Hey everybody! It’s Bapu. I know it’s been a little while. But we’re working hard on a whole new batch of episodes for you. And I just want to let you know that in the coming weeks and months, we’re going to take on a lot of interesting questions. Like why thousands of donated kidneys are thrown away each year while people die on transplant lists. Or: How retiring can affect your brain health. And a personal favorite, why men are so much more likely than women to call their own research “excellent.” That by the way is based on some research that I actually co-authored. And, I am tempted to say it’s excellent, but, you know, I also see the irony of that. Anyway, look, LOTS of great conversations ahead with fascinating doctors, economists, and the people who are working on and studying the front lines of healthcare. But in the meantime, I wanted to bring to you another medical mystery with master diagnostician Dr. Gurpreet Dhaliwal, who you may recall is from the University of California at San Francisco.
Gurpreet DHALIWAL: I work in the emergency department, the inpatient wards of the hospital and the clinic. And my area of interest is how doctors think. And in particular, how they diagnose.
I think he’s already become a fan favorite for listeners. And today, we’re going to hear him try to solve another actual medical mystery, and again, in real-time. At the end, you’ll hear from me about why making the right diagnosis in medicine is so difficult and how doctors often get it wrong. From the Freakonomics Radio Network, welcome to Freakonomics, M.D.
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To help us with this medical mystery challenge, I’ve asked another doctor back to the show to walk us through the clues of this very curious case of a man with back pain and confusion.
Sharmin SHEKARCHIAN: It’s a pleasure to be here. My name is Sharmin Shekarchian. I am an assistant professor affiliated with Stanford.
Sharmin was a student of Gurpreet’s at UCSF a long time ago. She’s now a doctor and leads an effort called Clinical Problem Solvers, which is all about teaching the next generation of doctors how to be better at making the right diagnosis. She’s prepared our patient case for this episode. Any identifying information about the patient has been scrubbed, but all of the information you’re going to hear is real, from the patient’s history all the way to the lab results. Ok. Sharmin, take it away:
SHEKARCHIAN: This is a 62-year-old man who was brought to the emergency room by his daughter. Eight days ago, he suddenly developed back pain. The pain got a lot worse over the past several days. Three days after his back pain, and that is about five days ago, he started having fevers up to 101 degrees Fahrenheit. He had tremors in both hands and felt really tired. The day before presenting to the emergency room, he could barely stay awake. The morning right before his daughter brought him to the emergency room, he was very confused. He didn’t recognize his daughter, thought he was in the factory that he retired from a few years prior. She noticed that he wasn’t really moving his legs. So she decided to bring him in. His past medical history includes chronic back pain, which had led to opiate dependence. He was taking 10 milligrams of oxycodone about four times per day. There was no recent changes to his medication or how he was taking it. For the past three decades, he has been smoking a pack of cigarettes per day. He lived in California with his family. He loved being outdoors, often spending most of his days, sitting in the backyard, reading books and newspapers. He had no recent travels or animal exposures that the family had noticed.
DHALIWAL: Thank you, Sharmin. So I’m just going to highlight the things that really caught my attention. His major problem is that he’s become really confused, which tells us that there’s a problem in his brain. The same problem that might be affecting his brain, the same problem that might be causing a fever, is also in his low back and affecting either the spinal cord or the nerves that run to the muscles of the legs.
Bapu JENA: All right. Gurpreet, I’m curious. What are you thinking? What might be causing that?
DHALIWAL: When we think about someone who has back pain and a fever, I worry a lot about an infection and then a little bit about a cancer. In the seventh decade of life cancers certainly arise with some frequency. I took note of the fact that he had smoked for many years, and tobacco increases the risk of many cancers. I also am taking note of where he lives. He lives in California and he’s outdoors quite a bit. And when people are outdoors, despite all its benefits it has risks and they’re everything from too much sun, to ticks and mosquitoes, to things that we might inhale in the air. And so as we go through the case, I will keep track of those factors, particularly if it turns out that it’s likely he has an infection.
JENA: Okay. Sharmin, so we’ve heard a little bit about what brought this gentleman to the hospital in the first place. Maybe you can tell us how he looked when he was first seen by doctors?
SHEKARCHIAN: Absolutely. On the exam, he had a fever of 102 degrees Fahrenheit. His heart rate was 94 beats per minute. He was sleeping and it was really hard to wake him up. His eyes were normal without any redness. He did not have any neck stiffness. His lungs, heart and abdominal exam were normal. He didn’t have any rashes. He knew his name, but as mentioned before, did not know what year it was or where he was. He had tremors in both hands and would randomly move and jerk his arms. He did not move his legs spontaneously. His knee and ankle reflexes were depressed. His lab work showed elevated white blood cells to 16.5. Upper limit of normal is 11. The rest of his labs, including electrolytes, kidney function and liver functions were normal. He tested negative for HIV and syphilis. And his urine toxicology screen returned positive for opioids.
