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S2D: The Symptom to Diagnosis Podcast - Episode 02: Syncope: Transient Loss of Consciousness
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S2D: The Symptom to Diagnosis Podcast - Episode 02: Syncope: Transient Loss of Consciousness
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Language: EN.
Segment:0 .
DR. CIFU: I'm Adam Cifu.
DR. STERN: And I'm Scott Stern.
DR. CIFU: And we're back with another episode of the Symptom to Diagnosis Podcast. This podcast teaches evidence-based strategies for diagnosing common medical symptoms. Each episode is divided into four parts. We begin each episode with a case unknown to one of us, we then discuss the five high yield features that help to accurately diagnose the cause of the symptom at hand, we then return to our case before finishing up with a discussion of fingerprints, common misconceptions, pet peeves and other random pearls of knowledge pertaining to the week's symptom.
DR. CIFU: The cases that we discuss are drawn from our clinical experiences but, because protecting patient privacy is part of our oath, we never discuss actual patients and most cases are composites. Our topic this week is syncope. Scott, you're the expert of the day. Do you have a case to present to me?
DR. STERN: Indeed, I do.
DR. CIFU: I'm looking forward to it. Let's hear it.
DR. STERN: Well, this is a 32-year-old woman who was walking down the street one day and suddenly lost consciousness.
DR. CIFU: Wow, interesting. So I guess hearing that I would start with a couple of thoughts. First of all, I'm a little bit surprised hearing about someone who's just walking losing consciousness and this woman is pretty young for syncope. The first thing that I always think about, I'm sure you will enrich us with is to make sure that it's actually syncope that we're talking about.
DR. CIFU: And so my question is, is this really syncope?
DR. STERN: Well, that's really the perfect first question. As you know, we tend to use syncope and loss of consciousness synonymously and they're not actually synonymous. And syncope actually refers to the subset of those folks who've lost consciousness because the quote unquote, "they've lost cerebral blood flow" which is almost always due to hypotension.
DR. CIFU: Okay.
DR. STERN: There are other causes of loss of consciousness, that are not related to hypotension and should not actually be called syncope.
DR. CIFU: And we'll probably get into later how you determine syncope versus not syncope. I guess my question and I might set you up here. I can see cerebral hypoperfusion leading to syncope. It has to be brief.
DR. STERN: Right.
DR. CIFU: Right?
DR. CIFU: So otherwise they're dead.
DR. CIFU: Okay, that's bad humor I guess. Okay, so I'm going to take it that this woman had syncope. And the thinking that goes through my mind is that, boy, young person fainting all of a sudden, vasovagal syncope would be by far the first thing that comes to mind. However that makes no sense in this case that's usually people standing for a long time, seeing blood, this woman is walking, she's active so I've kind of ruled that out to begin with.
DR. CIFU: And so the things that would go through my mind is, is this cardiogenic syncope? Does this woman have an arrhythmia? Does she have valvular disease? Is there something else wrong? That seems unlikely just given her age but I guess it's possible. And the other thing would be hypotension, is she hypotensive.
DR. CIFU: Again, that wouldn't really make great sense with her just walking around but who knows? So tell me what else happened with this lady?
DR. STERN: Well, I think just to emphasize your point, it really was syncopal, she had a rapid return of consciousness which argues against the other non-syncopal causes.
DR. CIFU: Great.
DR. STERN: And I think your other point about rapidly deciding it's not vasovagal syncope is spot on because she was walking and I just want to emphasize that people often will make the mistake of calling something vasovagal syncope when it's not and the history of her walking along and passing out without a trigger and a prodrome would be incredibly atypical.
DR. CIFU: Okay.
DR. STERN: So she went to the ground and her husband started calling around for help and she woke up quickly to see him calling around for help and the next thing she knows she was transported by an ambulance to the hospital.
DR. CIFU: Okay, so I think the things which are notable for me in that is that it does certainly sound short, it sounds like she regained consciousness and it sounds like she was pretty aware. She remembers being in the ambulance all that stuff.
DR. STERN: Right, exactly.
