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Chorea describes involuntary movements that are random, abrupt, and unpredictable, flowing from one body part to another. The most common cause of genetic chorea in adults is Huntington disease, which requires comprehensive, multidisciplinary care as well as support for care partners, who may themselves be diagnosed with the disease. In this episode, Aaron Berkowitz, MD, PhD FAAN speaks with Kathryn P. L. Moore, MD, MSc, author of the article “Huntington Disease and Chorea” in the Continuum® August 2025 Movement Disorders issue. Dr. Berkowitz is a Continuum® Audio interviewer and a professor of neurology at the University of California San Francisco in the Department of Neurology in San Francisco, California. Dr. Moore is an assistant professor and director of the Parkinson’s Disease and Movement Disorders Fellowship in the department of neurology at Duke University in Durham, North Carolina. Additional Resources Read the article: Huntington Disease and Chorea Subscribe to Continuum®: shop.lww.com/Continuum Earn CME (available only to AAN members): continpub.com/AudioCME Continuum® Aloud (verbatim audio-book style recordings of articles available only to Continuum® subscribers): continpub.com/Aloud More about the American Academy of Neurology: aan.com Social Media facebook.com/continuumcme @ContinuumAAN Host: @AaronLBerkowitz Guest: @KatiePMooreMD Full episode transcript available here Dr Jones: This is Dr Lyell Jones, Editor-in-Chief of Continuum. Thank you for listening to Continuum Audio. Be sure to visit the links in the episode notes for information about earning CME, subscribing to the journal, and exclusive access to interviews not featured on the podcast. Dr Berkowitz: This is Dr Aaron Berkowitz with Continuum Audio, and today I'm interviewing Dr Kathryn Moore about her article on diagnosis and management of Huntington disease and chorea, which appears in the August 2025 Continuum issue on movement disorders. Welcome to the podcast, Dr Moore. Could you please introduce yourself to our audience? Dr Moore: Yeah, thank you so much. I'm so excited to be here. I'm Dr Moore. I'm an assistant professor of neurology at Duke University, where I work as a movement disorder specialist. I run our fellowship there and help with our residency program as well. So, I'm excited to speak with our listeners about chorea today. Dr Berkowitz: Fantastic. And we're excited to talk to you about chorea. So, as a general neurologist myself, I only see chorea pretty rarely compared to other movement disorders like tremor, myoclonus, maybe the occasional tic disorder. And like anything I don't see very often, I always have to look up the differential diagnosis and how to evaluate a patient with chorea. So, I was so glad to read your article. And next time I see a patient with chorea, I know I'll be referring to your article as a great reference to have a framework for how to approach it. I hope our readers will look at all these helpful tables on differential diagnosis based on distribution of chorea in the body, potential etiologies, time course of onset and evolution, associated drug-induced causes, what tests to send. So, I highly recommend our listeners read the article. Keep those tables handy for when a patient comes in with chorea. I'm excited to pick your brain about some of these topics today. First, how do you go about distinguishing chorea from other hyperkinetic movement disorders when you see a patient that you think might have chorea? Dr Moore: One of the wonderful things about being a movement disorder specialist is we spend a lot of time looking at movements and training our brain to make these distinctions. The things that I would be looking out for chorea is involuntary, uncontrolled movements that appear to be brief and flowing from one part of the body to another. So, if you can watch a patient and predict what movements they're going to do, this probably isn't chorea. And it should be flowing from one part of the body to another. So, not staying just in one part of the body or having sustained movements. It can be difficult to distinguish between a tic or dystonia or myoclonus. Those things tend to be more predictable and repetitive than the chorea, which tends to be really random and can look like dancing. Dr Berkowitz: That's very helpful. So, once you've decided the patient has chorea, what's your framework for thinking about the differential diagnosis of the cause of the patient's chorea? Dr Moore: Well, that could be really challenging. The differential for chorea is very broad, and so the two things that I tend to use are age of the patient and acuity of onset. And so, if you're thinking about acute onset of chorea, you're really looking at a structural lesion like a stroke or a systemic issue like infection, hyperglycemia, etc. Where a gradually progressive chorea tends to be genetic in nature. When you're thinking about the difference between a child and an adult, the most common cause of chorea in a child is Sydenham's chorea. And actually, the most common cause of chorea that I tend to see is Parkinson's disease medication. So, if anybody's seen dyskinesia in Parkinson's disease, you've seen chorea. But it's those two things that I'm using, the age of the patient and the acuity. Somewhere in the middle, though---so, if you have subacute onset of chorea---it's important to remember to think about autoimmune conditions or paraneoplastic conditions because these are treatable. Dr Berkowitz: That's very helpful. So, like in any chief concern in neurology, we're using the context like the age and then the time course. And then a number of other helpful points in your article about the distribution of chorea in the body. Any comments you'd like to make about- we have this very helpful table that I thought was very interesting. So, you really get deep into the nuances of chorea and the movement disorder specialist expert level. Are there any aspects of parts of the body affected by chorea or distribution of chorea across the body that help you hone your differential diagnosis? Dr Moore: Certainly. I think where the chorea is located in the body can be helpful, but not as helpful as other conditions where you're localizing a lesion or that sort of thing. Because you can have a systemic cause of chorea that causes a hemichorea; that you can have hyperglycemia causing a hemichorea, or even Sydenham's chorea being a hemichorea. But things that we think about, if the forehead is involved, I would think about Huntington’s disease, although this is not pathognomonic. And if it's involving the face or the mouth, you can think about neuroacanthocytosis or, more commonly, tardive dyskinesia. Hemichorea would make me think about some of those systemic issues like hyperglycemia, Sydenham's chorea, those sorts of things, but I would rely more on the historical context and the acuity of presentation than the distribution itself. Dr Berkowitz: Got it. That's very helpful. So those can be helpful features, but not sort of specific for any particular condition. Dr Moore: Exactly. Dr Berkowitz: Yeah, I often see forehead chorea mentioned as sort of specific to Huntington's disease. Since I don't see much Huntington's disease myself, what does forehead chorea look like? What is the forehead doing? How do you recognize that there is chorea of the forehead? It's just sort of hard for me to imagine what it would look like. Dr Moore: It's really tricky. I think seeing the eyebrows go up and down or the brows furrow in an unpredictable way is really what we're looking for. And that can be hard if you're having a conversation. My forehead is certainly animated as we're talking about one of my favorite topics here. One of the tricks that I use with the fellows is to observe the forehead from the side, and there you can see the undulation of the forehead muscles. And that can be helpful as you're looking for these things. I think where it's most helpful to use the forehead is if you're trying to determine if someone with a psychiatric history has tardive dyskinesia or Huntington's disease, because there can be quite a lot of overlap there. And unfortunately, patients can have both conditions. And so, using the forehead movement can be helpful to maybe direct further testing for Huntington's disease. Dr Berkowitz: Oh, wow, that's a very helpful pearl. So, if you see, sort of, diffuse chorea throughout the body and the forehead is involved, to my understanding it may be less specific. But in the context of wondering, is the neuropsychiatric condition and movement disorder related by an underlying cause in the case of seeing orofacial dyskinesias, is the relationship a drug having caused a tardive dyskinesia or is the whole underlying process Huntington's, the absence of forehead might push you a little more towards tardive dyskinesia, presuming there is an appropriate implicated drug and the presence of forehead chorea would really clue you in more to Huntington's. Did I understand that pearl? Dr Moore: That's exactly right, and I'm glad you brought up the point about making sure, if you're considering tardive dyskinesia, that there has been an appropriate drug exposure. Because without that you can't make that diagnosis. Dr Berkowitz: That's a very helpful and interesting pearl, looking at the forehead from the side. That is a movement disorders pearl for sure. Sort of not just looking at the forehead from one angle and trying to figure out what it's doing, but going to look at the patient in profile and trying to sort it out. I love that. Okay. So, based on the differential diagnosis you would have crafted based on whether this is sort of acute, subacute, chronic, the age of the patient, whether it's unilateral, bilateral, which parts of the body. How do you go about the initial evaluation in terms of laboratory testing, imaging, etc.? Dr Moore: Well, certainly in an acute-onset patient, you're going to get a number of labs---and that's listed out for you in the paper---and consider imaging as well, looking for an infarct. One thing our learners will know is that sort of the typical answer to what's the infarct causing hemichorea would be the subthalamic nucleus. But really, those infarcts can be almost anywhere. There are case reports for infarcts in a wide variety of places in the brain leading to hemichorea. So, I think some general blood work and an MRI of the brain is a good place to start. For someone who has a more chronic course of the development of chorea, there are certain labs that I would get---and an MRI, because if you get an MRI and there's heavy metal deposition or other disease, structurally, that indicates a certain condition, that can help you pretty considerably. But otherwise, I'm looking for inflammatory markers, heavy metals, HIV, some general other things that are outlined, to help make sure that I'm not missing something that's treatable before I go down the route of genetic testing. And we may talk about this in a little bit, but if you start out with genetic testing and then you sort of have to back up and do more systemic testing, that can be very disjointed when it comes to good patient care. Dr Berkowitz: That's very helpful. So yeah, if it's acute, obviously this is the most straightforward scenario, acute and unilateral. We're imagining something lesional, as you said, either a stroke or---not sort of sudden, but fast, but not sudden---you might think of another structural lesion. Toxoplasmosis, right, has an affinity for the basal ganglia if you were seeing this in a patient who is immunocompromised. But in a case that, probably as you alluded to, sort of what we would see most commonly in practice, those still relatively rare, sort of subacute to chronic symmetric chorea. There's a long list of tests that are recommended. In your article and in other texts, I've read lupus testing, anti-phospholipid antibodies… but the list is long. I’ll refer readers to your article. Out of curiosity as a specialist, how often do you see any of these labs come back revealing any underlying diagnosis in a patient who's otherwise healthy and just has developed