proud and Finnish naturally rich noise


it is it's well read manager magazine every now and then but I've never read the rank I don't know whether I'm in it I don't need that I have other goals one of these is that Highness Allah now wants to open the world's largest Fitness Centre in North rhine-westphalia and let me write the Mariah's Japanese and means the future we think it's a perfect fit for the whole concept and


vision because what we want to create here is truly unique and has never been done before our goal is to become the world's fitness center fitness center embed bite severity Shanna thinks he's found the perfect location to realize his vision in Oberhausen he's rented an old factory complex at the moment the space is still being used to make steel parts but before long thousands of


customers will be exercising here the emergency exits path will be here and the offices on top seanny experienced his most traumatic experience to date in the area in 2010 21 people died and 54 were injured in a stampede at the Love Parade in duisburg shala had been the parade's organizer the cause of the panic has still not been conclusively determined how does an


entrepreneur in the fast lane deal with that kind of tragedy an event like that will haunt you always for the rest of your life I've got a moral responsibility I was the organizer if I could turn back time I would do it immediately before the scale of what happened but you can't make it undone you have to try to deal with what happened in the Musa Dagh Mitzvah Zulu once again dick Hoffman has


also seen setbacks and crises in the 90s we expanded dramatically hinted the Czech Republic Hungary and Poland I was also speculating on the stock markets a little too much and neglecting the company then in 1996 we suddenly had a loss of 12 million Deutschmarks the banks don't joke around if you're highly indebted and then you come in with huge losses that was critical and then I had


a heart attack in 96 but everyone knows that life can get tough and things got very tough back then incurred odd nights what is saying so I dialed back a bit including stock speculation I sold them all and thought the only thing on my table now is pulling the rossmann drugstore business through and dumped death it was the right move to focus on one thing and not do so many different


things horsemen emerged from that crisis stronger than ever he started speculating again but so he assures us only with his private wealth so let's see where gas promise I don't have a laptop I normally do this via NTV text 254 yeah here it says gas promised it 375 I could already sell those now I bought 250,000 of those so 250,000 times 20 cents that would give me 50,000 euros


profit but I won't sell I think it's gonna rise to 4 euros sometimes it works sometimes it doesn't but I enjoy that's why I don't play the lottery because I find that boring can a large fortune also be a burden the hoped it does I'd say that for most people although they wouldn't voluntarily give away their money the fact that they wanted to grow can be a burden they are


controlled by their own assets for example they'll move to Switzerland or somewhere to save on taxes and give up their entire circle of friends and basically become a slave to their fortune in my opinion that's absurd considering the conditions we currently have in German Finland conditions in Germany are currently more favorable than ever for the rich they pay significantly less tax than they did


25 years ago only minority still feels compelled to emigrate abroad article 14 of the german constitution states property entails obligations its use shall also serve the public good do the rich in Germany live up to this responsibility you finish fish dish I think it is important if you're successful if you're lucky enough to have reached a certain level of


prosperity and wealth to give something back to society Michele Otto is one of Germany's biggest donors his money helps fund the environmental cultural and social sectors like most rich people he prefers to decide himself what he spends his money on rather than leave that to the state Otto like many wealthy Germans donated millions for the construction of the air fill ammonia in Hamburg in


Germany wealthy people like to donate and this makes important contributions to society and public life but generally they're against the proposal of redistributing wealth by a higher taxes for the rich in film German businesses would yield to all the demands of let's say miss varnish to the left party then millions of people would be happy and things would be good for a while because


millions of people would have more money I know but a true redistribution of wealth has never led to more social justice in the long term not in any of the political systems that tried it it led to the impoverishment of these countries the landowner foot Christiana fund bechtolsheim sees higher taxes on the rich as dangerous as a philosopher I don't think much about this so-called


rich tax for two reasons firstly if the terminology alone is stigmatizing and we in Germany should avoid that and secondly the rich tax wouldn't do any good on the contrary it would cut into the backbone of the German economy because the typical German rich person is a media sighs business owner they make up the backbone of the German economy and if we want to destroy that we have no one to


blame but ourselves the special issue is ready things have basically stayed the same the rich have a few billion more the richest 1% of Germans now has personal wealth worth a quarter of the country's assets while a quarter of adults have no wealth or are in debt for this report we never really got access to the world of the wealthiest Germans they prefer to


hey guys and welcome to another fun and easy machine learning video on support vector machines so the other day I was walking through the park where I saw a lot of people with their pets dogs as well as cats and then I came across this strange creature just really challenging for me to tell whether it was a dog or get but I eventually figured it out that it was a cat groom like a dog now if it

Support Vector Machine (SVM) in 7 minutes - Fun Machine Learning


was challenging for me to figure out imagine how difficult and challenging it would be for a computer to precisely classify between a dog and a cat a really great algorithm for these types of applications is the support vector machine algorithm or SVM it looks at the extremes of the data sets and draws a decision boundary also known as a hyperplane near the extreme points in


the data set so essentially the support vector machine algorithm is a frontier which best segregates the two classes so how does it work to understand SVM Zapatera let's first take a look at why they called support vector machines so say we got some sample data over here of features that classify whether an observed picture is a dog or cat so we can for example look at the snout length


or the ear geometry if we assume that dogs generally have longer snouts and gets have much more pointy ear shapes so how would we decide where to draw our decision boundary well we can draw it over here or here or like this any of these would be fine but what would be the best if you do not have the optimal decision boundary we could incorrectly classify a dog with a cat so if we draw


an arbitrary separation line and we use intuition to draw it somewhere between this data point for the dhoklas and this point for the cat glass these points are also known as support vectors which are defined as data points that the margin pushes up against all points that are close to the opposing glass so the algorithm basically implies that only support vectors are important


whereas training examples are ignore an example of this is so that if we have in our case of a dog that loser cat or get that is chrome like a dog we want our classifier to look at the extremes and set our margins based on these support vectors so we have D plus which is the shortest distance to the closest positive point and D minus which is the shortest distance to the closest


negative point and then we have the margin of a separating hyperplane which is the positive plus the negative the line or decision boundary that segregates the two classes is commonly referred to as a hyperplane because s VMs can be used in multi dimensional data sets and the data points are referred to as vectors as they have coordinates within the space of data so


what we discussed so far is also known as linear support vector machines or L SVM because the class are linearly separable but what happens if we have a dataset that is not linear separable so say we are presented with data that looks like this where it looks almost impossible to use a single line to separate the two classes we can use a function to transform our data into high dimensional


space so you can see over here we go from one dimensional to two dimensional space we can apply a simple polynomial function to get a parabola and now you can easily see how we can draw our hyperplane we can do the same for this data set where it's easy to draw the hyperplane or line but for a machine will use a function to transform our data from two-dimensional to three


dimensional feature space now the only problem with transformation into higher dimensional feature space is that it's computationally expensive we can use a kernel trick to reduce the computational costs a function that takes as inputs vectors in the original space and returns the dot product of the vectors in the feature space is called a kernel function also referred to as kernel


trick using a kernel function we can apply the dot product between two vectors so that every point is mapped into a high dimensional space via some transformation so essentially we use it to transform a non linear space into a linear space if you look at some popular kernel types here are some popular kernel types that you can use transform our data into high dimensional


feature space there are polynomial kernel radial basis function RPF or RBF kernel sigmoid kernel amongst others unfortunately choosing the correct kernel is a non-trivial task and may depend on specific task at hand no matter which kernel you choose you need to tune the kernel parameters to get good performance from a classifier a popular parameter tuning technique


includes k-fold cross-validation you'll deal some of these parameters in our Python labs so the advantages of support vector machines are that they are effective in high dimensional spaces they are so effective in cases where a number of dimensions is greater than the number of samples they use a subset of training points in the decision function or support vectors so it's also memory


efficient suppose factors are first down so different kernels can be specified for the decision function common kernels are provided but it's also possible to specify custom kernels we can add kernel functions together to achieve even more complex hyperplanes the disadvantages however of sports vector machines include if the number of features is greater than the number of samples the


method is likely to give poor performance support vector machines do not directly provide probability estimates these are calculated using an expensive five fold cross validation if you take a look at the applications of support vector machines the support vector machine algorithm has numerous applications and can be a quite popular alternative to artificial neural


networks or a ends here are some applications from published journal papers so we can use support vector machines in medical imaging there's one application for SVM based regression models to study the Equality in urban areas in the city of Oviedo in Spain support vector machines is also used for image interpolation as well as medical classification tasks in the financial


industry support vectors are used for time series predictions as well as financial and there's one paper on the application of neural networks mixed with support vector machines in coding theory and practice there's also for pattern recognition for machine volts diagnosis which also uses support vector machines as well as page ranking algorithm and Dex an object correct


mission okay so that is it for me please don't forget to Like subscribe and share look at a lifeline if you'd like to see more machine learning tutorials and please don't forget to support us on patreon if you'd like to download the script to this video please click the link down below and download for free so stay tuned to the next lecture where we will implement a support vector machine


thank you it's a pleasure to be here I will give a talk for probably only about 30 minutes and we're really going to talk primarily about the basics of stroke and then I want to leave plenty of time for people to ask questions about topics of their interest stroke is a very broad topic lots of different research going on so hard to summarize it all in a short talk but be happy to

