Continuum Audio Myotonic Dystrophy With Dr. Paloma Gonzalez Perez
Myotonic dystrophies (DM), in addition to muscle weakness and myotonia, are associated with broad and variable multiorgan involvement. Neurologists need to recognize DM to ensure prompt diagnosis, effective symptom management, and prevention of life-threatening events.
In this episode, Casey Albin, MD, speaks with Paloma Gonzalez Perez, MD, PhD, author of the article "Myotonic Dystrophy" in the Continuum® October 2025 Muscle and Neuromuscular Junction 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. Gonzalez Perez is an assistant professor at Harvard Medical School in Boston, Massachusetts.
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Read the article: Myotonic Dystrophy
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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 Paloma Gonzalez-Perez about her article on myotonic dystrophy, which appears in the October 2025 Continuum issue on muscle and neuromuscular junction disorders. Welcome to the podcast, Dr Gonzalez-Perez. I'd love for you to introduce yourself to our listeners.
Dr Gonzalez-Perez: Thank you very much for the invitation. My name is Paloma Gonzalez-Perez. I'm a neuromuscular neurologist at Massachusetts General Hospital in Boston since 2018. And I'm originally from Spain. I did residency there and also here in Iowa City. And then I did the neuromuscular fellowship here at Mass General Brigham, and then I stayed here as a faculty. So, my focus is myopathies, and more specifically muscular dystrophies, and more particularly myotonic dystrophy, which is what we are going to talk today.
Dr Albin: Wonderful. And this is a really fantastic tour de force article about myotonic dystrophy. And in reading your article, it really did stand out to me that these myotonic dystrophies are probably under-recognized. And so, I was hoping that, just to start, you could tell us a little bit about, what is a myotonic dystrophy, and how should we sort of situate that within the larger context of all muscular dystrophies?
Dr Gonzalez-Perez: Yes, so muscular dystrophies, we have many of them, right? And mostly affecting the skeletal muscle. And basically, the definition of muscular dystrophy is a genetic or inherited muscle disease that causes a progressive muscle weakness. And also, in the muscle biopsies of patients with muscular dystrophies, we see some fractures that are characteristic of this category of muscle diseases, such as, for example, the nuclei of the muscle fibers are in the center---that's what we call internal nuclei---or maybe fat infiltration or increased connective tissue or a variability in the size of the muscle fibers. So, now in the last few years, the genetic testing is more accessible to us. So, we don't need muscle biopsies all the time to diagnose patients with muscular dystrophy. So many times, we go directly to genetic testing. And this is basically the category of muscular dystrophies.
Myotonic dystrophy is very fascinating muscular dystrophy in the sense that many times not only affect the skeletal muscle, but other organs can be affected. And it is true that other muscular dystrophies can affect other organs such as, for example, the brain and the heart, which is something that we always have in mind as a clinician to make sure this muscular dystrophy affect the heart or affect the brain, because it is important for patient care. But myotonic dystrophy actually can affect any organ in the body. I think it is one of these muscular dystrophies in which there is a multisystem involvement of the body. So, the immune, immunological system can be affected and the endocrine system can be affected, the GI system can be affected. In addition to, obviously, to the brain, to the heart, to the skeletal muscle. And sometimes that is why it is under-recognized because of course, if there is a very severe phenotype, maybe the patient comes very easily to a neurologist who is very familiar with myotonic dystrophy. But if the phenotype is a little bit milder, and maybe it doesn't affect much the skeletal muscle. So, these patients probably are in the care of other specialists, such as, for example cardiology or GI doctors, and obviously these specialists are not really aware of this muscular dystrophy. So, I think it is a complex disease because it is very variable in phenotype, can affect many organs and can be also mild.
Dr Albin: That is fantastic. That is just a wonderful overview of, really, muscular dystrophy. One of the things I was really curious about: the name includes myotonia. Is myotonia, like, always present, or is that a little bit misleading?
Dr Gonzalez-Perez: Yeah. I would say that it is a little bit misleading---maybe not too much in myotonic dystrophy type one, because it is true that in adults with myotonic dystrophy type one, many times they have the myotonia, but not many times they complain about the myotonia. This is the thing. So, it is a diagnostic clue that we have at bedside when we ask the patient, for example, to squeeze the hands and then release and we see the myotonia there. And then, obviously, this can actually give you the diagnosis at bedside, but the patients usually don't come to the clinic complaining of this myotonia, which is delaying the relaxation of the muscles. Sometimes they don't- they are not bothered by that. They don't need treatment for that. But it is a very important clue at bedside. I have to say, adults, myotonic dystrophy type one, because the congenital myotonic dystrophy type one you don't see myotonia, clinical myotonia. These babies, right, are born with severe muscle weakness and we don't see myotonia. And then myotonic dystrophy type two, many patients don't have clinical myotonia. And then, you know, the absence of myotonia, the absence of this delay in the muscle relaxation doesn't rule out a myotonic dystrophy, and especially doesn't rule out a myotonic dystrophy type two.
