
Neuropathy can present in many ways beyond the classic pattern of numbness and tingling. In this episode, Dr. Reza Seyedsadjadi discusses a practical diagnostic approach, highlighting key clinical clues, electrodiagnostic findings, and the role of genetic testing and other specialized studies in identifying common and uncommon causes of neuropathy.
In this episode, Casey S. Albin, MD, FAAN, speaks with Reza Sadjadi, MD, author of the article "The Diagnostic Approach to Neuropathy" in the Continuum® October 2026 Peripheral Nerve and Motor Neuron 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. Sadjadi is an assistant professor of neurology at Harvard Medical School and Massachusetts General Hospital in Boston, Massachusetts.
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Read the article: The Diagnostic Approach to Neuropathy
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Full episode transcript available here
Dr. Albin: The patient comes into your office with numbness and tingling, and it seems like it's probably a pretty straightforward neuropathy. But what about if it's not? Or what if the EMG and nerve conduction studies suggest something else? What if the patient is giving you extra clues about other symptoms where they feel ataxic or have systemic complications as well? All of those things may be part of a neuropathic picture. And today, we are so fortunate to talk to Dr. Seyedsadjadi about just this.
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: Hi, all. This is Dr. Casey Albin. Today, I'm interviewing Dr. Reza Seyedsadjadi about his article on the diagnostic approach to neuropathy. This article appears in the October 2026 Continuum issue on peripheral nerve and motor neuron disorders. Welcome to the podcast. I'm so excited to have you here, Dr. Seyedsadjadi. Just love for you to tell us a little bit about yourself and your background and how you got interested in this topic.
Dr. Seyedsadjadi: Hi. Thank you for the kind invitation and the opportunity to contribute to the Continuum. I'm a neuromuscular neurologist. I work here at Mass General Hospital. I got interested in peripheral nerve disease throughout my early training in neurology and continued with the fellowship in neuromuscular disorders, and I've been seeing patients with mostly neuropathy, inherited and acquired neuropathies here in Mass General Hospital.
Dr. Albin: Excellent. And so, you are the perfect person to write this intro article. And so, I always like to start with the basics. The patient comes to you. What are some of the symptoms that you're listening for that help you clue in that this is probably a neuropathy, not somewhere else in the peripheral nerve system?
Dr. Seyedsadjadi: What an excellent question. And it is still difficult to 100% be sure, but overall, I like to put things in different buckets to help you have a pattern recognition with what you think that makes sense to be a neuropathy, a neuronopathy, a radiculopathy. In general, I divide things into positive and negative sensory symptoms in terms of complaints. Positive ones like hyperesthesia, paresthesia, burning, tingling sensation. Negative sensory symptoms are a little bit more tricky, loss of sensation, balance issues. When somebody comes, you have to listen to all of these symptoms in conjunction with the distribution of the symptoms, how they evolve over time, to give you a clue whether this is a neuropathy or just neuropathic symptom related to a different process that could mimic neuropathy. And sometimes it would be difficult to delineate between the two, especially if a patient is very complex, has two different processes going on. But first off, it's good to know if you have positive sensory symptoms, it is more likely that this is a peripheral process than negative sensory symptoms. And some other features that we usually overlook when we see the patient in the clinical setting, especially if it's busy, those are the autonomic complaints that we can talk more about.
Dr. Albin: Yes. And I really wanna double-click on a lot of these features that you brought up. So, I'm hearing you're thinking about not only the symptom quality, but also that pattern of distribution. What about that sort of localized pattern of distribution?
Dr. Seyedsadjadi: Yeah. So typically, the general teaching is that nerves are very long in terms of the course, and when the damage happens to the nerve, the pattern would be a length-dependent pattern, meaning the longest nerve or the tip of the longest nerve will be affected, and this will gradually affect and go more proximally in a symmetrical pattern in more common known types of neuropathy. That's not always true. Sometimes you can have a non-length dependent neuropathy. You can have like an asymmetric neuropathy. But these are all small clues that you can use to see, to help you to narrow your differential diagnosis. So, you can have like a vasculitic neuropathy, which is necessarily not a length-dependent process. It affects one side, not necessarily the other side, and the progression of it, which could be stepwise rather than gradual progression of the disease.