chorea and comes to you with that chief concern? I feel like I've sent that mega-workup a few times; I'm obviously a general neurologist, but not nearly as many times as you have been. It's- I can't remember a time where something has come up, maybe an ANA one to forty or something like this that we don't think is relevant. But in your practice, how often do you end up finding a reversible cause in the laboratory testing versus ending up starting to go down the genetic testing route, which we'll talk about in a moment? Dr Moore: It's not common, but it is important that we capture these things. Because for a lot of those laboratory tests, there are treatments that are available, or other health implications if those come back positive. So, the case I think of is a polycythemia vera patient who had diffused subacute onset chorea and was able to be treated, was temporarily managed with medication for her chorea, and as her PV improved, she was able to come off those medications. As I was alluding to before---and I'm sure we'll talk about genetic testing---if you test for HD and it's negative, do you go down the route of additional expensive genetic testing, or do you then circle back and go, oops, I missed this treatable condition? As we talk about genetic testing as well, getting HD testing is a pretty involved process. And so, we want to make sure we are checking all those boxes before we move forward. So, it's not common, but we do catch some treatable conditions, and that's really important not to miss. Dr Berkowitz: That's very interesting. So, you diagnosed that polycythemia vera by blood smear, is that how you make the diagnosis? Dr Moore: Yes. Dr Berkowitz: And is that a once-in-a-career-so-far type of thing, or does that happen time to time? Dr Moore: For me, that's a once-so-far, but I don't doubt that I'll see it again. Dr Berkowitz: Great. And how about lupus and some of these other things we look for in the absence of other systemic features? Have you picked up any of these or heard of colleagues picking up something on laboratory testing? They said, oh, this patient came in for a referral for genetic testing, negative Huntington's disease. And good news, we found polycythemia vera; good news, we found undiagnosed lupus and we reversed it. I'm just curious, epidemiologically, seeing these long lists and not having the subspecialty practice that you do, how often you find a reversible cause like we do for neuropathy all the time, right? Oh, it's diabetes, it's B12---maybe not reversible, but preventing progression---or reversible dementia work up. You get so excited when you find low B12 and you replete the patient's B12, and they get better when they had been concerned they were developing an irreversible condition. How often does one in your subspecialty find a reversible cause on that initial mega-lab screen? Dr Moore: I think it's really uncommon, and maybe the folks that do are caught by someone else that never make it to Huntington's clinic, but I don't tend to see those cases. There are, of course, case reports and well-described in the literature about lupus and movement disorders and things of that nature, but that doesn't come to our clinic on a regular basis for sure. Dr Berkowitz: Got it. That's helpful to hear. Well, we've alluded to genetic testing a number of times now, so let's go ahead and talk about it. A lot of your article focuses on Huntington disease, and I was thinking about---in the course of our medical training in medical school, and then neurology residency, for those of us who don't become movement disorder experts like yourself---we learn a lot about Huntington disease. That's sort of the disease that causes chorea, until we later learned there are a whole number of diseases, not just the reversible causes we've been talking about, but a number of genetic diseases which you expertly reviewing your article. So, what are some of the red flags that suggest to you that a patient with chronically progressive chorea---and whom you're concerned for Huntington's or another genetic cause---what are some things you notice about the history, about the exam, the symptoms, the signs, the syndrome, that suggest to you that, actually, this one looks like it might not turn out to be HD. I think this patient might have something else. And as you have alluded to, how do you approach this? Do you send HD testing, wait for it to come back, and then go forward? Are there genetic panels for certain genetic causes of chorea? Do you skip just a whole exome sequencing, or will you miss some of the trinucleotide repeat conditions? How do you approach this in practice? Dr Moore: I'll try to tackle all that. One thing I will say is that a lot of patients with chorea, regardless of the cause, can look very similar to one another. So, if you're looking at chronic onset chorea, perhaps with some neuropsychiatric features, I'm going to most often think about HD because that's the most common cause. Certainly, as we mentioned before, if there's a lot of tongue protrusion, I would think about the acanthocytic conditions, neurocanthocytosis and McCloud syndrome. But generally in those conditions, we're looking at HD as the most likely cause. Certainly, if there is epilepsy or some other syndromic types of things going on, I may think more broadly. But it's important to know that while HD, as you mentioned, is the cause of chorea, many of our patients will have parkinsonism, tics, dystonia, a whole host of other movement phenomenologies. So, that wouldn't dissuade me from thinking about HD. When we think about the kind of patients that you're describing, upwards of 95% of those people will have Huntington's disease. And the process for genetic testing is fairly involved. The Huntington's Disease Society of America has organized a set of recommendations for providers to go about the process of genetic testing in a safe and supportive way for patients and their families. And so that's referred to in the article because it really is important and was devised by patients and families that are affected by this disease. And so, when we're thinking about genetic testing for HD, if I reveal that you have HD, this potentially affects your children and your parents and your siblings. You can have a lot of implications for the lives and health and finances of your family members. We also know that there is high suicidality in patients with HD, in patients who are at risk for HD; and there's even a higher risk of suicidality in patients who are at risk but test negative for HD. So, we do recommend a supportive environment for these patients and their families. And so, for presymptomatic patients or patients who are at risk and don't have chorea, this involves making sure we have, sort of, our ducks in a row, as it were, when we think about life insurance, and, do you have somebody supportive to be with you through this journey of genetic testing, no matter what the results are? So, oftentimes I'll say to folks, you know, there's this 20-page policy that I encourage you to look at, but there are Huntington's Disease Centers of Excellence across the country that are happy to help you with that process, to make sure that the patients are well supported. This is an individual genetic test because, as you mentioned, it is a CAG repeat disorder. And unfortunately, there is no chorea panel. So, if an HD test comes back negative, what we'll do then is think about what's called the HD phenocopies. As I mentioned before, some of these patients who look like they have HD will have a negative HD test. And so, what do you do then? Well, there's a handful of phenocopies---so, other genetic mutations that cause a very similar presentation. And so, we try to be smart, since there's not a panel, we try to be smart about how we choose which test to do next. So, for instance, there's a condition called DRPLA that is present in an African-American family here in my area, in North Carolina, as well as in Japan. And so, if someone comes from those backgrounds, we may decide that that's the next test that we're going to do. If they are white European descent, we may consider a different genetic test; or if they're sub-Saharan African, we may choose a different one from that. However, even if you do a really thorough job, all those blood tests, all those genetic tests, you will occasionally get patients that you can't find a diagnosis for. And so, it's important to know even when you do a good job, you may still not find the answer. And so, I think trying to do things with this complex of the presentation in a systematic way for yourself so you're not missing something. So, going back to our answer about, how do I look at lupus and polycythemia vera and all of that, to think about it in a systematic way. That when you get to the end and you say, well, I don't have an answer, you know you've tried. Dr Berkowitz: That's very helpful to hear your approach to these challenging scenarios, and also how to approach the potential challenging diagnosis for patients and their families getting this diagnosis, particularly in the presymptomatic phase. And your article touches on this with a lot of nuance and thoughtfulness. So, I encourage our listeners to have a read of that section as well. So, last here, just briefly in our final moments, you discuss in your article the various symptomatic treatments for chorea. We won't have time to go into all the details of all the many treatments you discussed, but just briefly, how do you decide which medication to start in an individual patient with chorea for symptomatic management? What are some of the considerations related to the underlying condition, potential side effect profiles of the particular medications, or any other considerations just broadly, generally, as you think about choosing one of the many medications that can be used to treat chorea? Dr Moore: Certainly. So, there is a group of FDA-approved medications, VMAT2 inhibitors, that we can choose from, or the off-label use of neuroleptics. And so, there's a lot of things that go into that. Some of that is insurance and cost and that sort of thing, and that can play a role. Others are side effects. So, for the VMAT2 inhibitors, they all do have a black box warning from the FDA about suicidality. And so, if a patient does struggle with mental health, has a history of suicidality, psychiatric admissions for that sort of thing, then I would be more cautious about using that medication. All patients are counseled about that, as are their families, to help us give them good support. So, the neuroleptics do not tend to have that side effect and can help with mood as well as the chorea and can be helpful in that way. And some of them, of course, will have beneficial side effects. So, olanzapine may help with appetite, which can be important in this disease. So, the big considerations would be the black box warning and suicidality, as well as, are we trying to just treat chorea or are we treating chorea and neuropsychiatric issues? Dr Berkowitz: Fantastic. Thank you for that overview. And again, for our listeners, there's a lot more detail about all of these medications, how they work, how they're used in different patient populations, their side effects, etc, to be reviewed in your excellent article. Again, today, I've been interviewing Dr Kathryn Moore about her article on diagnosis and management of Huntington's disease in chorea, which appears in the August 2025 Continuum issue on movement disorders. Be sure to check out Continuum Audio episodes from this and other issues. And thank you so much to our listeners for joining today. And thank you again, Dr Moore. Dr Moore: Thanks for having me. Dr Monteith: This is Dr Teshamae Monteith, associate editor of Continuum Audio. If you've enjoyed this episode, you'll love the journal, which is full of in-depth and clinically relevant information important for neurology practitioners. Use the link in the episode notes to learn more and subscribe. AAN members, you can get CME for listening to this interview by completing the evaluation at continpub.com/audioCME. Thank you for listening to Continuum Audio.