Stroke: The Basics


address anything that's that's on your mind so you heard a little bit about me I actually came to Stanford first in 1984 right after graduating Medical School came up here for my internal medicine neurology training and then a stroke fellowship so I've spent my entire career thirty years here at Stanford have never looked for a job elsewhere because I love being here it's

Stroke: The Basics


a great place to interact with other physicians and have a team approach to taking care of patients as well as doing research and as was mentioned we formed the Stanford Stroke Center in 1992 I began on the faculty after finishing my training in 89 at the same time that Gary Steinberg who's a neurosurgeon was just finishing up and starting as a new faculty member and neurosurgery with an

Stroke: The Basics


interest in stroke and Michael marks was a young guy who was interested in putting catheters up into the brain to try to treat stroke so he was a radiologist I was a neurologist and Gary was a neurosurgeon and the typical approach to stroke back then was that those three groups did their own thing that they didn't work together that they worked independently with what they

Stroke: The Basics


could offer and the idea that we had is that it would be a novel approach to work together as a comprehensive type of team where we could try to use the approach of the the team rather than the individual to treat patients and Stanford Hospital was very welcoming to that idea to give it a try gave us some funding to try to start the program together and all three of us

Stroke: The Basics


have stayed around for all this time because we really enjoy doing stroke research taking care of patients and trying to Train individuals who want to do make a difference in stroke so we've have medical students residents fellows who are training to be strokes about and now they've moved on to different places to start stroke programs and now it's in vogue to do comprehensive Stroke

Stroke: The Basics


Center to have multi collaborative approaches and they're doing accreditation now for comprehensive stroke centers so we were very happy to be the first in the country to be chosen as a accredited comprehensive Stroke Center so that's the background on the center and now what I want to do is just give a bit of an overview about stroke how to prevent it how to treat it

Stroke: The Basics


and then we'll end with a case example of somebody who recognized a stroke and alerted us to it right away so that we were able to to treat her husband and you can kind of look at the the different impression of a stroke in somebody who's having one versus somebody who's watching one and hopefully by at the end you guys will be ready so that if you see somebody who's

Stroke: The Basics


having a stroke you're gonna know what to do alright so stroke is a big problem it used to be the third leading cause of death it is now the fourth leading cause of death but death is really the least of the problems with stroke because most people with strokes don't die but most people with strokes are disabled so what people typically fear most about stroke is not

Stroke: The Basics


that they're gonna die from it but it's going to be disabling and that they're going to wind up in a nursing home or not be able to do the things that they like to do before because of the injury to the brain stroke continues to be very common it's become a little bit less common because of the treatments that we've had for risk factors particularly high blood pressure as we'll talk about

Stroke: The Basics


so that the chance of a given individual to have a stroke is actually less now than it was a few years ago because of risk factor control but the population of course is getting older baby boomer boomers like myself are starting to head up into the stroke prone age groups so that means that even though we have a little bit better control of the risk factors the number of strokes that we

Stroke: The Basics


anticipate over the next two decades is very high and that we're going to go well above the 780,000 strokes that occur right now in the US every year so this is a huge problem and I suspect that all of you have had your lives touched by stroke in one way or the other because you're here but even if you go to a general audience you'll find that most people usually about one

Stroke: The Basics


out of every three individuals has had their life touched by stroke either because it's a family member for them themselves or somebody very close to them so incredibly common and this is one of the things that that drew me to stroke that it was not treatable at all when I started and that this was such a common problem that it was something that could really get excited about

Stroke: The Basics


trying to make a difference so let's look at a little bit of the prognosis after stroke as I mentioned stroke is not a major problem in terms of given individual who's having a stroke is relatively unlikely to die from it even though it's the fourth leading cause of death it's only about a 15 percent chance that you'll die from the stroke the type of strokes that are most likely

Stroke: The Basics


to cause mortality are the bleeding type of strokes the hemorrhages and we'll talk about that the strokes that also can cause mortality or where you have a very large ischemic stroke and we'll will discuss that as well but usually what we're looking at is rehabilitation recovery and that the the brain can rewire itself which again is something new that we didn't realize

Stroke: The Basics


when I was in training is that the brain has the potential for rewiring and that with patients and with therapy that most patients will make a lot of improvement particularly in the first several months after a stroke but the improvement can go on for many years after the stroke stroke is one of the most costly medical diseases not just because it's expensive

Stroke: The Basics


when somebody's in the hospital and they may be in the hospital for many days or even weeks with a stroke but it's because stroke can hit at any age and even though it's more common in older patients many people of a stroke are still working so when you're looking at not only the cost of the stroke itself but you're looking at the cost of the lost productivity permit from the person

Stroke: The Basics


and people who have major stroke with major disabilities and you're looking at nursing home care so it really adds up to being one of the most expensive medical conditions that we have okay so time for some audience participation who can give me a definition of what a stroke is right here okay that's a good definition loss of oxygen to the brain is what was said anybody want to add to

Stroke: The Basics


that or take a little different approach a blood clot in the brain that certainly can cause a stroke any other definitions yeah that's one of the things that stroke is going to do cause paralysis so hemorrhage absolutely bleeding in the brain is in addition to a blood clot going up into the brain and blocking off the blood flow a blood vessel rupturing and causing hemorrhage is a stroke so

Stroke: The Basics


you can start to get the feeling from the responses that stroke is not totally straightforward and it is complicated so the definition that I like is that stroke is the brain injury that occurs when there is an abrupt disruption of the blood flow to the brain so that abrupt disruption of the blood flow to the brain can cause for two major reasons and you guys hit on both of them

Stroke: The Basics


one is that the blood flow is blocked by a clot that a clot comes from somewhere or it's formed in the Blayne and it prevents the blood from flowing into the brain the other cause of stroke is a blood vessel that ruptures so then you either get bleeding into the brain or around the surface of the brain and you can imagine those are very different problems right a blood vessel that's

Stroke: The Basics


blocked up with a clot we're going to approach that very differently than we would approach a blood vessel that has ruptured and now has blood spilling into her around the brain so two major problems which one do you think is more common absolutely absolutely this is much more common so we're going to focus on this but we'll talk briefly about some of the ruptured arteries so

Stroke: The Basics


ruptured arteries there's two major flavors here one is that it's a blood vessel within the substance of the brain that ruptures and this is a CT scan which is an x-ray picture this white blob is blood bleeding into the brain patient didn't make it and you can see the blood here in the center of the brain so this is a blood vessel that's piercing into the brain which

Stroke: The Basics


ruptures and why do you think that might happen yeah so an accident usually will cause some injury to the surface of the brain but a blood vessel deep in the brain usually ruptures for a different reason than an accident so an aneurysm is a good reason for a blood vessel to rupture we're going to get to that in the minute the aneurysms usually form at the blood vessels at the base of the

Stroke: The Basics


brain but a blood vessel that's piercing deep into the brain typically will rupture because of many years of high blood pressure that many years of high blood pressure pushing against the surface of that blood vessel wall weakens the blood vessel wall and one day it gives way and it starts bleeding so if we could control everybody's blood pressure we would see very few of these

Stroke: The Basics


hemorrhages because the vast majority of these deep in the brain hemorrhages are caused by high blood pressure there are some other unusual reasons like having an abnormal cluster of blood vessels in the brain that we call an AV malformation certain drugs like cocaine or amphetamine can cause blood vessels on the brain to rupture but hypertension is the one that that we could really

Stroke: The Basics


make a huge difference if we controlled it so the aneurysm which you guys mentioned causes what's known as a subarachnoid hemorrhage so the aneurysms sit actually on the surface of the brain they sit in an area called the Circle of Willis that we're going to talk about in just a few minutes and when they bleed the blood goes all around the surface of the brain so you can imagine this is

Stroke: The Basics


something that the brain doesn't like to happen to be covered in blood because blood is very irritating to the surface of the brain so having blood in the brain like in this example or having blood on the surface will cause bad headaches alright so typically somebody who's having a bleeding type of stroke will have a severe headache often the worst headache of their life now that's going

