Stiff Person Syndrome and GAD Antibody–Spectrum Disorders With Dr. Marinos Dalakas

Stiff Person Syndrome (SPS) is treatable if managed correctly from the outset. It is essential to distinguish SPS spectrum disorders from disease mimics to avoid both overdiagnoses and misdiagnoses.

In this episode, Allison Weathers, MD, FAAN, speaks with Marinos C. Dalakas, MD, FAAN, author of the article “Stiff Person Syndrome and GAD Antibody–Spectrum 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. Dalakas is a professor of neurology and director of the neuromuscular division at Thomas Jefferson University in Philadelphia, Pennsylvania; a professor of neurology and chief of the neuroimmunology unit and the National and Kapodistrian at the University of Athens in Athens, Greece.

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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 Marinos Dalakas about his article on stiff-person syndrome and GAD antibody-spectrum disorders, which is part of the August 2024 Continuum issue on autoimmune neurology. Dr Dalakas is a world- renowned expert in neuromuscular diseases and, really, the first name any neurologist thinks of when they hear the diagnosis of stiff-person syndrome. Dr Dalakas, this is such an honor to be able to speak to you today. Welcome to the podcast, and would you please introduce yourself to our audience?

Dr Dalakas: Yes, thank you very much. I'm so happy to participate in this interview. I'm the Chief of the Neuromuscular Division at Thomas Jefferson University in Philadelphia, and I am interested in autoimmune neuromuscular diseases for many years and also on disease mechanisms and immunotherapy.

Dr Weathers: Thank you again for talking with me today. So, given how very rare stiff-person syndrome and the GAD antibody-spectrum disorders are, prior to December 2022, I would have started our time together by asking you to explain this collection of diagnoses to our listeners and by also talking about how often they occur. It feels like that's a bit unnecessary ever since Celine Dion went public with her diagnosis - that moment really changed the public awareness of what was previously outside of neurology and almost unheard-of disease. So, instead, I'll start with, what is the key message of your article? If our listeners are going to walk away remembering one thing from our discussion, what would you like it to be?

Dr Dalakas: Well, I think the publicity has been very good for the disease, this disease spectrum. On the other hand, there have been some misleading messages, like, it's extremely rare, it's untreatable, it's disabling – which, they are partially correct, so, my message is, first, to make sure the neurologists make the correct diagnosis, because there are a lot of diseases similar to stiff-person, but they are not stiff-person. So, to make sure the diagnosis is correct and to make the patients aware of what to expect when they have this disease and what therapies we have and what we may have in the future. So, the number one message is the correct diagnosis and then to avoid overdiagnosis or misdiagnosis, because now we see both - we see overdiagnosis and misdiagnosis.

Dr Weathers: I think that's such a critically important point, and one you really delve into really beautifully in the article, so I encourage our listeners who do have access to it to really read through it. As I said, you do a great job really explaining that - and, actually, to go into that further, could you explain how you approach the diagnosis of a patient with possible stiff-person syndrome or one of the other GAD antibody-spectrum disorders? And I know you probably get asked that on a daily basis. As I was telling you before we actually formally started recording, I remember back when I was a resident and saw my first case of a suspected patient with stiff-person syndrome, my mentor advised me to look up your case series, your articles at the time, and really use that to guide my diagnosis. What do you feel is the most challenging aspect of diagnosing a patient with one of these conditions?

