Episode 55: POTS Basics – Chiari, Craniocervical Instability, and Tethered Cord

00:01 Announcer: Welcome to the Standing Up to POTS podcast, otherwise known as the POTScast. This podcast is dedicated to educating and empowering the community about postural orthostatic tachycardia syndrome, commonly referred to as POTS. This invisible illness impacts millions and we are committed to explaining the basics, raising awareness, exploring the research, and empowering patients to not only survive, but thrive. This is the Standing Up to POTS podcast.

00:30 Jill (Host): Hello fellow POTS patients and precious people who care about POTS patients. I'm your host, Jill Brook, and today we have an episode of POTS Basics with your favorite neurobiology professor and POTS advocate, Dr. Cathy Pederson. Today we're going to review a few of the POTS comorbidities that you may hear about or that you may actually have, which are not common, but they are overrepresented in the POTS community. We're going to talk about Chiari malformation, craniocervical instability, and tethered cord syndrome. I know that's a lot of big words. If you've ever tried to look up these conditions, like me, you may find that it can get confusing fast because of all the technical brain anatomy that's involved. A lot of big words! But luckily, Dr. Cathy Pederson is the perfect person to break it down for us because she is a tenured professor at Wittenberg University who has received awards for being so good at teaching us this stuff. She is also a POTS researcher, a POTS parent, and the President and founder of Standing Up to POTS. Thank you for being here, Dr. Pederson.

01:42 Dr. Pederson (Guest): Thank you, Jill.

01:43 Jill (Host): So, before we discuss Chiari malformation, I was wondering if maybe you could just give us a few basics about what a normal brain is kind of supposed to be like, so that later when we hear about some of these issues, we have something to compare it to.

2:00 Dr. Pederson (Guest): Absolutely. So, I think our listeners know that the brain is it, right? That's why I'm a neurobiologist. Physiology is dead.

02:07 Jill (Host): [Laughs]

02:08 Dr. Pederson (Guest): I'm only half kidding there, and no biology is really the last frontier in the body. We don't understand it. We understand what happens at a cell molecular level. We understand what happens at a behavioral level. But it's a huge black box in between. And so, it really is very interesting, but there still is a lot to learn about that. Here's what we know, though: we know that the brain makes you, you. Your personality, learning language, or two or three languages, the way that you move or walk or throw a ball, your personality, your feelings for what happens in a situation - all of those are being generated by our brains. If you were to open up and hold a brain, it's sort of like Jello. It's about that consistency. In fact, if you've ever been to a Halloween party where they have one of those brain Jello molds - I don't know Jill, have you ever been to one of those?

03:05 Jill (Host): Yeah.

03:06 Dr. Pederson (Guest): yeah, that's about what the consistency of your brain is.

03:11 Jill (Host): Wow!

03:12 Dr. Pederson (Guest): It's really, really flexible and malleable, and it needs protection. And so we're going to be talking about how some of these protections fail us a little bit later. But what we have to do is protect this brain. And so I'm sure our listeners are thinking OK, well, we've got the skull, right? We've got bone that's going around that, the skin that's on the outside of that, of course. And a lot of our listeners probably also know about this thing called cerebrospinal fluid that our brain is pretty literally floating inside of our skull and it's floating in this fluid that's actually made by cells in the brain that are part of something called the choroid plexus - they're in the holes of the brain called the ventricles - and the cerebrospinal fluid is very similar to the plasma in your blood. So essentially some cells in the brain are making this fluid and it circulates through these holes in our brain - we call them ventricles. And there's a hole in the spinal cord. But it also goes around the outside. So we've got the cerebrospinal fluid really all over the place on the outside of our brain and spinal cord as well as running through the middle of it. So those are the two protections that are probably the most famous, right? The bone and then the cerebrospinal fluid.

04:30 Jill (Host): So can I just ask about the cerebrospinal fluid - you mentioned that it's similar to the plasma in our blood, but I don't know what the plasma in our blood is like. [Laughs] So when you say that, do you just mean it's like watery or what does that mean?

04:44 Dr. Pederson (Guest): Yeah, no, that's a great question. See, I'm making assumptions - not a good thing. So the plasma in our blood is watery, you're absolutely right about that. But it's got lots of other stuff in it. So there are proteins in there. There are nutrients. There might be hormones. There might be markers of our immune system. So it's the watery substance plus anything else that's dissolved in that. So that's what we would see in the cerebrospinal fluid as well.

05:13 Jill (Host): So that's interesting because for anybody who recalls our conversation with Dr. Svetlana Blitshteyn and her hypothesis about POTS and how it might involve the central nervous system, one of the connections she made was that maybe having hypovolemia, or low blood and low blood plasma, could end up having some effect on the cerebrospinal fluid. [Transcriber’s note: As a reminder, Dr. Blitshteyn was featured on Episode 34 of the POTScast.] So, I did not realize at the time that maybe blood plasma has some similarities to cerebrospinal fluid, but I'm just kind of starting to maybe put those things together.