Progressive supranuclear palsy and corticobasal syndrome are closely related neurodegenerative disorders that present with progressive parkinsonism and multiple other features that overlap clinically and neuropathologically. Early recognition is critical to provide appropriate treatment and supportive care. In this episode, Teshamae Monteith, MD, FAAN speaks with Nikolaus R. McFarland, MD, PhD, FAAN, author of the article “Progressive Supranuclear Palsy and Corticobasal Syndrome” in the Continuum® August 2025 Movement Disorders issue. Dr. Monteith is the associate editor of Continuum® Audio and an associate professor of clinical neurology at the University of Miami Miller School of Medicine in Miami, Florida. Dr. McFarland is an associate professor of neurology at the University of Florida College of Medicine at the Norman Fixel Institute for Neurological Diseases in Gainesville, Florida. Additional Resources  Read the article: Progressive Supranuclear Palsy and Corticobasal Syndrome Subscribe to Continuum®: shop.lww.com/Continuum Earn CME (available only to AAN members): continpub.com/AudioCME Continuum® Aloud (verbatim audio-book style recordings of articles available only to Continuum® subscribers): continpub.com/Aloud More about the American Academy of Neurology: aan.com Social Media facebook.com/continuumcme @ContinuumAAN Host: @headacheMD Full episode transcript available here Dr Jones: This is Dr Lyell Jones, Editor-in-Chief of Continuum. Thank you for listening to Continuum Audio. Be sure to visit the links in the episode notes for information about earning CME, subscribing to the journal, and exclusive access to interviews not featured on the podcast. Dr Monteith: Hi, this is Dr Teshamae Monteith. Today I'm interviewing Dr Nikolaus McFarland about his article on progressive supranuclear palsy and cortical basilar syndrome, which appears in the August 2025 Continuum issue on movement disorders. Welcome, how are you? Dr Farland: I'm great. Thank you for inviting me to do this. This is a great opportunity. I had fun putting this article together, and it’s part of my passion. Dr Monteith: Yes, I know that. You sit on the board with me in the Florida Society of Neurology and I've seen your lectures. You're very passionate about this. And so why don't you first start off with introducing yourself, and then tell us just a little bit about what got you interested in this field. Dr Farland: I'm Dr Nicholas McFarlane. I'm an associate professor at the University of Florida, and I work at the Norman Fixel Institute for Neurological Diseases. I am a director of a number of different centers. So, I actually direct the cure PSP Center of Care and the MSA Center of Excellence at the University of Florida; I also direct the Huntington's clinic there as well. But for many years my focus has been on atypical parkinsonisms. And, you know, I've treated these patients for years, and one of my focuses is actually these patients who suffer from progressive supranuclear palsy and corticobasal syndrome. So that's kind of what this review is all about. Dr Monteith: You probably were born excited, but I want to know what got you interested in this in particular? Dr Farland: So, what got me interested in this in particular was really the disease and the challenges that's involved in it. So, Parkinson's disease is pretty common, and we see a lot of that in our clinic. Yet many times, roughly about 10 to 15% of my patients present with these atypical disorders. And they're quite fascinating. They present in different ways. They're fairly uncommon. They're complex disorders that progress fairly rapidly, and they have multiple different features. They're sort of exciting to see clinically as a neurologist. I think they're really interesting from an academic standpoint, but also in the standpoint of really trying to bring together sort of a team. We have built a multidisciplinary team here at the University of Florida to take care of these patients. They require a number of folks on that team to take care of them. And so, what's exciting, really, is the challenge of treating these patients. There are very limited numbers of therapies that are available, and the current therapies that we have often really aren't great and over time they fail. And so, part of the challenge is actually doing research. And so, there's actually a lot of new research that's been going on in this field. Recently, there's been some revisions to the clinical criteria to help diagnose these disorders. So, that's really what's exciting. The field is really moving forward fairly rapidly with a number of new diagnostics, therapeutics coming out. And hopefully we can make a real difference for these patients. And so that's what really got me into this field, the challenge of trying to treat these patients, help them, advocate for them and make them better. Dr Monteith: And so, tell me what the essential points of this article. Dr Farland: So, the essential points, really, of this article is: number one, you know, just to recognize the new clinical criteria for both PSP and corticobasal syndrome, the diagnosis for these disorders or the phenotypic spectrum has really expanded over the years. So, we now recognize many different phenotypes of these disorders, and the diagnosis has gotten fairly complicated. And so, one of the goals of this article was to review those new diagnostic criteria and the different phenotypic ways these diseases present. I wanted to discuss, also, some of the neuropathology and clinicopathological overlap that's occurred in these diseases as well as some of the new diagnostic tests that are available. That's definitely growing. Some of the new studies that are out, in terms of research and clinical trials. And then wanted to review some of the approaches for treatment for neurologists. Particularly, we're hoping that, you know, this article educates folks. If you're a general neurologist, we're hoping that recognizing these diseases early on will prompt you to refer these patients to specialty clinics or movement disorder specialists early on so they can get appropriate care, confirm your diagnosis, as well as get them involved in trials if they are available. Dr Monteith: And how has the clinical criteria for PSP and cortical basilar syndrome changed? Dr Farland: I think I already mentioned there's been an evolution of the clinical criteria for PSP. There's new diagnostic criteria that were recently published, and it recognizes the multiple clinical phenotypes and the spectrum of the disease that's out there, which is much broader than we thought about. Corticobasal clinical criteria are the Dr Armstrong criteria from 2013. They have not been updated, but they are in the works of being updated. But it does recognize the classic presentation of corticobasal syndrome, plus a frontal executive predominant and then a variant that actually overlaps with PSP. So, there's a lot more overlap in these two diseases than we originally recognized. Dr Monteith: And so, you spoke a bit about FTD spectrum. So why don't you tell us a little bit about what that is? I know you mentioned multiple phenotypes. Dr Farland: What I really want to say is that both PSP and corticobasal syndrome, they're relatively rare, and what- sort of as to common features, they both are progressive Parkinson disorders, but they have variable features. While they're commonly associated with Parkinson's, they also fit within this frontotemporal lobar spectrum, having features that overlap both clinically and neuropathologically. I just want folks to understand that overlap. One of this pathological overlap here is the predominant Tau pathology in the brain, an increasing recognology- recognition of sort of the pathological heterogeneity within these disorders. So, there's an initial description, a classic of PSP, as Richardson syndrome. But now we recognize there are lots of different features to it and there are different ways it presents, and there's definitely a lot of clinical pathological overlap. Dr Monteith: Why don't we just talk about some red flags for PSP? Dr Farland: Yeah, sure. So, some of the red flags for PSP and even corticobasal syndrome are: number one is rapid progression with early onset of falls, gait difficulty, falling typically backwards, early speech and swallow problems that are more prominent than you see in Parkinson's disease, as well as eye gaze issues. So, ocular motor features, particularly vertical gaze palsy. In particular what we talk about is the supranuclear gaze palsy, and one of the most sensitive features that we've seen with these is downgaze limitation or slowed downgaze, and eventually a full vertical gaze palsy and followed supranuclear gaze palsy. So, there's some of the red flags that we see. So, while we think about the lack of response to levodopa frequently as something that's a red flag for Parkinson's, there are many times that we see Parkinson's patients, and about a quarter of them don't really respond. There's some features that don't respond to levodopa that may not be so specific, but also can be helpful in this disease. Dr Monteith: And what about the red flags for cortical basilar syndrome? Dr Farland: So, for cortical basilar syndrome, some of the red flags again are this rapidly depressive syndrome tends to be, at least in its classical present presentation, more asymmetric in its presentation of parkinsonism, with features including things like dystonic features, okay? For limb dystonia and apraxias---so, inability to do a learned behavior. One of those red flags is a patient who comes in and says, my hand doesn't work anymore, which is something extremely uncommon that you hear in Parkinson's disease. Most of those patients will present, say, I might have a tremor, but they very rarely will tell you that I can't use my hand. So look out for that sign. Dr Monteith: And let's talk a little bit about some of the advances in the fields you mentioned, evolving biomarker and imaging capacities. So, how are these advances useful in helping us understand these conditions, especially when there's so much heterogeneity? Dr Farland: I might start by talking a little bit about some of the clinical criteria that have advanced. Why don’t we start there and just discuss some of the advances? I think in PSP, I think, originally we had both probable and possible diagnoses of PSP, and the diagnostic criteria were basically focused on what was what's called “classical PSP” or “Richardson syndrome”. But now we recognize that there are multiple phenotypes. There's an overlap with Parkinsonism that's slower in progression and morphs into PSP, the classical form. There's a frontal behavioral variant where patients present with that frontal behavioral kind of thing. There's a speech-language variant that can overlap with PSP. So they have prominent speech language, potentially even apraxia speech. So, recognition of these different phenotypes is sort of a new thing in this field. There's even overlap with cortical basal syndrome and PSP, and we note that the pathology can overlap as well. So, I think that's one of the things that have changed over time. And these were- recently came out in 2017 in a new publication in the Movement Disorders Society. So, in terms of diagnostic tests as well---and there's been quite a bit of evolution---really still to date, our best diagnostic test is imaging. MRI is really one of our best tests currently. Currently blood tests, spinal fluid, there's new biomarkers in terms of skin… they're still in the research phase and not necessarily very specific yet. So, we rely heavily on imaging still; and for PSP, what we're looking for largely are changes in the brain stem, and particularly focused on the midbrain. So disproportionate midbrain atrophy compared to the pons and the rest of the midbrain is a fairly specific intensive sign for PSP. Whereas in MSA we see more of a pontine atrophy compared to the midbrain. So that can be really helpful, and there are lots of different new measurements that can be done. PET scans are also being