Dr Dalakas: Well, the first is the clinical symptomatology. We say the patients present with spasms and stiffness, but also, there are phobias. They are very hyperexcitable to sudden stimulations, to sudden noises, to unexpected touches, and all of them can cause spasms, and then when you examine the patients, they have stiffness. Now, the stiffness (if there is a true stiffness) results in gait abnormalities (the patients are falling because they're so stiff), and also, the hyperexcitability causes a lot of anxiety and a lot of phobias (they're afraid to cross the street, they're afraid to make a destination promptly) – so, all these things are sort of suggestive of stiff-person. So, these are the symptoms that you hear, you listen, and you ask the patients, and then, when you examine the patient, you look for certain signs that there are, specifically, like stiffness of what we call agonist muscles and antagonist muscles, which means there is stiffness of the abdominal muscles and at the same time, stiffness of the back muscles - so, this concurrent stiffness of these opposing muscles is very specific, very characteristic of the stiff person, so if you see that, and then you listen to the history, you're very close to the diagnosis, and then you do the antibodies. And the antibodies (the specific antibodies, the GAD antibody), but it is specific as we say in the article, and we tried to make this very clear to the neurologists, that it's the high titers that matter, because low titers are not necessarily specific. So high titers of antibodies in the serum, above 10,000 by ELISA (or whatever method they use; but it has to be this many times above normal), and then if you have high serum titers and all the symptoms they mentioned, it is stiff-person. On the other hand, if the titers are low, then you may want to do a spinal tap to see if there is synthesis of antibodies in the spinal fluid. That helps you. Now if the GAD antibodies are negative, then you start wondering, is this seronegative SPS? And how do you confirm the seronegative SPS? You do electrophysiology, and the electrophysiology is, again, to see if there is activity (muscle activity) concurrently from the agonist and antagonist muscles - in other words, from the, let's say the tibialis anterior and the gastrocnemius (so, it's two opposing muscles, eg, biceps and triceps) - and if you see activity in both of these opposing muscle groups, and you see also hyperexcitability (you touch the patient, you stimulate just a little, and you see activity in other muscle groups). So, the electrophysiology is very important if the patient's antibody negative, but they have the other symptoms that I mentioned before.

Dr Weathers: I can imagine how challenging those must be (those seronegative cases) to try to really make sure you're identifying and carefully determining that you have the right disease as you alluded to at the beginning. I know how hard it must be for patients to want to at least have some answers to have a diagnosis.

Dr Dalakas: And this is the main thing today, because the publicity, as I mentioned, the beginning, increased the receipt of some information, so they overdiagnose it, like, “Oh, you have this and this and this, so it may be stiff-person”. And so, in fact, recently, we had a series of patients together with the Mayo Clinic Group of out of 173 patients referred to the Mayo Clinic for stiff-person – that’s referred to them - only 28% had stiff-person. It's a low percentage, but it is an indication that the neurologists now refer patients to us for stiff-person, but we need to be very careful to correctly make a diagnosis.

Dr Weathers: On one hand, it's good that people are aware and considering the diagnosis, but it does highlight that risk of overdiagnosing.

Dr Dalakas: Yeah. It's the opposite of when I started this stiff-person syndrome (was close to 30 years ago at NIH) - at that time was underdiagnosed. This was the most rare disease, and I collected patients because at the NIH, I was also the Chief of the neuromuscular division there, and I was doing a study, so it was easy to collect patients (I collected more than 100 patients), but at that time, it was misdiagnosed. So, we had patients that I was seeing and they're really disabled, because they have been having the disease for many years, but they had been diagnosed either for Parkinson disease, for anxiety disorder, for psychiatric diseases, or for MS, or for myelopathies, or for myelitis - so many different things, and of course, they didn't have the correct diagnosis and they were disabled.

Dr Weathers: The side effect of having one of the most famous celebrities in the world having this rare disease - you know, the downside of the increased awareness, as we've said. So, moving on from the diagnosis to treatment - again, you do a, obviously, you know, an incredible job in the article, really going through the treatment options and your algorithms - what would you say is the most common misconception you've encountered in treating patients with this disease?