Dr. Albin: I love that. Thinking not only just about the typical numbness and tingling in your fingers and toes, but recognizing that while that is a very common pattern of neuropathic symptoms, that you may have a patchy distribution and that you can still put neuropathy on your differential, even if it's asymmetric and even if it's not starting at tips of the fingers and tips of the toes.
Dr. Seyedsadjadi: Exactly. Nicely summarized.
Dr. Albin: One of the points that I really took away from your article was how sensory symptoms or motor symptoms, whether there's a predominance of one or the other, that actually may have some real importance in helping you think through the underlying process. So, can you tell us a little bit more about that?
Dr. Seyedsadjadi: Exactly. And also, I don't want to confuse this with necessarily involvement of sensory nerves because you can also have positive sensory and negative sensory symptoms. But looking at the signs in terms of how patients present- If you have predominance of, like, motor weakness, you have a patient who comes with the distal upper and lower extremity weakness, but sensory symptoms more than signs, are relatively milder. Obviously, you think more about process that is more chronic, affecting motor nerves more than sensory nerves, or equally at least, you think about more hereditary cases. Whereas when you have more sensory symptoms or predominance of sensory symptoms and less of motor involvement and more recent presentation, you think about more acquired causes of neuropathy. Now, that is not universal because we know that there are acquired neuropathies that affect the motor nerves more than sensory nerves, and we have hereditary neuropathies that purely affect sensory nerves like CANVAS syndrome. But in general, it's good to have, like, a pattern recognition. Now you can more comfortably look for those outliers that would be like a framework that you can approach them by looking for subtle signs and differences that they have from them.
Dr. Albin: I think that's so true of most of what we deal with in neurology. Like, most of neurology is being able to recognize the 75% to 80% that present in the normal typical pattern. But it's learning that for every localization within neurology, there are those variants. They don't read the textbook. But I do love that how if you're thinking about more sensory symptoms and more recent onset, you're generally thinking this is
acquired versus that motor really standing out above and beyond the sensory symptoms, thinking more, "Hmm, could this be a hereditary? Should I look a little bit further into the family history?" Great point. And then I heard, especially in our first opening statement, it can be really hard to screen for autonomic symptoms, but that is really a hallmark of neuropathies because the autonomic nervous system is also composed of nerves. So, in a busy clinical environment, how do you suss this out, and what are you asking patients about?
Dr. Seyedsadjadi: It's a great question, I don't think you can never be perfect on that because as you said, in order to do the justice, you really have to go through all systems. One way is to use some of the outcome measures that autonomic symptoms you can ask the patient sort of in ahead of the time. But there are some questions that are more important, and it is difficult to get them from patients if you don't really ask them. And sometimes we shy away for different reasons from those questions. Some of these could be related to the function of the bowel and bladder, erectile dysfunction, specific questions about orthostasis, IBS-like symptoms, early satiety, and some overlap syndrome symptoms like dry eyes and dry mouth could indicate different things. These are the main categories of the questions that you ask. And when you start asking these questions, sometimes patients start adding symptoms, "Oh, I don't have this, but I also have, like, some other dysmotility issue." So, that comes up.
Dr. Albin: Absolutely, because these are symptoms that the patient may not put together as part of the same syndrome. And I think that that's why it's one of those things that, you know, they're coming to talk to you about the tingling that they have in their fingers and toes, and it may not have occurred to them that their constipation was related to this, or that if we're not asking about erectile dysfunction, that may not come up as, like, the patient putting those two together is worthwhile. Certainly, with sicca symptoms, that may give us a not only about the autonomic neuropathy, but could this be part of some other rheumatologic process?
Dr. Seyedsadjadi: Precisely.
Dr. Albin: I think any neurologist has sort of a general framework of, oh, we got to look at hemoglobin A1c. We've got to think about SPEP/UPEP in terms of a paraproteinemia. But one of the things that I think really sets master clinicians apart is the ability to see a neuropathy as part of a larger picture. And so, I think about syndromes like Holmes syndrome, or now I feel like CANVAS has become this new hot topic where everyone with a cough is now needing to be worked up for CANVAS. But how do you tease out the run-of-the-mill diabetic neuropathy from some of the zebras that do exist out there that if we're not carefully looking for, we very well may miss?
