Continuum Audio A Pattern Recognition Approach to Myopathy With Dr. Margherita Milone
While genetic testing has replaced muscle biopsy in the diagnosis of many genetic myopathies, clinical assessment and the integration of clinical and laboratory findings remain key elements for the diagnosis and treatment of muscle diseases.
In this episode, Casey Albin, MD, speaks with Margherita Milone, MD, PhD, FAAN, FANA, author of the article “A Pattern Recognition Approach to Myopathy” 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. Milone is a professor of neurology and the director of the Muscle Pathology Laboratory at Mayo Clinic College of Medicine and Science in Rochester, Minnesota.
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Read the article: A Pattern Recognition Approach to Myopathy
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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, this is Dr Casey Albin. Today I'm interviewing Dr Margherita Milone on her article on a pattern recognition approach to myopathy, which appears in the October 2025 Continuum issue on muscle and neuromuscular junction disorders. Welcome to the podcast, Dr Milone. Thank you so much for joining us. I'll start off by having you introduce yourself to our listeners.
Dr Milone: Hello Casey, thank you so much for this interview and for bringing the attention to the article on muscle diseases. So, I'm Margherita Milone. I'm one of the neuromuscular neurologists at Mayo Clinic in Rochester. I have been interested in muscle disorders since I was a neurology resident many years ago. Muscle diseases are the focus of my clinical practice and research interest.
Dr Albin: Wonderful. Thank you so much. When I think about myopathies, I generally tend to think of three large buckets: the genetic myopathy, the inflammatory myopathies, and then the necrotizing myopathies. Is that a reasonable approach to conceptualizing these myopathies?
Dr Milone: Yeah, the ideology of the myopathies can be quite broad. And yes, we have a large group of genetic muscle diseases, which are the most common. And then we have immune-mediated muscle diseases, which include inflammatory myopathies as well as some form of necrotizing myopathies. Then we have some metabolic myopathies, which could be acquired or could be genetic. And then there are muscle diseases that are due to toxins as well as to infection.
Dr Albin: Wow. So, lots of different etiologies. And that really struck me about your article, is that these can present in really heterogeneous ways, and some of them don't really read the rule book. So, we have to have a really high level of suspicion, for someone who's coming in with weakness, to remember to think about a myopathy. One of the things that I like to do is try to take us through a little bit of a case to sort of walk us through how you would approach if someone comes in. So, let's say you get, you know, a forty-year-old woman, and she's presenting with several months of progressive weakness. And she says that even recently she's noted just a little bit of difficulty swallowing. It feels to her like things are getting stuck. What are some of the things when you are approaching the history that would help you tease this to a myopathy instead of so many other things that can cause a patient to be weak?
Dr Milone: Yes. So, as you mentioned, people who have a muscle disease have the muscle weakness often, but the muscle weakness is not just specific for a muscle disease. Because you can have a mass weakness in somebody who has a neurogenic paralysis. The problem with diagnosis of muscle diseases is that patients with these disorders have a limited number of symptom and sign that does not match the large heterogeneity of the etiology. So, in someone who has weakness, that weakness could represent a muscle disease, could represent an anterior horn cell disease, could represent a defect of neuromuscular junction. The clinical history of weakness is not sufficient by itself to make you think about a muscle disease. You have to keep that in the differential diagnosis. But your examination will help in corroborating your suspicion of a muscle disease. Let's say if you have a patient, the patient that you described, with six months’ history of progressive weakness, dysphagia, and that patient has normal reflexes, and the patient has no clinical evidence for muscle fatigability and no sensory loss, then the probability that that patient has a myopathy increases.
Dr Albin: Ah, that's really helpful. I'm hearing a lot of it is actually the lack of other findings. In some ways it's asking, you know, have you experienced numbness and tingling? And if not, that’s sort of eliminating that this might not be a neuropathy problem. And then again, that fatigability- obviously fatigability is not specific to a neuromuscular junction, but knowing that is a hallmark of myasthenia, the most common of neuromuscular disorders. Getting that off the table helps you say, okay, well, it's not a neuromuscular junction problem, perhaps. Now we have to think more about, is this a muscle problem itself? Are there any patterns that the patients describe? I have difficulty getting up from a chair, or I have difficulty brushing my hair. When I think of myopathies, I historically have thought of, sort of, more proximal weakness. Is that always true, or not so much?