Dr Albin: Fantastic. So probably is going to be a feature of the adult-onset type one. May or may not be present in type two. And then the congenital forum where children are presenting as infants, they're not going to tell you that, oh, I have delayed relaxation. That's not going to be part of that.
Dr Gonzalez-Perez: Exactly.
Dr Albin: This is one of those things that I think, unless you're in neuromuscular clinic, you might not think to ask people about. Maybe the patient isn't actually saying, oh, I have this delayed reaction. How do you get them to give you that history? Like, what are the questions that you ask?
Dr Gonzalez-Perez: Sometimes I will say, do your hands get locked? You know, this could be the first question that they noticed something there, and then they can give you maybe the clue. But actually, it's the exam more than the question. I will say it's more do the exam and, you know, intentionally test for myotonia. And you test for spontaneous myotonia and percussion myotonia. So spontaneous myotonia, we tell the patient to squeeze the hands very strongly and then open the hands quickly. And then if they cannot open the hands quickly, this is a delay in muscle relaxation. We call it grip myotonia, spontaneous grip myotonia. Or sometimes close your eyes very, very, very strongly and then open the eyes quickly. And if they have this delay in the eye opening, we call it eyelid myotonia. This eye is spontaneous myotonia, you don't touch the patient and you don't use your hammer yet. And then if we don't find anything, we go to the hammer. We use our reflex hammer, and then we try to test for percussion myotonia. And sometimes we with the reflect hammer, we tap the thinner eminence of the hand, and we can see that you tap, there is a contraction, and then the thumb goes up and then takes a while to go down again. It is a delay in the relaxation of the thinner eminence muscles. Or sometimes in the posterior aspect of the forearm, if we tap the extensor digitorum communis muscle. Again, so, there is a contraction of that muscle, the fingers go up and then take a while to go down. It is also a perfusion myotonia of the extensor digitorum communis muscle. Sometimes people do it even in the tongue. I don't do that because could be very painful. But you can, you know, use a tongue depressor and put it in the tongue, and you tap the tongue depressor and sometimes there is contraction of the tongue, which can be very painful. I don't do it. So- but this is the perfusion myotonia, that can give you also a clue.
Dr Albin: That's fantastic. I think this is one of the most memorable things that I saw in pediatric neurology. I remember very distinctly a kid coming in, and then us also examining the mother and having that delayed relaxation. And just one of those really great neurologic exams, those little findings to tuck away to really make a diagnosis, recognizing that not all patients with muscular dystrophy or myotonic dystrophy will have that finding. But so beautiful. And I think that's a really great explanation. And I will also direct our listeners, if you are a Continuum subscriber, she has some really wonderful videos in her article from the EMG sounds of this, which is another layer of being able to appreciate the physical exam finding. One of the things that I was really struck by, and that you've already mentioned, is that there is this really incredible spectrum of disease. That some of the myotonic dystrophy patients may barely have any skeletal involvement, and the ones with congenital myotonic dystrophy may have significant mortality even within the first year of life. Given how many subtypes of this disease there are in that varied presentation, let's just walk through sort of starting with congenital myotonic dystrophy. What are some of the clues to that diagnosis?
Dr Gonzalez-Perez: Yes. So, you know, these babies with congenital myotonic dystrophy, actually when they are born, the phenotype is what we call a floppy baby. Floppy baby syndrome right? So, they are very weak. There is generalized weakness, including the swallowing muscles and the respiratory muscles. So sometimes, you know, these patients, these babies have to be intubated---to have a feeling tube, right---to survive. So, that's why the mortality can be so high during the first year of life, because obviously swallowing and breathing is affected because the muscle, those muscles, are also affected. So, one of the clues, actually- you know, sometimes these patients may have, like, a tented mouth, which could be a sign of congenital myotonic dystrophy. The differential diagnosis for a floppy baby syndrome is very broad and can be caused by central nervous system problems or peripheral nervous system problems. So, it's very broad, but maybe the tented mouth can be a clue to suspect the congenital myotonic dystrophy type one. And I will say that also, examine the mom. Because sometimes the mom is not diagnosed with myotonic dystrophy, and as simple as going into the mom who is an adult and can have already the myotonia that we talked about before and maybe, you know, try to do, like, a grip myotonia, eyelid myotonia, or use your reflex hammer and tap a few muscles, and then can give you the diagnosis of potential congenital myotonic dystrophy in the baby. And I have to say that there is no newborn screening for myotonic dystrophy type one yet. Maybe in the future it's going to be, but not at this time. So, I'm pretty sure that pediatricians probably rule out other things before unless there is distinctive mouth or unless the mom is affected.