Dr. Seyedsadjadi: Yeah, and that's a very good question. What happens is the training, the pattern recognition. Everything makes sense except for something that doesn't make sense, and that raises clinical suspicion for something different. This is neuropathy, but it's not maybe just neuropathy, something else. So, you see a patient in clinic has a bread-and-butter neuropathy, has an EMG consistent with mixed axonal demyelinating neuropathy, even has diabetes, but you see something unusual about them. You see that they have finger clubbing. This is disproportionate to the degree of what you expect they would have. And then the workup ends up showing that they have POEMS, for instance. Or you see a patient, as you would nicely said, a patient has, like, an unusual cough and a neuropathy, or have a neuropathy, but the ataxia is disproportionate to the
degree of their nerve sensory neuropathy, or they have abnormal eye movements or ataxia. You think about CANVAS syndrome. So, this goes back to habit developing early on a framework and a pattern recognition, and obviously something that we are all getting more and more guilty of, listening to the patient and paying attention to details that we often miss if we rush through things.
Dr. Albin: Yeah. I think it really comes down to the fact that we are really master diagnosticians when we listen to patients, when we take a history, when we spend a little bit extra time at the bedside. Answering that, "Hmm, my spidey sense is a little bit up. This just doesn't feel completely right." To learn to listen to that intuition and just say, "Let me go back and double-check on... I didn't ask this question, but, like, maybe it's worth my time. Just go back in the room and see." All right, so let's switch gears and talk a little bit about EMG interpretation and nerve conduction studies. Because even if you don't go into neuromuscular neurology, if you're a neurologist, you are going to come across these EMGs and nerve conduction studies. So, when we're thinking about neuropathies, we're going to broadly characterize them into demyelinating and axonal. And I'd love to talk through with you how do those electrodiagnostics differ? Like, what would you see for axonal versus demyelinating? And then why does it even matter to make that distinction?
Dr. Seyedsadjadi: So, electrophysiology complements the clinical assessment of neurology. It helps in terms of, in general, knowing at a mechanism of neuropathy. So, if you know that the process is more or predominantly demyelinating, that narrows down your differential diagnosis. And by looking at the type of demyelination, is it predominantly distal? Is it predominant proximal? Is it uniform? Are there footprints of acquired demyelination, like a conduction block or a temporal dispersion to indicate that this is, like, a potentially an inflammatory process? It can help a lot with terms of narrowing down the differential diagnosis. And if it is axonal, it's, again, helpful in terms of knowing what is the pathophysiology, how it can help you differentiate between different types and severity and chronicity of the process. It is very, very helpful, but there are some pitfalls with neurophysiology, especially with regards to diagnosis of demyelination. Demyelination, in general, you are expecting to see slowing of the conduction velocity, but not every slowing means demyelination.
Dr. Albin: Yes, I saw that in one of your cases, and I thought that that was such a great pearl because as someone who's not a neuromuscular neurologist, when I hear slowed conduction, I think, "Oh, that must be demyelination." But tell me more. That is not the case.
Dr. Seyedsadjadi: Yes. And that's one of the pitfalls of diagnosis of chronic inflammatory demyelinating polyneuropathy, CIDP, is an overdiagnosis sometimes made based on an electrophysiology which is not over-interpreted or interpreted incorrectly. So, there are two things. One is about the degree of slowing. With some axonal loss, you can get some slowing in your nerve conduction studies as well. So especially if your motor response amplitudes drop below a certain level, your velocity can slow down, too. So, you have to be careful not to over-interpret the degree of slowing as demyelination. It may still indicate that there is some myelin dysfunction or what we call informally amongst each other myelin unhappiness, but it doesn't necessarily mean the primary process is demyelinating.
Dr. Albin: To give an example for this, this could be the patient with diabetic neuropathy who has an axonal process, but may also have a little bit of unhappy myelin. Is that fair to say?