05:50 Dr. Pederson (Guest): It does have similarities, but it's not like the plasma is moving into the brain and being used as cerebrospinal fluid. So, we ought to make that clear. So they are sort of related but not directly related in this way. So there are cells - people don't care - they're called ependymal cells. They're in these little things that looks like a little bit of cottage cheese in these holes in the brain that it's called choroid plexus that is secreting it. So, it is separate from plasma, but sort of analogous, if that makes sense.

06:18 Jill (Host): OK, thank you. That is really helpful.

06:20 Dr. Pederson (Guest): All right, the third protection of the brain - so we've got the bone and we've got this cerebrospinal fluid - the third protection are a series of membranes that are called the meninges. And there are three of these and my guess is that, again, our listeners have heard of these, but more from the most famous infection of them, which is called meningitis. So if folks have heard of meningitis, that's inflammation or infection of these meninges, which are membranes that are running around the outside of the brain and the spinal cord, and we have three of these meninges, three of these membranes. The outermost one is literally stuck - like glued to the inside of the skull - and it's called the dura mater and it literally translates to “tough mother”, right? I love that.

07:08 Jill (Host): [Laughs]

07:09 Dr. Pederson (Guest): I think that's hilarious anyway. Anyway, for our purposes today, the important thing about the dura is that there are a couple of places where the dura sort of folds inward. So, it's attached to the skull, but we've got some folds that are going to move down into the brain cavity, and one of these is up at the top of your head between your left and right cerebral hemisphere. So, it literally is coming down from the very top of that dura - the top of your head - down between those two hemispheres. So that keeps you and you, you know, move your head towards the left or the right, it keeps you from having the brain sort of slide way over one direction or the other. The other one that probably is more relevant for our topic today of Chiari is that there's another enfolding of this dura mater between the cerebrum - that's the main part of the brain that we think about - and then something called the cerebellum. Cerebellum literally means “little brain.” It looks like it's separate from the rest of the brain and is literally across the back of your head. So, if you fell on ice skates or roller skates or something, you gave your back of your head a good whack, the cerebellum would be right there where you're whacking it. OK? So it's really low on the backside of that head. And what it does is, again, it helps to hold the cerebral hemispheres - the big part of the brain that we think of the most - up above that, fold and then the cerebellum has its own little space underneath that fold. So, we're going to have a compartment for the cerebellum that we're going to come back to in a little bit. So that's the outer layer. The outer meninge is called the dura mater. The middle one we're going to talk about a couple more times and that's called the arachnoid mater. And when you think of an arachnid – it's taken from that word - that's a spider, right? And so if you were to get a good look at this arachnoid mater or layer, it looks like a spider web. That's how it got its name. So, there are all these little delicate strands that reminded whoever found them of a spider web. And the brain is sort of attached to that. So, the brain is being attached by these little delicate fibers coming down from the arachnoid, and that cerebrospinal fluid that we were just talking about is also circulating through this layer. So imagine the tendrils and where you've got open spaces is filled with cerebrospinal fluid. So this is here we're getting that floating action of our brain but also little suspension from these little tendrils that are holding onto it.

09:45 Jill (Host): This just sounds also cool and so amazing. I want to come take your classes. I somehow made it to you know almost 50 years old not knowing about these spidery things. So, keep going. Keep talking. This is very neat. [Laughs]

09:58 Dr. Pederson (Guest): OK, so we're working our way from outside to inside. So we have the dura mater and then the arachnoid mater which, again very important for what we're talking about today. And then the third layer is called the pia mater, and we're going to come back to that when we talk about tethered cord. But this actually looks like Saran Wrap. When you pull out a brain and you look at a brain, it looks very shiny and there's a really really thin transparent membrane that's literally stuck to the outside of your brain. And that's called the pia mater. And so anyway, we'll come back and talk about that one a little bit more later.

10:35 Jill (Host): OK, so that's the brain, and then I know the other thing that's going to tie into today's issue is the spinal cord. How does that tie into all of this?

10:46 Dr. Pederson (Guest): Yeah, that's a great question. We're talking a little bigger than what we have in some of our other basic episodes - a little bit more anatomy of the central nervous system. And the central nervous system, and you were mentioning this with Dr. Blitshteyn a couple minutes ago, is made up of two parts. So one part is the brain and the other part is the spinal cord. And so, the spinal cord is important, but not in the same way as the brain. So we still have that nervous tissue. It still is very sensitive. It's still housing bone, not the skull this time, but the vertebral column. So we've got the vertebral column and the spinal cord is running right down through the middle of that. I like to think of your spinal cord as sort of the superhighway between your brain, which is the king or queen of your body, and the body itself. So all of the motor commands, whether you are walking or talking or throwing a ball, whatever it is that you're doing, those are being generated by the brain, but they're sent down through the spinal cord and then out to the muscles. But the spinal cord is also using or moving sensory information as well. So, it's collecting sensory information which is coming in from your hands, from your feet, from your internal organs, and then taking all of that information back up to the brain again. So there's lots of work that's being done, but it's more of a conduit instead of the one that's generating the signals.

