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CNS Infections
29 Plays2 years ago
In this episode of Critical Matters, we discuss Central Nervous System (CNS) Infections. Our discussion focuses on the management of meningitis and encephalitis in the ICU. My guest is Dr. Catherine Albin, a neuro intensivist at the Emory Healthcare System in Atlanta, Georgia. Dr. Albin holds a faculty position as Assistant Professor of Neurology and Neurosurgery, in the Division of Neurocritical Care of Emory University School of Medicine.
Additional Resources
Infectious Meningitis and Encephalitis. R Bystritsky and F Chow: https://pubmed.ncbi.nlm.nih.gov/34798976/
Critical care management of meningitis and encephalitis: an update. M Thy, et al.: https://pubmed.ncbi.nlm.nih.gov/35975963/
Infectious Disease Society of America’s Clinical Practice Guidelines for Healthcare-Associated Ventriculitis and Meningitis: https://pubmed.ncbi.nlm.nih.gov/28203777/
Books Mentioned in this Episode
The Acute Neurology Survival Guide. By Catherine Albin and Sahar Zafar :bit.ly/45Ttfuo
Why We Sleep: Unlocking the Power of Sleep and Dreams. By Matt Walker: https://bit.ly/3MNoWs0
Recommended
Transcript
Introduction to Critical Matters Podcast
00:00:06
Speaker
Welcome to Critical Matters, a sound podcast covering a broad range of topics related to the practice of intensive care medicine.
00:00:14
Speaker
Sound provides comprehensive critical care programs to hospitals across the country.
00:00:19
Speaker
To learn more about our programs and career opportunities, visit www.soundphysicians.com.
00:00:26
Speaker
And now, your host, Dr. Sergio Zanotti.
Focus on CNS Infections
00:00:33
Speaker
In today's episode of the podcast, we will discuss CNS infections.
00:00:36
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We will focus on the management of meningitis and encephalitis, conditions associated with high rates of morbidity and mortality.
00:00:44
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Our guest is Dr. Catherine Albin.
00:00:46
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Dr. Albin is a neurointensivist and assistant professor of neurology and neurosurgery, the Division of Neurocritical Care of Emory University School of Medicine.
00:00:54
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She's a recognized clinician and educator, very active on social media as a medical educator.
00:00:59
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She's the author of numerous peer-reviewed publications and editor of the Acute Neurology Survival Guide, a practice resource for inpatient and ICU neurology.
00:01:07
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We are honored to have her our guest to discuss CNS infections in the ICU.
00:01:11
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Casey, welcome to Critical Matters.
00:01:14
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Hey, it's so good to be here.
00:01:15
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Thank you so much for the invitation.
00:01:16
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I'm delighted to join.
00:01:18
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Absolutely.
00:01:19
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So I believe this is a very important topic, but let's hear it from our expert.
Importance of Diagnosing CNS Infections
00:01:24
Speaker
Why should clinicians in the ICU care about TNS infections?
00:01:28
Speaker
Yeah, I think this is a critical thing because it's rare, right?
00:01:32
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Many, many, many patients in the ICU are encephalopathic and they're confused.
00:01:37
Speaker
But most of the time that's due to sort of a septic encephalopathy or a toxic metabolic encephalopathy or some critical illness encephalopathy.
00:01:47
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CNS infections are rare, but they are potentially devastating.
00:01:52
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I mean, this is a condition that has a very high morbidity and mortality.
00:01:57
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And so I think it's one of those things that if we're not constantly sort of
00:02:01
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keeping in the back of our mind, then we may miss.
00:02:05
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And that's devastating for the patient.
00:02:07
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So I think it's because it's rare, but critically important to make the diagnosis that this really makes such a difference.
00:02:17
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Absolutely.
00:02:18
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And I think that of many of the conditions that we that we treat in the ICU, it's hard to think of one that has almost more of a time sensitive component.
00:02:28
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Right.
00:02:29
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We missed the boat in terms of starting therapy early.
00:02:32
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Our patients are going to do very poorly.
00:02:35
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I absolutely agree.
00:02:37
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So tell us a little bit about the incidents and what are we seeing today in ICUs?
00:02:42
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Obviously, you said it's not very frequent, but what do we know of what's out there and what's often referred to in the literature?
00:02:50
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Yeah.
00:02:51
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So I think the important thing to keep in mind is that the average immunocompetent American has a very, very low chance of getting bacterial meningitis.
00:03:03
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that is not necessarily the same truth for many of the patients who are in ICUs already.
00:03:11
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So many of the patients who are in ICUs may have immunosuppression due to their transplant status.
00:03:17
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They may have bone marrow transplants, they may have solid organ transplants, or they may have severe immunocompromised due to HIV and AIDS.
00:03:27
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And I think when we start to think about these infections,
00:03:31
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Knowing a little bit about the host is actually critical in determining how likely is it that this patient has a bacterial meningitis.
00:03:40
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Again, rare for the immunocompromised, immunocompetent normal average, walks in through the ED, very unlikely that you just diagnose bacterial meningitis.
00:03:51
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However, patients who are either immunocompromised or immunocompromised,
00:03:57
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that they have recent TBI, right?
00:04:01
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They have a CNS or a CSF leak, or they've had recent neurosurgery, or they have an external ventricular drain.
00:04:12
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All of these patients are at higher risk of getting bacteria into the
00:04:17
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the meninges than your average person.
00:04:20
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So I think it's really important for all ICU clinicians to think about, you know, is the patient I'm taking care of at a higher risk of a bacterial meningitis?
00:04:29
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When we think about viral meningitis, then I think it's actually, you know, the average immunocompetent American actually can get viral meningitis.
00:04:41
Speaker
This is going to be a often less severe type of meningitis.
00:04:47
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But I think it's important to know that there are seasonal ebbs and flows.
00:04:51
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So the incidence of viral meningitis is highest in the summer when we see enterovirus and then arbovirus.