used as well. And there are new PET markers, but they still remain kind of research-based, but are becoming more and more prevalent and may be available soon for potential use. Although there's some overlap with PET tracers with Alzheimer's disease and different Tau isoforms. So, something to be wary about, but we will be seeing some of these soon coming out as well. More kind of up-to-date things include things like the spinal fluid as well as even some of the skin biopsies. And I think we've heard some word of recent studies that have come out that potentially in the very near future we might actually have some Tau protein tests that we can look at Tau either in spinal fluid or even in a skin biopsy. But again, still remains research-based and, we still need more information as to whether these tests can be reproducible and how sensitive or specific they are. Dr Monteith: It sounds like, when really approaching these patients, still, it's a lot of back to the history, back to the clinical and some basic imaging that we should be able to identify to distinguish these types of patients, and we're not quite where we need to be yet for biomarker. Dr Farland: I totally agree with you. I think it starts, really, with the clinical exam and that's our main focus here; and understanding some of the new clinical criteria which are more sensitive, but also specific, too. And they're really useful to look at. So, I think reviewing those; patients do progress, following them over time can be really useful. And then for diagnosis, getting imaging if you suspect a patient has an atypical presentation of parkinsonism, to look for signs or features that might be specific for these different disorders. Dr Monteith: Why don't we take a typical case, a typical patient that you would see in clinic, and walk us through the thought process---especially, maybe they presented somewhat early---and the different treatment approaches to helping the patient, and of course their family. Dr Farland: Yeah, sure. So, a typical patient might be someone who comes in with, like, a three year history of progressive gait problems and falling. And let's say the patient says, I'm falling backwards frequently. They may have had, like, a rib fracture, or they hit their head once, and they're describing some speech issues as well. Now they're relying on a walker and family members saying they rarely let them be by themselves. And there may be some slowing of their cognitive function and maybe a bit of withdrawal. So that's a typical patient. So, the approach here is really, what are some of the red flags? I think already you hear a red flag of a rapidly progressive disease. So, Parkinson's disease patients rarely have frequent falls within the first five years. So, this is within three years or less. You're already hearing early onset of gait problems and falling, and particularly falling backwards rather than forwards as often Parkinson's disease patients do. You're hearing early speech problems and maybe a subtle hint of cognitive slowing and some withdrawal. So, a lot of things that sort of are red flags. So, our approach really would be examining this patient really closely. Okay? We'd be listening to the history, looking at the patient. One thing is that some of these patients come in, they may be in a wheelchair already. That's a red flag for us. If they're wearing sunglasses---sometimes we see that patients, they have photosensitivity and they're in a chair and they're wearing sunglasses---you take the glasses off and you look at their face and they have that sort of a facial stare to them---not just the masked face, but the stare---and their eyes really aren't moving. So, another kind of clue, maybe this is probably something atypical, particularly PSP is what I'm thinking about. So, the approach is really, do a thorough exam. I always recommend looking at eye movements and starting with volitional saccades, not giving them a target necessarily, but asking them to look up and then look down. And then particularly look at the speed of downgaze and whether they actually have full versions down, are able to do that. That's probably your most sensitive test for a patient who has PSP. Not the upgaze, which can be- upgaze impairment in older patients can be nonspecific. So, look for that down gaze. So, if I can get out one message, that's one thing that can be easily done and examined fairly quickly for diagnosis of these patients. And then just look for signs of rigidity, bradykinesia, maybe even some myelopraxia, and then look at their gait carefully so that there's a high suspicion. Again, if there's some atypical features, imaging is really important. So, my next step would be probably getting an MRI to evaluate whether- do they have brain somatrophy or other widespread atrophy or other signs? You need to think about your differential diagnosis for some of these patients as well. So, common things are common; vascular disease, you can't have vascular parkinsonism or even signs of NPH. Both of those can present with progressive gait difficulty and falls. So, the gait may look more like Parkinson's rather than ataxic gait that we see in classic PSP, but still they have early gait issues, and that can be a mimicker of PSP, So looking for both of those things in your imaging. Think about sort of autoimmune potentially causes. So, if they have a really rapid progressive cause, there are some rare autoimmune things. There have been recent reports of things like IgLON5, although there's limited cases, but we're doing more screening for some of those autoimmune causes. And then even some infectious causes like Whipples, that are rarely present like this. Okay? And have other signs and features. Dr Monteith: So, let's say you diagnose this patient with PSP and you're assessing the patients to see how you can improve their quality of life. So, what are some potential symptomatic managements that will help our patient? Dr Farland: I recommend for most all of these patients… while the literature indicates that many patients with PSP, and especially corticobasal syndrome, don't respond well to levodopa. So, the classic treatment for parkinsonism. However, we all recommend a trial of levodopa. These patients may respond partially to doses of levodopa, and we try to push the doses a bit higher. So, the recommended trial is usually a dose up to roughly 1000 milligrams of levodopa per day. And give it some time, at least two, if not actually three months of a trial. If not well-tolerated, you can back off. If there's no response at all or no improvement, then slowly back off and taper patients off and ask them to tell you whether they feel like they're actually worsening. So, many patients, sometimes, don't recognize the improvements, or family members don't recognize it until we actually taper them back off. And they may end up saying there are some other things that even recognize. Even some nonmotor benefits can be seen with levodopa. In some cases, we do keep them on levodopa, but levodopa's our best therapy for this. Dopamine agonists, MAO inhibitors, have all been sort of tried and they’ve been studied, but often don't really help or fail to help benefit these patients and could be fraught with some other side effects. I think many people do also turn to Amantadine as a treatment for Parkinson's, gait problems, freezing, if you see it in these disorders. Yet Amantadine is fraught with issues of side effects, including cognitive issues, and I think is not well-tolerated. But there are the rare patient who actually does respond to this or claims they respond to this. By and large, these patients relentlessly progress, unfortunately. So, beside treatment of other symptoms, I think it's really important to recognize that they require supportive cares and therapy. So, starting those early on and getting your allied healthcares kind of involved. So that includes people like physical, occupational therapy for the gait issues, the falls, occupational therapy for doing daily activities. Speech language pathology can be really a critical player for these because of the early speech and language issues, as well as swallow difficulties. Swallow is compared quickly in these patients. And so, we do recommend the screening evaluation, then often following patients either every six- or even annually, at least, with a swallow evaluation. And we recommend the fluoroscopic-guided kind of modified barium swallow for these patients.  Dr Monteith: And how does that differ if, let's say, the patient had cortical basilar syndrome? What are some of the symptomatic treatments that would be high on your consideration? Dr Farland: So actually, these patients also have a very similar approach, and they often have some overlapping features. Maybe a little bit of difference in terms of the level of apraxia and some dystonic features that you see in corticobasal syndrome. So, as I mentioned earlier that these patients have a more typ- when they present, typically have a more asymmetric presentation. And one of the biggest issues is this limb apraxia. They may have abnormal movements as well as, like, the alien limb-type phenomena as well. So, the focus of therapy, while similar in the sense we focus on the parkinsonism, I do always try levodopa and try to ramp up the doses to see if it benefits. It does often fail, but it's definitely worth trying. The other focus of these patients is trying to treat symptoms. Dystonia, those features… in some cases, we can help; if it's painful or uncomfortable, muscle relaxants can be used. If it's vocal, things like Botox can be really helpful. Often times it is more palliative than actually restorative in terms of function, but still can be really helpful for patients who ask about pain and discomfort and trying to treat. And then of course, again, the focus on our supportive care. We need to build that network and build that team of folks, the therapists, the physical, occupational, and the speech therapist to help them. If they have language problems---like either in PSP or corticobasal---I'll also include my request to a speech language pathologist to work on cognitive function. That's a special, additional thing you have to ask for and then specifically request when you make a referral to a speech language pathologist. Dr Monteith: That is so important. I think keeping the simulation, keeping the social support, and I would probably guess that you would also include screening for sleep and mood disorder. Dr Farland: Absolutely. Mood disorders are really big in these diseases. Patients are suffering terribly. You do hear about labile mood in both of these diseases, particularly PSP; and even what's called pseudobulbar palsy, where the mood is not always congruent with the affect. So they may laugh or cry inappropriately, and particularly the crying can be very disturbing to family and caregivers to see that. And so, treating those things can be really important. So always asking about the mood issues. Depression in particular is something that we're very sensitive about, and there is a higher incidence of suicidal ideations. Asking about that and feeling and making sure that they are in a safe environment can be really important. Dr Monteith: Thank you so much. Dr Farland: Thank you. Dr Monteith: Today I've been interviewing Dr Nikolaus McFarland about his article on progressive supranuclear palsy and cortical basilar syndrome, which appears in the August 2025 Continuum issue on movement disorders. Be sure to check out Continuum Audio episodes from this and other issues, and thank you to our listeners for joining today. Dr Monteith: This is Dr Teshamae Monteith, Associate Editor of Continuum Audio. If you've enjoyed this episode, you'll love the journal, which is full of in-depth and clinically relevant information important for neurology practitioners. Use the link in the episode notes to learn more and subscribe. AAN members, you can get CME for listening to this interview by completing the evaluation at continpub.com/audioCME. Thank you for listening to Continuum Audio.