Dr Dalakas: The most common is now (with the publicity) is that it is a disabling disease. Well, it is disabling, but if you treat the disease correctly and early on, I'm not saying we’re curing the disease - many diseases (autoimmune diseases), we help a lot, so there are some we make the patient feel normal, but the disease is there - so, if we start the correct therapy early, a good number of patients respond very well. But by the time the patients come to us, they are so stiff, they walk like a statue, or they come in a wheelchair - of course, it's difficult to reverse this, although we have been very happy to see patients with immunotherapies to get out of the wheelchair, to walk, to enjoy normal activities. So, we have made enough progress with the therapists to help a good number of patients. Now, what is the first therapy we do? Well, is what we call the antispasmodics - these are drugs that relax the stiffness that patients have, sort of a symptomatic therapy. It's not going to address the disease itself, but we address the symptoms. And of course, the symptomatic therapy in SPS is not just to relax the patients - it is related to the so-called GABAergic inhibition. So, the drugs that we use (like the benzodiazepines, or the baclofen, et cetera), these are the drugs that work on the GABAergic pathways. So, it is symptomatic therapy, but it works also on the mechanism, so it's not just a relaxing basis - but since the patients have a lot of phobias, the benzodiazepines also help the phobias. The anxiety and the phobias make the patients worse - they make them more stiff. And in the beginning, they go to psychiatrists because they are so phobic - they're phobic to walk. They hear something, they get so stiff. And I have patients coming at the National Airport in Washington to come to there needing aids in getting out of the plane - some of them get so stiff, they have to get an ambulance to come to the hospital because they're stiff everywhere. So, these phobias and anxiety have triggered a lot of my interest to the point of asking the investigators at the National Institute of Mental Health to see if there is any such thing like autoimmune phobias, because these patients have an autoimmune disease, so, well, maybe we can treat the phobias of immunology - well, we did not find anything, but I just sort of brought the idea maybe we have an autoimmune phobia. But on the other hand, when the patients get better, the phobias are reduced and they're more comfortable to walk. So, it's a very interesting complexity of the symptoms altogether.

Dr Weathers: That is – and, actually, that leads into my next question somewhat, that, as I mentioned in your introduction, you are the world expert in this rare disease. How did that happen? You talked about it a little bit just now. But how did you develop this particular interest and expertise? What drew you to this particular disease?

Dr Dalakas: Yes. It's interesting. I was interested in autoimmune neuromuscular diseases (many of them) and neuropathies and myopathies, and one day, I had a good friend of mine who was the clinical director of NINDS at that time, Dr Hallett. So, he saw patients in the movement disorder clinic and they had stiff-person (I don't know why they went to the movement disorder, but they went there), and Dr Hallett said, “Well, this is an autoimmune disease. You should work on this.” And then, I started seeing one or two patients, and I was very impressed. Really, the symptomatology is so interesting. The patients are suffering, and they sort of give the impression that they're neurotic. So, it's just a combination of when you listen to the symptoms, I was very impressed with the depth of the discomfort that they have and without seeing anything - but, when you examine the patient, you see the stiffness and nothing else. They're not weak, like, we see patients with MS, with myopathies, with neuropathies - they have weakness. They may use a cane, they may use two canes, they may use a walker, because they're stiff. So, it's a different disability than you see in patients who are weak. So, this really made me so interested to understand the mechanism - what's going on here - and that's the reason I started and I put the protocol. And then, we did a lot of immunological studies to understand the mechanism, electrophysiological studies to look at these agonist and antagonist muscles - and of course, we named it also. You know, in the beginning, the syndrome was described as stiff man (stiff-man syndrome), and they're all women. They are most of them, women. In fact, there is an article in a major journal, three women with stiff-man syndrome - and this was many years ago. So, stiff-person will be a more proper term. And then we're seeing a lot of patients or more women, but also we have enough men.

Dr Weathers: So, we've talked a lot about the change with this disease in public awareness. How has that changed your day-to-day life - has it (with the change in public awareness)? Are you bombarded with media requests?

