Therapeutic Approach to Autoimmune Neurologic Disorders With Dr. Tammy Smith

Over the past 20 years, more than 50 antibodies have been identified and associated with autoimmune neurologic disorders. Although advances in diagnostic testing have allowed for more rapid diagnosis, the therapeutic approach to these disorders has largely continued to rely on expert opinion, case series, and case reports.

In this episode, Allison Weathers, MD, FAAN, speaks with Tammy L. Smith, MD, PhD, an author of the article “Therapeutic Approach to Autoimmune Neurologic Disorders,” in the Continuum® August 2024 Autoimmune Neurology issue.

Dr. Weathers is a Continuum® Audio interviewer and associate chief medical information officer at the Cleveland Clinic in Cleveland, Ohio.

Dr. Smith is a GRECC investigator and staff neurologist at George E. Wahlen Veteran Affairs Medical Center and an assistant professor of neurology, at the University of Utah in Salt Lake City, Utah.

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Transcript

Full episode transcript available here

Dr Jones: This is Dr Lyell Jones, Editor-in-Chief of Continuum, the premier topic-based neurology clinical review and CME journal from the American Academy of Neurology.  Thank you for joining us on Continuum Audio, which features conversations with Continuum’s guest editors and authors who are the leading experts in their fields. Subscribers to the Continuum journal can read the full article or listen to verbatim recordings of the article and have access to exclusive interviews not featured on the podcast. Please visit the link in the episode notes for more information on the article, subscribing to the journal, and how to get CME.

Dr Weathers: This is Dr Allison Weathers. Today, I'm interviewing Dr Tammy Smith about her article on therapeutic approach to autoimmune neurologic disorders, which she wrote with Dr Stacey Clardy. This article is a part of the August 2024 Continuum issue on autoimmune neurology. Although, one of the things I love most about being an interviewer for Continuum is getting the opportunity to meet new neurologists and learn all about their areas of expertise, there's something really special when I get the chance to interview and catch up with old colleagues - and today, I'm fortunate to do just that. I had the privilege of working with Dr Smith when she was a resident at Rush, and I'm so excited to be able to speak to her today about her fantastic and really comprehensive article on this very timely topic. Welcome to the podcast, Dr Smith, and please introduce yourself to our audience.

Dr Smith: Hi. Yeah, thank you for inviting me to participate in the podcast and to write this article. So, I'm Tammy Smith. I am a neurologist who practices in Salt Lake City. I primarily work at the Salt Lake City VA Medical Center where I get to treat veterans with all sorts of neurologic diseases. I'm also an assistant professor of neurology at the University of Utah in the division of Neuroimmunology and Autoimmune Neurology, and I serve as a Clinical Consultant for ARUP Laboratories to help improve diagnostic testing for immune-mediated neurologic diseases.

Dr Weathers: Wow. That is a lot of different roles and things that you have on your plate. I want to start, actually, by talking about the article. Again, you cover so much ground (you and Dr Clardy) in this really comprehensive article, but if you had to choose the one most important message - if you wanted our listeners to walk away remembering one key point, what would it be?

Dr Smith: I think the key point I want our listeners to think about is just to use the resources that are available to you. Nobody can have all of these drugs (as we're talking about treatment of autoimmune neurologic diseases in this article) - no one can have all of those drugs memorized, all of the mechanisms of action, all of the approved treatments and off-label treatments, and all of the symptomatic therapies. But that's why resources like the Continuum exist - so that we can provide those resources to clinicians who are busy at that touch of, er, hopefully - or when they open their issue - to get the information they need to make decisions to take good care of their patients.

Dr Weathers: I think that is so reassuring. As I was reading this article, that was, like, one of the things that really struck me is that, you know, thinking about even being a resident and studying for something like the rate exam, you know, how much easier it used to be when there was such a limited number of drugs thinking about the autoimmune diseases or epilepsy, where just the number of drugs has just, kind of, multiplied so manyfold since I was in training, that it's really overwhelming. And I think you make a great (and as I said, a very reassuring) point that we don't have to memorize these, that there are these incredible resources (like Continuum) where it's not any longer about kind of memorization and keeping it in our heads, that it's more about knowing where to look and thinking about what's the right thing for the patient - knowing how to go and get the information is the more important knowledge there. And, actually, thinking about that and moving on, given your expertise, how do you personally approach the management of a patient with an autoimmune neurologic disorder? Again, in the article, you speak about all the different things to keep in mind, both from a therapeutic (really, treatment) standpoint, as well as a symptomatic standpoint - but what is your personal approach?