Dr. Seyedsadjadi: That's a very good example. In diabetes, you can have involvement of myelin as well. So, you can have a mixed axonal and demyelinating pattern. But as you nicely outlined, it is possible that the findings in a patient with diabetes over-interpreted as a primary demyelinating polyneuropathy, which can lead to a wrong diagnosis.
Dr. Albin: Right. So, we suspect that this is just run-of-the-mill diabetes. It is actually truly just run-of-the-mill diabetes. But if we over-interpret that slowed conduction to say, "Oh, this is demyelination," then all of a sudden, we're thinking about plasma exchange or IVIG for someone who has a diabetic neuropathy and not CIDP.
Dr. Seyedsadjadi: Correct.
Dr. Albin: Got it. So really have to be careful in interpreting these.
Dr. Seyedsadjadi: And also, I have to mention that CIDP is slightly more common in patients who have diabetes too.
Dr. Seyedsadjadi: So that's going to be the tricky part because then you have to go back to what's the clinical scenario, what's the clinical history, and how you're going to interpret these electrodiagnostic testing in this context. So, they can become a little bit tricky, but overall, this is correct. The other problem with electrophysiology is the technical aspect of it. So, the temperature, the lab that is doing it, under stimulation, overstimulation, these are the parts that have to be controlled for, and you have to have reliable data from a reliable lab to be able to make diagnosis.
Dr. Albin: This is a constant source of frustration to us in the ICU. You know, I work in critical care world, and how frustrating it is with all of our electrical interference, our patients are cold, we're not getting the best nerve conduction in EMG. It's a real challenge, you know, to make sure that we're providing reliable results when we're making these really important diagnoses.
Dr. Seyedsadjadi: Exactly. And that's why it's, like, complementary to the clinical judgment rather than replacing the clinical judgment. So, electrophysiology has to always back up what you have from your clinical impression rather than replacing it.
Dr. Albin: I think that that could be a key takeaway for just all of neurology. It comes down to your clinical intuition, your history, your physical exam. On the other side of your great history and physical exam. And so, when I read your article, those three things, the sort of MRI, nerve and skin biopsies, and then the enormous influence of genetic testing. As someone who does this day in and day out, how do you think about meaningfully using those tests?
Dr. Seyedsadjadi: If I want to start, I would say I would go to genetic testing first. Genetic testing, I think, has advanced more than anything else over the past two or three decades, and it's becoming more and more available, and it's becoming cheaper and cheaper. And if you have a genetic diagnosis, it bypasses many other tests that are
more expensive and more laborious or have side effects or complications. I have lower threshold for doing genetic testing, obviously because in the setting that I am, I do most of these inherited neuropathies and acquired neuropathies. But once you have a clinical suspicion that somebody has some sort of a hereditary neuropathy based on the clinical scenario that we just talked about or a family history, I think it can, especially, and sometimes that you cannot get electrophysiology to help you delineate between axonal or demyelinating process because the nerves are gone, for instance. Or you have, like, a very young patient or a pediatric case that it would be more challenging to arrange for electrophysiology. Genetic testing can come very early on and can help with an earlier diagnosis. Obviously, we have not yet discovered all the genes that could cause neuropathy, and roughly between 25% to 50% of people who have hereditary neuropathy, they may have inconclusive genetic testing. But if it comes back positive, it would be very helpful nailing the diagnosis and reducing the need for unnecessary treatment or unnecessary testing. And the testing is now more widely available and cheaper. Obviously, there are some pitfalls with that, too. Genetic testing, and you find a variant of unknown significance, and now you have to figure out if that actually has something to do with patient's presentation. So, it has to be done also carefully. It doesn't necessarily mean that you should do it and then you have the answer necessarily. Skin biopsy, nerve biopsy, MRI, they have their own places. So, skin biopsy can be helpful in terms of diagnosis of small fiber neuropathy, predominantly small fiber neuropathy. Obviously, it has some pitfalls, so some clinicians like to use them and some others just rely on patient's clinical presentation. The common pitfall is that it can have abnormal testing depending on the lab that you're using, even if you don't have small fiber neuropathy.
Dr. Albin: And just remind me and maybe our listeners, what is the patient coming in with that would make you suspect that they have a small fiber neuropathy? Like, what are those patient symptoms?