Stroke: The Basics


to be very different from the more common types of stroke usually have no headache or very mild headache which are the blood clot blocking off blood flow but these more serious brain hemorrhage are typically going to present with neurologic symptoms and a very very bad headache because of that blood okay let's now shift gears and we're not going to talk so much about the bleeding types because

Stroke: The Basics


that's only about 15% of strokes about 85% of strokes or when you have a blood vessel either in the neck or in the brain that's blocked off with a blood clot so we need to know a little bit about the anatomy to understand stroke there's two sets of blood vessels that bring blood to the brain the anterior circulation the front circulation or the carotid arteries and

Stroke: The Basics


these are very easily accessible you can feel your own carotid if you put your finger just below the angle of the jaw and don't press too hard there but if you press gently you can feel the carotid artery right here which is pulsing so you've got one on either side going up the front of the neck in the back of the neck you have the vertebral column and you have the vertebral

Stroke: The Basics


arteries and if you look at the picture you can see that these blood vessels actually go through little holes in the spine and then the two sets meet together to go up to the brain stem so the carotid arteries are going up to the hemispheres of the brain the vertebral arteries are going in the back towards the brainstem now these two sets of blood vessels come together with what's

Stroke: The Basics


called the Circle of Willis so you see this circle here it links the two together and it's very nice if you're born with a good Circle of Willis because what that means is that if you have one blood vessel that's blocked up that you can get help from the other blood vessels that's known as collateral circulation means one blood vessel can help out another one that's blocked up

Stroke: The Basics


and some people can block off the whole carotid artery and not have a problem because the other vessels are helping out some people can actually block off both of their carotid arteries the biggest blood supply to the brain slowly blocks off and the other vessels in the back can take over so the Circle of Willis is important then how the blood vessels come together on the

Stroke: The Basics


surf to the brain to help each other out is also important these are things that we don't have control over this is how you were born you're either born with a nice Circle of Willis or not and you're born with a nice collateral circulation it doesn't necessarily matter how old you are but how you were born so you can thank your parents for if you had good collaterals or not there's things that

Stroke: The Basics


you can do to make the collaterals work less well like smoking cigarettes will block up the collaterals having high blood pressure high cholesterol will block them up but you're kind of born with a set of collaterals so one of the things that you can imagine is since these blood vessels go to different regions of the brain the symptoms of the stroke are going to be quite different

Stroke: The Basics


depending on what blood vessel is blocked so we'll talk a little bit about that first we'll show a little bit more detailed picture of what this Sokolov Willis looks like you can see there's a whole bunch of blood vessels that come together to make this circle we can take pictures of that to try to understand when somebody's having stroke what other blood vessels are going to be

Stroke: The Basics


available to help out okay so let's get into the symptoms the symptoms depend on what part of the brain is involved symptoms of a stroke are much more complicated than symptoms of a heart attack if we're talking about the stroke that is due to blood clots we refer to that as a scheme 'extra which means there's no bleeding in the brain and if there's no bleeding in the brain it

Stroke: The Basics


usually doesn't hurt okay so that's one of the disadvantages for stroke compared to heart attack if it doesn't hurt people are much less motivated to go to the emergency room right stroke also frequently occurs in the middle of the night so you're asleep and you don't notice it because it doesn't hurt yeah I had a heart attack in the middle of the night it would wake you up from sleep

Stroke: The Basics


the brain is very complicated so the right side of the brain is going to be doing things that are very different from the left side of the brain so the hemispheres of the brain are primarily fed by the carotid arteries we call that the anterior circulation the brainstem in the cerebellum which is a coordination area are primarily fed by the vertebral we call that the posterior

Stroke: The Basics


circulation so depending on what blood vessel is blocked up the symptoms can be incredibly variable so what would you expect might happen if you blocked off the left carotid artery what kind of symptoms yeah so we heard language and that's right most of the language function for both left-handers and right-handers is in the left hemisphere so and then heard numbness so what side of the body would

Stroke: The Basics


be numb if you blocked off the blood flow to the left side of the brain right and what in addition to numbness and language trouble what else would be a prominent symptom somebody mentioned it earlier what's that vision yeah vision can be lost because the carotid artery is going to supply the blood supply to the eye on that side so if your left carotid is blocked you may

Stroke: The Basics


have some trouble with your left eye it is also supplying so part of the visual areas that look at the right side of the world so you could have be missing vision from the right side of the world or the left eye if your left carotid was blocked well one of the most prominent symptoms is going to be weakness all right people mention that before so it's the right side of the body that's going

Stroke: The Basics


to be weak if you have trouble in the left hemisphere and the weakness from stroke normally comes on abruptly it's not the type of weakness that builds up slowly over days weeks or months it's a type of weakness where you're absolutely fine one minute and then you can't move the arm the next moment so it's abrupt onset because when that blood clot blocks off the blood flow

Stroke: The Basics


suddenly the function stops doesn't mean the tissue dies right away but suddenly the function stops so the symptoms come on very quickly so somebody with left carotid stroke may not be able to speak or they may not be able to understand words so they may be able to make no words nonsense words or have trouble getting the words out they may also have trouble understanding what you're saying

Stroke: The Basics


so when you're talking to them it sounds like you're talking a foreign language so that if you ask them to do something like close their eyes or lift up their arm they won't because they can't understand what you're saying so different language areas in different parts of the left hemisphere can affect the patient differently so it could be very mild where there

Stroke: The Basics


having trouble finding the right word or saying a few nonsense words all the way to what we call a Broca's aphasia where you can't get any words out you become completely mute okay now on the right side of the brain there's usually no language function some left handers I'll have some language function on the right side but what they will have would be the control of the left body and they

Stroke: The Basics


have something called neglect particularly if it's kind of the mid portion what we call the parietal lobe which means they don't realize they're having a stroke okay so people who are having a stroke on the left hemisphere usually can't tell you about it very well because they can't talk so they can't call 9:1 and say I'm having a stroke people in the having a stroke on the

Stroke: The Basics


right side they don't think they're having a stroke so even though they can't talk and call nine-one-one they see no reason to because they don't realize that their left side is weak so they often will be confused but neglect means that they don't realize what's going on that they can't tell that that their left arm is not working or the left leg is not working they just seem

Stroke: The Basics


to be you know thinking that it's not even their own arms sometimes you mean you can lift up their weak left arm and say whose arm is this and they say well that's my aunt Tilly's arm or they or that's your arm they don't even recognize that part so again you can see why we have trouble getting people in because stroke has a lot of complicated different symptoms and that it's hard

Stroke: The Basics


for the patient who's having a stroke to call 911 so somebody else has to do it right stroke in the back part of the brain can be very confusing also because sometimes it doesn't have as dramatic a presentation with the weakness and the language trouble it may just be double vision the sir seeing double or it may be some vertigo things are spinning around and people are off-balance

Stroke: The Basics


they're trying to walk and they wind up leaning to one side or the coordination goes off when they're trying to use their arm or leg so different symptoms and sometimes it can be very dramatic where you have the right and left hemisphere are all funneling down through the brainstem so if you have a bad stroke in this posterior area you could lose control of all four

Stroke: The Basics


extremities which we call a quadruped heiresses you can't move your arms you can't move your legs and if it's really really bad it may be the only thing you can move is to move your eyes up and down which is called a locked-in syndrome so again it could be anything from very subtle a little bit of double vision a little bit of unsteadiness to all the way to having no movement in the

Stroke: The Basics


arms or legs so it's not so easy to figure out that somebody is having a stroke from other conditions if they're having some of the subtle symptoms and sometimes you know even the neurologists are puzzled in the emergency room so oftentimes we're going to have to do some imaging to sort it out but you can see what the main symptoms are the main symptoms are going to be trouble with

Stroke: The Basics


the language weakness on one side numbness on one side headache if it's a bleeding kind of stroke so if you have those symptoms coming on abruptly that should be a key to call 9-1-1 okay so what's going to cause a blood clot to block off a blood vessel and cause a stroke well most of the causes are summarized here the number one cause is atherosclerosis also known as hardening

Stroke: The Basics


of the arteries so it's the same process that causes a heart attack it builds up cholesterol plaque and the blood vessels of the heart and that's going to cause a lack of blood flow and a lack of oxygen to the heart if it does it on the way to the brain it's going to cause a stroke so this is the aortic arch that comes off the heart this can develop atherosclerosis here's the carotid