Dr Albin: Great pearls about how to take it to the bedside and try to look for that hereditary nature of this. Let's move up a little bit in sort of the childhood and adolescent onset. What are some of the clues that you're seeing for those children who come to presentation a bit later in life, but still probably more likely to be seen in pediatric clinic?
Dr Gonzalez-Perez: Yes. So, the childhood and adolescent onset in myotonic dystrophy type one, it is interesting because the skeletal muscle may not be the organ that is more affected or the organ that impacts the life of the patient and the family of the patient. So, it's- the phenotype is predominantly focused on behavioral and intellectual disabilities. They may develop at some point myotonia, and they may develop also muscle weakness. But for the most part they are ambulatory. They eat by themselves, they breathe okay, and there is not too much problem with the skeletal muscle, but mostly with behavioral problems such as, for example, ADHD or intellectual disability. So, they may need some help in school and things like that. So, it is more, I will say, a central nervous system phenotype at this age.
Dr Albin: Yeah, I love that that this is- to me, this was part of the complexity of this was that, while we call it myotonic dystrophy, the muscle part of this disease really may not be the main issue for the patients and their families. And that we're actually looking for something that involves the central nervous system, endocrine system, GI system. And knowing that maybe the muscle is not the main problem here, why is it so important that these patients actually get the correct diagnosis?
Dr Gonzalez-Perez: Exactly. So, it is very important. And I always think about the heart. You know, the heart can be affected in the sense like the rhythm of the heart can be abnormal. And sometimes, you know, the patient doesn't have symptoms. But it's important to detect this because, you know, an abnormal rhythm in the heart can cause sudden death. So that's why it's so important. The diagnosis of this muscular dystrophy at this time, and of course in the future when we have a treatment, right, will be very important also to have the diagnosis, the earlier is the better, because probably the treatment is going to be more effective in the earlier stages than in the later stages. But I will say that right now making sure that the heart is in a good shape and the patient has a cardiologist on board if they have myotonic dystrophy. And also, you know, there are consensus-based care recommendations for myotonic dystrophy type one for the pediatric population and the adult population, and also for myotonic dystrophy type two for the adult population, that are published. And I also included in the chapter because they are very important to look for things that maybe the patient it doesn't complain about, but it's important to look for them in the case that we can prevent some future complications.
Dr Albin: Absolutely. I really love that. This is a systemic disease that has multiple manifestations, and while the skeletal muscle involvement may or may not be causing problems, we really do have to get the right diagnosis, particularly as it impacts the heart and preventing fatal cardiac arrhythmias. Up to this point, we've mostly been talking about type one myotonic dystrophy. What sets type two apart?
Dr Gonzalez-Perez: Yes. So, type two is, I think, even more under-recognized, probably because the phenotype is even more variable than type one and can be much milder in some sense. We are not aware of, you know, like, there are some pediatric cases that have been reported, but for the most part it's an adult muscular dystrophy, type two. So, we diagnose these muscular dystrophies usually in the forties, fifties. The thing is, like, sometimes patients actually may only have muscle pain. And not even muscle weakness. And so… and actually some of these patients may receive a diagnosis of fibromyalgia, for example, just because of the muscle pain. And it is more difficult to obtain myotonia on exam, actually. I think there is a delay in diagnosis in this population, and also the multisystem involvement, which is present but maybe even more variable than that in type one. And we have less patients, so we understand less the phenotype of these patients. But for the most part it is, I think, more under-recognized in the type one.
Dr Albin: Fascinating. So again, could have pretty mild skeletal involvement and may just have cramps and muscle pain. So, you have to be really sort of mindful of keeping this on the differential for people with multiple areas of pain in the muscles. When is this suspected? Are you usually sending genetic tests to confirm? How do we get to the diagnosis?
