Transcription:
Risk Factors and Symptoms of Pediatric Stroke Patients

Caitlin Whyte: Welcome. You're listening to Pediatric Insights, advances and innovations with Children's Health. I'm Caitlin Whyte. While stroke and interruption of blood flow to the brain due to a narrowed artery or blood clot seems like an unlikely condition in children, it does happen. In fact, pediatric stroke occurs as often as leukemia and brain tumors in children. But despite its health consequences, it often is not recognized by parents or physicians.

In this episode, we'll explain why children have strokes and how to treat them more effectively. Our expert today is Dr. Wilmot Bonnet, a pediatric neurologist at Children's Health and Assistant Professor at UT Southwestern. So Dr. Bonnet, thank you again for joining us today. Tell us first off why do children have strokes.

Wilmot Bonnet, MD: Children have strokes for a few different reasons than we typically think of in adults. Most people are aware of strokes in adults because they happen more often in adults. People think of things like high blood pressure, diabetes, smoking, cholesterol, things like that. Those cause strokes in adults because they go on for years, decades even, and then cause a narrowing of the small vessels of the brain and that's how adults have small vessel strokes, which are the most common cause of strokes in adults.

In children, of course, they haven't had time for that to happen, so most of the pediatric stroke mechanisms are a little bit different. The most common cause of stroke in children is due to something called arteriopathies, which is narrowing of a blood vessel.

One of the main ones people think about in children is focal cerebral arteriopathy, which is where you actually have direct inflammation of the vessel wall. The vessel is a tube and so, when you have inflammation or swelling of the blood vessel, it causes stenosis or narrowing of the blood vessel. And that can cause stroke two ways. You can have a clot formation, kind of behind the area of stenosis. Anytime you have stagnant blood flow or turbulent blood flow, clots can form within the blood vessel. So behind the area of stenosis, you can have clot formation. And then, because the blood vessel is narrowed, if you have an acute drop in your blood pressure, you can have hypoperfusion distal to that stenosis. That's what's called a watershed infarct. Those are the two main ways you can have a stroke due to narrowing of the blood vessel.

Now, you can have narrowing for a couple of reasons. The one people think about most is inflammation. So there's something called focal cerebral arteriography, which can happen in children. It's thought to be either a direct viral infection causing inflammation in the vessel wall or a post-infectious inflammation, like an auto-immune phenomenon. This is most commonly or classically associated with varicella, which thankfully most of our children are vaccinated against. Yet another reason for kids to get vaccines. Most people don't think a stroke is something vaccines can prevent, but it can.

There's many other mechanisms by which blood vessels can be narrowed within the brain. Another common one is called Moyamoya. So that's actually chronic, instead of inflammation, it looks like it's fibromuscular narrowing. We're not exactly sure why, but it's chronic narrowing of the distal internal carotid artery, usually bilateral. It happens in kids with sickle cell disease or trisomy 21. And those kids are at risk for multiple strokes over time if t hat's not caught.

Another common cause of arteriopathy is actually trauma, so things like dissection, which is a tear in the vessel wall that can usually be caused by forceful turning of the neck, which unfortunately in children can happen doing things like falling off a trampoline, playing football, going to the chiropractor. Outside of the chiropractor is kind of the fun stuff that kids want to do, wrestling. And so we have seen that in children before.

The other big category of stroke in children is cardioembolic stroke. So strokes coming from the heart or clots coming from the heart and causing stroke. Now, I mentioned that clots can form any time there's turbulent or stagnant blood flow. And anytime you have a structurally different heart, blood flow is more turbulent. There are either areas of the heart where the blood is sitting around and that you're at risk for clot formation with blood that's not moving. And then, there's blood that's moving in a turbulent fashion, which I always say like rapids in a river that also can predispose to clot formation. So any structurally abnormal heart can cause clot. Now, this is rare. But when you work at a place like Children's with a big cardiac surgery center, we see a lot of kids with structurally different hearts that have to come in for cardiac surgery.

In general, children that have stroke have multiple risk factors. And so a lot of times, most kids with structurally different hearts or congenital heart disease don't necessarily have strokes. But if they have another risk factor at the same time, like having a lot of inflammation, that may set up kind of the perfect storm necessary to create a stroke in a kid.

I mentioned kind of the other big category of risk factors in children, which is a hypercoagulable state. These can be transient, like I mentioned with inflammation, times in which the blood is more likely to make a clot. And then there are some families that actually have genetic risk factors or genetic changes that make them more likely to make clots. And in children, even in adults, a lot of these things like factor V Leiden are known as causing venous clots like DVTs and maybe even a pulmonary embolus. But in kids, they're more likely to cause arterial ischemic stroke. And again, when I say stroke, I'm mainly talking about ischemic stroke because it would take a long time to also go through to hemorrhagic and venous strokes. When people say the word stroke, they're usually thinking ischemic stroke.