Stroke: The Basics


artery here's the blood vessels in the brain atherosclerosis can happen anywhere along this tree that's the number one cause of stroke atherosclerosis next most common is going to be an embolism from the heart an embolism means a clot that started in one spot and it travels somewhere else so the most common heart condition that could cause a clot to form in the heart

Stroke: The Basics


is called atrial fibrillation so atrial fibrillation is when the top chambers of the heart instead of beating nice and regular like this start to do this they fibrillate so the blood swirls in the top chambers of the heart and swirling around it can form a clot the clot can then break loose and favorite place where to go is up into the brain so patients with atrial

Stroke: The Basics


fibrillation are at risk of stroke and we have treatments to prevent them from having a stroke if you have a sick heart valve that can be a spot where a clot can form a sticky heart valve can form a clot and if you have a big heart attack then the main pumping chambers the ventricles aren't working very well the blood can also swirl around there and form a clot so when somebody comes in

Stroke: The Basics


with a stroke we're thinking about let's take a look at the blood vessels and look for atherosclerosis let's take a look at the heart and see if we've got something going on with the heart that could predispose to a clot formation and if that's not the cause then you can start thinking about the blood right what if the blood gets too sticky for some reason sticky blood could form a

Stroke: The Basics


blood clot and the blood clot then could cause a stroke so a variety of causes but most of them relate to the blood vessels the heart or the blood itself okay so number one cause of stroke is atherosclerosis we're gonna show a movie to show you how a thorough sclerosis progresses over time and unfortunately everybody gets some there is no way to go through a long life and not develop

Stroke: The Basics


some atherosclerosis in fact even when you look at soldiers who who died in a military accident if you look at their blood vessels you'll start to see the beginnings of atherosclerosis so we all have to deal with it a little bit one way or the other so here is a speeding up over what one might see over many many years okay so this is the blood vessel and this is where the blood would

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travel and this is the atherosclerosis plaque you don't need an infection to start that having infections may promote some atherosclerosis but infection it's not the biggest cause of atherosclerosis we'll talk about the risk factors in a minute but what do you think is in that plaque this is not there is some inflammatory component but that's not the main component cholesterol exactly

Stroke: The Basics


so what we're seeing here is a buildup of cholesterol on the wall if you look carefully you would see some inflammatory reaction so the cholesterol itself is really not such a huge problem in this stage it's well contained this is called the endothelium the inside lining of the blood vessel wall and as long as this endothelium is smooth and shiny and not sticky it

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doesn't matter so much that there's cholesterol building up here okay because it can't really do much as long as it's encased in this smooth and Ophelia lining the blood here does absolutely fine until you block off about 70% of the area here right so here is less than 50% blocked there is no reduction in blood flow here blood flow is getting in just fine if this gets to

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the point where it's starting to block 70 80 90 percent it's going to start to reduce blood flow so it's like a plumbing problem not enough blood flow but that's not usually how atherosclerosis gets you usually it's what we're going to see here is that before it blocks off all the vessel the plaque is going to rupture okay so you see this spot here this is the lining

Stroke: The Basics


the lining is now ruptured this is called plaque rupture this cholesterol material is extremely sticky so when this cholesterol material comes in contact with flowing blood what's gonna happen here we go alright it comes in contact with the blood boom we form a clot so that clot can do what it's done here and completely blocked off the blood flow now we have a completely

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blocked vessel or if it doesn't completely block it off pieces of that clot may blake loose and head up into the brain so this is what we're fighting against this progression of atherosclerosis so causes a stroke atherosclerosis and the large vessels meaning the ones we talked about in the neck about 25% atherosclerosis and the small vessels vessels in the brain about 20% of stroke

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20% are clots that form in the heart from atrial fibrillation or other heart problems 15% we talked about bleeding bleeding in the brain or bleeding in the subarachnoid space and look at this even now when we do a very detailed evaluation we take pictures of everything 30% we don't the cause cryptogenic stroke is what we call that or idiopathic some people say

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idiopathic means the doctors an idiot they couldn't find it right and this is frustrating for the doctor it's very frustrating for the patient because the patient wants to know why did I have a stroke it's actually a good thing overall because the prognosis for having another stroke is quite favorable if you've been very thorough and you've found no cause so even though patients

Stroke: The Basics


are not happy overall it's a good sign if you find that the vessels are all blocked up you can imagine the prognosis is not as good but sometimes you can deal with that get the vessels cleaned up and usually the heart conditions can be dealt with pretty well so that if somebody's stroke came from the heart typically we can find ways to prevent it from happening again okay so lots of

Stroke: The Basics


stroke is caused by atherosclerosis atherosclerosis affects the vessels in the heart in a similar way to the vessels in the neck and the brain so no surprise how to prevent them right you've all heard this before cigarette smoking promotes atherosclerosis it makes the blood vessels stickier it makes the blood vessels narrow so this is one of the you know biggest you know

Stroke: The Basics


most treatable risk factors because treating it is going to can reverse the situation with a lot of the damage to the blood vessels alcohol abuse is a problem for stroke for a number of reasons it can cause heart rhythm problems it can cause increased risk of bleeding in the brain and it can cause an increased risk of blood clots forming in the brain so heavy alcohol use is a bad thing

Stroke: The Basics


drinking a glass of wine a day is slightly protective right so it's not a recommendation to start drinking if you don't drink but drinking a glass of wine it's not a risk factor for stroke actually it may reduce stroke risks just to touch compared to people who don't drink at all but drinking too much is a big risk factor physical inactivity lack of exercise is a risk factor and then

Stroke: The Basics


the whole host of the usual medical conditions for stroke high blood pressure is the most important it's the most powerful prevalent risk factor for a stroke so again both for the atherosclerosis type of strokes as well as the bleeding the brain type of strokes this is what we could do to prevent the most and that would be control everybody's blood pressure atrial fibrillation we talked

Stroke: The Basics


about cholesterol as obviously what's building up the blood vessels and patients who have diabetes have more atherosclerosis faster than people who don't have diabetes so getting good control of the diabetes is important if you've had a stroke you're increased risk for having another one so again we need to try to sort out why did that stroke occur and what can

Stroke: The Basics


we do to prevent it so a transient ischemic attack is atia who knows what a T ia is how would you define that I like that definition so you've got a blood clot that's gone into the brain and before any injury to the brain has happened your body dissolve that blood clot you have little enzymes in your blood that try to dissolve blood clots and if it dissolves it before it does any damage

Stroke: The Basics


it's a TI a so the symptoms will be the same symptoms of stroke but they'll be brief you know 10 15 20 minutes would be typical duration of symptoms and we know it's at EIA by taking a picture and seeing exactly what you said there's no injury if the symptoms last for 20 minutes and we take a picture and we see that there's a little bit of injury then it's a stroke just like a heart attack

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versus angina a heart attack is when you damage some heart muscle and Gina's when you've got chest pain because not enough blood flow to the heart but you didn't damage any heart muscle and what you can see is that if you've had at EIA the risk of having a stroke in the next two days is 5% okay so what does that tell you about a TI a better not ignore it right it's not the type of

Stroke: The Basics


thing you schedule an appointment and a week and tell your doctor that you had a 20 minute episode where you couldn't lift your arm or you had a 15 minute episode where you couldn't talk in the right side of the body was numb because the highest-risk time is in the first couple of days so we want to see these patients get into the emergency room we want to have them evaluated very rapidly

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if they have the symptoms of a stroke but they disappeared so what are we going to do well if you control the blood pressure you're going to reduce your stroke risk by up to 40% that's huge absolutely huge to reduce stroke risk by 40% so if you're somebody at high risk of stroke 10% per year you could reduce it down to 6% per year just by getting the blood pressure under control

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smoking is amazing that people who've been smoking even they've smoked for many years if they stop they can cut their stroke risk in half within a year of stopping smoking so incredibly motivational - you know it's hard to stop smoking but a huge payoff if you stop and the risk from stroke smoking goes almost away after five years if your cholesterol is high it will your

Stroke: The Basics


stroke risk can be cut down by about 20 percent by using these statin medications okay like torva statin or lipitor is a popular one or simvastatin pravastatin these are medicines that reduce cholesterol and probably have other beneficial effects that we'll talk about in a minute and look at blood pressure so here's a graph that shows you the relationship between cardiovascular

Stroke: The Basics


events and blood pressure over a 15-year time period so this includes both heart attacks and strokes and you can look at the rate of heart attacks and strokes and somebody whose blood pressure is in the 140 over 90 type of range 130 over 85 and 120 over 80 and you can see that the lower the better so that lower blood pressures lower risks of cardiovascular events

