Parkinson disease is a neurodegenerative movement disorder that is increasing in prevalence as the population ages. The symptoms and rate of progression are clinically heterogenous, and medical management is focused on the individual needs of the patient. In this episode, Kait Nevel MD, speaks with Ashley Rawls, MD, MS, author of the article "Parkinson Disease" in the Continuum® August 2025 Movement Disorders issue. Dr. Nevel is a Continuum® Audio interviewer and a neurologist and neuro-oncologist at Indiana University School of Medicine in Indianapolis, Indiana. Dr. Rawls is an assistant professor at the University of Florida Health, Department of Neurology at the Norman Fixel Institute for Neurological Diseases in Gainesville, Florida Additional Resources Read the article: Parkinson Disease 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: @IUneurodocmom Guest: @DrRawlsMoveMD 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 Nevel: Hello, this is Dr Kait Nevel. Today I'm interviewing Dr Ashley Rawls about her article on Parkinson disease, which appears in the August 2025 Continuum issue on movement disorders. Ashley, welcome to the podcast, and please introduce yourself to the audience. Dr Rawls: Thank you, Kait. Hello everyone, my name is Dr Ashley Rawls. I am a movement disorder specialist at the University of Florida Fixel Institute for Neurologic Diseases in Gainesville, Florida. It's a pleasure to be here. Dr Nevel: Awesome. To start us off talking about your article, can you share what you think is the most important takeaway for the practicing neurologist? Dr Rawls: Yes. I would say that my most important takeaway for this article is that Parkinson disease remains a clinical diagnosis. I think the field has really been advancing and trying to find a biomarker to help with diagnosis through ancillary testing. For example, with the dopamine transporter, the DAT scan, an alpha-synuclein skin biopsy, an alpha-synuclein amplification assay that can happen in blood and CSF. However, I think it's so critical to make sure that you have a very strong history and a very thorough physical exam and use those biomarkers or other testing to help with, kind of, bolstering your thoughts on what's going on with the patient. Dr Nevel: Great. And I can't wait to talk a little bit more about the ancillary testing and how you use that. Before we get to that, can you review with us some of the components of the clinical diagnosis of Parkinson disease? Dr Rawls: Yes. So, when I think about a person that comes in that might have a neurodegenerative disease, I think about two different features, mainly: both motor and Manon motor. So, for my motor features, I'm thinking about resting tremor, bradykinesia---which is fullness of movement with decrement over time---rigidity, and then a specific gait disturbance, a Parkinsonian gait, involving stooped posture, decreased arm swing. They can also have reemergent tremor while walking if they do have tremor as part of their disease process, and also in-block turning as they are walking down the hallway. So, those are my motor features that I look for. So now, when we're talking about a specific diagnosis of Parkinson disease, the one motor feature that you need to have is bradykinesia. The reason why I make sure to speak about bradykinesia, which is slowness of movement with decrement over time, is because people can still have Parkinson disease without having tremor, a resting tremor. So even though that's one of the core cardinal features that most of us will be able to notice very readily, you don't have to necessarily have a resting tremor to be diagnosed with Parkinson' disease. When I talk about nonmotor features, those are going to be the three, particularly the prodromal features that can occur even ten years before people have motor features, can be very prominent early on in the disease process. For example, hyposmia or anosmia for decrease or lack of sense of smell. Another one that we really look for is going to be RBD, or rapid eye movement behavior disorder; or REM behavior disorder, the person acting out their dreams, calling out, flailing their limbs, hitting their bed partner. And then the other one is going to be severe constipation. So those three prodromal nonmotor symptoms of hyposmia/anosmia, RBD or REM behavior disorder, and severe constipation can also make me concerned as a red flag that there is a sort of neurodegenerative issue like a Parkinson disease that may be going on with the patient. Dr Nevel: Great, thank you so much for that overview. While we're talking about the diagnosis, do you mind kind of going back to what you mentioned in the beginning and talking about the ancillary tests that sometimes are used to kind of help, again, bolster that diagnosis of Parkinson disease? You know, like the DAT or the alpha-synuclein skin biopsy. When should we be using those? Should we be getting these on everyone? And what scenarios should we really consider doing one of those tests? Dr Rawls: The scenario in which I would order one of the ancillary testing, particularly like a DAT scan or a skin biopsy, looking for alpha-synuclein is going to be when there are potential red flags or a little bit of confusion in regard to the history and physical that I need to have a little bit more clarification on. For example, if I have a patient that has a history of using dopamine blocking agents, for example, for severe depression; or they have a history of cancer diagnosis and they've been on a dopamine agent like metoclopramide; those I want to be mindful because if they're coming in to see me and they're having the symptoms of Parkinsonism---which is going to be resting tremor, bradykinesia rigidity, or gait disturbance---I need to try to figure out is it potentially due to a medication effect, particularly if they're still on the dopamine blockade medication, or is it something where they're actually having a neurodegenerative illness underneath it, like a Parkinson disease? The other situation that would make me order a DAT skin or a skin biopsy is going to be someone who is coming in that maybe has elements of essential tremor, they have more of a postural or an intention tremor that's very flapping and larger amplitude, and maybe have some mild symptoms and Parkinsonism that might be difficult to distinguish between other musculoskeletal things like arthritis, other imbalance issues from, you know, hip problems or knee problems and what have you. Then I might say, okay, let's see if there is some sort of neurodegeneration underneath this; that may be- that there could be, you know, potentially two elements like a central tremor and Parkinson disease going on. Or is this someone who actually really has Parkinson disease, but there's other factors that are kind of playing into that. Dr Nevel: Great, thank you for that. Gosh, things have really changed over the past fifteen years or so where we have this ancillary testing that we're able to use more, because what you read in the textbook isn't always what you see in clinic. And as you described, there are patients who… it's not as clear cut, and these tests can be helpful. Could you tell us more about the levodopa challenge test? How is this useful in clinical practice? And what are some key points that we should know about when utilizing this strategy for patients who we think have Parkinson disease? Dr Rawls: So, before we had all this ancillary testing with the DAT scan, the skin biopsy, the alpha-synuclein amplification assay, many times if you had a suspicion that a person that had Parkinson disease, but you weren't entirely sure, you would say, hey, listen, let us give you back the dopamine that your body may be missing and see if you have an improvement, in particular in your motor symptom. So, when I talk with my patients, I say, listen, I might have a strong suspicion that you have Parkinson disease. Doing a levodopa trial can not only be diagnostic, but also can be therapeutic as well. So, with this levodopa trial, what I end up doing is saying, okay, we're going to start the medication at a low dose because we are looking to see if you have improvement in three of the main cardinal motor symptoms. Obviously, tremor is much easier for us to see if it gets better. It's very obvious on exam, and the patients are more readily able to see it. Whereas stiffness and slowness is much harder to quantify and try to figure out. Am I stiff and slow because of potential muscle tightness from Parkinson disease, or is it something that's more of a musculoskeletal issue? So, I will tell persons, okay, we're looking for improvement in these three cardinal motor symptoms, and things that we're looking for is getting into and out of a car, into and out of a chair, turning over in bed, seeing how do we navigate ourselves in our daily lives? I give people the example of going through the grocery store, going through a busy airport. Are we able to move better and respond better to different changes in our environment which can give us a better clue of if our stiffness and slowness in particular are being improved with the medication? The other part of this is talking about potential side effects of the carbidopa- of the levodopa in particular. One big thing that I think limits people initia