So the main broad categories of risk factors for kids are really arteriopathies, cardioembolic strokes and then hypercoagulable states. And that kind of guides our workup of any child with a stroke. So we look at the blood vessels to see if there's any areas of narrowing. We look at an echocardiogram to make sure that the heart is of normal structure. And then we look at the hypercoagulable labs to see if they have what we describe to parents as sticky blood or bood that's more likely to make clots.

It's important to recognize that most kids that have a stroke actually have a couple of risk factors. So we have to check all these things for each kid that has a stroke, because a lot of times, most kids even with congenital heart disease, most of them don't have strokes, so a lot of times they have to have other stuff going on that causes the stroke to happen.

Caitlin Whyte: Now, are there certain pediatric populations that are more prone to strokes?

Wilmot Bonnet, MD: Yeah. The kids with congenital heart disease is certainly one, as I mentioned. I think the other big population that people think of is sickle cell disease, so children with sickle cell disease. Their cells are shaped different. So they have trouble getting through the very small blood vessels all over the body, but also including the brain. So they actually have a pretty high risk of stroke, some of which are silent. So we actually do MRIs on these kids. A lot of times we find strokes that no one ever knew about. So sickle cell is a big population that's at high risk; congenital heart disease, as I mentioned; and then there's even trisomy 21 for various reasons. They have heart issues and they can have hypercoagulable states.

Caitlin Whyte: What are the symptoms of a pediatric stroke? What can we look out for?

Wilmot Bonnet, MD: Right. One important thing with stroke is that it should be acute onset. In general, it's a little more difficult in children because they can't communicate, you know, especially the little ones can't necessarily communicate that stuff to us as well. They may not recognize the fact that their arms stops working is a big deal while they're playing with blocks or doing whatever they're doing, right? So we're relying a little bit on caregivers, but the primary symptoms for some of our typical strokes are somewhat similar to adults.

You know, there was the big FAST initiative, which is a public health initiative aimed at increasing recognition among the public of stroke, right? And so FAST is F-A-S-T, which stands for face drooping, arm weakness, speech difficulty, and then time to call 911. Those symptoms in children make you think of pediatric stroke. It's still important to recognize these things in a quick manner. But children can have other symptoms that are less commonly associated with stroke in adults.

We're part of the International Pediatric Stroke Study. And some members of that look back at what were the most common symptoms of children presenting with stroke that were eventually confirmed to have a stroke. And the two most common symptoms were actually headaches and seizures, which if you've ever worked in a pediatric ER, headache and seizures comes in every day and pediatric stroke is very rare. So the important part is to look for a combination of these, especially if they have some of the risk factors we talked about like congenital heart disease.

Seizures are tricky, too, because we see seizures all the time as a pediatric neurologist. We see seizures basically all day, every day. It can be tricky because focal seizures, so if you have focal epilepsy and it causes right arm jerking, you can have something where after your seizure you have weakness of that arm. And so that's called Todd's paralysis. And classically, if a child came in with a focal seizure and weakness on one side, people would chalk it up to the seizure and there wouldn't be much more workup.

Well, since the advent of readily available MRI, we found that a lot of these children with new-onset focal seizures actually are having strokes. And so it's important to take any child with new-onset weakness seriously. They will require an MRI to help rule out stroke, because there are things we need to do if a stroke is there to help prevent further strokes.

The other thing is that the FAST, face, arms, speech, time, that really only talks about strokes in the front part of the brain. Strokes in the back part of the brain are more common in children and they can present with just altered awareness, headache, vomiting and vertigo like imbalance. And so those are our kind of more nonspecific things. And especially in a toddler, a viral gastroenteritis could look like that. So if the kid's very altered and can't stand up, even in the setting of throwing up, even if you think that they may have a viral illness, you should be thinking of doing some brain imaging because it could actually be a posterior circulation stroke. So that's important to recognize.

Caitlin Whyte: This kind of leads me into my next question, but why are strokes so hard for physicians and parents to recognize?

Wilmot Bonnet, MD: Well, so in adults, the most common cause of an acute neurologic syndrome, acute weakness or acute altered mental state is stroke. Whereas in children, it's only about 30 to 40% of the time. So it's very rare. And conventionally, people just don't usually think about children as having strokes.

But the other thing is kids can't tell you. A four-year-old may not be able to tell you that his arm is numb. He may say it tickles or something like that. And that's kind of hard to parse out. The other thing is that, let's say, you look over at your four-year-old and he's not using his right arm. Well, not using his right arm is usually due to something other than the stroke, right? The most common thing is usually like arm pain or arm injury. So you can have nurse maid's elbow, you can even have like a broken arm. And so we've actually had kids that had a stroke, but the first study done was actually an x-ray of the arm. We've had that multiple times. It's difficult because it is a rare thing.

Most of the symptoms can be explained by more common things, but you just have to have the pediatric stroke in the back of your mind. And if things don't look quite right, you need to pursue that, because they can sometimes be hard to recognize. And I feel for my ER providers and my PCPs, because it is difficult.

Caitlin Whyte: So what can be done after a stroke is identified? What happens next?