Stroke: The Basics


particularly strokes so what we like to see is blood pressure is getting down towards 120 over 80 if people are spending a lot of time up in the 130s or one 40s that's too high okay so eventually you get to a point where you can't go too low you go too low with your blood pressure you pass out but most people even elderly individuals can tolerate blood pressures

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down in the low 120s and for the top number the systolic and the diastolic down close to 80 and that's what we try to shoot for and particularly somebody who's had a TI a or a previous stroke we're going to be pretty aggressive about trying to get the blood pressure down we talked about the cholesterol medicines these statins these are often very controversial medicines that

Stroke: The Basics


patients have a lot of rumors that they've heard about that these are going to cause their muscles to dissolve or their liver to cause problems but these medicines seem to have benefits above and beyond just reducing the cholesterol they have what are called pliat trophic effects which means that they help preserve that endothelial cell layer that smooth layer that's helping to

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protect that plaque from rupturing so that there's benefits from these agents in in many ways but we want to see the cholesterol down did a big study many years ago called the sparkle study where we took patients who'd had a stroke we put them on a high dose of this atorvastatin medicine lipitor which is a common statin 80 milligrams and many of the patients were nervous oh that's too

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high it's a big big dose and the other comparison was the placebo right so big dose of atorvastatin versus placebo and the number who complained of muscle aches in the statin group was identical to the number complained of muscle aches in the placebo group so the conclusion is in our age everybody's got muscle aches right and we like to blame it on something so patients like to blame it

Stroke: The Basics


on these statins but the stands really don't cause muscle aches a lot more than than not taking a statin there's some very small risk it's gonna irritate the liver so you need to check blood tests periodically to make sure that it's not doing that but most people tolerate these medications very well so virtually everybody comes to the hospital with a TI a or an ischemic stroke is going to

Stroke: The Basics


expect to go out on one of these statin agents unless their cholesterol is really low on its own and just like blood pressure what the studies have shown is that the lower the bad cholesterol the better so the LDL cholesterol we used to think get it down to 120 then 100 now we're targeting more like 70 or 80 for the LDL bad cholesterol again particularly in people

Stroke: The Basics


who've got evidence of atherosclerosis we'd had a hope that giving estrogen replacement to postmenopausal women who had stroke would help them have a lower rate of stroke and when we tested it we found it didn't work if anything it made things worse so that the estrogens can make the blood a little bit stickier so that's not something that we do for a postmenopausal woman who has a stroke

Stroke: The Basics


and even somebody on birth control pills is that a little bit increased risk of forming clots and their legs are having a stroke because the estrogens can make the blood a little bit stickier so how do we make the blood a little bit less sticky well here's a detailed picture schematic looking at blood clotting so blood clotting involves something called platelets which become activated when

Stroke: The Basics


you have injury right to help you form a blood clot but they can also be activated by that cholesterol plaque the atherosclerosis and they can trap blood cells in this fibrin fibrous net to form a blood clot so taking a medicine that makes the platelets less sticky can reduce the chance that a blood clot is going to form on a sticky surface so the most famous aspirin it's a good medicine

Stroke: The Basics


to make the blood less sticky then we have other prescription medicines like plavix which is clopidogrel or aggregate ragnaroks which is a combination a diaper a tamal which is another prescription medicine and aspirin they can make the blood less sticky if you have a blood clot that's forming in the heart usually aspirin is not enough to prevent that so somebody with atrial

Stroke: The Basics


fibrillation we're going to use a stronger type of blood thinning medicine that we call an anticoagulant the most famous is coumadin now we have four new prescription medicines that have some advantages over coumadin as more potent blood thinners and if you have to give it intravenously then its medicines called heparin okay so how are we going to choose what we need to do is the

Stroke: The Basics


patient comes in and we need to sort out why they had the stroke sometimes there's rare causes that we don't have time to talk about tonight but most of the time you're going to find out that the guilty party is atherosclerosis or it's a problem at the heart or as I said about 30% of the time we don't figure it out if we don't figure it out we read it as if it's atherosclerosis and

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we assume that there may be some mild atherosclerosis that we couldn't find yeah that we didn't just didn't have sensitive enough tests to pick it up so these patients are typically going to go out on antiplatelet therapy so the least expensive is aspirin clopidogrel which is plavix is also a popular choice if it is a problem with a heart valve atrial fibrillation a heart attack forming a

Stroke: The Basics


blood clot in the heart then typically we're going to use one of these more potent anticoagulants and you can imagine those are a little more dangerous they have higher bleeding risk they need a little bit more monitoring in general so those are the typical choices here's some studies so we've been involved in several of these over the years saying that if you have one of

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these heart conditions like atrial fibrillation that aspirin works but the stronger blood thinners like coumadin which is also known as warfarin they work better okay the way that warfarin was discovered is that this is a medicine that can cause rats to bleed it's rat poison big dose of warfarin and the rat dies and they bleed so some patients don't like this

Stroke: The Basics


because they don't like us to prescribe rat poison and as I said now we have newer agents that don't have that checkered history that work even better than warfarin and are very safe options now the other thing you can do is try to pull the atherosclerosis out so there's the surgical option which is called carotid endarterectomy this is a picture of somebody's carotid

Stroke: The Basics


you know like in that video I showed you this you know is blocked up with one of those cholesterol plaques it can cut it open and carefully dissect it off the other approaches you can go up there with a balloon and you can squish it against the wall and put a little metal stent in there which is called carotid stenting so this would be approach if you had a minor stroke or you had a TI a

Stroke: The Basics


and you find out that that kurata it's blocked up we're probably going to want to think about cleaning that out and here's a actual picture of what this looks like so you know the years of haagen-dazs and peanut butter and potato chips you can see that the remnants here have wound up in the carotid artery and what's this red thing boycott yeah so that's the platelets

Stroke: The Basics


that have formed this clot and it's really a combination of the cholesterol plaque and the clot that's causing the trouble so how to prevent a stroke we're going to control the treatable risk factors high blood pressure being the most important diabetes smoking and cholesterol exercise you're going to take an antiplatelet agent or an anticoagulant to make the blood less

Stroke: The Basics


sticky and if you've got a big buildup of plaque we may be able to get it out of there surgically so what we hope to prevent strokes but when they occur we want people to call 9-1-1 and get into the emergency room immediately because if you're in the midst of having a stroke which is a blood clot sitting here the other name is thrombus we need to treat it so how could you treat it if

Stroke: The Basics


somebody had a stroke that happened 15 minutes ago and they rushed into the emergency room TPA what's that but a window of like three hours to give TPA TPA is like Drano for the brain right it is a clot buster it dissolves blood clots so it would make a lot of sense that if a stroke is caused by a blood clot like 85% of them are that if you could dissolve that clot and make it

Stroke: The Basics


disappear quickly that you could make the patient better so TPA is a clot dissolve it's made by Genentech just up the road and that is the mainstay of treatment that was the first treatment ever proven to be effective for stroke the amount of injury that's going to happen from the stroke is going to depend how long the blood vessel the blood vessel is blocked

Stroke: The Basics


by the clot and how good the collateral flow is right so if you have other blood vessels who are helping out then the stroke will progress much more slowly so again we hope that we have good collateral flow if we ever have a stroke we also hope that that clot can be dissolved quickly so TPA stands for tissue plasminogen activator and what that is is that in everybody's blood

Stroke: The Basics


they have something called plasminogen which is basically a key that can unlock a clot and if you activate that plasminogen it will start to tear these ropes apart that are the mesh work of a clod the ropes are called fibrin so when you activate the plasminogen to something called plasmon it starts to eat away at these little ropes and it can dissolve the clot so

Stroke: The Basics


your own system is going to try to do it on the on their own but if it's a big clot probably won't be able to solve it on your own and you probably won't have a TI a you know need some help from more TPA to dissolve that clot so the FDA just as you mentioned said we have three hours to give it so the approval of the FDA is that we can give it if somebody shows up and we can get it into them

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within three hours when they come to the ER we have to take a picture of the brain because you can imagine if you have one of those bleeding strokes the worst thing you could do would be to give TPA they're already bleeding in the brain you don't want to give a clot dissolving medicine so it means we got to get a picture of the brain we have to do some blood tests we have to check what's

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going on even if things go very quickly in the ER that typically is going to take at least 45 minutes to do all those things you need to do so a three hour treatment window means the patient better have arrived within two hours of when the symptoms started or we can't give it right so if you woke up with the symptoms we don't know when it started right if nobody was there to call 9-1-1

Stroke: The Basics


we don't know when it was started so this is the biggest problem we have a very tight treatment window there have been studies that show that TPA actually works out to about four and a half or five hours and in Europe the equivalent of the FDA has approved it to four and a half hours so it's Stanford and many other stroke centers even though our FDA says three hours we'll go out to about