Dr Milone: Yeah. So, there are muscle diseases that involve predominantly proximal weakness. For example, the patient you mentioned earlier could have, for example, an autoimmune muscle disease, a necrotizing autoimmune myopathy; could have, perhaps, dermatomyositis if there are skin changes. But a patient with muscle disease can also present with a different pattern of weakness. So, myopathies can lead to this weakness, and foot drop myopathies can cause- can manifest with the weakness of the calf muscles. So, you may have a patient presenting to the clinic who has no the inability to stand on tiptoes, or you may have a patient who has just facial weakness, who has noted the difficulty sealing their lips on the glasses when they drink and experiencing some drooling in that setting, plus some hand weakness. So, the muscle involved in muscle diseases can vary depending on the underlying cause of the muscle disease.
Dr Albin: That's really helpful. So, it really is really keeping an open mind and looking for some supporting features, whether it's bulbar involvement, extraocular eye muscle involvement; looking, you know, is it proximal, is it distal? And then remembering that any of those patterns can also be a muscle problem, even if sometimes we think of distal being more neuropathy and proximal myopathy. Really, there's a host of ranges for this. I really took that away from your article. This is, unfortunately, not just a neat way to box these. We really have to have that broad differential. Let me ask another question about your history. How often do you find that patients complain of, sort of, muscular cramping or muscle pain? And does that help you in terms of deciding what type of myopathy they may have?
Dr Milone: Many patients with muscle disease have muscle pain. The muscle pain could signal a presence of inflammation in skeletal muscle, could be the result of overuse from a muscle that is not functioning normally. People who have myotonia experience muscle stiffness and muscle pain. Patients who have a metabolic myopathy usually have exercise-induced muscle pain. But, as we know, muscle pain is also very nonspecific, so we have to try to find out from the patient in what setting the pain specifically occurs.
Dr Albin: That's really helpful. So, it's asking a little bit more details about the type of cramping that they have, the type of pain they may be experiencing, to help you refine that differential. Similarly, one of the things that I historically have always associated with myopathies is an elevation in the CK, or the creatinine kinase. How sensitive and specific is that, and how do you as the expert sort of take into account, you know, what their CK may be?
Dr Milone: So, this is a very good point. And the elevation of creatine kinase can provide a clue that the patient has a muscle disease, but it is nonspecific for muscle disease because we know that elevation of creatine kinase can occur in the setting of a neurogenic process. For example, we can see elevation of the creatine kinase in patients who have ALS or in patients who have spinal muscular atrophy. And in these patients---for example, those with spinal muscular atrophy---the CK elevation can be also of significantly elevated up to a couple of thousand. Conversely, we can have muscle diseases where the CK elevation does not occur. Examples of these are some genetic muscle disease, but also some acquired muscle diseases. If we think of, for example, cases where inflammation in the muscle occurs in between muscle fibers, more in the interstitium of the muscle, that disease may not lead to significant elevation of the CK.
Dr Albin: That's super helpful. So, I'm hearing you say CK may be helpful, but it's neither completely sensitive nor completely specific when we're thinking about myopathic disorders.
Dr Milone: You are correct.
Dr Albin: Great. So, coming back to our patients, you know, she says that she has this dysphasia. How do bulbar involvement or extraocular eye movement involvement, how do those help narrow your differential? And what sort of disorders are you thinking of for patients who may have that bulbar or extraocular muscle involvement?
Dr Milone: Regarding dysphagia, that can occur in the setting of acquired myopathies relatively frequent; for example, in inclusion body myositis or in other forms of inflammatory myopathy. Your patient, I believe, was in their forties, so it's a little bit too young for inclusion body myositis. Involvement of the extraocular muscles is usually much more common in genetic muscle diseases and much less frequent in hereditary muscle disease. So, if there is involvement of the extraocular muscles, and if there is a dysphagia, and if there is a proximal weakness, you may think about oculopharyngeal muscular dystrophy, for example. But obviously, in a patient who has only six months of history, we have to pay attention of the degree of weakness the patient has developed since the symptom onset. Because if the degree of weakness is mild, yes, it could still be a genetic or could be an acquired disease. But if we have a patient who, in six months, from being normal became unable to climb stairs, then we worry much more about an acquired muscle disease.
Dr Albin: That's really helpful. So, the time force of this is really important. And when you're trying to think about, do I put this in sort of a hereditary form of muscle disease, thinking more of an indolent core, something that's going to be slowly progressive versus one of those inflammatory or necrotizing pathologies, that's going to be a much more quick onset, rapidly progressive, Do I have that right?