Wilmot Bonnet, MD: We actually do have some things we can do, which it didn't always used to be the case in neurology. Pediatric stroke is rare and so there's no FDA approved treatment for acute stroke. However, we have to do the best we can because in rare disease, it's difficult to study the population and get into randomized control trial and get a good P-value because we don't really have the power. So we have to extrapolate from adult data and build consensus among experts to decide what the best way of intervening is.

And so in general, we do a lot of what they do on the adult side. So we can do tPA, which is thrombolytic therapy. It's an IV injection that's a thrombolytic agent and it can go in and it can bust the clot up in the brain. So we can do that within the first four and a half hours and that's for kind of any stroke in a kid over age two that has significant weakness and things like that.

We can also do something called a thrombectomy. The interventional radiologist does this if a child meets criteria and has what's called a large vessel occlusion. So that's a big clot in one of the big arteries of the brain that includes a large stroke area. And so they can actually go up with a wire and physically remove the clot from that part of the brain. And we've done that in children. And in the adult side, you can do that in certain patients all the way up to 24 hours. So that's kind of our windows of acute intervention in children. Four and a half hours for the IV therapy and all the way up to 24 hours for the large vessel occlusion for the thrombectomy.

That's what we can do acutely. Not all children will meet our specific criteria for that intervention. And we have kind of a higher bar because luckily, in general, kids do better after strokes than adults. But after that acute intervention, we have to figure out how best to prevent a further stroke. So that's why we do that workup with the vessel imaging, the echo and the hypercoagulable workup. And then we decide whether or not we're going to put them on either antiplatelet therapy with aspirin or anticoagulation with something like heparin, Lovenox, Coumadin, something like that.

Usually, we have them on anticoagulation until we figure out exactly what may have caused the stroke, again because many of the risk factors that children have actually require anticoagulation for secondary stroke prevention. We usually have them on anticoagulation for a few months and then eventually transition back to aspirin.

Caitlin Whyte: Can you tell us a bit about the Pediatric stroke clinic at Children's Health?

Wilmot Bonnet, MD: Absolutely. So the stroke team is made up of myself, I'm new faculty here, and Dr. Michael Dowling. He's my mentor. We make up the Children's acute stroke team. We have a multi-disciplinary clinic with hematology, and it's actually in the hematology clinic in the Children's main hospital. We usually see our pediatric stroke patients there two to three months after they get out of the hospital. Sometimes they're coming straight from the rehab hospital. Sometimes they've been out of the rehab hospital for a couple of weeks or they come straight from home if they have a minor stroke.

We see them there because, as I mentioned, many of our children are on anticoagulation. We're kind of following up on the hypercoagulable labs, which certainly our hematology colleagues help us sift through. So it's kind of more their specialty. And so it's nice, we're able to save our parents extra trips to the hospital because we can both see them at the same time. But then we can also talk about what to do. As I mentioned, in pediatric stroke, a lot of things are based off of consensus. And there's not kind of hard and fast rules a lot of times because we don't have the data yet. And we may not get the data because it's such a rare disease. So we kind of are able to talk through things with our colleagues and decide on the best course of action. So we have that clinic. Usually, that's just one or two visits there until we're able to take the child off of anticoagulation, if we're able to take their child off of anticoagulation. Some children need that long-term if they have ongoing risk factors, such as congenital heart disease.

We 're going to have a longitudinal pediatric stroke clinic, that's multidisciplinary with physical medicine and rehab. And this will be for kids with more severe strokes than the ongoing rehab needs. And we'll see them together actually over at Cityville, which is very close to the hospital and the physical medicine and rehab clinic. And again, it's about saving visits to the hospital, especially in these kids where they've had more severe strokes. It's harder to get them out of the house and transported so we can save them a trip. But then we're also going to discuss other considerations.

Post-stroke complications are common. So a lot of children that have had a stroke have issues with seizures, have issues with spasticity, stiffness on one side, which is one of the things that the physical medicine and rehab doctors really focus on and things like dystonia and movement disorders. And so we'll be there to kind of help discuss how to treat kids with those issues in their same visit. So we're planning on getting that up off the ground here pretty soon and to be able to follow kids for a longer period of time.

Caitlin Whyte: Wrapping up here, doctor, what message would you like to send to physicians about strokes in kids?

Wilmot Bonnet, MD: The main thing is just to know that stroke does happen in kids. And any time you see an acute change or acute neurologic change in children, you need to ask yourself, could this be a stroke and does this kid have risk factors for stroke? Even if he doesn't have risk factors for stroke, you should be thinking of stroke in the back of your mind, because there are interventions that we can do.

So time is of the essence. The old adage is time is brain. And so it's important to act quickly if there's new weakness or an acute neurologic change in children. And for the most part, they should come to the ER very quickly. And then of course, we're available. One of us is always on-call for pediatric stroke. So if there's ever any question, they can always call the neurology on-call and we can help guide treatment decisions and things like that if there's concern for stroke.

Caitlin Whyte: Well, thank you so much for joining us today, doctor, and doing this important work at Children's Health. And as always, thank you for listening to Pediatric Insights. For more information, head on over to childrens.com/neurology. I'm your host, Caitlin Whyte. Stay well.