Dr Dalakas: Well, it has stimulated me to write more about the disease and more articles, but also to highlight certain things that were not known before. For example, I had recently a paper on late-onset stiff-person. So, people, we see now patients who develop stiff-person at the age of seventy - they are above sixty or so, overall - and they have more severe disease. These patients also have not good tolerance to the medications we use - so, it's a more challenging group, so it is important to make the diagnosis even in patients with late-onset. These people do less well, because, first of all, they're all misdiagnosed, because if you're a little stiff at the age of sixty-five or seventy - well, you have a bad back, so you all have degenerative disc disease, so you don't think of stiff- person in that age. So, the stimulus was to identify some other issues with the stiff-person. The other is to think of new trials - and I have been working on two new trials. They're not out yet. I'm working to see how best to apply the new therapies. And also, it came up the idea of what are the best ways to assess, objectively, to assess the response, because this is an issue from the beginning. When I did controlled trials at the NIH, and we had established the so-called stiffness index to see how stiff they are measurably, but it is still subjective. It's not really objective, it's not (weakness to measure). So, we have gait analysis, we have the time to walk. So, I think establishing objective criterion to assess response to therapy, it’s an important one - and so, I have been working on this how to make it more objective or as subjective as we can.

Dr Weathers: I think that's fantastic. And you actually, I think, have already answered my question - which is, what is the next breakthrough coming in the diagnosis and management of patients with stiff-person syndrome and the GAD antibody-spectrum disorders - and I think it's going to be the outcomes of these trials. Is there anything else that you're really excited about coming along in this field?

Dr Dalakas: Well, I think that the hope is, then, better immunotherapy, because the patients respond to IVIG based on the controlled study. We did one with anti-B-cell therapy - it was not statistically positive, but we had some placebo effects, because that second trial included some patients who did not have severe disease, so it was difficult to assess mild response. So, I'm interested in other similar immunotherapies, and we were approaching companies to see if they can sponsor such a trial. I think the publicity helps a lot, because if I was going to approach a company before the publicity, nobody would be interested in - there's no, you know - it's money-driven, so they will not do it. But at the NIH, I did it, because NIH had the grants there to sponsor the trials. So, I think the publicity will help us. And I know talking to companies, there are one or two companies that they have expressed a lot of interest, and, hopefully, we can do some new trials and go work on it, but I don't have any clear drug at the moment. I cannot discuss a real drug.

Dr Weathers: Of course, of course, more to come, but still very exciting. And so, still to learn more about you - again, you're so well known, obviously, for what you've done for the field of neurology. What do you like to do outside of seeing neuromuscular patients in your research career? What do you do for fun for your hobbies?

Dr Dalakas: Well, I have two hobbies. One is I'm an art collector of abstract expressionism. So, I go to a lot of auction houses, and I bid often for certain artists that I'm very interested, some French artists, some at the New York School of Modern Art. The eras of the forties and fifties of the abstract expressionism - so that's my collection and my interest in not missing auctions. And the other was I have a interest in wine collection – but, so, most of the time, I read art and I collect art.

Dr Weathers: That is a great answer. I appreciate art. I am not (fortunately) at the auction and collecting stage yet, but that I will have to learn from you. That's wonderful.

Dr Dalakas: Yeah. I'm originally from Greece, and I have also a professorship at the University of Athens, and also I go there. I also have some European artists in my collection.

Dr Weathers: That's wonderful. We have one more modern piece that we've been lucky enough to have.

Dr Dalakas: Yeah, I started with the impression impressionistic art, but I evolved into abstract.

Dr Weathers: Who is your favorite artist?

Dr Dalakas: Well, it's, you know, Rothko and Newman. So, these are very expensive artists, of course, so I can, but in that school, so these artists are not alive now, but people who are working with Rothko and Newman in the other group - so, there are four or five of them that I collect.

Dr Weathers: I feel like we need a whole separate interview just to talk about that.

Dr Dalakas: But, they are very stimulating, because the colors talk to you, and it's not like an impressionistic piece that, sort of, their flowers are nice, et cetera - so the colors talk to you differently.

Dr Weathers: They do. I love Rothko. Well, thank you, Dr Dalakas, for joining me on Continuum Audio. This has been a wonderful conversation. Again, today, I've been interviewing Dr Marinos Dalakas, whose article on stiff-person syndrome and GAD antibody-spectrum disorders 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 us 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.