DR. CIFU: Okay, and so as we'll talk about later, I think that makes things like seizures and other causes less likely 'cause it sounds like she came right to. So I guess maybe I'll put myself in the seat of the emergency room doc right now what I'd be really interested in is I'd love to hear what her heart sounds like, hear if she's got terrible aortic stenosis, I'd like to know what her vital signs are, is she tachycardic, is she bradycardic when she comes in?
DR. CIFU: I'd love to know orthostatics. And I'd love to know if there are any other symptoms. I guess, I sort of brushed off orthostasis which I really kind of doubt this is but if it was, I guess I'd want to know is she having abdominal pain? Is she having thigh pain? Has she been having melena? Is there something that would make me think that's a possibility?
DR. STERN: Great, so those are incredibly important points. So her vital signs when she arrived in the emergency room were stable. Her blood pressure was about 130 over 85. It didn't really change from standing to sitting and her pulse was about 92 and regular. Her O2 sat was normal and she was afebrile.
DR. CIFU: Can I call you on something like I would call a medical student presenting to me.
DR. STERN: Of course.
DR. CIFU: You can't say her vital signs were stable when you have one reading, right?
DR. STERN: [laughs] Fair enough, all right.
DR. CIFU: I think you mean that they're normal.
DR. STERN: I did mean that they're normal, thank you for that clarification and that's the spot on.
DR. CIFU: And orthostatics did you tell me?
DR. STERN: I did, there was no change.
DR. CIFU: Okay, great.
DR. STERN: And I did not tell you her cardiac exam that you asked for.
DR. CIFU: Yes.
DR. CIFU: Her pulse was regular rate and rhythm and she did not have any significant murmurs, gallops or rubs.
DR. CIFU: Okay, and is there anything else she's complaining about? Palpitations, chest pain, did she know this was coming on?
DR. STERN: She didn't complain of palpitations or chest pain, she did notice before she lost consciousness that she was short of breath when she was walking.
DR. CIFU: Oh, that's interesting. That's an important piece of information, it's certainly not something that I often think of when I think about syncope but I guess hearing that would make me think of a couple of things. I guess that pushes arrhythmia a little bit higher on the list. I could certainly imagine that if she was tachycardic and maybe somebody who didn't feel that much, that would certainly make her short of breath.
DR. CIFU: The other things would be other abnormalities which would decrease cerebral perfusion. I usually think of that as being outflow but I guess it could be preload compromise and pulmonary embolism would come to mind then. So I guess what I would ask you is, any risk factors for PE?
DR. STERN: Well, she's never had a prior pulmonary embolism
DR. CIFU: Okay.
DR. STERN: or DVT.
DR. STERN: She has not had a family history of that, she's not on any oral birth control pills. She has recently flown from Germany to the United States on a trip.
DR. CIFU: Okay, so there's something in mind there that I would at least think about. Should we go on with further workup now or should we move on to some of your key points for syncope?
DR. STERN: Well, I think it's worth reviewing the key points while we're here. And I think the first key point is the one that we've both emphasized already which is the first step is to really distinguish whether it's syncope or not. And that distinction is usually pretty easy if it's abrupt in onset, if it's short in duration and the patient recovers rapidly without any help, like sugars, et cetera that really suggests syncope.
DR. STERN: And if those are not true like a prolonged recovery, you asked a very good question, "Does she remember the ambulance ride?" If she doesn't then you think of the non-syncopal causes such as seizures and hypoglycemia. So that's really the first take-home point and you rapidly zeroed in on this being syncope appropriately.
DR. CIFU: Okay, so let me stop you for a second. Since we're putting aside a lot of things that people often describe as syncope that are not syncope, I think you just mentioned hypoglycemia, you mentioned seizures. Certainly we see a lot of people with intoxication who sort of pass out drunk and then wake up later.
DR. STERN: Sure.
DR. CIFU: Are there other common things that we should know?
DR. STERN: Well, some of the things a little bit less common, massive subarachnoid hemorrhage, patients will sometimes wake up from massive stroke. It does have to be a pretty massive stroke to make you lose consciousness, and head trauma of course.