JENA: So in addition to that physical exam and some of those initial laboratory studies, several of which were actually normal, it looks like from the file that an MRI of both his brain and spinal cord were done. Gurpreet, the brain MRI was normal, but the MRI did show an abnormal signal in the spinal cord from the level of the ninth thoracic vertebrae, all the way down to the bottom of the spinal cord. The radiologist reading the MRI felt that the imaging suggested something called transverse myelitis, which as you know, is inflammation of the spinal cord. So Gurpreet, what are you thinking at this point?
DHALIWAL: What I’m really struck by is how sleepy he is. We get the sense that everything the daughter has told us has been verified. That he has a fever, that he’s not thinking clearly, and that he’s having uh, tremendous difficulty moving his legs. A fever tells us that the body is inflamed. A large percentage of time when the body is inflamed, it is because it’s reacting to an infection. There are all different types of infections that exist. But at this point we can’t tell which one of those pathogens, as we would say, is responsible. When the doctor taps on the kneecaps with a hammer and just sees if the leg will move on its own, that’s also testing the wiring between the muscle and the spinal cord, and I think he had a pretty limited response there. And right away we have a job to do as soon as we detect that, which is we have to figure out is something compressing the spinal cord? Literally, something smushing it from the outside. And that can be things like cancer in the bones that are right next to the spinal cord. It can be an infection in the bones right next to the spinal cord, which sometimes make their way to the cord itself. It can be bleeding that’s there, or occasionally even our own bones and discs and smush the cord. But in this case, the MRI showed us that nothing is pressing on the spinal cord. But that the inflammation is in the cord itself. And when that’s discovered, it makes us think about what could cause swelling inside there, and oftentimes it falls into a handful of categories. My suspicion is that it’s going to be an infection. And what’s happening in that spinal cord might also be happening in the brain because the spinal cord doesn’t explain the problem in his thinking. That abnormality has to be in the brain itself. However the MRI didn’t show us the answer to that. So we’ll probably have to study the brain in another way. Like by getting a lumbar puncture or so-called spinal tap.
JENA: And that’s what happened next. The doctors did a spinal tap. Sharmin, what did that spinal tap reveal?
SHEKARCHIAN: The opening pressure, the color of the fluid and the glucose levels were normal. The cerebral spinal fluid, bacterial, fungal, viral, and tuberculosis culture were negative as were his blood cultures.
JENA: And it looks like a whole slew of the other tests on a spinal fluid were normal?
SHEKARCHIAN: Strepacaucus species, e- coli, lysteria, and Haemophilus for fungal organisms, cryptococcus and Coxie. And for viruses, enterovirus, herpess zosters, EBV CMV, HHV six, HTLV were all negative. The autoimmune and paraneoplastic panels were also negative.
Okay. So that’s everything there is, including all of the test results. There is a lot there and Gurpreet will help us understand what it all means. We’re going to give him 60 seconds to digest all this information and give us his best guess at a final diagnosis. Stay with us.
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DHALIWAL: So, they tested for all those different categories of infection. Could there be a bacteria, could there be a fungus, could there be a virus? And those tests were all negative. And I think there’s a temptation, for all of us, both doctors and patients, to look at a test as being binary. It’s a yes or no, it’s a positive or negative. But when those tests come back negative, what I don’t say to myself is, the patient can’t have those diseases. I shift to, it was a strong possibility, to it’s unlikely. Because there’s virtually no test that’s perfect in medicine. They all have what we call false positives and false negatives. But if I was trying to put all of this together and say, what do I have here? I have a 62-year-old man who has a problem with his thinking. We call that encephalopathy. He has inflammation in his spinal cord. We call that myelitis. He has a high fever, which tells me the immune system is revved up, but oftentimes points to an infection in particular. And then we learned that he really enjoys spending time outdoors. I have to ask myself, could that all come together in one coherent diagnosis. Is there something you can get from the outdoors that may attack both of those parts of the nervous system? When he’s outside, enjoying the sun and the fresh air from time to time, he may come across a mosquito. And if that’s the case, he is at risk for getting West Nile virus. And West Nile virus is a type of infection that can render inflammation in the brain, in the spinal cord, make you weak. And it happens only to a small percentage of people who get that. But I think this case would be fitting. And so the testing for that virus is something that I would get at this point.
JENA: Sharmin, I have a lot on my mind right now. [laughs] I want to hear what you have to say next.