00:04:59
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So either, you know, tick or mosquito transmitted diseases having their peak.
00:05:05
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So I think
00:05:07
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For the ICU clinician, it's really important to think about who is the host?
00:05:12
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Is that host at high likelihood of getting bacterial meningitis because of their immunocompromised status or other sort of CNS leak?
00:05:22
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Or is this a patient...
00:05:24
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who, you know, it's the peak of the summer, and we're looking at increased rates of viral meningitis because of that seasonal ebb and flow.
00:05:31
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So again, both are pretty rare, but they become more common in patients who, for whatever reason, are not sort of the run-of-the-mill patients.
Differences Between Meningitis and Encephalitis
00:05:43
Speaker
Excellent.
00:05:43
Speaker
And before we move forward, can we just maybe give like basic definitions?
00:05:48
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I think a lot of times we talk, we throw words around, but it's always good to make sure that we're all on the same page in terms of what we're talking about.
00:05:55
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And specifically, if you could just define for us meningitis versus encephalitis, and what do people mean when they talk about meningoencephalitis?
00:06:03
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Yeah, absolutely.
00:06:04
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I think that's critical.
00:06:05
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So meningitis is inflammation only of the meninges, which are two types.
00:06:11
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They can be pachymeningitis, which is inflammation of the dura, or leptomeningitis, which is inflammation of the leptomeninges, which are the layer of the brain that's more closely associated with the brain's surface.
00:06:25
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So you can have dural inflammation, you can have leptomeningeal inflammation.
00:06:30
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Oftentimes you have both.
00:06:32
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What's a little bit tricky about the term meningitis is that we talk a lot about aseptic meningitis or bacterial meningitis.
00:06:43
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Aseptic meningitis means that nothing grew in the culture, but this can still be an infectious meningitis.
00:06:52
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Um,
00:06:53
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So viral and fungal causes of meningitis, they might not actually have positive cultures.
00:06:57
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These are still infectious meningitis.
00:06:59
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So the way I think that it's better to think about it is sort of your infectious versus non-infectious meningitis.
00:07:07
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There are a lot of causes of non-infectious meningitis.
00:07:12
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These can be autoimmune.
00:07:13
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They can be perineoplastic.
00:07:14
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They can be para-infectious.
00:07:16
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We very commonly see leptomeningeal carcinomatosis, which is a fancy way of saying cancer-related meningitis.
00:07:23
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And then on the flip side, there are a bunch of etiologies of infectious meningitis.
00:07:28
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So bacterial, fungal, viral, and bacterial might be the only thing that reliably grows in culture.
00:07:36
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But aseptic meningitis really just, that's a term I have a lot of trouble with.
00:07:42
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And so I really try to steer people away from that.
00:07:45
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So that's a meningitis.
00:07:48
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Encephalitis means you actually have inflammation of the brain parenchyma itself.
00:07:55
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And this too becomes, you know, can come in all sorts of different flavors.
00:07:59
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We have a lot of autoimmune, paraneoplastic, parainfection, malignancy related encephalitis.
00:08:07
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And then we also have infectious causes of encephalitis.
00:08:10
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So again, meninges are the layering covering the brain.
00:08:16
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Encephalitis means you actually have to have brain parenchyma inflammation.
00:08:21
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Both of these are often associated with evidence of inflammation on the CSF, the lumbar puncture and the CSF we get.
00:08:34
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Most of the time, both of these are associated with an elevated white count.
00:08:39
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Every now and then, encephalitis can trick you and not have that elevated white count.
00:08:44
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It can sometimes be actually a little bit difficult to get to the diagnosis of encephalitis, particularly when we're talking about autoimmune forms that may not create sort of a robust inflammatory response system in the brain parenchyma itself, but still cause altermental status.
00:09:03
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Does that sort of make sense in terms of... Absolutely.
00:09:06
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And one question I have, I mean, is being in the ICU, I'm a little bit more detached maybe from like the aseptic meningitis that immunocompetent people have, but it seems to be that...
00:09:19
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from what you're telling me and from what I've read, is that a lot of those septic meningitis diagnosis that younger people would have are really probably viral, right?
00:09:30
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And that's why that misnomer is problematic in terms of understanding what we're really dealing with.
00:09:35
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Absolutely.
00:09:36
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I think most aseptic meningitis is viral.
00:09:40
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However, you can have chemical meningitis.
00:09:41
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We talk about Tordal causing a chemical meningitis where you can actually have like inflammation just due to the drug itself.
00:09:49
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So there are tons of different etiologies of this, which is why I think it's so confusing.
00:09:54
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Meningoencephalitis just means that you have both.
00:09:57
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The meninges are inflamed.
00:09:58
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The brain parenchyma is inflamed.
00:10:01
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Two other terms that kind of come up and I wanted to briefly mention...
00:10:05
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Cerebritis is a term that sometimes gets thrown around.
00:10:08
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This is a really vague term.
00:10:13
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What I think, and I think most of the literature sort of talks about cerebritis in a way that means it's a separative infection.
00:10:20
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It's invading multiple spaces in the brain.
00:10:23
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So either in the brain parenchyma, in the meninges, in sort of the dural space.
00:10:28
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And it's...
00:10:29
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I think the best way to think about what the radiologist is trying to say when they say, ah, evidence of cerebritis is like pre-abscess.
00:10:37
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Like this is not quite an abscess.
00:10:39
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It hasn't formed a collection, but there's this really purulent collection there.
00:10:45
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So that's a vague term and I really don't like it, but it does get thrown around in radiology reports.
00:10:52
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And then ventriculitis is specifically inflammation of the ventricles.
00:10:58
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This is almost always associated with an EVD catheter, like the patient has a device in their ventricles, that device got infected, and now the ventricles are infected.
00:11:10
Speaker
So again, meningitis, encephalitis, ventriculitis, cerebritis, there are a bunch of different terms, but they do have nuances in what we mean by them.