DR. CIFU: Great, okay, those are important things to think about. Okay, so number one, as far as key points here seem to be, make sure this is actually syncope and you define syncope well as a rapid loss of consciousness with rapid regaining of consciousness related to cerebral hypoperfusion. So what's next?
DR. STERN: The next one is to determine the type of syncope. There are really three categories of syncope, cardiac syncope which is life-threatening, reflex syncope of which the most common is vasovagal syncope the most common cause of syncope and finally, orthostatic syncope.
DR. CIFU: Okay, so vasovagal syncope, I will talk about a little bit when we get to the pet peeves but that is something that's almost, let's say a reflex diagnosis. How do you think about vasovagal syncope? What is vasovagal syncope?
DR. STERN: So vasovagal syncope is simply when the vagus nerve is triggered and it causes two things simultaneously, bradycardia and vasodilatation and both drop your blood pressure but it needs to be triggered. And so typically patients are going to have some emotional trigger such as seeing blood, or prolonged standing which can trigger the vagus nerve to fire.
DR. STERN: Typically there's a prodrome. So they may feel abdominal discomfort, sweaty, uncomfortable queasy feeling and then typically they have no cardiac clues.
DR. CIFU: Got it, got it. I have to tell a great vasovagal syncope story. Years and years ago, my wife and I collected antique fans, okay, which didn't have any sort of safety things.
DR. STERN: Okay.
DR. CIFU: And we had some friends over on a very hot, Chicago summer night and we actually, we geared up one of our antique fans and my wife as she was placing it, slipped her hand, stuck her hand into the blade and not only cut her hand but splashed blood all over the wall and she went out like a light.
DR. STERN: I'm sure she didn't find that very funny.
DR. CIFU: I think that would be the definition of vasovagal syncope.
DR. STERN: I think that's pretty good.
DR. CIFU: Okay, so we've talked already about making sure it's syncope and then really breaking it down into these three important kinds of syncope, vasovagal, orthostatic and cardiac. What comes next? What's number three?
DR. STERN: The third point is that we have to consider, we have to know when to consider cardiac syncope because it's the type of syncope that can kill you.
DR. CIFU: Sure.
DR. STERN: And when we should think about that it's actually two issues. One is they have risk factors, symptoms or signs of cardiac disease of course. But the other is, if it's not orthostatic and it's not reflex syncope, it is cardiac syncope. And sometimes you get there because you say, boy, this isn't orthostatic and it's not reflex even though it didn't occur to me that it was cardiac syncope in fact it must be.
DR. CIFU: That is a terrific point. So if you're seeing a patient who you're absolutely sure has had syncope and you say, boy, this is really atypical for vasovagal syncope, I can't make that diagnosis. And the person is not orthostatic when you're seeing them. You're basically saying, well, there's a high likelihood that this is cardiogenic syncope and therefore that person needs an evaluation urgently?
DR. STERN: Urgently and to be admitted. So that's a key point.
DR. CIFU: Got it, got it. And I think a point that, I mean, I've certainly seen people make this mistake, right?
DR. STERN: Absolutely.
DR. CIFU: Where they say
DR. CIFU: this might be vasovagal syncope and discharge the person, send them home, recognizing that maybe this was a potentially lethal arrhythmia.
DR. STERN: Exactly and they may lose the opportunity to save their lives.
DR. CIFU: Got it, got it. Okay, let's move on to the next one.
DR. STERN: So the fourth key point is if it's cardiac syncope you really need to admit and evaluate the patient which we just said. And the final one is if it is orthostatic syncope, you have to figure out the cause of that orthostatic syncope.
DR. CIFU: Right, great, great point. So actually, if you're in the outpatient setting, in an urgent care and you see someone with orthostatic syncope, you certainly might be reassured that it's not cardiogenic syncope which is terrible but certainly there is a long list of terrible things which can cause orthostasis. And so maybe syncope is not the big issue but their ruptured AAA might be the-
DR. STERN: Exactly, and that would be bad to miss.
DR. CIFU: [chuckles] That might be the understatement of the day. Okay, so we have our five key points then. And so let's get back to the case. When we were talking about the case originally, we had a 32-year-old woman, syncopal episode out walking with her husband in the emergency chute room she's got normal vital signs, normal orthostatics, a normal cardiac exam and the only interesting part of her history is that she recalls being short of breath walking prior to the event.