Dr Milone: In general, the statement is correct. They tend, acquired muscle disease, to have a faster course compared to a muscular dystrophy. But there are exceptions. There have been patients with immune mediated necrotizing myopathy who have been misdiagnosed as having limb-girdle muscular dystrophy just because the disease has been very slowly progressive, and vice versa. There may be some genetic muscle diseases that can present in a relatively fast way. And one of these is a lipid storage myopathy, where some patients may develop subacutely weakness, dysphagia, and even respiratory difficulties.
Dr Albin: Again, I'm hearing you say that we really have to have an open mind that myopathies can present in a whole bunch of different ways with a bunch of different phenotypes. And so, keeping that in mind, once you suspect someone has a myopathy, looking at the testing from the EMG perspective and then maybe laboratory testing, how do you use that information to guide your work up?
Dr Milone: The EMG has a crucial role in the diagnosis of muscle diseases. Because, as we said earlier, weakness could be the result of muscle disease or other form of neuromuscular disease. If the EMG study will show evidence of muscle disease supporting your diagnostic hypothesis, now you have to decide, is this an acquired muscle disease or is this a genetic muscle disease? If you think that, based on clinical history of, perhaps, subacute pores, it is more likely that the patient has an acquired muscle disease, then I would request a muscle biopsy. The muscle biopsy will look for structural abnormalities that could help in narrowing down the type of muscle disease that the patient has.
Dr Albin: That's really helpful. When we're sending people to get muscle biopsies, are there any tips that you would give the listeners in terms of what site to biopsy or what site, maybe, not to biopsy?
Dr Milone: This is a very important point. A muscle biopsy has the highest diagnostic yield if it's done in a muscle that is weak. And because muscle diseases can result in proximal or distal weakness, if your patient has distal weakness, you should really biopsy a distal muscle. However, we do not wish to biopsy a muscle that is too weak, because otherwise the biopsy sample will result just in fibrous and fatty connected tissue. So, we want to biopsy a muscle that has mild to moderate weakness.
Dr Albin: Great. So, a little Goldilocks phenomenon: has to be some weak, but not too weak. You got to get just the right feature there. I love that. That's a really good pearl for our listeners to take. What about on the flip side? Let's say you don't think it's an acquired a muscular disease. How are you handling testing in that situation?
Dr Milone: If you think the patient has a genetic muscle disease, you pay a lot of attention to the distribution of the weakness. Ask yourself, what is the best pattern that represent the patient's weakness? So, if I have a patient who has facial weakness, dysphagia, muscle cramping, and then on examination represent myotonia, then at that point we can go straight to a genetic test for myotonic dystrophy type one.
Dr Albin: That's super helpful.
Dr Milone: So, you request directly that generic test and wait for the result. If positive, you will have proof that your diagnostic hypothesis was correct.
Dr Albin: You're using the genetic testing to confirm your hypothesis, not just sending a whole panel of them. You're really informing that testing based on the patient's pattern of weakness and the exam findings, and sometimes even the EMG findings as well. Is that correct?
Dr Milone: You are correct, and ideally, yes. And this is true for certain muscle diseases. In addition to myotonic dystrophy type one, for example, if you have a patient who has fascial scapulohumeral muscular weakness, you can directly request a test for FSHD. So, the characterization of the clinical phenotype is crucial before selecting the genetic test for diagnosis.
Dr Albin: Wonderful.
Dr Milone: However, this is not always possible, because you may have a patient who has just a limb-girdle weakness, and the limb-girdle weakness can be limb-girdle muscular dystrophy. But we know that there are many, many types of limb-girdle muscular dystrophies. Therefore, the phenotype is not sufficient to request specific genetic tests for one specific form of a limb-girdle muscular dystrophy. And in those cases, more complex next-generation sequencing panels have a higher chance of providing the answer.
Dr Albin: Got it, that makes sense. So, sometimes we're using a specific genetic test; sometimes, it is unfortunate that we just cannot narrow down to one disease that we might be looking for, and we may need a panel in that situation.
Dr Milone: You are correct.
Dr Albin: Fantastic. Well, as we wrap up, is there anything on the horizon for muscular disorders that you're really excited about?
Dr Milone: Yes, there are a lot of exciting studies ongoing for gene therapy, gene editing. So, these studies are very promising for the treatment of genetic muscle disease, and I'm sure there will be therapists that will improve the patient's quality of life and the disease outcome.
Dr Albin: It's really exciting. Well, thank you again. Today I've been interviewing Dr Margarita Malone on her article on a pattern recognition approach to myopathy, 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 to our listeners for joining us today. And thank you, Dr Milone.
Dr Milone: Thank you, Casey. Very nice chatting with you about this.
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.