SHEKARCHIAN: I have to first say that I’ve had the privilege of learning from Gurpreet since I was a first year medical student and I never get tired of hearing him think out loud. I always learn something new. Mr. Williams was diagnosed with West Nile virus, encephalitis and transverse myelitis. There is no specific antiviral treatment for the West Nile virus infection. He went to rehab after the hospitalization. Over the following three months, his cognition was back to normal and he had gained some strength and function in his legs.
JENA: I feel incredibly, I feel incredibly stupid. I’m overwhelmed first of all, but I also feel really stupid right now.
SHEKARCHIAN: That he can just go through this, and just to pick out the signal out of the noise. It’s quite impressive.
JENA: Suffice it to say, I’m stunned. Gurpreet, you were amazing. I will say that you’re probably gonna get a lot of emails after this and, I’m opening up a 1-800-Dr. Dhaliwal hotline, literally right now.
DHALIWAL: Okay. You’ll be manning that phone number, right?
JENA: Obviously you’re an expert at this. You’re an expert at clinical reasoning and making diagnoses. How many times have you done this? Like, what did it take for you to get to the point where someone could ask you a question in real time and have you come to the right diagnosis?
DHALIWAL: That’s very nice of you to ask. I want to give a disclaimer, which is that there is a difference between doing this in the sanitized version we’re doing here, right? Where the case details are selected and portrayed in a way that makes it challenging, but probably doesn’t reflect all of the challenges of everyday clinical care. For instance, some of the details have been synthesized, the tests have been packaged nicely together. In the real world, I’m not sure I perform this well. And I say that as a point of humility. I would only just add that I have tried to catalog the many, many times I’ve been stumped and tried to keep those lessons front of mind. As an example, I have missed the diagnosis of West Nile virus in an exercise like this. And one of the lessons I learned from it was there was a clue that the person was outdoors a lot. I thought that was just background information, right? As Sharmin alluded to earlier, that sometimes you have to figure out signal and noise. And so in previous iterations, I put that in the noise category. But from that mistake, I’ve learned to at least consider it in part of the signal category.
JENA: Yeah. Interesting. So there’s this concept that I have heard before, the term master clinician, what does that term mean to you?
DHALIWAL: I think it’s really attending to two elements of doctoring. One is I think what we saw here, which is trying to master the knowledge and skills and medical science that we’re supposed to keep striving to get better and better at. But the other is the humanistic part of being a physician. And that is caring and communication. And I think you have to develop both of those in parallel in order to really be a great physician. And there is no end point to that. Both of them are subject to continuous improvement.
JENA: I see. So Sharmin, let me ask you a follow up question. With that definition, would you consider him to be a master clinician?
SHEKARCHIAN: I think he’s as close as it comes to that definition. And the reason I say as close as it comes, because I’ve had the privilege of knowing Gurpreet and what I admire so much about him is his growth mindset. I think it’s also very effort dependent. The hours and hours of reading through cases. Sitting in conferences. Yes, talent is part of it, but a lot of it is just the passion to do this process and also the hard work that goes into it.
DHALIWAL: I really appreciated Sharmin’s analysis, but not of me, it was the idea of the growth mindset. I’m happy with how I’ve grown in the last five years, but I’m looking forward to how much better I’ll be five years from now. And I know the same is true of Sharmin. She has that exact same orientation around it. We really try to think about as many opportunities as possible to practice thinking through those problems, and their intersections. So we try to get ourselves in front of cases where people have back pain. And we try t o get ourselves in front of cases where people have confusion. And we try to get ourselves in front of cases where people may have weakness. And then there are challenges where all of those intersect. Like, this is not the first time Sharmin or I are analyzing this combination of symptoms.
I want to thank the two excellent diagnosticians you heard from in this week’s episode. Sharmin’s work with Clinical Problem Solvers is fascinating. It’s a really great resource for medical professionals who want to improve their skills in this area.
Now, listening to Gurpreet think out loud … you’re probably thinking getting the right diagnosis is easy. But it’s not.
Diagnostic errors are actually a big problem. In 2015, the National Academies of Medicine convened a panel to study the issue of diagnostic errors in medicine. I participated on that committee, actually. The report, which compiled results from many, many studies, found for example that 1 out of 20 U.S. adults who receive outpatient care have a diagnostic error occur in one of those visits. The report also cited research from decades of postmortem exams that about 10 percent of patient deaths involve a diagnostic error.
My colleagues Ziad Obermeyer, David Cutler, and I, we studied this issue of diagnostic errors in the Medicare population. And we focused on patients who’re treated in the emergency room, since a lot of patients, particularly older ones who are seen in the ER, have symptoms that are often serious, but without a clear diagnosis. Which means that the job of the emergency medicine doctor is to figure out what’s wrong and they have to do it fast.