00:11:20
Speaker
Perfect.
00:11:20
Speaker
And are there any other CNS infections that might be relevant to the ICU?
00:11:25
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I think that obviously ventriculitis is very relevant to neuro ICUs, and we see that very commonly.
00:11:32
Speaker
Cerebritis, like you said, is a term that gets thrown around and just understanding what it is.
00:11:37
Speaker
But are there any others that come to mind maybe, Casey, that we should mention?
Causes of CNS Infections
00:11:40
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Every now and then we get abscesses, like we get CNS abscesses.
00:11:44
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And that's important because often those are going to need, like, you know,
00:11:50
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control.
00:11:51
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And so CNS abscesses really require sort of a good surgical team that's willing to help kind of get source control there.
00:12:00
Speaker
Perfect.
00:12:01
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Can we talk about specifically etiology of meningitis versus encephalitis?
00:12:07
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And maybe even we can clarify acute versus chronic for each one of these.
00:12:13
Speaker
Yeah, this is, I mean, there are hundreds of etiologies for both of these, and it can be quite tricky.
00:12:21
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I think the things that we need to think through as intensivists are, you know, just as you say, defining, is this an acute process, or is this more of a subacute or even chronic process?
00:12:34
Speaker
So chronic, when we talk about chronic meningitis or chronic encephalitis, we're meaning more than four weeks.
00:12:43
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Versus acute, it's usually those more infectious etiologies.
00:12:48
Speaker
Most of our infectious etiologies are going to present with acute meningitis or acute encephalitis.
00:12:56
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So specifically when we think about meningitis...
00:12:59
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the most common etiologies are going to be viral.
00:13:01
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These are going to be the interoviruses, arboviruses.
00:13:05
Speaker
Oftentimes we don't even really figure out what it is.
00:13:07
Speaker
I think it's important to think about, you know, does the patient have risk factors for Lyme disease?
00:13:12
Speaker
Lyme usually causes more of a radiculitis, more, um, um, coating of the, the nerve roots as they leave sort of in the spinal canal, but it can cause a meningitis as well.
00:13:25
Speaker
Um, um,
00:13:26
Speaker
And other sort of travel risk factors, you know, for where they've been and mosquito bites that they got or other sort of arbovirus exposures.
00:13:38
Speaker
The vast majority of meningitis is the aseptic meningitis that we talk about where nothing grows in the culture is viral and the treatment is supportive, right?
00:13:48
Speaker
Bacterial meningitis.
00:13:50
Speaker
The two most common endiologies, and again, this is really rare in the immunocompetent patient, but the ones we really have to worry about are pneumococcal meningitis and meningococcal meningitis.
00:14:03
Speaker
Both of these can have very severe presentations.
00:14:06
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These are patients who often come in like very high fevers, obtunded.
00:14:11
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They look very, very sick.
00:14:12
Speaker
This is a very, very...
00:14:16
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critical disease with high mortality and morbidity.
00:14:19
Speaker
And time really is of the absence of those patients.
00:14:23
Speaker
So the acute ones are, I think, the ones that we have to, you know, act more quickly to tease out, is this an acute viral meningitis or is this acute bacterial meningitis?
00:14:33
Speaker
And while we don't, while we're doing that workup, I really think it's important that we just treat for the things that we can treat for, which is bacterial meningitis and HSV or with acyclovir.
00:14:46
Speaker
When we think about encephalitis, again, there is such a wide range of things that causes encephalitis.
00:14:55
Speaker
But from the sort of infectious standpoint, the most common acute cause of encephalitis is HSV encephalitis.
00:15:03
Speaker
And again, there's a treatment for that with acyclovir, which is why it's so important that as you're working patients up, you know, you have that treatment on board until you kind of can narrow it and say, you know, I feel confident this is not what's going on.
00:15:15
Speaker
Now,
00:15:16
Speaker
when we get into sort of that chronic or subacute period, we're really dealing with either autoimmune or granulomatous diseases, or we're dealing with sort of your atypical pathogens.
00:15:31
Speaker
And the people who are at risk for these atypical pathogens are often our immunocompromised patients.
00:15:37
Speaker
So the things that I think of when people have a smoldering course of meningitis or meningoencephalitis,
00:15:45
Speaker
are the fungal infections.
00:15:46
Speaker
So cryptococcus or any of the like coccidiumycosis, histoplasmosis, sister sarcosis.
00:15:54
Speaker
Um, clearly it's really important in those patients to take a good history.
00:15:59
Speaker
Cryptococcus is everywhere.
00:16:01
Speaker
All of these other sort of regional fungi are more specific to various geographic locations in the U S. Um, um,
00:16:08
Speaker
Cryptococcus, I think, is something that you should pop into your mind for any patient who's complaining of bad headaches who's immunocompromised, right?
00:16:16
Speaker
These patients can have wildly elevated CSF pressures, and they often depend on CSF diversion.
00:16:26
Speaker
Other things that can cause sort of this subacute onset of meningitis or meningoencephalitis, TB, the great mimicker of everything, often has an assiduous onset, can cause a really dramatic pachymeningitis with that inflammation of the dura and sort of skull base.
00:16:44
Speaker
And then finally, thinking of, you know, does the patient have risk factors for an iatrogenic CSF infection, like they have ventriculitis because they have an EVD, which can also kind of present in this sort of, you know, the patient's not looking well for a couple days.
00:17:00
Speaker
And you have to have a really heightened level of, like, we got to check that CSF to make sure the glucose isn't going down and there's nothing growing in the culture.
00:17:09
Speaker
Those patients, unfortunately...
00:17:11
Speaker
grow atypical pathogens a lot of the time.
00:17:13
Speaker
You know, most of the time, staph epidermis is not going to cause a run-of-the-mill de novo meningitis, but our patients with devices in their heads, they can have staph epi, they can have pseudomonas growing.
00:17:28
Speaker
I mean, these are really more hospital-acquired pathogens.