12:16 Jill (Host): OK, interesting. So, in a minute we're going to be discussing the use of MRI to diagnose some of the issues, and just so that we understand what that is all about, can you talk about what is an MRI and how do those work?

12:33 Dr. Pederson (Guest): Absolutely. MRIs have not been around that long, for you and me, Jill. For some of our younger listeners, it's been around their whole life, but these things really were not invented until the late 80s or early 90s, and they really revolutionized the way that we do medicine, and so the MRI is wonderful. Number one, MRI stands for magnetic resonance imaging and one of the best things about this is it does not use radiation. So if you get a CT scan, that's mega radiation. It's like a ton of X rays all at one time. But the MRI doesn't use any radiation at all, so it's much safer. We can use it on pregnant women, for example, if something is going on there and without worrying about hurting that child. And instead of using radiation, it uses these giant magnets. And I think a lot of our listeners have probably had an MRI. I know my daughter has. Have you had them, Jill?

12:32 Jill (Host): No, I think I had the CT scan with all the radiation. [Laughs]

12:36 Dr. Pederson (Guest): Oh yeah? I've had a CT scan, too. The MRI's are super loud. Like really really loud. And that's from these big coils of the magnets and essentially the way that it works is they activate these magnetic coils and it literally shakes the protons in your body. Protons are positively charged particles. What we're really talking about in most tissue is water. So your water is made up of oxygen and two hydrogens. Well the hydrogens are just the protons. OK, we don't need to go too far into the chemistry of this. [Laughs] But it shakes the hydrogen on the water, and that's how we create the picture. Super cool.

14:19 Jill (Host): So it's able to take a picture of any kind of tissue in your body?

14:23 Dr. Pederson (Guest): Yeah, so the beauty of MRI is that it can pass through the bone. So you think about like an ultrasound, that is great. It's cheap, again, no radiation. We think of that with pregnancy, but we can use it for abdominal tumors and all sorts of things. But boy, when you get to the brain and spinal cord that are housed in bone, we need something like the CT scan or the MRI to be able to literally see through that very dense tissue.

14:51 Jill (Host): So, I know that in some of your research over the years you have done a lot of work looking at brain MRIs. So I'm just curious, like, how similar or different do different people's brains look? Is there a lot of variety in the layout of the brain or the shape or anything? Or do healthy brains all look alike and it's just the ones with issues that look different?

15:13 Dr. Pederson (Guest): That's a great question, and I think it depends on how close you look. So you're right, I did MRI research for about 2 decades and recruited women from the community into my lab for a variety of projects. So before my daughter got sick, I did other kinds of research. I've really stopped that and moved everything into chronic illness. But when I was younger, I did work with post-traumatic stress disorder secondary to child abuse in women and looking for changes in the brain from that kind of experience. I did a second smaller study looking at the relationship between sexual orientation and the volume of some brain areas. So I did a lot of that kind of work when I was younger. I was really really lucky - I met a physician who was a neuroradiologist in town here and he donated these MRI's for a long time and that was just really really lucky. I teach at a small school and MRI's are expensive. So, shout out to Dr. Robin Osborne who did that with me for a long long time. To answer your question though, when you watch the scan being done, and I was lucky enough, Dr. Osborne was really super and he would let me in with the lab technicians who were running the scans. And it is sort of like watching Grey's Anatomy or one of those shows where literally you see the scans pop up as it's taking them. And so when you're looking at sort of that level, most brains look very similar. Now there are some people that will have a lot more gyri, or the sulci in between the valleys in between these sort of crests are more obvious, in those people that sort of correlate with higher intellect. There were few, unfortunately, that the brain was a little smoother than you might want it to be because, I think, of the severe to extreme abuse that they suffered as children. But it was very few on either extreme. Most of them looked very, very similar as those MRI's popped up. What my students would do, though, is really go in and trace each slice of something like the hippocampus which is involved in learning and memory. And so, as you do that, and you're really studying the hippocampus through the brain of the women, they're quite different. It's amazing how different they are. So there is a lot of variability if you look closely enough at individual brain regions.

17:55 Jill (Host): Interesting, OK. So let's get into Chiari Malformation. I think it's sometimes called Arnold Chiari Malformation for the full name. What is that?