Dr. Seyedsadjadi: Very similar to large fiber neuropathy, which is predominantly in this patient group, they come with positive more than negative sensory symptoms. But that is also possible that they may have negative sensory symptoms as predominant presentation too. And typically, they would have normal electrophysiology, meaning that they don't have abnormal EMG or nerve conduction study. So, the responses are normal.
Dr. Albin: Got it. So, this is a patient who may have numbness, tingling, pain, no motor findings. You do your typical EMG. You don't really find a lot. That's the person who maybe nerve and skin biopsies make sense, although we do have to bear in mind that there could be a sort of false positive report for those.
Dr. Seyedsadjadi: Correct. And/or false negative. So that's the other problem with it, because you can biopsy, which there's a typical biopsy site of where you go above the ankle. But if that area is not affected and your, let's say, small fiber neuropathy is a non-length-dependent process, the test negative, but you still have small fiber neuropathy. The utility of nerve biopsy has significantly changed over the past, again, two or three decades with the genetic testing and other tests that we do. So, we used to do them for everybody we suspected they have vasculitis. Now, with the better serology, we don't have to. But amyloid, a lot of amyloid patients who have hereditary amyloidosis, we don't necessarily need a nerve biopsy to confirm a diagnosis. And for inflammatory neuropathies, again, electrophysiology and some markers can help with the diagnosis.
The utility of nerve biopsy has been now limited to, like, mostly with amyloid or inflammatory or infiltrative neuropathies. With regards to MRI, this is something that I often do together if I have to, looking for a process that is affecting a certain nerves in certain pattern to select a nerve for biopsy or to look for the course of inflammation or an infiltrative process affecting the nerves. MRI is getting more used in diagnosis of, or imaging in general, including ultrasound and MRI, in diagnosis of inflammatory neuropathies, like mainly CIDP. You can see enhancement in the course of the nerve, or the nerve roots, and the changes in the structure of the peripheral nerves in the ultrasound, that can give you a clue. And with the more recent diagnostic criteria for inflammatory neuropathies, now these are incorporated with the diagnostic criteria to establish diagnosis of inflammation. And at times, these can be very helpful, especially when you have limited electrophysiology or cases not necessarily a textbook case of an inflammatory neuropathy.
Dr. Albin: Got it. So, it's helping both to sort of the diagnosis of an inflammatory neuropathy, but also if you do feel like you need to go to a biopsy, trying to use a place where you can see some inflammation without maybe complete burnout, so that you're gonna see an active lesion, but not one that's so active that it may just be scar tissue or, I guess, degenerated nerve?
Dr. Seyedsadjadi: Yeah. Or an unhappy nerve.
Dr. Albin: An unhappy nerve, right. We really want to get the biopsy where the nerve is unhappy, but not dead.
Dr. Seyedsadjadi: Not dead. Exactly. And that's one of the pitfalls of biopsy. If you do a biopsy of a sural nerve, somebody who has a very advanced neuropathy, you may just find the fibrotic tissue and may not show you an inflammation or even the type of neuropathy.
Dr. Albin: And this has been such a fantastic way for us to sort of think about this larger picture of neuropathy and motor neuron disease. And I am excited to hear the rest of the interviews with all of our colleagues. Really detailed questions, because I think what you have done is opened the door to say this is actually quite complicated in a lot of ways. And the testing, and specifically in terms of thinking about genetic testing, has really evolved and expanded. We have more tests, but that doesn't necessarily mean that more tests equals better diagnosis in all cases.
Dr. Seyedsadjadi: Exactly. Yeah. It goes back to your clinical intuition.
Dr. Albin: I love it. Again, today I have been interviewing Dr. Reza Seyedsadjadi about his article on the diagnostic approach to neuropathy. This article appears in the October 2026 Continuum issue on peripheral nerve and motor neuron disorders. Be sure to check out Continuum Audio episodes for this and other issues. And thank you so much for our listeners for joining today. And Dr. Seyedsadjadi, thank you so much for being here.
Dr. Seyedsadjadi: Thank you. Thanks a million.
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
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