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four and a half five hours with TPA but we're doing this against the advice of the FDA because they say give it very very early but that means that only about 5% of stroke patients are going to get it because they don't come in soon enough we've done a study here at Stanford showing very nice benefit of TPA out to six hours if you can take a picture of the brain and show that the

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stroke has not gotten very big in that six hours so this is called penumbral imaging the penumbra means the part of the brain that is likely to die over the next few hours but is not yet dead so to be able to get to this we developed an MRI sequence called diffusion imaging it was one of the Stanford faculty members who discovered this MRI technique which allows you to

Stroke: The Basics


see the stroke as it's occurring before that we would just do CT scans and a CT scan doesn't show up the stroke usually 4 6 8 10 hours it's too late so we want to see the stroke as it's developing so with this technique you can see this pink area is the tissue that is irreversibly injured it's dead but the green area is the tissue that's likely to die over the next several hours so if

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a patient comes in like this one at six hours after symptom onset and they have a small amount of tissue that's are irreversibly injured but a large amount that is still salvageable we call that a large penumbra that means that there's areas to save salvageable tissue and for these patients we're going to be very aggressive we're going to try to get that blood clot dissolved

Stroke: The Basics


even though they're beyond the approved window for TPA so we can give TPA a little bit longer than its approved or we can physically go after the clot and the first mechanical device to be approved by the FDA to pull clots out of the brain is this mercy retriever this is from a company in Mountain View called concentric which has subsequently been sold to Stryker so both TPA and

Stroke: The Basics


this first approved mechanical device are local Bay Area products so the person who developed this was actually a French neuroradiologist and you can imagine was thinking maybe a little bit about wine and how you get the cork out of a wine bottle it's kind of the same idea of how you get a blood clot out of a blood vessel so this catheter is a tube that you're going to

Stroke: The Basics


put all the way up into the brain and you're going to try to get this corkscrew like device into the clot so here's a blood clot in the brain you bring this wire up by putting it through a blood vessel in the leg all the way up into the brain and it turns into a corkscrew you try to screw it into the clot get a hold of the clot and then pull it out and this was the first

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device we now have more sophisticated devices that don't look like cork screws but basically do the same thing they go up into the brain they capture the clot and they bring it out those devices have approvals out to eight hours so it gives us more time but still many patients don't come into the emergency room until the next day right they think they slept on their arm wrong and then they wait

Stroke: The Basics


till it doesn't get better the next day they call their primary care doctor and say hey my arm doesn't move they say go to the ER but it's too late okay we're gonna end and we're gonna end with this case study this is a patient I had a few years ago 45 year old man who was recovering from a surgical procedure at Stanford and he was there in his WA in the room with his wife when he had the

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abrupt onset of left-sided paralysis it was confused so what do you think the problem might be right side of his brain yeah yeah he didn't recognize that he was having a stroke okay so it was again that area of the brain the parietal of where you don't recognize that your he knew something was going on and you'll see in the video that he was aware but his wife was on top of it and alerted

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the staff immediately that something was up with her husband now what do you think the treatment option might be ROK's up at the top yeah on the the right side you want to give somebody like this TPA why not just had a surgical procedure right so TPA you have to think carefully before you give it because TPA can be a double-edged sword right it can cause bleeding as well as dissolve a blood

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clot so somebody who's either already got a big stroke or who has just had a surgical procedure TPA could be a problem so what other option would you have that wouldn't involve TPA yeah one of these clot removal devices and this was a patient who was in the hospital very shortly after that corkscrew-like catheter was approved so the patient went straight to the cath lab they

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pulled it out and he got all better from the stroke so dramatic recovery and let me show you the video so you can look at the different perspective of the patient and his wife my speech was felt a little labored I felt tired what I felt the tactile sensation seemed to be okay every place on my bites and I could do that it was just that motor skills were a challenge it's not good that you have

Stroke: The Basics


a stroke but we sure had a stroke of luck to be here so he was completely paralyzed and did you hear his description a little problem with my hand a little motor problem so yeah it's the he's no never would have called night one one even though he's completely paralyzed on the left side so it is time for some questions or comments yeah go ahead yeah so it's a great great question the

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question is what's what's this three hour window business why are we being so restricted and we don't like being restricted the reason for the treat three hour window is because there were big studies done using the three hour window back in 1995 showing benefit of patients treated up to three hours and subsequent studies that have looked at later time windows have not been as

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positive as I said there was a big European study that showed benefit to four and a half so we don't like to street stroke based on time because everybody's brain is differently it's different particularly the collaterals so we see patients like this one that I showed you here who at six hours had TPA and had this clot dissolved and had a fantastic recovery from the stroke because this

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patient had good collaterals and only little damage was done by six hours we also see patients who had an hour and a half have massive damage so TPA will not help them they came in within the 3-hour window but the damage was already done so we need a different approach rather than TPA so the arbitrary time windows we don't like and what we've been doing is studies to try to show that it makes

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a lot more sense to look at the brain with sophisticated imaging and then try to figure out who has salvageable tissue so if you wake up with a stroke and come to Stanford and we take a picture and it looks like this we're going to go after that blood clot if you show up two hours into the stroke and the tissue is already massively injured we're not going to remove the blood clot we're

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going to try to do something to reduce the swelling because a big stroke it's going to cause even more trouble from the swelling so it's a great question but that's the rule of the FDA yeah what difference genetic differences between people it would say some people haven't need more cholesterol than other people no no no you know there's really not some people who need more it there

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was some concern that if you have very little cholesterol that your blood vessels may be a little bit more likely to cause a hemorrhage and there is some evidence that if you look at some Asian populations who tend to run very low cholesterol that they may have slightly higher brain hemorrhage rates but when you look at the studies that use the high dose of the statin versus a medium

Stroke: The Basics


dose both were heart attack and for stroke the lower the cholesterol goes the lower the stroke rate it's like the blood pressure the lower the better so there may be some point you know you can't go down to zero right it's like the blood pressure you can't go to low but in general what we found from the studies is lower cholesterol is lower heart attack and stroke rates the goal

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for somebody varies on what their situation is but if you've had a stroke from atherosclerosis that we want to get down below 80 on what's called the LDL the low-density right the LDL the bad cholesterol by HDL you want to get it as high as possible yeah so the question is that passing out after eating so postprandial syncope that's not a stroke but it is a problem which can be

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difficult to treat and usually it's eating you know multiple small meals to try to deal with that you know it's difficult to comment about individual people's medical problems from from the podium but usually it doesn't get worse it's usually something that can be managed yeah okay up front yeah there was a team some years ago at University of Iowa - look the ischemic optic neuropathy and

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found that it correlated actually with - too little blood pressure in the optic artery causing a loss of blood flow of the blood vessel itself collapsed and and they showed that the coupling of taking an antihypertensive when going to bed with with the natural diurnal Brides and follow the blood pressure that was the worst time to be taking a medication like that and it seems that when I

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mentioned this to people in the medical profession most people oh that's that that's new to me I've never heard of that but I'm wondering whether anybody is looking at these 30% of cases that are idiopathic whether there's any chance that there was a blood vessel in the brain that actually collapsed because of because I heard a blood pressure drop and medication was a strong antihypertensive

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at the same time actually caused blood pressure blood pressure to drop in and blood flow to the brain to be kind of off to that or that part of the brain we kind of because there wasn't sufficient planning for this yeah so it's a complicated question but what's being asked is that we talked about blood pressure being too high as a cause a stroke can blood pressure being too low

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because a stroke as well and the answer is yes that there certainly are situations particularly for patients who have you know major blockages of vessels where you know the plumbing is blocked up you can imagine if you don't have enough pressure you're going to run into trouble and typically the type of strokes we see from that are called watershed strokes where you have two

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major vessels and in between them is going to be the area of low flow just like if you have two sprinklers right and you turn down the pressure you're going to get a dry area in between so there are issues and like most things there there's a you know an advantage and a disadvantage you do not want blood pressure to go too low under certain circumstances and the other part of the

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question was that you know the timing of blood pressure medicines which is very important what you can do is a 24 hour blood pressure monitor and sometimes it'll be very surprising to see the over the course of the day things are fluctuating a lot and just taking a blood pressure in the office can be very misleading often times people's blood pressure is quite high when they go in because we're

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scary with our white coats on so it can be helpful and planning out how to give the blood pressure medicine certainly is an important issue in the back yeah it's a great question so question is had symptoms that may or may not have been at EIA the doctors didn't agree that it's not unusual with a stroke it's pretty easy to say yes or no because the picture will say is there brain injury