But what we found in our study was a little bit sobering, actually. Among otherwise previously healthy emergency room patients who were discharged home from the ER – so, these are folks that the hospital thought were stable enough to be sent home – about 1 in 1,000 patients died within seven days. This amounted to nearly 10,000 deaths nationally every year.
Getting the right diagnosis feels more important than ever in medicine. And that’s because technology and treatments have improved so much. If we’re right about what’s wrong, we can do so much more to help patients now compared to years ago.
Now, there are lots of reasons why medical errors occur. The explanations range from a doctor’s relative lack of knowledge about certain diseases and their symptoms; could be breakdowns in attention and missed information that are gonna naturally arise when doctors are treating large numbers of patients; there could be problems of communication with patients; it’s difficult to actually identify when a diagnostic error has occurred, which makes it hard for physicians to learn from their and others’ errors. Turns out the culture of medicine can make it difficult for doctors to openly communicate with one another when diagnostic errors are made, partly out of fear and perhaps partly out of embarrassment. There’s structural racism; and an area that’s of particular interest to me, because it lies at this intersection between medicine and economics, is cognitive biases.
For example, my colleague Dan Ly showed that doctors who recently treated a patient with a pulmonary embolism – which is a clot in the blood vessels that supply the lung – those doctors increased their rates of pulmonary embolism testing in subsequent patients, some of whom were unlikely to actually have that condition.
This is just one example of how diagnostic decisions of doctors can be affected by cognitive biases, in this case something that Amos Tversky and Daniel Kahneman termed the “availability heuristic.” For doctors who’ve recently treated a patient with a pulmonary embolism, the diagnosis may just be more front of mind or mentally available, leading them to prioritize testing for that condition over other more likely diagnoses in future patients.
Those of you who’ve been listening since the start of this show know that in the pilot episode, Stephen Dubner asked me about my name, which is Bapu. It’s what many Indian kids call their father. And it’s been my nickname since I was a kid. It’s also a famous nickname for Mahatma Gandhi. So, I wanna end today’s show with a saying that’s fitting and often been attributed to Gandhi. And that is: “A correct diagnosis is three-fourths the remedy.”
That’s it for this week’s episode of Freakonomics, M.D. Thanks for listening and we’ll be back soon with a brand new batch of episodes.
If you have any thoughts on the show, ideas, anything at all … I’d love to hear from you. You can email me at bapu@freakonomic s.com. That’s B A P U at freakonomics dot com.
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Freakonomics, M.D. is part of the Freakonomics Radio Network, which also includes Freakonomics Radio, No Stupid Questions, and People I (Mostly) Admire. This show is produced by Stitcher and Renbud Radio. Original music by Luis Guerra. You can find us on Twitter and Instagram at @drbapupod. This episode was produced by Tricia Bobeda and mixed by Eleanor Osborne. We had help from Adam Yoffe. Our staff also includes Alison Craiglow, Greg Rippin, Emma Tyrrell, Lyric Bowditch, Jacob Clemente and Stephen Dubner. If you like this show or any other show in the Freakonomics Radio Network, please recommend it to your family and friends. That’s the best way to support the podcasts you love. As always, thanks for listening.
- Gurpreet Dhaliwal, professor of medicine at the University of California at San Francisco.
- Sharmin Shekarchian, assistant professor affiliated with Stanford University and president of The Clinical Problem Solvers.
- “The Influence of the Availability Heuristic on Physicians in the Emergency Department,” by Dan P. Ly (Annals of Emergency Medicine, 2021).
- “Early Death After Discharge From Emergency Departments: Analysis of National U.S. Insurance Claims Data,” by Ziad Obermeyer, Brent Cohn, Michael Wilson, Anupam B. Jena, and David M. Cutler (BMJ, 2017).
- “Quality Chasm Series: Improving Diagnosis in Health Care,” by John R. Ball, Elisabeth Belmont, Robert A. Berenson, Pascale Carayon, Christine K. Cassel, Carolyn M. Clancy, Michael B. Cohen, Patrick Croskerry, Thomas H. Gallagher, Christine A. Goeschel, Mark L. Graber, Hedvig Hricak, Anupam B. Jena, Ashish K. Jha, Michael Laposata, Kathryn McDonald, Elizabeth A. McGlynn, Michelle Rogers, Urmimala Sarkar, George E. Thibault, and John B. Wong (The National Academies of Science, Engineering, and Medicine, 2015).
- “How to Solve a Medical Mystery (Freakonomics, M.D. Ep. 5),” by Freakonomics, M.D. (2021).