18:07 Dr. Pederson (Guest): This is a fascinating syndrome, and I'll tell you I first found it when I was doing that PTSD study. And Dr. Osborne called me and he's like, “Cathy, we've got a problem.” [Laughs] And this was several years in, and he'd never called me about one of my participants before. And it turns out she had Chiari - Type 1 Chiari. I'd never heard of it. And she was a college student and freaked me out, freaked her out, but she didn't have any symptoms at all. None. And so it was sort of a non-finding, an accidental finding is what they would call it, where she wasn't having any symptoms but maybe it was something then that they were going to watch. So, they went back and rescanned her again to just really look at this. But here's what happens in a Chiari Malformation. We talked about the central nervous system, which is the brain and spinal cord. And of course, those are connected. So there's got to be a hole at the bottom of the skull where the spinal cord can pass up and connect with the brain, right? That makes sense. We call it the foramen magnum is the Latin name for it, which literally means “big hole.” The foramen magnum – the big hole. So there's this big hole and it's sitting where the cerebellum and the brainstem are right on top of this. So those are the lowest parts of the brain and then the spinal cord is moving up through this hole, through this foramen magnum. What happens in Chiari is that there are a number of things that can cause this, but often that part of the skull where the cerebellum, that little brain right at the back of your head is sitting, is either too small or it's misshapen. It's got a weird shape to it. Maybe it's got a slant or something like that. And what that causes is, as the brain grows, as the skull grows, and what we see mainly in POTS patients is it there what we're going to come down to is Type 1, which is the less severe form. And it's often seen in teenagers or young adults. So think about that growth spurt of the teenager, and now for whatever reason, the cerebellum is not sitting in the back part of the skull the way that it should. And so that presses the cerebellum forward which presses on this brain stem, and often those end up being forced - there's too much pressure - and it forces them down into that big hole that we call the foramen magnum, which is where the spinal cord is supposed to be. So that causes 2 problems: One: I've got pressure on a very delicate tissue. So the brainstem is where you have your basic biological functions. The bottom part of that is called the medulla – controls sort of trivial things like heart rate, respiratory rate, super important, right? And so putting pressure on this area can cause big big problems for folks. It also can force the cerebellum down in there. The lower part, we’ll call the cerebellar tonsil, gets forced down in there, which actually puts more pressure on the brainstem. So we've got this downward push of brain through this hole – the foramen magnum - that's not supposed to be. We’re supposed to have spinal cord there, we're not supposed to have brain there. That's the most common cause of Chiari Malformation. There's another one that's much less common, but could happen. That's a cerebral spinal fluid problem where something has happened where that fluid has been drained out in a way that maybe it shouldn't be. So that could be an injury, you know, think car accident, take a blow to the head, could be a disease or infection maybe that causes that to happen. And remember our brain and spinal cord are supposed to be floating in this fluid. So if I've lost some of that that can cause me problems. And then the last potential cause we're also going to come back and talk about - and it's at the joint of the skull and the vertebral column - and they call this the cranial cervical junction. ‘Cranium’ is the name for the part of the skull that encases the brain and ‘cervical’ are the top vertebrae in that vertebral column. And so if the joint between the skull and the vertebral column is too loose, and we're going to come back and talk about that, that can cause all kinds of other problems, right? So we could literally slide the skull away from the vertebral column a little bit, right? So we're pulling on that nervous tissue, which is not a good thing.

22:36 Jill (Host): Ah, so you're talking about, if at the very, very top of the spine where it meets the skull, if there's too much movement there.

22:45 Dr. Pederson (Guest): Exactly. And the brain and spinal cord, they are, they've called nervous tissue ‘irritable tissue’. It's really insulting as a neurobiologist - irritable. But what that means is it's really sensitive and it starts firing if it gets stressed. So, if it's being stressed or or stretched or having too much pressure on it, these neurons fire when they shouldn't, and obviously that can lead to all kinds of problems as well.

23:13 Jill (Host): So, we hear about different types of Chiari malformation. What are those?

23:19 Dr. Pederson (Guest): That's a great question, and I went and did a little research for this episode, and there are three or four different types of Chiari malformation depending on the source that I looked at. I'm going to talk only about the first two that are most common, but the one that's most common in POTS patients is type 1, so a Chiari malformation type 1. And this is the one that I mentioned just a minute ago where people are generally diagnosed in late childhood or adolescence or early adulthood. And so, we are also seeing that this type 1 Chiari malformation is more common in folks with Ehlers Danlos Syndrome and particularly a POTSie’s best friend - the hypermobility type. And so again, all these comorbidities sort of pile on for us as a chronic illness community, unfortunately. So, what they think is with this type 1 is that this is the one that's caused by the growth spurt, where maybe the cerebellum grows a little bit too big for the skull area that's holding it, or the skull area just isn't growing as large as it should, but either way it's putting pressure that pushes that cerebellum down through that foramen magnum, that big hole, and into position where the spinal cord should be.

24:44 Jill (Host): So then, what are the typical symptoms that result from that?