Multiple system atrophy is a rare, sporadic, adult-onset, progressive, and fatal neurodegenerative disease. Accurate and early diagnosis remains challenging because it presents with a variable combination of symptoms across the autonomic, extrapyramidal, cerebellar, and pyramidal systems. Advances in brain imaging, molecular biomarker research, and efforts to develop disease-modifying agents have shown promise to improve diagnosis and treatment. In this episode, Casey Albin, MD speaks with Tao Xie, MD, PhD, author of the article “Multiple System Atrophy” in the Continuum® August 2025 Movement Disorders issue. Dr. Albin is a Continuum® Audio interviewer, associate editor of media engagement, and an assistant professor of neurology and neurosurgery at Emory University School of Medicine in Atlanta, Georgia. Dr. Xie is director of the Movement Disorder Program, chief of the Neurodegenerative Disease Section in the department of neurology at the University of Chicago Medicine in Chicago, Illinois. Additional Resources Read the article: Multiple System Atrophy Subscribe to Continuum®: shop.lww.com/Continuum Earn CME (available only to AAN members): continpub.com/AudioCME Continuum® Aloud (verbatim audio-book style recordings of articles available only to Continuum® subscribers): continpub.com/Aloud More about the American Academy of Neurology: aan.com Social Media facebook.com/continuumcme @ContinuumAAN Host: @caseyalbin Full episode transcript available here Dr. Jones: This is Dr Lyell Jones, Editor-in-Chief of Continuum. Thank you for listening to Continuum Audio. Be sure to visit the links in the episode notes for information about earning CME, subscribing to the journal, and exclusive access to interviews not featured on the podcast. Dr Albin: Hello everyone, this is Dr Casey Albin. Today I'm interviewing Dr Tao Xie about his article on diagnosis and management of multiple system atrophy, which appears in the August 2025 Continuum issue on movement disorders. Welcome to the podcast, and please introduce yourself to our audience. Dr Xie: Thank you so much, Dr Albin. My name is Tao Xie, and sometimes people also call me Tao Z. I'm a mood disorder neurologist, professor of neurology at the University of Chicago. I'm also in charge of the mood disorder program here, and I'm the section chief in the neurodegenerative disease in the Department of Neurology at the University of Chicago Medicine. Thank you for having me, Dr Albin and Dr Okun and the American Academy of Neurology. This is a great honor and pleasure to be involved in this education session. Dr Albin: We are delighted to have you, and thank you so much for the thoughtful approach to the diagnosis and management. I really want to encourage our listeners to check out this article. You know, one of the things that you emphasize is multiple system atrophy is a fairly rare condition. And I suspect that clinicians and trainees who even have a fair amount of exposure to movement disorders may not have encountered that many cases. And so, I was hoping that you could just start us off and walk us through what defines multiple system atrophy, and then maybe a little bit about how it's different from some of the more commonly encountered movement disorders. Dr Xie: This is a really good question, Dr Albin. Indeed, MSA---multisystem atrophy----is a rare disease. It is sporadic, adult-onset, progressive, fatal neurodegenerative disease. By the name MSA, multisystem atrophy. Clinically, it will present with multiple symptoms and signs involving multiple systems, including symptoms of autonomic dysfunction and symptoms of parkinsonism, which is polyresponsive to the levodopa treatment; and the symptom of cerebellar ataxia, and symptom of spasticity and other motor and nonmotor symptoms. And you may be wondering, what is the cause- underlying cause of these symptoms? Anatomically, we can find the area in the basal ganglia striatonigral system, particularly in the putamen and also in the cerebellar pontine inferior, all of the nuclear area and the specific area involved in the autonomic system in the brain stem and spinal cord: all become smaller. We call it atrophy. Because of the atrophy in this area, they are responsible for the symptom of parkinsonism if it is involved in the putamen and the cerebral ataxia, if it's involved in the pons and cerebral peduncle and the cerebellum. And all other area, if it's involved in the autonomic system can cause autonomic symptoms as well. So that's why we call it multisystem atrophy. And then what's the underlying cellular and subcellular pathological, a hallmark that is in fact caused by misfolded alpha-synuclein aggregate in the oligodontia site known as GCI---glial cytoplasmic increasing bodies---in the cells, and sometimes it can also be found in the neuronal cell as well in those areas, as mentioned, which causes the symptom. But clinically, the patient may not present all the symptoms at the same time. So, based on the predominant clinical symptom, if it's mainly levodopa, polyresponsive parkinsonism, then we call it MSAP. If it's mainly cerebellar ataxia, then we call it MSAC. But whether we call it MSP or MSC, they all got to have autonomic dysfunction. And also as the disease progresses, they can also present both phenotypes together. We call that mixed cerebellar ataxia and parkinsonism in the advanced stage of the disease. So, it is really a complicated disease. The complexity and the similarity to other mood disorders, including parkinsonism and the cerebellar ataxia, make it really difficult sometimes, particularly at the early stages of disease, to differentiate one from the other. So, that was challenging not only for other professionals, general neurologists and even for some movement disorder specialists, that could be difficult particularly if you aim to make an accurate and early diagnosis. Dr Albin: Absolutely. That is such a wealth of knowledge here. And I'm going to distill it just a little bit just to make sure that I understand this right. There is alpha-synuclein depositions, and it's really more widespread than one would see maybe in just Parkinson's disease. And with this, you are having patients present with maybe one of two subtypes of their clinical manifestations, either with a Parkinson's-predominant movement disorder pattern or a cerebellar ataxia type movement disorder pattern. Or maybe even mixed, which really, you know, we have to make things quite complicated, but they are all unified and having this shared importance of autonomic features to the diagnosis. Have I got that all sort of correct? Dr Xie: Correct. You really summarize well. Dr Albin: Fantastic. I mean, this is quite a complicated disease. I would pose to you sort of a case, and I imagine this is quite common to what you see in your clinic. And let's say, you know, a seventy-year-old woman comes to your clinic because she has had rigidity and poor balance. And she's had several falls already, almost always from ground level. And her family tells you she's quite woozy whenever she gets up from the chair and she tends to kind of fall over. But they noticed that she's been stiff,and they've actually brought her to their primary care doctor and he thought that she had Parkinson's disease. So, she started levodopa, but they're coming to you because they think that she probably needs a higher dose. It's just not working out very well for her. So how would you sort of take that history and sort of comb through some of the features that might make you more concerned that the patient actually has undiagnosed multiple systems atrophy? Dr Xie: This is a great case, because we oftentimes can encounter similar cases like this in the clinic. First of all, based on the history you described, it sounds like an atypical parkinsonism based on the slowness, rigidity, stiffness; and particularly the early onset of falls, which is very unusual for typical Parkinson disease. It occurs too early. If its loss of balance, postural instability, and fall occurred within three years of disease onset---usually the motor symptom onset---then it raises a red flag to suspect this must be some atypical Parkinson disorders, including multiple system atrophy. Particularly, pou also mentioned that the patient is poorly responsive to their levodopa therapy, which is very unusual because for Parkinson disease, idiopathic Parkinson disease, we typically expect patients would have a great response to the levodopa, particularly in the first 5 to 7 years. So to put it all together, this could be atypical parkinsonism, and I could not rule out the possibility of MSA. Then I need to check more about other symptoms including autonomic dysfunction, such as orthostatic hypertension, which is a blood pressure drop when the patient stands up from a lying-down position, or other autonomic dysfunctions such as urinary incontinence or severe urinary retention. So, in the meantime, I also have to put the other atypical Parkinson disorder on the differential diagnosis, such as PSP---progressive supranuclear palsy---and the DLBD---dementia with Lewy body disease.