Dr Smith: My personal approach really involves considering whether the diagnosis of an autoimmune neurologic disorder is correct, first and foremost, and gathering the information to help support that diagnosis - and I think that's something that often gets overlooked in the excitement of a patient coming in with a rare-looking syndrome. Someone sends off diagnostic testing, rules out a few things, decides it's autoimmune, and starts down a pathway and keeps pushing forward. And I understand that inclination on a busy neurology service or in a busy clinic to just decide on one path and move forward, but I'm always questioning the diagnosis, even in the presence of positive antibody results sometimes. If my patient doesn't respond to the treatment that I'm giving them based on their presentation and the antibody results, I reassess and wonder if there's something else going on, are there two syndromes going on, or was that antibody result really not the right answer for some reason. So, I think my approach, really, is to always have a healthy amount of skepticism around the diagnosis, and even when I'm fairly confident in the diagnosis, to continually reassess that patient and their unique response to treatment. And then, also, their unique circumstances - so, everyone will need different symptomatic management, as well as different rehabilitation resources and other resources mobilized to help them maximize their recovery. And so, there's just not a “one size fits all” approach, but always keep talking to the patient, keep re-evaluating, stay curious, and don't be afraid to change paths when things aren't making sense.

Dr Weathers: I think that is incredibly sound, really thoughtful advice. So, I can imagine how incredibly challenging those cases must be when you think you have the right answer, it looks like it's lining up, the antibodies are pointing you in the right direction, and then, they're not responding. What else do you feel is the most challenging aspect of the management of these conditions? Is there some other kind of aspect that you also feel is really challenging in the treatment of these patients?

Dr Smith: Yeah, I think other challenges are really access to state-of-the-art therapies due to financial barriers - I think that's a pretty significant challenge for a lot of these patients, and I think we need to continue to work on advocacy efforts to make sure all patients have access to the medications they need to treat the disorders they are diagnosed with. And it's a real challenge, even when there's FDA-approved therapeutics - a lot of them are quite expensive, and then we end up playing the insurance game, and we learned that AI is automatically denying people's insurance claims, and so, we're battling computers as well as insurance companies. And I think that's a really significant challenge for a lot of these patients. And then, really, just the fact that a lot of immune-mediated neurologic disorders have a long tale. So, we don't treat a patient the same way we do for an infection and expect a dramatic and rapid recovery - a lot of the recovery for these patients happens over months to years. It's a process, and I think it's really important to be counseling patients and caregivers and other providers and educating them about this that we continue to mobilize resources to help our patients long past their inpatient hospitalization and the most dramatic part of their recovery.

Dr Weathers: Again, you raised some really insightful points there. No, I think they're really key. And I think, to your point, that even for some of these patients, that even if we can get over the economic barriers of the medications themselves and get them authorized, get them covered, you're left with, for a lot of patients, all of the other limitations of some of their social determinants of health challenges, right? So, the transportation challenges to even kind of get them to the appointments, and some of the other challenges they face, which makes some of these treatments very, very hard for them to be able to accomplish. So, it is very challenging - I think that's a very important call-out. What do you think is the easiest mistake to make when treating patients with autoimmune neurologic disorders, and how should our listeners avoid it?