00:17:32
Speaker
So that's how I kind of break this down.
00:17:33
Speaker
You know, time is at the absence for those acute meningitis, meningoencephalitis patients, and
00:17:39
Speaker
You have to treat them as if they were bacterial until you know for sure that they're not.
00:17:43
Speaker
And then for the subacute, you're really thinking more of mycobacteria or fungal infections.
00:17:49
Speaker
And as you mentioned, obviously, and we'll talk about it as we move to evaluation diagnosis, also very important to consider the patient, the individual patient, what risk factors they have, and also temporal in some of these presentations.
00:18:02
Speaker
But I guess the thing we can't overemphasize is that for acute meningitis, we think of strep and meningococcus.
00:18:12
Speaker
And for acute encephalitis, we think of acyclovir.
00:18:15
Speaker
All those can be treated.
00:18:16
Speaker
They're time-sensitive.
00:18:18
Speaker
while we're trying to figure things out, we start therapy.
00:18:21
Speaker
Absolutely.
00:18:22
Speaker
I think that those are the key things to remember.
00:18:25
Speaker
If you can treat, you know, for pneumococcal, meningococcal, and then HSV, like, that's most of the pathogens that we really need to worry about.
00:18:37
Speaker
And trying to get medications on board for those as soon as you even suspect that this is maybe a meningitis or an encephalitis patient.
00:18:44
Speaker
So one more question regarding a chalogy that is a...
00:18:48
Speaker
seems to be a favorite in the boards is like listeria.
00:18:52
Speaker
Super rare, but when should we be thinking of listeria?
00:18:55
Speaker
Yeah, we think of this more in immunocompromised, or not necessarily immunocompromised hosts, but younger children, so babies, and then older individuals.
00:19:06
Speaker
So you should have empiric coverage for listeria in a patient who's older than 60.
00:19:10
Speaker
So, you know, that's not a very old patient.
00:19:13
Speaker
That's kind of, you know, middle-aged that you should think about treating with...
00:19:19
Speaker
ampicillin up front.
00:19:21
Speaker
It is a tricky diagnosis to make.
00:19:23
Speaker
Some of these patients can look really, really sick and other patients can have sort of a more smoldering course.
00:19:28
Speaker
It does grow in cultures.
00:19:29
Speaker
So hopefully you will get a positive diagnosis, but those are the young, the young, young babies and then are sort of middle-aged and older people and certainly immunocompromised patients.
00:19:40
Speaker
This is rare and it does kind of happen in spontaneous outbreaks.
00:19:45
Speaker
So it
00:19:46
Speaker
It is something that you have to kind of keep in the back of your mind.
00:19:51
Speaker
Excellent.
00:19:51
Speaker
Let's talk about evaluation and
Evaluating CNS Infections in ICU
00:19:54
Speaker
diagnosis.
00:19:54
Speaker
As you mentioned, a lot of the presentations might be very common in people coming to the ICU for other reasons, but there are certain maybe characteristics that should alert the clinician.
00:20:05
Speaker
So why don't we start, Casey, with a clinical presentation and some of the physical findings that would be of interest for you as a neurointensivist when you're trying to include this in your differential?
00:20:17
Speaker
Yeah.
00:20:17
Speaker
Yeah.
00:20:18
Speaker
Again, I am always thinking about what are my patients' risk factors for this?
00:20:22
Speaker
Is this a patient who's immunocompromised?
00:20:24
Speaker
Is this a patient who's had, you know, some trauma to their skull base recently?
00:20:28
Speaker
That really helps me to narrow in on this.
00:20:32
Speaker
The other things clinically that I'm looking for, meningitis.
00:20:35
Speaker
Okay, so the patient has inflammation of the meninges.
00:20:39
Speaker
That's really painful.
00:20:42
Speaker
These patients have horrible headaches, like really impressive.
00:20:46
Speaker
They just feel pain.
00:20:48
Speaker
like their head is going to explode.
00:20:50
Speaker
This is always on my differential, you know, with subarachnoid hemorrhage and pituitary apoplexy, worst headache of life.
00:20:56
Speaker
I'm always thinking, does this patient also have meningitis?
00:20:59
Speaker
Fever.
00:21:00
Speaker
Fever.
00:21:01
Speaker
photophobia.
00:21:03
Speaker
Most of the patients are very febrile.
00:21:04
Speaker
You know, they have temperatures in the, you know, 101, 102, 103, very high fevers.
00:21:11
Speaker
And then stiff neck.
00:21:12
Speaker
We think about this, you know, I feel like this is one of those, did you check for nucle rigidity and people are always sort of like, yeah, maybe.
00:21:20
Speaker
This is not just like, oh, the patient like can't move their neck like a little bit, like they're a little stiff.
00:21:25
Speaker
It's like,
00:21:26
Speaker
They are in horrific pain if you move their neck.
00:21:30
Speaker
And that's because all those nerves that run down the back of the neck are inflamed.
00:21:35
Speaker
It's that inflammation that's causing this like incredible pain with neck flexion.
00:21:41
Speaker
So I do check for nuchal rigidity.
00:21:43
Speaker
And when you see it, it's really quite dramatic.
00:21:47
Speaker
On the flip side, encephalitis is really actually inflammation of the brain itself.
00:21:52
Speaker
And so a key finding has to be that they have altered mental status.
00:21:57
Speaker
Because the brain is involved and inflamed, these patients very frequently present with seizures.
00:22:04
Speaker
So when I'm trying to decide if someone has encephalitis, I'm looking for a triad of altered mental status, fever, and quite frequently seizures.
00:22:14
Speaker
Not all the time.
00:22:15
Speaker
And there are obviously way more causes of altered mental status and fever than just encephalitis.
00:22:21
Speaker
I mean, many patients in the ICU have fever and they're altered.
00:22:26
Speaker
And they have, you know, they're critically ill.