---Bear this in mind. So, I want to get more history and more thorough bedside assessment to rule in or rule out my diagnosis and differential diagnosis. Dr Albin: That's super helpful. So, looking for early falls, the prominence of autonomic dysfunction, and then that poor levodopa responsiveness while continuing to sort of keep a very broad differential diagnosis? Dr Xie: Correct. Dr Albin: One of the things that I just have to ask, because I so taken by this, is that you say in the article that some of these patients actually have preservation of smell. In medical school, we always learn that our Parkinson's disease patients kind of had that early loss of smell. Do you find that to be clinically relevant? Is that- does that anecdotally help? Dr Xie: This is a very interesting point because we know that the loss of smelling function is a risk effect, a prodromal effect, for the future development of Parkinson disease. But it is not the case for MSA. Strange enough, based on the literature and the studies, it is not common for the patient with MSA to present with anosmia. Some of the patients may have mild to moderate hyposmia, but not to the degree of anosmia. So, this is why even in the more recent diagnosis criteria, the MDS criteria published 2022, it even put the presence of anosmia in the exclusion criteria. So, highlight the importance of the smell function, which is well-preserved for the majority in MSA, into that category. So, this is a really interesting point and very important for us, particularly clinicians, to know the difference in the hyposmia, anosmia between the- we call it the PD, and the dementia Lewy bodies versus MSA. Dr Albin: Fascinating. And just such a cool little tidbit to take with us. So, the family, you know, you're talking to them and they say, oh yes, she has had several fainting episodes and we keep taking her to the primary care doctor because she's had urinary incontinence, and they thought maybe she had urinary tract infections. We've been dealing with that. And you're sort of thinking, hm, this is all kind of coming together, but I imagine it is still quite difficult to make this diagnosis based on history and physical alone. Walk our listeners through sort of how you're using MRI and DAT scan and maybe even some other biomarkers to help sort of solidify that diagnosis. Dr Xie: Yeah, that's a wonderful question. Yeah. First of all, UTI is very common for patients with MSA because of urinary retention, which puts them into a high risk of developing frequent UTI. That, for some patients, could be the very initial presentation of symptoms. In this case, if we check, we say UTI is not present or UTI is present but we treat it, then we check the blood pressure and we do find also hypertension---according to new diagnosis criteria, starting drop is 20mm mercury, but that's- the blood pressure drop is ten within three minutes. And also, in the meantime the patients present persistent urinary incontinence even after UTI was treated. And then the suspicion for MS is really high right at this point. But if you want increased certainty and a comfortable level on your diagnosis, then we also need to look at the brain MRI mark. This is a required according to the most recent MDS diagnosis criteria. The presence of the MRI marker typical for MSA is needed for the diagnosis of clinically established MSA, which holds the highest specificity in the clinical diagnosis. So then, we have- we’re back to your question. We do need to look at the brain MRI to see whether evidence suggestive of atrophy around the putamen area, around the cerebellar pontine inferior olive area, is present or not. Dr Albin: Absolutely. That's super helpful. And I think clinicians will really take that to sort of helping to build a case and maybe recognizing some of this atypical Parkinson's disease as a different disease entity. Are there any other biomarkers in the pipeline that you're excited about that may give us even more clarity on this diagnosis? Dr Xie: Oh, yeah. This is a very exciting area. In terms of biomarker for the brain imaging, particularly brain MRI, in fact, today there's a landmark paper just published in the Java Neurology using AI, artificial intelligence or machine learning aid, diagnoses a patient with parkinsonism including Parkinson's disease, MSA, and PSP, with very high diagnostic accuracy ranging from 96% to 98%. And some of the cases even were standard for autopsy, with pathological verification at a very high accurate rate of 93.9%. This is quite amazing and can really open new diagnosis tools for us to diagnose this difficult disease; not only in an area with a bunch of mood disorder experts, but also in the rural area, in the area really in need of mood disorder experts. They can provide tremendous help to provide accurate, early diagnosis. Dr Albin: That's fantastic and I love that, increasing the access to this accurate diagnosis. What can't artificial intelligence do for us? That's just incredible. Dr Xie: And also, you know, this is just one example of how the brain biomarker can help us. Theres other---a fluid biomarker, molecular diagnostic tools, is also available. Just to give you an example, one thing we know over the past couple years is skin biopsy. Through the immunofluorescent reaction, we can detect whether the hallmark of abnormally folded, misfolded, and the phosphorate, the alpha-synuclein aggregate can be found just by this little pinch of skin biopsy. Even more advanced, there's another diagnosis tool we call the SAA, we call the seizure amplification assay, that can even help us to differentiate MSA from other alpha-synucleinopathy, including Parkinson disease and dementia with Lewy bodies. If we get a little sample from CSF, spinal cerebral fluids, even though this is probably still at the early stage, a lot of developments still ongoing, but this, this really shows you how exciting this area is now. We’re really in a fast forward-moving path now. Dr Albin: It's really incredible. So, lots coming down the track in, sort of, MRI, but also with CSF diagnosis and skin biopsies. Really hoping that we can hone in some of those tools as they become more and more validated to make this diagnosis. Is that right? Dr Xie: Correct. Dr Albin: Amazing. We can talk all day about how you manage these in the clinic, and I really am going to direct our listeners to go and read your fantastic article, because you do such an elegant job talking about how this takes place in a multidisciplinary setting, if at all possible. But as a neurointensivist, I was telling you, we have so much trouble in the hospital. We have A-lines, and we have the ability to get rapid KUBs to look at Ilias, and we can have many people as lots of diagnosis, and we still have a lot of trouble treating autonomiclike symptoms. Really, really difficult. And so, I just wanted to kind of pick your brain, and I'll start with just the one of orthostatic hypotension. What are some of the tips that you have for, you know, clinicians that are dealing with this? Because I imagine that this is quite difficult to do without patients. Dr Xie: Exactly. This is indeed a very difficult symptom to deal with, particularly at an outpatient setting. But nowadays with the availability of more medication---to give an example, to treat patients with orthostatic hypertension, we have not only midodrine for the cortisol, we also have droxidopa and several others as well. And so, we have more tools at hand to treat the patient with orthostatic hypertension. But I think the key thing here, particularly for us to the patient at the outpatient setting: we need to educate the patient’s family well about the natural history of the disease course. And we also need to tell them what's the indication and the potential side effect profile of any medication we prescribe to them so that they can understand what to expect and what to watch for. And in the meantime, we also need to keep really effective and timely communication channels, make sure that the treating physician and our team can be reached at any time when the patient and family need us so that we can be closely monitoring, their response, and also monitoring potential side effects as well to keep up the quality of care in that way. Dr Albin: Yeah, I imagine that that open communication plays a huge role in just making sure that patients are adapting to their symptoms, understanding that they can reach out if they have refractory symptoms, and that- I imagine this takes a lot of fine tuning over time. Dr Xie: Correct. Dr Albin: Well, this has just been such a delight to get to talk to you. I really feel like we could dive even deeper, but I know for the sake of time we have to kind of close out. Are there any final points that you wanted to share with our listeners before we end the interview? Dr Xie: I think for the patients, I want them to know that nowadays with advances in science and technology, particularly given a sample of rapid development in the diagnostic tools and the multidisciplinary and multisystemic approach to treatment, nowadays we can make an early and accurate diagnosis of the MSA, and also, we can provide better treatment. Even though so far it is still symptomatically, mainly, but in the near future we hope we can also discover disease-modifying treatment which can slow down, even pause or prevent the disease from happening. And for the treating physician and care team professionals, I just want them to know that you can make a difference and greatly help the patient and the family through your dedicated care and also through your active learning and innovative research. You can make a difference. Dr Albin: That's amazing and lots of hope for these patients. Right now, you can provide really great care to take care of them, make an early and accurate diagnosis; but on the horizon, there are really several things that are going to move the field forward, which is just so exciting. Again today, I've been really greatly honored and privileged to be able to talk to Dr Tao Xie about his article on diagnosis and management of multiple system atrophy, which appears in the August 2025 Continuum issue on movement disorders. Be sure to check out Continuum Audio episodes for this and other issues. And thank you again to our listeners for joining us today. Dr Xie: Thank you so much for having me. Dr Monteith: This is Dr Teshamae Monteith, Associate Editor of Continuum Audio. If you've enjoyed this episode, you'll love the journal, which is full of in-depth and clinically relevant information important for neurology practitioners. Use the link in the episode notes to learn more and subscribe. AAN members, you can get CME for listening to this interview by completing the evaluation at continpub.com/audioCME. Thank you for listening to Continuum Audio.