Dr Gonzalez-Perez: In the history, in the past medical history, you have probably- sometimes you have the clue. For example, a patient with muscle pain, imagine like for example a forty-eight-year-old male with muscle pain comes to the clinic, and then he tells you that he had cataract surgery at the age of twenty. And then you see a CK that is a little bit more elevated than usual. And then at that time I will go for genetic testing right away, for my myotonic dystrophy type two. Because of the muscle pain is so characteristic of myotonic dystrophy type two, and the multiorgan involvement sometimes includes a very early cataracts, the same as in type one. But the muscle pain is much more typical for type two than for type one. So, that's why I will go, in this specific scenario to type two.
If I still think that my alternative dystrophic type two is a possibility, although I'm not totally convinced if it is or not, I usually go for EMG. I mean, if you don't see myotonia at the side, maybe with the EMG and the needle in the muscle, you can see this electrical myotonia that I have some videos in the chapter to see if there is this motorcycle sound of the electrical discharges from the muscle that are consistent with- they can be seen in myotonic dystrophy type two. They are not as specific, but can be seen in myotonic dystrophy type two. So if I have a patient with muscle pain and then I see this electrical myotonia on EMG, so then I will go then next to a genetic testing for myotonic dystrophy type two. Sometimes if there are some family history, it gives you also clues about the possibility of myotonic dystrophy in general, but also myotonic dystrophy type two. Myotonic dystrophy type two, usually the muscle weakness, when it is present, it's more proximal. While in myotonic dystrophy type one it's more distal. So, this also, you know, helps you to differentiate. But specifically in this myotonic dystrophy area, I think the past medical history helps you a lot and the family history helps you too. If you see an autosomal dominant inheritance of muscle or other organ problems, you suspect this type of muscular dystrophy. And I have low threshold to test for this if it is possible because, as we mentioned before, knowing what the patient has helps a lot in their care.
Dr Albin: Absolutely. I love that. Spoken like a true neurologist, using the history, the physical, thinking about the family history, using EMG as an extension of our physical to really find and clinch that diagnosis, and then using genetic tests as a confirmation to get to the right answer. I love the mention of early-onset cataract. Are there any other things that pop into your mind or when you're reading the chart and you look at the medical history that, like cataracts, stand out to you as, this really clues me into myotonic dystrophy?
Dr Gonzalez-Perez: Yes. So, for example, a pacemaker at early age---in their thirties, in their forties---; a family history of sudden death---for example, having a surgery for whatever reason, having a surgery like for example, surgery for appendicitis and have complications from general anesthesia, like a delay in the awakening from the general anesthesia because patients with melatonin dystrophy are very sensitive to anesthetics and also any sedative medication. So, that gives me a clue that, you know, patients with melatonin dystrophy can have this type of history. I think that those will be the main ones. Sleep apnea is very common, but we know it's also common in the general population. So, maybe sometimes, actually, we may think too much and it is, you know, normal for the general population, more frequent in the general population. But, yeah. And daytime sleepiness that can be caused by the sleep apnea. But sometimes these patients have profound daytime sleepiness. Like, they really complain about that. You know, I need to nap very often during the day because of this. Those features, I think, increase my suspicion for myotonic dystrophy.
Dr Albin: Fantastic. So, in the brief time that we have left, I'd love for you to tell us a little bit about what's on the horizon for treatment for these patients.
Dr Gonzalez-Perez: Yes, we have exciting preclinical and clinical trials in myotonic dystrophy type one; not yet in myotonic dystrophy type two. And these trials try to target the genetic defect at the level of the DNA or at the level of RNA. So, we have small molecules in clinical trials. We have also some antisense oligonucleotides in clinical trials. We have some small interfering RNAs in clinical trials. And then the CRISPR, which is another new technology, that is trying, you know, to repair this long function that causes myotonic dystrophy type one. And the important thing is, like, once we know what works for myotonic dystrophy type one, we may have good clues also for myotonic dystrophy type two because they share the common pathogenic mechanism.
Dr Albin: Fantastic. So, it sounds like there's some genetic therapy in the pipeline. There is some small molecule treatments that are going to be available. So, really an exciting time. There's going to be a lot of changes coming forward to these patients. Again, today I've been interviewing Dr Paloma Gonzalez-Perez about her article on myotonic dystrophy, which appears in the October 2025 Continuum issue on muscle and neuromuscular junction disorders. Be sure to check out Continuum Audio episodes from this and other issues, and thank you so much to our listeners for joining again today.
Dr Gonzalez-Perez: Thank you very much for the invitation. My pleasure.
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