24:49 Dr. Pederson (Guest): There are a number of symptoms, and like anything else, it depends on how much pressure is there, how far the brainstem and the cerebellar tonsil have been pushed down. One of the common symptoms is headache and headache that's really starts at that back of your head where, again, the skull is connecting with or joining with the vertebral column. And so I talked to someone yesterday who's got a Chiari malformation just to be sure I've got good stories for this. And it was really interesting because she has POTS and she has EDS and she's got Chronic Fatigue Syndrome, like many of us in the community do. But she also has this Chiari and she said she'd gets POTS headaches, but she also gets Chiari headaches, and she can tell them apart. And I said, “Do tell! I would like to know.” And she said the Chiari headaches really start – they're very intense and they start at the back of the head. She said they can radiate, you know, to other parts of the head or down the neck, but it always starts at the base of the skull. She said her POTS headaches are more like what most people experience - sort of the sinuses behind the eyes up in the forehead region. So that headache - if you're getting headaches at the base of the skull, that may be an indicator, right? It's something to at least ask the doctor about. Neck pain is common. But as the pressure increases, we could see other kinds of problems. The cerebellum is related to posture and balance, sort of in a nutshell. And so, as this progresses, people can really develop problems with their balance because again, we've got this extra pressure as we're forcing that cerebellum down through that big hole, that foramen magnum. They might have problems with fine motor skills. So, think about typing or writing or playing a musical instrument - anything that you're doing with your hands that require fine finger coordination can be affected by this Chiari malformation.

26:54 Jill (Host): So that could be a real double whammy for people who also have joint hyper mobility and they have trouble just stabilizing those joints on top of it. Wow.

27:04 Dr. Pederson (Guest): Yeah, absolutely. Numbness and tingling in the hands or feet is another one. And so, I know someone else who went to school with one of my daughters who had a Chiari malformation. And one of the weirdest symptoms I've ever heard is that she couldn't tell whether a surface was wet or dry by feeling it. She'd lost that sensation. So she had some numbness and tingling, but she was also having difficulty telling temperature with her hands or whether the surface was wet or dry. And then dizziness, but my gosh, so many people with POTS have issues with dizziness, how would you ever know with that one? And then things like difficulty swallowing. Sometimes people will have an exaggerated gag reflex, so they gag really easily. They choke maybe more than they feel like as normal. Or vomiting. But again, the vomiting, nausea and vomiting is common in the POTS population, so that wouldn't be one that might raise a particular red flag here. And then some people will have speech problems. Their voice will get really hoarse because we've got some nerves that are going to the head and neck that are in that brainstem region. So that's type 1. That's the most common, may be related to that growth spurt, often is found a little bit later, and again tied to that Ehlers Danlos Syndrome that so many in our community have.

28:29 Jill (Host): Well, I only know a few people with Chiari malformation and my sense, and sometimes it's, you know, the least of their problems. The other thing that's come up with a few of them is that they can be really sensitive to changes in barometric pressure, like if there's a storm coming or a heat wave. And now that you are explaining about the pressure, that starts to make sense because I could see how just even a little bit of a change in pressure changes what's getting pushed on in their brain. Does that make sense?

29:03 Dr. Pederson (Guest): Yes, it does. But again, I think my daughter is very sensitive to pressure changes as well. I don't think she's got a Chiari malformation going on there. So I think that's common in the POTS community, too. So it's really hard to tease some of this apart, I feel like.

29:19 Jill (Host): OK. Well, one thing that's amazing to me is that that's the more mild form of Chiari, right?

29:26 Dr. Pederson (Guest): It is. Type 2 is more severe, almost always diagnosed either in infancy or actually in utero before the baby is even born. So, it's a much more severe type. It's often associated with a neural tube defect that's called spina bifida, and so folks may know spina bifida. The most famous form is where they've got this lump sort of on the back side where the spinal column didn't close all the way. So you actually end up with nervous tissue on the outside of the body. That's the most severe kind of spina bifida. And so this is much more severe, again seen very, very early, not typically what we're talking about in the POTS community, although it could be. What we see here is that even more of that cerebellum and brainstem are being pushed down through that hole - through the foramen magnum - a lot more pressure and a lot more issues as a result of that. So if you remember, I said the lowest part of the brainstem is something called the medulla, which I tell my students controls all of your life functions: heartbeat, respiratory rate, you know, your breathing. And so they see actually changes in their breathing pattern because there's so much pressure on the brain stem. But swallowing problems and gagging is a big issue. But one of the tell tales of this one, and again, more often in young children, is that they have these involuntary eye movements where their eyes will sort of dart downward. So it's a really quick like you're looking down towards the floor, and then they pop back up again. And again, without being too complicated, there are 12 pairs of cranial nerves that run along this brainstem. And if we put pressure in the wrong place, it causes weird things to happen. Weakness in the upper extremities in the arm is also really common there. The other couple of types are even less common than this. So there are some other types, but again, I think when we're talking Chiari in our population - in the POTS population - we're probably talking type 1.

31:36 Jill (Host): Now my understanding is that Chiari malformation is rare, but it's less rare among POTS patients. But do we know anything more about the relationship? Does one cause the other or are they both a result of something else or does just nobody know?