Dr Smith: Yeah, that's an excellent question. One of the most common mistakes I see is either overvaluing diagnostic testing or not ordering the appropriate diagnostic testing for the clinical syndrome in any given patient. And where this comes into play, really, is the fact that when we order diagnostic testing in the United States for immune-mediated neurologic disorders, these autoantibody panels are available to us that test for a multitude of autoantibodies all at the same time, and if we don't choose the appropriate test for the clinical syndrome that the patient is there with, we run the risk of getting a positive result for an antibody that's unrelated to the syndrome we're seeing in the patient – and no test is 100% specific (or 100% sensitive, for that matter), but these low-specificity issues when you indiscriminately test really can cloud the clinical picture and delay getting the appropriate diagnosis. And so, I really think that one of the biggest mistakes is seeing maybe a low-positive result for an antibody that does not match the clinical syndrome if you go back to the books and use your resources to figure out if that result is meaningful - overvaluing that antibody result and maybe plowing forward with a treatment plan that involves a long course of immunomodulatory therapy is a pretty significant mistake. And then, on the flip side is that because these panel tests, you order them as a block, and you think that you ordered the right thing - or you think that whoever you asked to order the order for you ordered the right thing – and so often, people say the panel was negative, and they don't look at the individual results of the antibodies that were tested in the panel, and because different antibody panels are designed to test for different clinical phenotypes. I see the error where a clinician thinks that all of the antibodies necessary to test for were tested for and negative, and now they feel like their hands are tied. And so, it's both this overvaluing the diagnostic testing and forgetting to question the testing results if they're not what you expect once you get more clinical data - I think both of those are pretty big mistakes. And continuing, again, always be curious, always recheck results, and don't take laboratory values in an EMR that are in black and white as the stone-cold truth that tells you your answer - you have to stay curious about the patient, their history, their neurologic presentation, their response to treatment over time, and really keep assessing. My other soap box here about diagnostic testing is that, historically, a lot of the antibodies that we test for were called paraneoplastic (and that's because they were some of the first antibodies discovered, so, they were some of the earliest ones that we developed tests for), and clinical reference laboratories continue to offer paraneoplastic panels for historical reasons and because a lot of people think that that's what they want. But, paraneoplastic panels, in and of themselves, are not representative of a specific clinical phenotype - they just diagnose patients who have a high risk of malignancy associated with an antineural antibody. And so, most of the clinical reference labs I know of - certainly at ARUP, we have a notice on our testing page, I know Mayo Clinical Laboratories also has a notice that says, “Paraneoplastic panels are not generally the recommended panel to test for antineural antibodies. Consider ordering the phenotype-specific panel that fits the patient's clinical syndrome”. And I think that's super important – we still have paraneoplastic stuck in our head for historical reasons, and it is almost never the right answer.

Dr Weathers: It's really interesting. At my organization, you know, we actually have had some really thoughtful conversations about, do we really restrict it (you know, as part of lab stewardship efforts) - and, you know, these are expensive, and to your point, they can be frankly, really dangerous, you know, to really send somebody down this wrong path with a lot of surveillance, committing them to immunomodulatory therapies, and take you in completely the wrong direction when, actually, your low test probability was very low. So, I think that is an excellent one to really call out and for people to be very thoughtful of - and the way, again, to avoid it is to be very thoughtful about the panels. And for people, certainly, they are very convenient, but people need to be really aware of what's in them and what they are ordering and how to interpret them. And I love that advice about not just thinking about the wholesale as negative - really, you know, for many of us, they are still coming in as scan documents, you know, click into them, read every line, really understand what those results mean.

Dr Smith: And I would also say that I think people don't realize, but clinical reference laboratories would love for you to reach out when there are questions. So, if you don't understand the diagnostic testing that was performed or result, you pretty much all have hotlines. You can call and reach out to an expert in the testing and ask them some questions, and don't be afraid to reach out to your colleagues who might have more experience. We love hearing from people with questions and helping to direct them to the right testing and help them get the answers that they really want to for their patients.

Dr Weathers: I think that is a great plug. Before you order, preferably, before you send in.

Dr Smith: I do like when I hear from people before mistakes were made. Yes. That's nice.

Dr Weathers: It’s a great point.

Dr Smith: When you order these panels, you do run the risk of having these low positive results that may or may not be clinically meaningful. And we do recommend that most of the diagnostic testing be ordered in both serum and CSF. And so, a good example of a mistake that can be made is a very low-positive NMDA-receptor antibody in serum - maybe it was ordered for a patient with cognitive decline or confusion (maybe not under the ideal clinical scenario for ordering), and then it's negative in the CSF. So, an NMDA-receptor positive, negative in the CSF, not the right clinical picture, people can get really jazzed and want to treat an NMDA-receptor encephalitis, that in that case, really isn't meeting diagnostic criteria, and there are excellent diagnostic criteria that have been developed and published for that disorder and for several other autoimmune neurologic disorders, and I think going back to those criteria and really questioning yourself before you start blindly down a path based on a lab result is really important.

Dr Weathers: I think that's excellent advice, too, always keeping that in mind that just because you have gone down this path and gotten that result doesn't mean that you are stuck and committed to it. Always keeping that criteria in mind, always going back, always checking it is really important as well. Moving on from mistakes to kind of an adjacent question, what do you think is the biggest controversy right now when it comes to the treatment of patients with autoimmune neurologic disorders?