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or not TI a no brain injury so there are lots of things that can mimic it the good news is that most of those treatments for at EIA are things that we should all do whether we've had a TI or not right blood pressure under control cholesterol under control taking an aspirin as a pretty benign approach so it is not unusual to have controversies even neurologists will disagree even

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stroke specialists who see a patient they cannot agree on TI a if you image it at the time you can look at the blood flow and actually see a blood flow reduction but that doesn't happen very often that you're in and get the picture in the midst of the TI a or right afterwards where we may see a footprint of that blood pressure reduction so not unusual but the type of things that

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you're going to do after TI a are good things to do anyway yes great question does every er have TPI and you know many years ago the answer was certainly no that you know people were slow to adopt TPA because it was a big change from what they were used to doing all this rushing around stroke patients there was no treatment they were like the last priority so in the

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Bay Area that most of the hospitals now are what are called primary stroke centers meaning that they have TPA and they have a plan and then some stroke centers have the comprehensive designation meaning they can go up with catheters and defense you're imaging so in our area we're pretty lucky of it if you call 9-1-1 at this point it's almost certain that the hospital you're going

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to go to is TPA ready that wasn't the case a decade ago TPA is typically administered the question is how's TPA administered typically it's just given by vein intravenous infusion sometimes when we go up there with one of those catheters you try to pull out the clot and little pieces break loose and then we'll squirt some TPA to get the smaller cloth so it can be administered directly

Stroke: The Basics


up into the clot in the brain but typically it's through the vein question in the back there yes your head the question is for the statin agents does it matter if it's named brand or generic there doesn't seem to be a key difference there so I think the generic is fine far in the back yes it's inserted in the question is where as the catheter inserted its inserted in the

Stroke: The Basics


femoral artery and then up into the brain yes so the femoral artery is it's right next to the groin area so it's the top of the leg where you you get that blood vessel yeah so question can you go elsewhere it doesn't really take any time to push it from the leg up to the brain versus the arm and it's easier it's a bigger target it's a little safer to go into the leg than the arm but if

Stroke: The Basics


the leg is all blocked up you can go into the arm years ago when they first started to do this they went through the neck that didn't go so well up right I'm interested in you mentioned there are those discrete situations that they would be used in or shouldn't many coumadin people be thinking about going on to those and secondly do the hospitals in our area generally yeah so

Stroke: The Basics


the question about these new anticoagulants and they're there for so some insurance was call cover one versus the other the first one on the market was called Pradaxa you've probably heard about that one most hospitals would you're gonna have access to that and many will have the other ones that have come out more recently so these are typically for patients with atrial

Stroke: The Basics


fibrillation they have not been shown to be effective for people who have heart valve problems like a mechanical heart valve so it kind of depends on the reason that somebody's on coumadin if they're on for atrial fibrillation and they're having some trouble with the coumadin there's a you know these offers some advantages for somebody who has a stroke from atrial fibrillation most

Stroke: The Basics


doctors now would be talking about using one of these newer agents rather than going with coumadin because you don't have to do the frequent blood tests there's not so much in the way of food and drug interactions so they're much more convenient for the patient back there yeah you sorry I don't know anybody's name yeah so the question is can mini-strokes lead to dementia so a TI a doesn't lead

Stroke: The Basics


to dementia because as we said by definition a TI a doesn't damage the brain but little tiny strokes they can lead to dementia so dementia being a lack of cognitive ability so you can imagine if you're starting to knock off lots of little spots the connections between different areas of the brain are going to be affected those typically occur again in people with high blood

Stroke: The Basics


pressure that the small little blood vessels deep in the brain get narrowed and you start to get these little tiny strokes that people often call lacunar strokes and they can cause dementia so we don't want those to build up if there's if we can prevent a second row there go ahead yeah so question is about omega-3 and it's been a controversial area we find that the the statins have

Stroke: The Basics


much more evidence to support them so we would recommend the statin agents the guidelines recommend the statins over the omega-3 question in the question over there have we expired our time I think one more question okay our curricular I have friends who yeah so the final question is about these new anticoagulants and are they easier to regulate in the coumadin and

Stroke: The Basics


they are definitely easier to regulate they were all tested all four of them in huge huge trials where one half took coumadin and had all the regulation issues and the other half took these new medicines with no regulation okay so you weren't upping and adjusting the dose like you have to do with coumadin and all four of these you know were either as good or better than coumadin in these

Stroke: The Basics


big trials so they were as good or better without all that regulation so somebody who's blood thinning is jumping all over the place on coumadin these are much smoother now the disadvantage is that we don't have great tests to monitor how much is in the blood with coumadin we can tell exactly how much is in there with it with the blood tests the newer agents that's a little bit

Stroke: The Basics


trickier and then there's a little bit of an issue with reversal of these newer agents that coumadin is hard to reverse also but we have medicines with a lot more we have a lot more experience reversing cumin if somebody comes in bleeding but overall patients typically did better with these newer agents so I think we have reached the end thank you very much for coming I appreciate all

Stroke: The Basics


hello everyone and welcome back to my channel today we're trying something a bit different which is I'm going to be talking about my research area today which is machine learning but I really hope that any of you guys that are coming from a non mathematical or computer background if you are watching along that you can understand this because I tried to make it

Supervised vs Unsupervised vs Semi / Self Supervised vs Reinforcement Learning | Machine Learning


understandable to a general audience and if you are watching anyways let me know in the comments below if you are able to follow along with this and if it made sense to you guys because I'm always trying to make sure that research areas can be accessible to everyone even if it's not your research area so I'm doing a PhD in computer science but my background is in maths and statistics


and that's how I came across machine learning but some of you guys have been asking for me to do more machine learning on computer science videos and that's not something I really saw about doing on this channel but I did one to have it be more general PhD stuff but to kind of try this out for this month I want to do one sort of day a week on machine learning or computer science


programming that kind of thing one day a week on more general PhD stuff so that might be writing or skill so I've talked about transferable skills before so it could be something like that and then one day week that's more on the personal side of doing a PhD so things like routines weekly or daily vlogs which people have seem to respond really well to and things like you know financial


aspects of being a PhD student side hustles for students all of that kind of thing and then one day a week that's all the planning productivity stuff that tends to be what most people are interested in so that's kind of this the general plan I'm gonna have one of those each day and probably have one day of these study with me kind of videos as well but it is a lot so I'm gonna be


trying that at this month seeing if it's something I can keep up with but what will be really important to me is understanding what is working for you guys so if there's a video style you like be sure you are liking be sure you are commenting below and be sure you are subscribing because that's what helps me understand which videos are working and which ones I should continue doing


so if you want me to continue doing one type of video be sure you're engaging with that video type or multiple video types if you love all the videos you want to see more videos about machine learning and my kind of research or PhD stuff in general then be sure you do subscribe and that you hit the notification valve so that you know when new videos are out so this first video is going to be an


introduction to machine learning in general just so you guys have a general understanding if anyone is like learning about machine learning for the first time here that you guys will have an understanding and then in future weeks we can get into some of the general algorithms and then as well I can show you the programming that goes alongside those things but let me know if you'd


rather see more general stuff or you'd rather see things that I specifically used in my research so what is machine learning so machine learning is a branch of artificial intelligence which is a technique that enables machines to act similarly to humans so trying to learn how to do things the same way that people do and then machine learning is a branch of that which uses statistical


methods to enable machines to improve with experience so they learn based on their own experience and or from the experience that's in the data obviously so machine learning is essentially applied statistics so my background is in mathematics and statistics and that's how I first learned about machine learning was in my degree in statistics and in my master's in data analytics so


it's not 100% computer science it is more statistics you need kind of the mixture of statistics and computer science skills to be able to use machine learning and then deep learning I'm just going to mention briefly as well is another subcategory of machine learning and it's basically it has the ability to work with a multi-layer network of algorithms essentially of different


layers of things going on and that's how it makes decisions but before I get started with talking about data I just want to mention briefly as well I'm gonna be talking about features to do with data everyone in school probably would have done some form stats where you have different variables that are the input and then you have one that's the output so the features are the input variables


so one example I'm going to talk about later is housing prices so the features might be the rooms the number of rooms and highest the number of bathrooms the square footage all of that stuff and then the output variable will be the housing price that's associated so just to mention that briefly as well so I'm going to do some examples and I thought like how could I make these


examples a bit different if anybody is familiar with machine learning so I decided to do things that are all based on YouTube so here we see one of my videos I'm actually wearing the same cost are kind of not ideal anyways so one of the things that YouTube offers the employees with speech recognition because you've got these captions that are auto-generated it says that there on