31:52 Dr. Pederson (Guest): I think the jury is probably out. It is listed as a potential underlying cause of POTS, but I don't think that we've got a good research answer to that. Let me tell you an anecdotal story. I know three people with Chiari malformation. All of them are the type 1. All of them have POTS. And the most mild one - and I'm not saying that her POTS or any of her symptoms are mild - I spoke with her yesterday. And she has Chiari, has some pressure, gets the headaches. It used to be she was getting that sort of headache at the back of the skull once every few months. In the last several months, it's happened more often. Stress brings on those headaches. And also, and I didn't mention this up above I guess, but sneezing and coughing - so that kind of sudden jerking movement, or if you're physically straining to do something - worsens the Chiari and can bring on the headache. And so she's having a lot more headaches. She's a couple of years out of college now and sort of getting into the real world and that sort of thing. She has not had the surgery - there's a decompression surgery that they can do for it - and has had MRIs for several years, just sort of watching it to see if it was getting worse or not. And so the way that they actually look at this is a lot of physicians will use an upright MRI, or they use an open MRI, if people have heard of that. And instead of having the person lay down flat, they have them sitting. So, here's the thing with Chiari - it's more visible when gravity is pulling the brain downward. So when you're sitting up, it may pull that cerebellar tonsil and the brainstem down through that foramen magnum a little bit more. So that's the advantage of it. The bad news of that is that the open MRI's have smaller magnets and so you don't get as good a picture. Her doctor didn't do that. Her doctor used the regular MRI where you lay on your back and get the picture, and it took about an hour, she said, to run this particular scan. But hers is enough that even when she's not sitting upright, they can see that movement of the cerebellum down through there. So, she went in every year for two or three years. Didn't see a change. And because her symptoms are stable, decided not to do any intervention. And so that's where she is. The person that I'm thinking about that’s sort of in the middle had pretty bad POTS symptoms. She was the one that wasn't able to tell that wetness, you know, on the surface, if she was touching it. And she was also fainting, having dizziness, having trouble eating - a lot of things that we associate with POTS. She went ahead and had the surgery. So there's not really very good medication for Chiari malformation, unfortunately. So the treatment - the main treatment - is to go ahead and do surgery and they call it a posterior fossa decompression, right? Who names these? Posterior means towards the back. Fossa is a depression. So, they're going for that depression that your cerebellum is sitting on, and they're trying to give the cerebellum more space. So, the surgery is to remove some bone from that area to give the cerebellum more space so that there's not pressure on the cerebellum, and it keeps everything where it's supposed to be. And she had the surgery and things got better. Now, she didn't have a complete recovery and she's still symptomatic, but definitely better after the surgery The third person that I know had the worst case that I'm aware of, and maybe you can one up me, Jill. We'll see. I hope not, actually. I hope not. A kid, 13 at the time, and had been very athletic, played flag football and that sort of thing. And at age 11 or 12, became very symptomatic, sort of the story that we all know too well. Dizziness, nausea, trouble keeping food down, weakness, fatigue, ended up in a wheelchair, at times had to have supplemental feeding and G-tube, that sort of thing, to get the nutrients in. Got to the point where he couldn't focus to read anymore. So, the cerebellum helps with that, too, as it turns out. And the mother was desperate, right? So, her kid who had been young and strong and typical, healthy, and within two years was in a wheelchair, could barely stand to go to the bathroom, was sometimes needing feeding tubes, couldn't coordinate that eye movement. And went to several physicians asking about Chiari. Eventually he was diagnosed with Ehlers Danlos Syndrome, which gave a hint that maybe Chiari was in the mix for him. And he had MRIs taken and they were the supine kind, so he wasn't sitting up in them. Had three different doctors look at them. They said, “Nope, no Chiari, nothing to be done.” And they sent it off to the Chiari Association and they said absolutely, he's got this problem. And so this kid had the decompression surgery, where again, they're making more room for the cerebellum. And the recovery was very difficult. But you know what? Every single one of his symptoms went away.

37:14 Jill (Host): Wow!

37:15 Dr. Pederson (Guest): In his case, all of the symptoms had been caused by this compression of the brain stem and the cerebellum. And so he could read, he could walk, he could eat - just an amazing recovery after having that surgery done. So, you know, it's hard to know and surgery is always risky. So if your symptoms are stable, if you feel like it's the least of your worries with a bunch of other things going on, maybe you don't do it. But if it looks like it's more severe and maybe it's the underlying cause, it's worth having a talk with a neurologist and/or a neurosurgeon. That's interesting.

37:56 Jill (Host): Right! And then also just reading up on the extra considerations about surgery, if you do have Ehlers Danos Syndrome or mast cell activation syndrome or some of these other things and I know it can get pretty gnarly to figure out what's the best route. I think you touched on it a little bit before, but sometimes in connection with Chiari malformation, we also hear about something called craniocervical instability. What is that?