Dr Smith: You know, one of the big controversies that I see and I'm concerned about is that we've gotten into a habit of treating the way we've always treated based on expert opinion, and while experts have their opinions based on a lot of experience, they don't take the place of well-designed randomized controlled clinical trials - and in rare diseases (like autoimmune neurologic diseases), it can be really challenging to conduct those trials, especially in the face of people who have a pathway that they always do with their patients. If they have a NMDA-receptor encephalitis patient, they feel very comfortable doing their standard of care with IV steroids and then either plasma exchange or IVIG, and then possibly (and very often), I see following with a B-cell inhibitor, like rituximab, as sort of just a “kitchen-sink” approach to treatment. And while I understand the passion and the desire to make a really sick patient sitting in front of us better as fast as possible, I don't think we have adequate evidence to support that being the “one-size-fits-all kitchen-sick” approach for treatment. And I really am passionate about all clinicians all over the world, supporting randomized controlled clinical trials that are well-designed with the backing of experts in the community, so that when we look at a patient and tell them that we recommend a course of treatment, we're recommending it based on the best quality evidence available, not just what everyone's always done before. I think we can do better than that. And I think there's some controversy in this. Some people think that it doesn't make sense, we already know the answer, but I would say we haven't asked the right question and thoroughly investigated enough. And this is especially important with children, right? We know pediatric patients often don't have well-designed clinical trials to guide their treatments - but in NMDA-receptor encephalitis, many of the patients are children, and I think that they deserve to be involved in well-designed clinical trials in order to support the recommendations that we make for treatment.

Dr Weathers: And in addition to children, think about all of the other patient populations that have traditionally not been well represented in trials, right - pregnant patients, patients of color (historically very underrepresented in trials) - many, many other patient populations that have not been adequately represented.

Dr Smith: Absolutely. Yeah. I think we need to really care about that and face that problem head on and speak to it. We can't just say this is the way we've always done things, so we're going to keep doing it that way. I think we owe it to our patients and ourselves, when we look our patients in the eye, to say that we have good evidence to support the recommendations we're making.

Dr Weathers: I think we have already answered this question in many ways with each of the questions we've already talked about, but is there any other strong arguments that you can make for why it's important for neurology clinicians to read your article?

Dr Smith: Dr Clardy and I spent a lot of time working on this article, trying to put together a piece that will be a resource that people could turn to again and again. I don't think that this article is something that you should read from top to bottom and think that you've absorbed and digested everything, right? So, what we work to do was to really provide a structure and a framework to think about the treatment of immune-mediated neurologic diseases. So, rather than memorizing specific drugs for specific conditions, we developed sort of a space where you could talk about B-cell targeting therapies and the different ways we can target B-cells, we talked about complement inhibitors, neonatal FC receptors, and, really, just at a high level, how these drugs work and how they're targeted, so that going forward in three, four, five years, what I believe we'll know more about each of the individual diseases mediated by antineural antibodies. When we understand what causes that disease, we'll be able to go to a resource like this and choose rationally based on mechanism of action, a drug to treat our patient - even if it's in a patient with such a rare disease that we don't have the luxury of a clinical trial to guide our choices.

Dr Weathers: That's a really excellent point - and I know I've said it a few times, but I think you guys did such a really excellent job at really laying it out in a way that makes it this really comprehensive, really easy-to-use resource at that point of care for providers to be able to do exactly that. Well, I always like to end on a hopeful note, so, this is always my favorite last question – but, what do you think is the next breakthrough coming in the treatment of patients with autoimmune neurologic diseases?

Dr Smith: Yeah, I think in the near future (I certainly hope, at least) that the next breakthrough is going to be in really being able to deliver personalized care based on what we understand about the mechanisms of a patient's rare disease. So, again, right now, I find we're kind of left with the “kitchen-sink” approach because we know so little about the mechanisms that drive each of these unique neurologic diseases and we don't have enough information from clinical trials to inform rational treatment decisions, so we go with these broad approaches - and I really think that in the near future, with work being done by a lot of people (dedicated people over the world) on biomarkers and things that predict either onset of disease or relapse or disease severity or really looking at basic fundamental mechanisms that drive disease, we're going to be able to make more rational choices in the treatment of these patients and mobilize the resources that are expensive, but valuable for the right patient at the right time.

Dr Weathers: That is a very exciting and hopeful future to look towards. Thank you, Dr Smith, for joining me on Continuum Audio. It was wonderful to get to spend this time with you again. Again, today, I've been interviewing Dr Tammy Smith, whose article on therapeutic approach to autoimmune neurologic disorders, written with Dr Stacey Clardy, appears in the most recent issue of Continuum on autoimmune neurology. 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 this 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.