the screen that they are auto-generated meaning that I didn't provide the captions for this video instead they use a speech recognition software that turns my speech into text and that's automatically done and it's not always a hundred percent obviously especially when you have things like accents like I do say that I recorded in English from Ireland and then they obviously use some


things so I mean that part already looks but it like looks like it's correct so that's good but that's one thing that they do so that's an application of machine learning and sometimes some of these examples are also going to be using deep learning so it's hard to send a separate the two because you never know a lots of things that can be done using pure machine learning algorithms


can also be done or are done with deep learning algorithms so the next thing that they do is spam classification so you see on my comments this is an YouTube studio but I have likely spam so they have they know when a couple of comments are going to be spammy so these are people who comment down below subversive and things like that so they get put into the likely spam or they had


helped to review and then I can go back and approve these comments time's comments that seem completely normal are come up with spam for some reason so it's not really 100% but you know like you know when Gmail obviously you've got your spam and that's pretty accurate like I've rarely ever had anybody anything in spam that's not spam so yeah so that's one thing that they do


that's done with machine learning as well so they learn the difference between spam and not spam by using they have examples of ones that have been labeled by people who said this is a spam email or this is an OnStar me mail and they learn how to categorize those as spam and not spam another thing that they do is text generation so you can see I have this comment here from eco wander shout-out


to you for commenting on my video thank you so much you contribute to my growth here on youtube so thank you and and so you can see that YouTube has started doing this in YouTube studio where you have like generated comments that you can just reply now I don't use those because obviously it's better to have longer comments if you want to get the engagement up so it looks better in the


algorithm and it looks better for you guys if I'm doing longer comments and I'm engaging with you more when I can and so these are things that they do now though you can do automatically generated and that will be they'll read the machine learns how to understand the conflict the content of that comment and what would be an appropriate response based on previous interactions they've


seen on YouTube so they would have seen something similar to this on YouTube and had somebody some people are applying these kinds of comments and that's how they learn and that's how they come up with the responses and the last example that I'm going to show to do with ytube is recommender systems and that's really what I work in is recommender systems and you'll know this from things like


Netflix or Amazon but as well YouTube does recommend you videos and you homepage will be a recommended paint like a recommended set of videos that are specifically for you based on what you watched before and there's different ways that you can go by that so if you want to hear more about recommender systems that's my main research area that's the thing I know more about of


like different ways that they can work so one way would be like people who like this video also liked this video and then another is you know finding similarities between the videos themselves and not actually taking into account the human side of things and then another thing would be taking into account people that are similar to you and finding what kind of videos they


liked so um there's just a couple different ways if you want to hear more about recommender systems let me know in the comments below so now we're going to go into the types of learning algorithms very basic introduction to these different learning algorithms and just so that you have an understanding of the basic categories of machine learning so supervised learning and the first one


we're going to talk about so the the main two categories are supervised and unsupervised learning but then there's also subcategories they're like semi-supervised and self supervised learning I'm gonna talk about those and then there's also reinforcement learning so I'm gonna talk about all of these in this video and but supervised learning basically what that means is you have a


training data set with Associated labels so you essentially know the right answer in this situation and these labels have been provided by a human supervisor so somebody has labeled this data set so I've got the example that I was talking about here so we know the size of a house we know the amenities whether it's said facing your north's facing all of that kind of thing and then the


accompanying housing price was obtained from whenever the house was sold so we have this training data which is actual houses and the actual housing prices they sell - and then you want to learn how to form the housing price based on the description so we have a description solution and we want to learn a general solution for when we have new descriptions but no solutions so for


example we have a new house coming onto the market we know all of the information obviously we know that number of rooms number of bathrooms all of that stuff but obviously it hasn't gone to market we don't know the price but we can use the previous examples we can train a model on this data to kind of come up with an estimate of the housing price based on the fact that we


don't know based on all the information we do know so that's the general supervised problem is we have training data with labels and we want to learn based on the training data features what would the label be and what issue with supervised learning always is that it's very hard to find label data and for bigger free for problems that have a ton of different options it can be hard


to do so for example in speech recognition you know there's an endless number of combinations of words that could be said so to get somebody to come up with all of the possible sentences ever like that's not possible and then having labels so having the audio file and the accompanying labels it's just so difficult to come up with all of that so that's the problem with supervised


learning is it's not always possible to get this kind of labeled data but then there are times that the housing prices that is definitely possible because you would have things like that on record and the good thing about modern times is that there's a ton of data being collected all the time by different apps and things like that and in those circumstances you often come up with a


lot of labeled data naturally so unsupervised learning then is we have training data and it doesn't have labels so the goal here is to identify interesting structure in the data because we don't know the answer is necessarily but you can see in the graph they have associated here because I'm supervising something people don't grasp as easily because you're kind of thinking well what would


be the point of this but one example is anomaly detection so that's when you're trying to something that's a complete outlier and it's either it's something new or it's just you know a total outlier so you can see we have in the data we have these clusters that we can see and obviously in a 2d data set like this it's very easy to see these clusters with your


eyes not necessarily using any kind of algorithm so we can see we have these clusters of blue spots that are normal and then we have these orange ones that are being classified as noise because they don't fit into these clusters so those are the kinds of things you might want to look up for in a data set and obviously you're saying you know why do we need unsupervised algorithms if we


can just see this but in a multi dimensional problem so here we've just got two variables if we have like 50 you can't see this with your own eyes when there's outliers like that but you can use an algorithm to cluster your data and then if we have data points that are so far away from the center of a cluster and I cluster is a group here so you can see them in the graph as well if we have


something that's so far away from a cluster then we know it's probably an outlier or something like that so that's an example now we're gonna go into this sort of sub categories here of supervised and unsupervised so hopefully you have a general understanding of the difference here supervised we have labels unsupervised we don't and so the first example we're talking about is


self supervised learning so we have an unlabeled data set but actually what people do in these self supervised learning is they actually turn an unsupervised they turn an unlabeled data set into a label data set by manipulating the data in some way so the basic task here is to find the missing part given and one part so to explain that better want to imagine if we have


like what we had before was a set of sentences that was the data we were given what the um what the researcher does is they take as one part of and they generate this training data set with labels so we have the information is the trick the sentence with a piece missing and the answer is the piece that's missing so they train this way and this way we have labels because we have these


sentence with the piece missing and we have the missing piece so they generate this label data set from unlabeled data so it works in these kinds of situations so in speech recognition well in sentence like if you're trying to understand the semantics of sentences you can take a sentence remove one piece and see if the system can learn to fill in the blanks and similarly with images


we can take out a small part of the image and see kind of a system learn to spot fill in that missing part of the image and actually it has been relatively like pretty successfully be surprised if you want to look up self supervised learning it is pretty interesting to see how a system can learn these things and that's usually done with deep learning because it's not


something a traditional machine learning algorithm can necessarily do myself like a linear model is not going to do that and so yeah basically in this sort of learning you want to learn about the underlying properties of the data and this would have required a lot more data if you don't do it this way so this is kind of like the system's being thrown into the deep end being expected to


generate this missing piece from basic examples that they've seen before so moving on we have semi-supervised learning so I mentioned before that labels are very hard to obtain and especially in cases like speech recognition and web content classification so if you've got a webpage and you want to add tags to it you know it's hard to it's very time consuming for a person to sit down and


read through that entire webpage and manually assign tags and then as well you probably have to have a couple of different people doing it so that they can it's not like it's one person's bias it's a few people who are collectively doing so it's very time-consuming it takes a lot of Human Resources to do all of that labeling so semi-supervised learning algorithms have been developed for the


cases where we only have a small amount of labeled data and I'm a very small amount when there is a huge amount of data that could potentially be there so what I said about sentences there's unlimited possibilities for sentences and we might have a small number of labeled audio to sentence and files and a ton of audio data that haven't been labeled so basically this is used in any


task that requires a big amount of human resources to do the labeling and when there's a big amount of possibilities so the characteristics here are that we have a huge amount of unlabeled data otherwise we would just use a supervised learning algorithm and there's an input/output proximity symmetry so what does that mean it basically means that the underlying requirement here is that


if two inputs are similar their output should be similar and that's a very simple thing to understand but it's if it's not present this won't work because you can't make things you can't get the system to learn that to some inputs that are similar should be very different you know this kind of algorithm wouldn't make sense in that way so that's one other requirement and another


requirement is that the labeling should be relatively simple so we have we need we need the simpler labeling to be not more difficult if we have this middle step so trying to get the labels from the small set of label data should not be more difficult than it would be if we had humans doing it as well like generally we'd have this is a low dimension problem meaning that there's