DR. CIFU: We talked a little bit about pulmonary embolism not a common cause of syncope but being a possibility here. And the woman at least has a risk factor with recent European travel. So I guess from my point of view if I was the managing physician right now, I would start with routine blood tests, I try to stay away from saying routine blood tests but I would love to see electrolytes in this woman as I'm still, I guess, thinking of arrhythmia, I'd love to see a CBC as a hint about blood loss though of course she's not orthostatic arguing against acute blood loss which would be important here.
DR. CIFU: And to be honest with you if those are normal and I don't have a clue then I think PE ends up being pretty high on my list then I would go down that track, where are we? What went on with her?
DR. STERN: Well, her CBC was normal. Although I have to point out that even if it's acute hemorrhage as you know, the hemoglobin can be normal until it's been serially diluted by intake of fluid either oral or IV, even a massive hemorrhage can be normal and her electrolytes were normal. And you're kind of missing a key diagnostic test here that you would do routinely.
DR. CIFU: Oh, of course, she should have an EKG.
DR. STERN: Thank you.
DR. CIFU: I guess I think of that as being automatic. So yes, let me hear about her EKG.
DR. STERN: Right, and that is a point worth making that the EKG is essential in every syncopal person, one can even argue when it looks like vasovagal syncope to do an electrocardiogram.
DR. CIFU: There's a-- and what we're looking for there, we're unlikely to see an arrhythmia at the time when this woman is there with a normal heart rate, a regular rhythm but what we're looking for are signs of either underlying cardiovascular disease, Wolff-Parkinson-White, anything that would put her at higher risk for cardiogenic syncope.
DR. STERN: That's exactly right. You're not going to usually make the diagnosis but if it's abnormal it's a clue. And it's worth emphasizing something you said which is that the arrhythmias if patients have had them are often gone when they show up. So if they had an arrhythmia, they lost consciousness, the arrhythmia aborted on its own and they show up and it's fine but it doesn't rule it out. So her EKG showed normal sinus rhythm, no acute S or T wave changes, normal PR interval, no signs of an accessory pathway, no acute changes.
DR. CIFU: Great, so that's important, makes her chance of underlying cardiovascular disease less likely, but certainly doesn't rule that out. And I hope I'm not going down the wrong track with PE 'cause I've become sort of obsessed with it. The fact that there are no signs of right heart strain on the EKG does absolutely nothing towards ruling out that diagnosis and I guess you and I will say over and over again that the absence of signs or symptoms does not rule out a disease.
DR. STERN: Absolutely true.
DR. CIFU: Would you like to just repeat that?
DR. STERN: The absence of signs and symptoms never rules out a disease, the data shows that overwhelmingly, they can be very helpful when there but meaningless when absent.
DR. CIFU: Shall we talk about that paper that we wrote that we still haven't gotten published?
DR. STERN: No, I don't think so that'd be very painful.
DR. CIFU: Okay, so I guess if I was managing this woman right now I would say, boy, the only diagnosis that I'm thinking about really is pulmonary embolism. I would skip the D-dimer because I think if that was negative I wouldn't even, I would still evaluate her. I would say she needs a chest CT to rule out pulmonary embolism, if that's positive, I need to treat that, if that's negative, I would admit her with the idea that she's got cardiogenic syncope that I just haven't been smart enough or able to make the diagnosis and she needs further evaluation.
DR. STERN: Exactly. So that was their thought as well in the emergency room and they did do a CT scan which remarkably enough showed multiple large segmental pulmonary emboli distributed bilaterally.
DR. CIFU: Wow, I guess we should underline that. Not only my brilliant diagnosis [chuckles] but this is not a common cause of syncope.
DR. STERN: No, but actually it's more common than it's often given credit for.
DR. CIFU: Is that right?
DR. STERN: So if you look
DR. STERN: at patients who've been admitted for syncope, 17% of them were actually diagnosed with pulmonary embolism. So in the patients who are suspected of having cardiac syncope where the etiology is not clear, it should be part of the workup.