00:22:28
Speaker
They have sepsis.
00:22:30
Speaker
They have, you know, other reasons to be encephalopathic.
00:22:34
Speaker
So encephalitis, again, much more rare.
00:22:37
Speaker
And you have to be clued into what would be my patient's specific risk factors for having encephalitis.
00:22:45
Speaker
Can you mention on the presentation of focal neurologic findings and meningitis or encephalitis?
00:22:51
Speaker
Is that something that occurs?
00:22:55
Speaker
It's a good question.
00:22:56
Speaker
So meningitis can certainly occur with no focal findings.
00:22:59
Speaker
I mean, the vast majority of patients who have viral meningitis, they just have a really bad headache and fever.
00:23:10
Speaker
So you do not have to have focal findings for meningitis.
00:23:13
Speaker
Encephalitis, again, your brain is inflamed.
00:23:17
Speaker
And so you might, depending on where that inflammation is, have easily detectable focal findings, right?
00:23:24
Speaker
Like if you have inflammation that involves the motor cortex, you may have weakness.
00:23:32
Speaker
Since HSV is sort of the most common cause of encephalitis,
00:23:37
Speaker
it really likes to affect the medial temporal lobes.
00:23:42
Speaker
The medial temporal lobes are very important for memory, for cognition.
00:23:46
Speaker
And so these patients may not have focal neurologic deficits.
00:23:51
Speaker
They may just be confused.
00:23:53
Speaker
And I think that's why we have to have such a heightened level of suspicion for particularly HSV encephalitis because they really may not show you like, oh, I have weakness in my arm or leg.
00:24:06
Speaker
The other thing to kind of keep in mind for both of these infections is that they can both lead to increased intracranial pressure.
00:24:15
Speaker
Whether you have meningitis or encephalitis, ICP crisis is a possibility.
00:24:23
Speaker
And so when evaluating these patients, I try to look for signs of increased ICP.
00:24:29
Speaker
That could include that the patient really can't look up very well.
00:24:32
Speaker
It could include that the patient is very sleepy.
00:24:36
Speaker
It could include, you know, hopefully not, but sometimes anti-sicoria, you know, as we start to see medialization of the uncas of the temporal lobe.
Diagnostic Techniques for CNS Infections
00:24:47
Speaker
So I'm always...
00:24:48
Speaker
Whenever I see these patients, I'm trying to assess, you know, is there elevated ICP and can I detect that on bedside?
00:24:55
Speaker
But one of the things that's hard about this is that the neurologic findings may be really nonspecific in a lot of cases or even absent in a patient with sort of just run-of-the-mill meningitis.
00:25:07
Speaker
You talked about suspicion of ICP, and I just have a tangential question.
00:25:11
Speaker
I haven't done a fundoscopic exam in a very long, long, long time.
00:25:18
Speaker
At one point, I was reading that some people were looking at the optic nerve with ultrasound.
00:25:24
Speaker
Is that something that is real?
00:25:27
Speaker
What are your thoughts on that, Casey?
00:25:29
Speaker
Yeah, I think that this is, you shouldn't hang your hat on optic nerve sheath diameter.
00:25:33
Speaker
There are certainly limitations on this.
00:25:36
Speaker
I do like to do an optic nerve sheath diameter assessment as a proxy for, as a non-invasive way to screen for elevated ICP.
00:25:46
Speaker
But you certainly shouldn't be like doing this for the first time on a patient with meningitis.
00:25:52
Speaker
Like,
00:25:53
Speaker
Do this if it's part of your clinical practice and you've screened a lot of patients and you know how to measure optic nerve sheet diameter.
00:25:59
Speaker
I think it's helpful in that situation.
00:26:01
Speaker
I really, really like pupilometry.
00:26:03
Speaker
Like if you are someone that has access to the pupilometer.
00:26:08
Speaker
at your institution.
00:26:10
Speaker
I think pupil omnipery is really helpful in these patients who, you know, they look really sick.
00:26:15
Speaker
They're very altered.
00:26:16
Speaker
They're sleepy.
00:26:18
Speaker
Having that sort of normalized pupillary index to tell you, hey, their pupils are becoming sluggish.
00:26:24
Speaker
That is also a very effective non-invasive way to screen for ICP issues.
00:26:31
Speaker
The fundoscopic exam, papilledema takes a while to develop.
00:26:36
Speaker
So your patients with acute
00:26:39
Speaker
very frequently don't have papilledema, that's more of a chronic finding in patients who've had chronically elevated ICP.
00:26:49
Speaker
So I think
00:26:51
Speaker
you know, looking at pupilometry, if you have it, using optic nerve sheet diameter, if that's part of your practice, and then really taking a good look at the head CT to look at, you know, are the basal cisterns obliterated?
00:27:05
Speaker
Are there, is there sort of like flattening of the sulci of the brain?
00:27:10
Speaker
Those would all point me to think that this patient's got high ICP and poor brain compliance.
00:27:16
Speaker
So again, it's really important
00:27:19
Speaker
looking at all the information that you can get from sort of non-invasive bedside maneuvers to your radiographic findings.
00:27:26
Speaker
Perfect.
00:27:27
Speaker
So we talked about the clinical presentation, some of the important physical findings.
00:27:31
Speaker
As you're working up these patients, Casey, let's start with some just basic labs before we really go for the gold, which is the LP.
00:27:38
Speaker
Yeah.
00:27:39
Speaker
Yeah.
00:27:40
Speaker
So everyone needs a basic CBC, basic metabolic panel.
00:27:46
Speaker
The CBC, you're really looking for evidence of high white count and inflammation.
00:27:50
Speaker
You also, if you really think that the patient has bacterial meningitis, screen for DIC.
00:27:55
Speaker
Meningococcal encephalitis really like, I mean, meningitis really does cause a DIC.
00:28:01
Speaker
And you want to know that before you're doing the lumbar puncture, right?