Essential tremor is the most common movement disorder, although it is often misdiagnosed. A careful history and clinical examination for other neurologic findings, such as bradykinesia, dystonia, or evidence of peripheral neuropathy, can reveal potential alternative etiologies. Knowledge about epidemiology and associated health outcomes is important for counseling and monitoring for physical impairment and disability. In this episode, Lyell Jones, MD, FAAN, speaks with Ludy C. Shih, MD, MMSc, FAAN, author of the article “Essential Tremor” in the Continuum® August 2025 Movement Disorders issue. Dr. Jones is the editor-in-chief of Continuum: Lifelong Learning in Neurology® and is a professor of neurology at Mayo Clinic in Rochester, Minnesota. Dr. Shih is clinical director of the Parkinson's Disease and Movement Disorders Center at Beth Israel Deaconess Medical Center in Boston, Massachusetts. Additional Resources Read the article: Essential Tremor Subscribe to Continuum®: shop.lww.com/Continuum Earn CME (available only to AAN members): continpub.com/AudioCME Continuum® Aloud (verbatim audio-book style recordings of articles available only to Continuum® subscribers): continpub.com/Aloud More about the American Academy of Neurology: aan.com Social Media facebook.com/continuumcme @ContinuumAAN Host: @LyellJ Guest: @ludyshihmd Full episode transcript available here Dr Jones: This is Dr Lyell Jones, Editor-in-Chief of Continuum. Thank you for listening to Continuum Audio. Be sure to visit the links in the episode notes for information about earning CME, subscribing to the journal, and exclusive access to interviews not featured on the podcast. Dr Jones: This is Dr Lyell Jones, Editor-in-Chief of Continuum: Lifelong Learning in Neurology. Today, I'm interviewing Dr Ludy Shih, who recently authored an article on essential tremor for our latest issue of Continuum on movement disorders. Dr Shih is an associate professor of neurology at Harvard Medical School and the clinical director of the Parkinson's Disease and Movement Disorder Center at Beth Israel Deaconess Medical Center in Boston. Dr Shih, welcome, and thank you for joining us today. Why don't you introduce yourself to our listeners? Dr Shih: Thank you, Dr Jones, for having me. It's a real pleasure to be here on the podcast with you. I'm a neurologist, I trained in movement disorders fellowship, and I currently see patients and conduct clinical research. We offer a variety of treatments and diagnostic tests for our patients with movement disorders. And I have developed this interest, a clinical research interest in essential tremor. Dr Jones: And so, as an expert in essential tremor, the perfect person to write such a really spectacular article. And I can't wait for our listeners to hear more about it and our subscribers to read it. And let's get right to it. If you had, Dr Shih, a single most important message for our listeners about caring for patients with essential tremor, what would that message be? Dr Shih: Yeah, I think the takeaway that I've learned over the years is that people with essential tremor do develop quite a few other symptoms. And although we propose that essential tremor is this pure tremor disorder, they can experience a lot of different comorbidities. Now, there is some debate as to whether that is expected for essential tremor or is this some part of another syndrome, which we may talk about later in the interview. But the fact of the matter is, it's not a benign condition and people do experience some disability from it. Dr Jones: And I think that speaks to how the name of this disorder has evolved over time. right? You point out in your article, it used to be called benign essential tremor or benign familial tremor. But it's really not so straightforward as it. And fairly frequently these symptoms, the patient's tremor, can be functionally limiting, correct? Dr Shih: That is correct. In fact, the reason I probably started getting interested in essential tremor was because our center had been doing a lot of deep brain stimulation for essential tremor, which is remarkably effective, especially for tremor that reaches an amplitude that really no oral medication is going to satisfyingly treat. And if you have enough upper limb disability from this very large-amplitude tremor, a surgical option may make a lot of sense for a lot of patients. And yet, how did they get to that point? Do they continue to progress? These were the sort of interesting questions that got raised in my mind as I started to treat these folks. Dr Jones: We'll come back to treatment in just a minute here, because there are many options, and it sounds like the options are expanding. To start with the diagnosis- I mean, this is an extraordinarily common disorder. As you point out, it is the most common movement disorder in the US and maybe the world, and yet it seems to be underrecognized and frequently misdiagnosed. Why do you think that is? Dr Shih: Great question. It's been pretty consistent, with several case series over the decades showing a fairly high rate of quote/unquote “misdiagnosis.” And I think it speaks to two things, probably. One is that once someone sees a postural and kinetic tremor of the arms, immediately they think of essential tremor because it is quite common. But there's a whole host of things that it could actually be. And the biggest one that we also have to factor in is also the heterogeneity of the presentation of Parkinson's disease. Many people, and I think increasingly now these days, can present with not a whole lot of the other symptoms, but may present with an atypical tremor. And it becomes actually a little hard to sort out, well, do they have enough of these other symptoms for me to suspect Parkinson's, or is the nature of their tremor suspicious enough that it would just be so unusual that this stays essential tremor and doesn't eventually develop into Parkinson’s disease? And I think those are the questions that we all still grapple with from time to time in some of our clinics. Dr Jones: Probably some other things related to it with, you know, our understanding of the pathophysiology and the availability of tests. And I do want to come back to those questions here in just a minute, but, you know, just the nomenclature of this disorder… I think our clinical listeners are familiar with our tendency in medicine to use words like essential or idiopathic to describe disorders or phenomena where we don't understand the precise underlying mechanism. When I'm working with our trainees, I call these “job-security terms” because it sounds less humbling than “you have a tremor and we don't know what causes it,” right? So, your article does a really nice job outlining the absence of a clear monogenic or Mendelian mechanism for essential tremor. Do you think we'll ever have a eureka moment in neurology for this disorder and maybe give it a different name? Dr Shih: It's a great question. I think as we're learning with a lot of our neurologic diseases---and including, I would even say, Parkinson's disease, to which ET gets compared to a lot---there's already now so much more known complexity to something that has a very specific idea and concept in people's minds. So, I tend to think we'll still be in an area where we'll have a lot of different causes of tremor, but I'm hopeful that we'll uncover some new mechanisms for which treating or addressing that mechanism would take care of the tremor in a way that we haven't been able to make as much progress on in the last few decades as maybe we would have thought given all the advances in in technology. Dr Jones: That's very helpful, and we'll be hopeful for that series of discoveries that lead us to that point. I think many of our listeners will be familiar with the utility---and, I think, even for most insurance companies, approval---for DAT scans to discriminate between essential tremor and Parkinsonian disorders. What about lab work? Are there any other disorders that you commonly screen for in patients who you suspect may have essential tremor? Dr Shih: Yeah, it's a great question. And I think, you know, I'm always mindful that what I'm seeing in my clinic may not always be representative of what's seen in the community or out in practice. I'll give an example. You know, most of the time when people come to the academic Medical Center, they're thinking, gosh, I've tried this or that. I've been on these medicines for the last ten years. But I've had essential tremor for twenty years. We get to benefit a little bit from all that history that's been laid down. And so, it's not as likely you're going to misdiagnose it. But once in a while, you'll get someone with tremor that just started a month ago or just started, you know, 2 or 3 months ago. And you have to still be thinking, well, I’ve got to get out of the specialist clinic mindset, and think, well, what else really could this be? And so, while it's true for everybody, moreso in those cases, in those recent onset cases, you really got to be looking for things like medications, electrolyte abnormalities, and new-onset thyroid disorder, for example, thyroid toxicosis. Dr Jones: Very helpful. And your article has a wonderful list of the conditions to consider, including the medications that might be used for those conditions that might result or unmask a tremor of a different cause. And I think being open-minded and not anchoring on essential tremor just because it's common, I think is a is a key point here. And another feature in your article that I really enjoyed was your step-by-step approach to tremor. What are those steps? Dr Shih: Well, I think you know first of all, tremor is such common terminology that even lay people, patients, nonclinicians will use the word “tremor.” And so, it can be tempting when the notes on your schedule says referred for tremor to sort of immediately jump to that. I think the first step is, is it tremor? And that's really something that the clinician first has to decide. And I think that's a really important step. A lot of things can look superficially like tremor, and you shouldn't even assume that another clinician knows what tremor looks like as opposed to, say, myoclonus. Or for example a tremor of the mouth; well, it actually could be orolingual or orobuccal dyskinesia, as in tardive dyskinesia. And another one that tremor can look like is ataxia. And so, I think- while they sound obvious to most neurologists, perhaps, I think that---especially in the area of myoclonus, where it can be quite repetitive, quite small amplitude in some conditions---it can really resemble a tremor. And so, there are examples of these where making that first decision of whether it's a tremor or not can really be a good sort of time-out to make sure you're going down the right path to begin with. And I think what's helpful is to think about some