DR. CIFU: That's terrific, that's good to underline. And I guess the people who you work that up in are those who you don't have another clear diagnosis.
DR. STERN: Exactly.
DR. CIFU: Okay, good, good. Wow, that's a really interesting case. How did she do?
DR. STERN: She did well. It's worth pointing out that PE and syncope actually means there has to be massive pulmonary embolism.
DR. CIFU: Right, right.
DR. STERN: And one of the shocking things about patients is if they don't die from the massive pulmonary embolism they survive to be in the hospital. Presumably what happened is the pulmonary embolism that was blocking the right side of pulmonary blood flow has now fractured and gone to other parts of the lung which restore circulation to the left heart so that blood pressure comes back up. So they often look relatively well and actually a quarter of such patients had no other symptoms of pulmonary embolism.
DR. CIFU: Wow.
DR. STERN: But if you do an echo, 90% of them actually have signs of right ventricular dysfunction 'cause it was a massive PE. So she did well, she was treated with thrombolytic therapy, she had a hypercoagulable workup and is going to be treated for a minimum of six months and potentially longterm.
DR. CIFU: Great, that's a really interesting point that to cause syncope it needs to be very large pulmonary embolism, emboli at least initially and so many of these people I assume are going to be candidates for thrombolysis.
DR. STERN: Well, potentially as you know, if they're still in a hemodynamic shock, absolutely.
DR. CIFU: Sure, sure.
DR. STERN: Since she was no longer hemodynamically compromised, she would be treated with standard anticoagulant therapy.
DR. CIFU: Unless there's significant right-sided abnormalities. Okay, well, let's move on to the last part of our podcast which is always when we talk about fingerprints, common misconceptions, pet peeves and clinical pearls. Scott, why don't you start with some of the fingerprints?
DR. STERN: Well, one of them is, there are certain fingerprints for seizures. Lateral tongue laceration and abnormal movements before someone loses consciousness often a seizure generalizes and in that brief period of time before it generalizes patients may act strange, they may have head turning, unusual posturing and all of those have likelihood ratios of 12 or more strongly suggesting a seizure.
DR. CIFU: Wow, interesting. So those are clearly findings that you'd love to have witnesses to be able to talk to.
DR. STERN: Sure.
DR. CIFU: To be with the patient alone you might not get any of that. I'll throw out, we're sort of saying yours are, okay, seizures, things that are not syncope, mine would be for vasovagal syncope, fingerprints, high positive likelihood ratios are if the person tells you that before their syncope they were standing for a long period of time, they had abdominal discomfort or if it was before a shot, an IV placement, a blood draw and the likelihood ratios for those are generally in the seven to nine range.
DR. CIFU: So also really diagnostic.
DR. STERN: Great.
DR. CIFU: Let's move on to where people mess up. You have any common misconceptions that you think about?
DR. STERN: I do, one of the most common misconceptions I've seen over the decades is actually seeing various physicians order carotid ultrasound to look for carotid stenosis as a cause of syncope. And it turns out that you have to have global cerebral hypoperfusion to pass out. So if you block one carotid, you might have a TIA, you might have a stroke, you might have nothing but syncope is not part of it and you should stop ordering those.
DR. CIFU: Right, I'm with you on that, that drives me crazy. There's a terrific article from a few years ago in the journal of Hospital Medicine, I believe, they have a series called "Things We Do For No Reason". And I think the actual first article in their series was about carotid Doppler's for syncope. And I never understand, is that being done because people don't know, because people are just scared of missing anything or is it just essentially craft and they're trying to like take money from Medicare. [chuckles]
DR. STERN: I hope it's not craft. I think misconceptions are often passed down from generation to generation.
DR. CIFU: Yeah, true, true.
DR. STERN: Do you have one?
DR. CIFU: Like kind of gene mutations, right? So I think mine is actually probably something that you already mentioned is that very often people use the CBC to exclude acute hemorrhage. We may have actually talked about this also in the abdominal pain podcast something that obviously both of us are a little bit hung up on.