00:28:04
Speaker
Like patients in DIC, you're probably still going to do the lumbar puncture, but you're going to do it with more care and you might give them a little cryoprecipitate before you do it.
00:28:12
Speaker
So I get this, the CBC to know, you know, platelet count, are they safe to LP?
00:28:18
Speaker
And then basic metabolic panel, because often when patients are sick, they can develop hyponatremia from SIIDH.
00:28:26
Speaker
I feel like one of the things that students always tell me when they rotate in the neuro ICU is like,
00:28:31
Speaker
why does no one have a normal sodium here?
00:28:33
Speaker
And I really do feel like brain inflammation and sodium are just constantly connected.
00:28:41
Speaker
So those are the, you know, the two things I'm looking for, certainly thinking about DIC, if I have a patient who has, you know, just appears very sick, with very high fever, altermental status, you know, is this bacterial?
00:28:53
Speaker
And if so, are they in DIC?
00:28:55
Speaker
So that's
00:28:55
Speaker
Those are the things that I want before we even get to the lumbar puncture.
00:28:59
Speaker
Also, sending blood cultures, right?
00:29:01
Speaker
It may take a minute if you are not a shop that does a bunch of lumbar punctures to get set up to do the lumbar puncture.
00:29:08
Speaker
And anyone who's got altermental status.
00:29:11
Speaker
it is my practice to get a head CT first, right?
00:29:14
Speaker
If a patient walks in off the street and tells me in the ED, I've got the worst headache of my life, I've had this fever, I don't really feel good, but they're having a conversation with me about it.
00:29:26
Speaker
Like they tell me they have like the worst headache ever and they don't feel good, but they're conversing with me and it's probably viral meningitis.
00:29:34
Speaker
Maybe I'll forego a head CT, but I'll be very honest with you that like,
00:29:40
Speaker
I'm CT-ing 99% of people before I put a needle in their back.
00:29:46
Speaker
And that also probably relates to the types of patients that come to the ICU, right?
00:29:51
Speaker
Because the ones that are having a conversation probably are not the ones that come to the ICU immediately.
00:29:57
Speaker
But before we dive into the lumbar puncture, you did mention that anybody with altered mental status, you would do a CT before the LP.
00:30:08
Speaker
Are there any other factors that would also kind of push you in the CT before LP direction?
00:30:15
Speaker
Yeah, any immunocompromised person also getting a head CT before they get an LP.
00:30:21
Speaker
Really, I'm really almost always CT-ing people before I stick a needle in their back.
00:30:25
Speaker
It's like I have to have a really good reason not to.
00:30:31
Speaker
I don't want to be surprised.
00:30:33
Speaker
I just would like to know what their brain looks like before we go and take CSF.
00:30:37
Speaker
And what we're trying to avoid is masses or a reason for high ACP that could potentiate a complication with the LP.
00:30:44
Speaker
Yeah.
00:30:46
Speaker
Absolutely.
00:30:46
Speaker
Yeah.
00:30:46
Speaker
And I'm going to look really closely at the basal cisterns on that MRI.
00:30:51
Speaker
If there's crowding already at the basal cisterns, like where they're, you know, I don't see a good pre-pontine cistern, their uncas already seems a little medialized, then I'm going to, if I'm going to tap them, I'm going to take off like two cc's of CSF.
00:31:08
Speaker
I work at a place where we have an amazing neurosurgeon group.
00:31:12
Speaker
And I, if I see a really, really swollen brain, I may forego the LP altogether and in favor of an external ventricular drain.
00:31:21
Speaker
So putting, getting CSF from a drain from above.
00:31:25
Speaker
So again, I can't think of many reasons that I'm, I'm ever angry that I got a head CT and then, you know, get the blood cultures, get the head CT and then, you know,
00:31:37
Speaker
set yourself up to do a safe LP.
00:31:38
Speaker
Mm-hmm.
00:31:40
Speaker
Perfect.
00:31:41
Speaker
So let's talk a little bit more about the LP.
00:31:44
Speaker
I grew up with a heuristic that if you're thinking of an LP, you probably should do the LP.
00:31:49
Speaker
Yet over and over again, it seems that it's always complicated or people have excuses, quote unquote.
00:31:57
Speaker
And there's still some confusion around timing, how to do it.
00:32:01
Speaker
What are we looking for?
00:32:02
Speaker
Yet it's probably needed to make these diagnoses over and over again.
00:32:08
Speaker
So when should we do an LP?
00:32:09
Speaker
Yeah, this is a clinical gestalt.
00:32:13
Speaker
I do kind of like that.
00:32:14
Speaker
Like if you've thought about it, you probably should do it.
00:32:19
Speaker
I tend to also agree that, and again, I've done hundreds of LPs.
00:32:23
Speaker
So it just doesn't feel like it's that much of an undertaking.
00:32:26
Speaker
So if I like sort of, it crosses my mind, like it would be helpful for me to have an LP, but
00:32:32
Speaker
there's just not a lot of reasons.
00:32:33
Speaker
Like I, it's way easier for me to talk myself into doing an LP than it is for me to talk myself out of it.
00:32:39
Speaker
But I recognize like, that's kind of unique to a neuro intensivist.
00:32:42
Speaker
This is part of my like daily practice.
00:32:44
Speaker
And it's very, we have a head CT scanner on our floor.
00:32:49
Speaker
Like I just send the patient over to scan and reassure myself, like, this is not going to be that dangerous.
00:32:55
Speaker
It takes me, you know, 20 minutes to set up and do an LP.
00:32:57
Speaker
I've answered the question and I move along with my day.
00:33:00
Speaker
I realized that that is not the case in a non-neurointensive care situation.
00:33:06
Speaker
So I think, again, it comes back to who is your patient?
00:33:10
Speaker
Like, are they at particularly high risk for developing a CNS infection because they're immunocompromised or because they have some recent skull-based trauma?
00:33:20
Speaker
You know, then...