38:26 Dr. Pederson (Guest): Absolutely. So, cranial cervical instability is at that joint between the skull and the top of your vertebral column. And so, you know the vertebral column is made up of a series of small bones that allows us to be able to bend backwards and forwards, and left and right, and be able to move around a little bit. And so that top bone has a joint, essentially, in that articulation with the bottom of the skull. And it used to be thought that really we only saw this if there was trauma or some sort of an inflammatory disease like rheumatoid arthritis - this cranial cervical instability is actually really common with that. But more recently, they've found that this is really prevalent in people with that hypermobile EDS, and I even saw a paper or two that said maybe even people that had myalgic encephalomyelitis or chronic fatigue syndrome may also have a higher rate of cranial cervical instability. And again, what we're talking about is the articulation of the joint between the skull and the vertebral column. And so, you know, we've got the bones there, but the bones aren't the whole picture. You have ligaments, and ligaments connect bones to bones. So it's easy to think about ligaments maybe in your knee - people have problems with their ACL – the L of that is ligament, or their MCL. It's connecting bones to bones. Well, we have the same thing in our neck and attaching to the skull. And so in the case of EDS, it may be that they're too stretchy and so they allow that skull to slide forward in a way that it shouldn't do normally. In other cases, maybe it's been weakened by it being stretched over time, or ruptured completely. And so, what can happen again is that that skull slides a little bit out of position. We're not talking a foot. We're probably not even talking an inch, but we're talking about a little bit of change out of position from where it should be. And when it does that, it puts pressure on our new friend now - the brainstem and the cerebellum. And also can really pull on that upper part of the spinal cord. And so this one, it is a little bit different, but Chiari and craniocervical instability often go hand in hand. What a lot of people say, or the way that they describe this is that they feel like their head is too heavy for their neck to support, right? That's not a thing that most people say. An example of really gross over exaggeration would be like a bobblehead statue. Have you ever seen those, where the head's really enlarged and it sort of moves back and forth, right, the bobble head. And the body is stationary and smaller. Sort of that idea where the head is too much for those ligaments or for that joint, and it can't be supported properly. And so, the symptoms that we see of cranial cervical instability are very similar to that Chiari malformation type 1 that we were talking about. So, balance problems, dizziness, headache, numbness, weakness, fatigue. And so again, you know, it would be a good thing, especially if you're having those headaches that seem to be coming from the back of the head to go and talk to a neurologist or to a neurosurgeon about that.

41:51 Jill (Host): OK, so we've got one more on our menu and that is tethered cord syndrome. What is this one?

41:59 Dr. Pederson (Guest): We're moving to the other end of the spinal cord here. So we've been at the top, right? We've been up at the part of the spinal cord that's coming directly out of that brainstem and then running down through the vertebral column. Tethered cord is usually associated with the lower part of the spinal cord. And so what happens in this case is that you get abnormal tissue that's sort of sticking the spinal cord - maybe to that dura mater, that meninge that's going around it - in places where it's not supposed to. And so we end up limiting the movement of the spinal cord within the vertebral column. So again, remember, you should be able to bend over or bend to the side and back and forth and your spinal cord should move with that inside of that vertebral column. And in tethered cord it gets stuck. So, there are two sort of general causes of tethered cord. One is what we call congenital. That means you're born with it. And so, people are born with an extra attachment or a stronger attachment at the bottom of that spinal cord than what most people have. The other thing that can happen, though, is trauma. So again, car accident, playing football maybe would be a great example of that. And the nervous tissue may heal but you might get a little scar tissue and that scar tissue sticks the spinal cord to the structures around it so that it's not moving the way that it should.

43:32 Jill (Host): So just to make sure that we understand it correctly, or that I understand it, I feel like I'm a little confused. So the spinal cord is not supposed to be attached to anything on a side? Like what is it attached to?

43:45 Dr. Pederson (Guest): Right. Well, remember what we said about the brain floating. The spinal cord floats as well. So the brain and spinal cord are the central nervous system that are bathed in the cerebral spinal fluid that we talked about at the top of this episode. So, it should be sort of floating in this fluid in the arachnoid layer, if you remember that from earlier, and what we usually have is at the very bottom of the spinal cord, there is a extension of the pia mater - that innermost part of the meninges that looked like Saran Wrap - and it actually runs a long way. So. here's an interesting fact: I'm going to come back to that. But did you know that the spinal cord does not run the whole length of the vertebral column?

44:32 Jill (Host): No, did not know that.

44:34 Dr. Pederson (Guest): It does not.

44:35 Jill (Host): But then again, I never thought about it.

44:36 Dr. Pederson (Guest): Right!

44:36 Jill (Host): I don’t know what I thought.

44:37 Dr. Pederson (Guest): I know, it's fascinating! So it runs through the top, right, the top vertebrae are called the cervical vertebrae. Those are the ones in the neck. It runs through - they're called the thoracic vertebrae. Those are the ones that the ribs are all attached to, and then right under that we have lumbar vertebrae. And so, the spinal cord ends at the top lumbar vertebrae. So, then you've got four more of those, and then you've got a sacrum and coccyx, which is your tailbone. So there's no cord there. Now, there are nerves that are running and together we call them the cauda equina - it reminded someone of a horse's tail, right? So that's what it means in English translated from the Latin. But we have this long extension of the pia mater. It's called the filum terminale, if anyone wants to look it up. It goes down through these nerves and it attaches to your tailbone. The fancy word for that is the coccyx. And so, it's anchored, if you will, just like a ship could be anchored, but the ship can still move, right? And the spinal cord can still move. So we've got this long fiber coming off of the pia mater that's sort of our anchor there.