DR. CIFU: So if someone is profoundly orthostatic but their hemoglobin is 14, they have just bled and the CBC does nothing to rule it out. I guess if someone is not orthostatic and has a normal CBC that makes blood loss very uncommon.
DR. STERN: Agreed.
DR. CIFU: So how about pet peeves? How about things that just bug you?
DR. STERN: Well, I was going to mention carotid Doppler's but I think I've emphasized that enough. So I think another thing that bugs me is patients who haven't had syncope by history and are worked up for syncope. So the patient who loses consciousness and doesn't remember the ambulance ride, doesn't remember how they got to the hospital that really suggests another process. And so not paying attention to that is really a problem.
DR. CIFU: It seems like those people's syncope workup would probably be negative.
DR. STERN: Would probably be negative and they miss the seizure and potentially the tumor that was causing the seizure.
DR. CIFU: Right, right. Or if they actually find something, person gets treated for something completely different and they haven't treated the underlying problem.
DR. STERN: Right.
DR. CIFU: My pet peeve is probably the idea that everybody who faints has vasovagal syncope and it's very common, it's an easy diagnosis to make, it's benign so sort of it requires no further evaluation and I think therefore it's a tempting diagnosis to make but as we talked about, there are clear fingerprints. There are things that should really make you think about vasovagal syncope. And if those are lacking, you should really think hard about other things.
DR. STERN: I think we should call that the square peg round hole phenomenon where people take a disease they know and the patient doesn't fit it at all but they decide that's what's wrong. And so even though it doesn't fit, they try to push it through and they make terrible mistakes.
DR. CIFU: It's so interesting that comes up so frequently. I think about that with BPPV, and vertigo certainly it's been said for generations that everything that wheezes is not asthma, tension headaches and a 60-year-old who comes in with new headaches, it's a tension headache, that's not a tension headache. So maybe that should be a new category for future podcasts.
DR. STERN: Right.
DR. CIFU: So let's alternate with some clinical pearls before we wrap it up here. What are things that you want people to remember?
DR. STERN: Well, one that I already mentioned that arrhythmias may have resolved. It's tempting when the patient comes in with a normal sinus rhythm to assume that they didn't have an arrhythmia and that's just may not be the case.
DR. CIFU: Right, I'll underline something that you said for one of mine is that if you have a patient in the emergency room who cannot remember how they got there, okay, that's probably not syncope and it's very likely to be seizure actually because the postictal state has carried them through from the end of their seizure until they've arrived in the emergency room.
DR. STERN: I guess the other pearl I've already stated which was to think about pulmonary embolism in these cases, it's not something that rapidly comes to mind but if you have someone who comes in with clearly syncope and you think it's cardiac and you're scratching your head and their echocardiogram is normal and you don't know you should really evaluate them for that.
DR. CIFU: Okay and I'm also going to beat a dead horse here but maybe from another perspective. We talked about the fact that a normal hemoglobin doesn't rule out acute blood loss, the other thing that doesn't rule out acute blood loss, maybe with a normal hemoglobin is a normal supine blood pressure. There are plenty of people, often young healthy people who if they're lying down, will have a perfectly normal blood pressure or a lowish blood pressure which might just go along with being young and healthy but if you stand that person up, their blood pressure drops and maybe they have another syncopal event.
DR. CIFU: So you have to, have to, have to order orthostatics if you're considering orthostatic hypertension as a cause of syncope.
DR. STERN: Well, I couldn't have said that better myself. So I think that concludes the pearls that I had. Do you have any others you want to add?
DR. CIFU: No, that's good for me. I think there are a few things that nobody will leave this podcast forgetting. So we hope you found this episode of the Symptom to Diagnosis podcast useful and a bit enjoyable. As a reminder, our textbook "Symptom to Diagnosis: An Evidence-Based Guide" takes a much deeper dive into how to think about and reason through the diagnosis of medical presentations.
DR. CIFU: The book is available in print through all usual places and also available and fully searchable via the Access Medicine website available worldwide from McGraw Hill and also available on your iPhone or other handheld device.
DR. STERN: Thank you very much.
DR. CIFU: Thank you. The music for the S2D Podcast is courtesy of Dr. Maylyn Martinez.