00:33:22
Speaker
Again, you really got to come up with a reason to not do an LP if that patient's febrile.
00:33:26
Speaker
Then you got to just, you know, and altered.
00:33:29
Speaker
Then I think you really are doing the patient a disservice if you talk yourself out of this.
00:33:37
Speaker
Now, if you've got a altered...
00:33:41
Speaker
high fever patient and you have a clear reason, like they have cholecystitis and like, you know, there's a bunch of reasons that they're very sick, then yeah, I don't think that they need an LP.
00:33:51
Speaker
Like you've got an answer.
00:33:53
Speaker
I tend to think about this as in the very sick, confused patient with a high fever who you don't really have a source.
00:34:02
Speaker
Then I think, then you got to think about it.
00:34:05
Speaker
And again, you know,
00:34:08
Speaker
If you do these frequently enough, like they don't, they don't often take that terribly long.
00:34:15
Speaker
If you are going to do this, and this is especially true in the emergency department where we're trying to rule this out, try and get enough CSF.
00:34:24
Speaker
Unless it's like one of those situations where you're really worried about precipitating herniation.
00:34:29
Speaker
And again, if this is an LP is not like part of your daily practice, then maybe that's the patient that you hold off on because you can make things worse.
00:34:37
Speaker
Um, but aside from that sort of rare situation, if you're doing a lumbar puncture, please get enough CSF that you answer the question.
00:34:45
Speaker
Nothing is worse than like, oh, we did the lumbar puncture and we took out, you know, three CCs of CSF, but we didn't have enough to run both the cell count and the culture.
00:34:55
Speaker
And we couldn't send the bio fire.
00:34:57
Speaker
And, you know, we didn't really fully answer the question, like get at least 10 CCs of CSF, um,
00:35:05
Speaker
Quite frequently when I'm doing LPs, I try to get 25 cc's so that I don't, you know, have to, I'm sure that I will never have to do this again.
00:35:13
Speaker
I'll have all the CSF I need.
00:35:15
Speaker
So I think that's a little like pearl.
00:35:18
Speaker
If you're going to go through the trouble of doing it, make sure you get enough.
00:35:22
Speaker
So before we dive into the important aspects or the things we should measure in the LP, I have two questions that I have.
00:35:32
Speaker
One is related, I guess, to evidence, and the other one's more of a practice, just thought, or opinion.
00:35:40
Speaker
So regarding evidence...
00:35:43
Speaker
delays obviously in initiating antibiotics are important and also getting the LP soon is important now ideally if you can if things go very well you can do the LP as as soon as possible and then start the antibiotics that's a perfect world but doesn't always happen what are your thoughts um Casey on we gave the antibiotics and some people say well now there's no point of doing the LP that is that true ah no that is not true
00:36:08
Speaker
One, because the BioFire exists now, and so this is that meningoencephalitis panel.
00:36:14
Speaker
It's a PCR panel.
00:36:16
Speaker
So even if you lys all the bacteria and you don't grow anything in the culture, BioFire's, like the BioFire assay, and there may be other, I don't have any, like, stock in BioFire.
00:36:26
Speaker
There may be other of these assays now, but they are PCR-based.
00:36:32
Speaker
And so you very...
00:36:36
Speaker
perfectly reliably but pretty reliably still get good data for the the pathogens that they include which are most of the common community acquired these are not so good for detecting uh staph epi or pseudomonal or things that are hospital acquired um cns infections but they're very good for community acquired csf infections so 100 you can still get the biofire and that's very helpful even if it's been a day since they've been on you know they've been on um
00:37:06
Speaker
CNS dosing of antibiotics for a full 24 hours, still very helpful for the bio fire.
00:37:12
Speaker
The other thing that's helpful is the glucose.
00:37:15
Speaker
The glucose is going to take a while to normalize in bacterial meningitis.
00:37:19
Speaker
So even if your cultures are negative, but your glucose is like 15 on the LP, that to me still says this patient had bacterial meningitis.
00:37:29
Speaker
Maybe it's a little frustrating that now the cultures are sterilized and we're not going to know what kind of bacterial meningitis it is if it's not picked up by the biofire.
00:37:38
Speaker
But that to me tells us, oh, we were on the right track.
00:37:40
Speaker
Like we thought this patient had a bacterial meningitis.
00:37:44
Speaker
The glucose suggests that it's either bacterial, fungal, or mycobacterial.
00:37:50
Speaker
You know, we at least are still, we have convinced ourselves that this truly was a meningitis.
00:37:55
Speaker
So ideally you always get the, you know, you start the antibiotics.
00:37:59
Speaker
You still have two to four hours before you sterilize your CSF.
00:38:03
Speaker
So again, it's not like you have to,
00:38:06
Speaker
You know, you have to get the LP before you start antibiotics.
00:38:12
Speaker
And once you start antibiotics, like that second it's over, you still have some time.
00:38:18
Speaker
But regardless, I mean, you can get a lot of information, especially now that we have PCR based detection of pathogens.
00:38:27
Speaker
Perfect.
00:38:27
Speaker
And just to, we'll get there.
00:38:31
Speaker
But the second question I have, I've often heard we didn't get the LP because we don't have consent.
00:38:38
Speaker
And that doesn't sound right where you've done all these other things emergently to this patient.
00:38:43
Speaker
Any thoughts on that?
00:38:45
Speaker
Yeah, I mean, this is an emergency.
00:38:46
Speaker
You do emergency consent.
00:38:48
Speaker
Like you're doing, you're acting in the best interest of the patient.
00:38:50
Speaker
We do central lines.
00:38:51
Speaker
We do A lines.
00:38:52
Speaker
We do intubations.
00:38:54
Speaker
We do CPR without consent.
00:38:56
Speaker
Like this should also be an emergency procedure where you're acting in the best interest of the patient.
00:39:02
Speaker
You know, I do two physician emergency consent frequently if we can't get in touch with the family member.