46:04 Jill (Host): So did not know that. That's fascinating! So, the whole thing is like, literally floating and it can get stuck to part of the spine, if I'm hearing this correctly, and that's why it's called tethered. So, what are the consequences or the symptoms if that happens?

46:23 Dr. Pederson (Guest): Yeah, so you know a lot of times we'll see this worsen over time. So if person has a tethered cord like this, often the symptoms are progressive - meaning that they get worse over time - and the reason for that is we're stretching the spinal cord and pulling on it in ways that we should not be. If it's tethered to something and you bend, then you're pulling on some of this nervous tissue in a way that you shouldn't. So a lot of these symptoms are nondescript. They could be a lot of different things. So one is back pain. So just like we had the headaches up top, right, now we've got back pain down lower. Could be numbness in the legs or the feet, right? We're holding or pulling on that cord, and so all of our connection to the brain is through that spinal cord. And then an interesting one is physical changes in the feet. So a hammer toe, where the toe doesn't lay down all the way, the feet turning in or out or really high arches. So all of those are maybe correlated with this tether cord. I'm not sure, again, that it's a direct cause relationship there. Sometimes people with tethered cords will start walking on their toes - like on their tip toes - but again, there are other things that cause that. The one that I think of first is muscular dystrophy with the tightening of those muscles. So you can't say from the walking on the toes that it's a tethered cord. One that often gets people's attention is incontinence, where they lose control of their bladder. And so, especially if this is a kid or a teenager or a young adult where they've had control of this over many years and now all of a sudden they lose that control, that'll send them to the doctor. So that's one that's often at the forefront. Constipation is also one. Remember that all these nerves, even though we're not conscious of saying, “OK, I want my bowels to contract,” it's connected to the nervous system. And so if our spinal cord isn't working correctly, we end up with all sorts of seemingly unrelated problems. And then the last one is - it's really common for people with a tethered cord to get urinary tract infections. Again, I don't know exactly what the relationship is there, but that's something that's been noticed.

48:39 Jill (Host): So is there any treatment for tethered cord syndrome?

48:43 Dr. Pederson (Guest): Unfortunately, there are not medications that I'm aware of that will do much significant for this. And so again, we're talking surgery here, where they go in and they call it ‘detethering the cord,’ meaning that they're cutting that scar tissue or those attachments that were abnormal, so that again the spinal cord can float and flex the way that it's supposed to.

49:06 Jill (Host): So, if anybody is concerned that they have any of these conditions, what is the type of doctor that deals with them typically?

49:16 Dr. Pederson (Guest): You'd really want to see a neurologist, would probably be the first step, and if they see something either clinically in the symptoms that you're presenting, or they have imaging done and suspect Chiari or craniocervical instability or tethered cord, they'll likely refer you then to a neurosurgeon. And I would say you want a surgeon who does this every day. You don't want a surgeon, when you're dealing with the nervous system like this, who does one tethered cord a year or one Chiari a year. You want the person who does this every day or every week and is the absolute expert in the area.

49:56 Jill (Host): Yeah, that makes a lot of sense and I kind of mentioned this earlier, but if you have mast cell activation syndrome or Ehlers Danlos Syndrome or any kind of connective tissue disorder, I think you want to discuss that with your surgeon ahead of time, too, because there's some special considerations, and I think there's been some good articles written by specialists that kind of tell you what some of the considerations would be and ways to make it safer.

50:21 Dr. Pederson (Guest): Absolutely.

50:22 Jill (Host): So, is there anything else we should say about Chiari malformation, craniocervical instability, or tethered cord syndrome?

50:32 Dr. Pederson (Guest): I guess I just want our audience to realize that these are relatively rare even within the POTS community. We do see it more in folks that have Ehlers Danlos Syndrome as part of their mix, but even in that population we're looking at really small numbers. I don't have percentages and I don't think it's been well studied. Now it is more common in our population than the general population, but this is not something that everybody should have checked out. That said, if you have some of the symptoms, if you listen to this and you're like, “Wow, that sort of sounds like me,” it doesn't hurt to mention it the next time you see a neurologist.

51:11 Jill (Host): Great, well I feel very lucky that we had you our resident neurobiologist to walk us through all of this, because it was a lot, but it was really interesting. I wish I could sit in on one of your classes. Dr. Pederson, thank you so much for taking the time to fill us in again on more POTS basics which are escalating in complexity. I don't know that they're that basic anymore, but you always clarify everything so nicely. Thank you.

51:35 Dr. Pederson (Guest): Thank you, Jill.

51:36 Jill (Host): And hey listeners, as always this is not medical advice. I know you know that, but we still have to say it. Please consider rating us or subscribing as it helps us grow the community and possibly raise more money for POTS research. But mostly, thank you for listening. Remember, you're not alone, and please join us again soon.

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