of the clinical definitions of a tremor. And tremor is really rhythmic, it's oscillatory. You should see an agonist and antagonist muscle group moving back and forth, to and fro. And then it's involuntary. And so, I think these descriptors can really help; and to help isolate, if you can describe it in your note, you can probably be more convinced that you're dealing with the tremor. The second step that I would encourage people to really consider: you've established it’s a tremor. The most important part exam now becomes, really, the nontremor part of the exam. And it should be really comprehensive to think of what else could be accompanying this, because that's really how we make diagnosis of other things besides essential tremor. There really should be a minimum of evidence of parkinsonism, dystonia, neuropathy, ataxia- and the ataxia could be either from a peripheral or central nervous system etiology. Those are the big four or five things that, you know, I'm very keen to look for and will look pretty much in the head, neck, the axial sort of musculature, as well as the limbs. And I think this is very helpful in terms of identifying cases which turn out to have either, say, well, Parkinson's or even a typical Parkinson disorder; or even a genetic disorder, maybe even something like a fragile X tremor ataxia syndrome; or even a spinal cerebellar ataxia. These cases are rare, but I think if you uncover just enough ataxia, for example, that really shouldn't be there in a person, let's say, who's younger and also doesn't have a long history of tremor; you should be more suspicious that this is not essential tremor that you're dealing with. And then the last thing is, once you've identified the tremor and you're trying to establish, well, what should be done about the tremor, you really have to say what kind of tremor it is so that you can follow it, so you can convey to other people really what the disability is coming from the tremor and how severe the tremor is. So, I think an example of this is, often in the clinic, people will have their patients extend their arms and hands and kind of say, oh, it's an essential tremor, and that's kind of the end of the exam. But it doesn't give you the flavor. Sometimes you'll have a patient come in and have a fairly minimal postural tremor, but then you go out, take those extra few seconds to go grab a cup of water or two cups of water and have them pour or drink. And now all of a sudden you see this tremor is quite large-amplitude and very disabling. Now you have a better appreciation of what you really need to do for this patient, and it might not be present with just these very simple maneuvers that you have at bedside without props and items. And then the severity of it; you know, we're so used to saying mild, moderate, severe. I think what we've done in the Tremor Research Group to use and develop the Essential Tremor Rating Assessment Scale is to get people used to trying to estimate what size the tremor is. And you can do that by taking a ruler or developing a sense of what 1 centimeter, 2 centimeters, 3 centimeters looks like. I think it'd be tremendously helpful too, it's very easy and quick to convey severity in a given patient. Dr Jones: I appreciate you, you know, having a patient-centered approach to the- how this is affecting them and being quantitative in the assessment of the tremor. And that's a great segue to a key question that I run into and I think others run into, which is when to initiate therapy? You know, if you see a patient who, let's say they have a mild tremor or, you know, something that quantitatively is on the mild end of the spectrum, and you have, you know, a series of options… from a medication perspective, you have to say, well, when does this across that threshold of being more likely to benefit the patient than to harm the patient? How do you approach that question? What's your threshold for starting medication? Dr Shih: Yeah. You know, sometimes I will ask, because---and I know this sounds like a strange question---because I feel like my patients will come for a couple of different reasons. Sometimes it's usually one over the other. I think people can get concerned about a symptom of a tremor. So, I actually will ask them, was your goal to just get a sense for what this tremor is caused by? I understand that many people who develop tremor might be concerned it might be something like Parkinson's disease. Or is this also a tremor that is bothering you in day-to-day life? And often you will hear the former. No, I just wanted to get checked out and make sure you don't think it's Parkinson's. It doesn't bother me enough that I want to take medication. They're quite happy with that. And then the second scenario is more the, yeah, no, it bothers me and it's embarrassing. And that's a very common answer you may hear, may be embarrassing, people are noticing. It's funny in that many people with essential tremor don't come to see a doctor or even the neurologist for many years. And they will put up with it for a very long time. And they've adopted all sorts of compensatory strategies, and they've just been able to handle themselves very admirably with this, in some cases, very severe tremor. So, for some of them, it'll take a lot to come to the doctor, and then it becomes clear. They said, I think I'm at the point where I need to do something about this tremor. And so, I think those three buckets are often sort of where my patients fall into. And I think asking them directly will give you a sense of that. But you know, it can be a nice time to try some as-needed doses of something like Propranolol, or if it's something that you know that they're going to need something on day-to-day to get control of the tremor over time, there are other options for that as well. Dr Jones: Seems like a perfect scenario for shared decision-making. Is it bothersome enough to the patient to try the therapy? And I like that suggestion. That's a nice pearl that you could start with an a- needed beta blocker, right, with Propranolol. And this is a question that I think many of us struggle with as well. If you've followed a patient with essential tremor for some time and you've tried different medications and they've either lost effectiveness or have intolerable adverse effects, what is your threshold for referring a patient for at least considering a surgical neurostimulator therapy for their essential tremor? Dr Shih: Yeah, so surgical therapies for tremor have been around for a long time now, since 1997, which was when it was approved by the FDA for essential tremor and Parkinson tremor. And then obviously since then, we have a couple more options in the focus ultrasound thalamotomy, which is a lesioning technique. When you have been on several tremor medications, the list gets smaller and smaller. It- and then chance of likely satisfying benefit from some of these medications can be small and small as you pass through the first and second line agents and these would be the Propranolol and the primidone. And as you say, quite a few patients- it's estimated between 30 to 50% of these patients end up not tolerating these first two medications and end up discontinuing them. Some portion of that might also be due to the fact that some of our patients who have been living with essential tremor for decades now, to the point that their tremor is getting worse, are also getting older. And so, polypharmacy and/or some of the potential side effects of beta blockers and anticonvulsants like primidone may be harder to bear in an older adult. And then as you talk about in the article, there's some level of evidence for topiramate, and then from there a number of anticonvulsants or benzos, which have even weaker evidence for them. It's a personal decision. As I tell folks, look, this is not going to likely extend your life or save your life, but it's a quality of life issue. And of course, if there are other things going on in life that need to be taken care of and they need that kind of care and attention, then, you know, you don't need to be adding this to your plate. But if you are in the position where those other things are actually okay, but quality of life is really affected by your being unable to use your upper limbs in the way that you would like to… A lot of people's hobbies and applications are upper limb-based, and enjoying those things is really important. Then I think that this is something- a conversation that we begin and we begin by talking about yes, there are some risks involved, but fortunately this is the data we have on it, which is a fairly extensive experience in terms of this is the risk of, you know, surgery-related side effects. This is the risk of if you're having stimulation from DBS stimulation-related side effects, which can be adjustable. It's interesting, I was talking with colleagues, you know, after focused ultrasound thalamotomy was approved. That really led more people to come to the clinic and start having these discussions, because that seemed like a very the different sort of approach where hardware wasn't needed, but it was still a surgery. And so, it began that conversation again for a bunch of people to say, you know, what could I do? What could I tolerate? What would I accept in terms of risk and potential benefit? Dr Jones: Well, I think that's a great overview of a disorder where, you know, I think the neurologist's role is really indispensable. Right? I mean, you have to have this conversation not just once, this is a conversation that you have over time. And again, I really want to refer our listeners to this article. It's just a fantastic overview of a common disorder, but one where I think there are probably gaps where we can improve care. And Dr Shih, I want to thank you for joining us, and thank you for such a great discussion on essential tremor. I learned a lot from your article, and I learned even more from the interview today. I suspect our readers and listeners will too. Dr Shih: Well, thank you again for the invitation and the opportunity to kind of spread the word on this really common condition. Dr Jones: Again, we've been speaking with Dr Ludy Shih, author of a fantastic article on essential tremor in Continuum's latest issue on movement disorders. Please check it out, and thank you to our listeners for joining today. Dr Monteith: This is Dr Teshamae Monteith, Associate Editor of Continuum Audio. If you've enjoyed this episode, you'll love the journal, which is full of in-depth and clinically relevant information important for neurology practitioners. Use the link in the episode notes to learn more and subscribe. AAN members, you can get CME for listening to this interview by completing the evaluation at continpub.com/audioCME. Thank you for listening to Continuum Audio.

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