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. Additional Resources Read the article: Myotonic Dystrophy 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 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 sound