00:39:08
Speaker
Perfect.
00:39:09
Speaker
So clearly, an LP is going to be important if we're suspecting encephalitis or meningitis.
00:39:16
Speaker
We talked about the time-sensitive nature of this, and we'll get to treatment soon.
00:39:21
Speaker
But we also talked about when to get a CT scan before doing the LP.
00:39:26
Speaker
But in patients, like you said, who don't suspect a mass, are not immunosuppressed, or are not totally altered, you might go ahead and do the LP first.
00:39:37
Speaker
Now, you also emphasize, Casey, that be generous with the amount of CSF you get in most cases.
CSF Analysis and Detection Methods
00:39:44
Speaker
Let's walk through the LP.
00:39:45
Speaker
What are the important aspects of what we should be checking?
00:39:49
Speaker
So opening pressure.
00:39:51
Speaker
Yeah.
00:39:52
Speaker
Opening pressure is crucial in these situations.
00:39:55
Speaker
I mean, it's actually always important.
00:39:57
Speaker
The thing to know about opening pressure is that to have a reliable opening pressure, A, the patient can't be on positive pressure ventilation, which, you know, sometimes they have to be intubated.
00:40:07
Speaker
And I, you know, that's more, protecting their airway is always more important than getting a, you know, pristinely measured opening pressure.
00:40:16
Speaker
But just be aware that, you know, positive pressure ventilation does tend to push your opening pressure higher than
00:40:22
Speaker
than the true ICP.
00:40:25
Speaker
The patient can't be balled up.
00:40:27
Speaker
So, you know, when we are doing lumbar punctures, we often have the knees like tucked in.
00:40:34
Speaker
So you're getting the patient into like as much of a little ball as they can kind of comfortably be in.
00:40:41
Speaker
Um, if those legs are up, that's, that's really causing higher abdominal pressure and all the compartments are related.
00:40:48
Speaker
So that pushes your ICP up.
00:40:50
Speaker
So if you really want a true ICP, you have to actually straighten the patient's legs enough that they're not compressing, um, the belly.
00:40:57
Speaker
It doesn't have to be like all the way straight, but they have to just relax the belly enough.
00:41:02
Speaker
Um,
00:41:02
Speaker
What I tend to do is I confirm that I'm in the right space.
00:41:06
Speaker
I get some CSF flow back.
00:41:07
Speaker
I put the stylet back in.
00:41:09
Speaker
I have the nurse kind of like help me sort of release their legs ever so slightly just so that we're releasing that abdominal pressure and then measure the opening pressure.
00:41:21
Speaker
When you're using the opening pressure, it's important to know that what you're measuring is in centimeters of water.
00:41:29
Speaker
Centimeters of water...
00:41:31
Speaker
And millimeters of mercury are not the same thing.
00:41:35
Speaker
So when you are measuring an opening pressure and you get an opening pressure of 20, you might be tempted to think, oh my gosh, that's very high ICP.
00:41:45
Speaker
This is, this is, the patient's in an ICP crisis.
00:41:50
Speaker
It's important to know that in an opening pressure of 20 centimeters of water, which is how you're measuring the lumbar puncture,
00:41:58
Speaker
is about 15 millimeters of mercury.
00:42:02
Speaker
All the guidelines for elevated ICP...
00:42:07
Speaker
talk about ICPs in millimeters of mercury.
00:42:09
Speaker
So just recognize that, you know, millimeters of mercury and centimeters of water are not the same.
00:42:15
Speaker
And what you're measuring when you measure an opening pressure for a lumbar puncture is in centimeters of water.
00:42:21
Speaker
So what I tell the resident is like, get your opening pressure and then I want you to convert it into millimeters of mercury.
00:42:27
Speaker
So you're telling me an ICP that I'm like used to, you know, to normalizing.
00:42:33
Speaker
People who have high, um,
00:42:36
Speaker
ICP on the lumbar puncture, it's going to like shoot up.
00:42:39
Speaker
It's usually really not, it's not subtle.
00:42:42
Speaker
Like it's like you stick the needle and you put the manometer on and it like shoots through the top.
00:42:48
Speaker
Like that's the person who has a high ICP.
00:42:52
Speaker
I also check a closing pressure.
00:42:54
Speaker
Once I remove CSF, I always check like what was the closing pressure.
00:42:59
Speaker
Mostly it just gives me sort of a sense of like how easy it was to lower the ICP.
00:43:05
Speaker
Um, so opening pressure, crucially important, measure it correctly.
00:43:09
Speaker
Perfect.
00:43:10
Speaker
Other questions.
00:43:11
Speaker
And what about cell count?
00:43:13
Speaker
Yes.
00:43:13
Speaker
So what I typically do is I send cell count from the first tube and from the fourth tube, um, that will allow us to see, you know, a lot of times we have traumatic taps.
00:43:23
Speaker
Um, and what you should see is that the red cell count, you know, is highest in tube one.
00:43:28
Speaker
By the time you get to tube four, you've kind of cleared those red blood cells and you have a, um, a more, um,
00:43:36
Speaker
a more accurate reflection of really what's actually going on in the CSF than just what's going on with some blood mixed in.
00:43:42
Speaker
So I measure cell counts on tube one and tube four.
00:43:45
Speaker
Again, I put at least, I don't know, like two or three cc's in tube one and tube four so they can measure those.
00:43:52
Speaker
Five cells or less is normal if you have no white blood cells.
00:43:57
Speaker
For every about 800 red blood cells, you can get, you buy yourself another one RBC.
00:44:04
Speaker
I'm sorry, one white blood cell.
00:44:05
Speaker
So again, 800 RBCs equals one white blood cell.
00:44:11
Speaker
So if you have, you know, I don't know, 2000 red blood cells and you have, you know, six or seven white blood cells, that's still going to be a normal LP.
00:44:23
Speaker
I'm not going to be terribly concerned about the fact that the white blood cell count was slightly higher.
00:44:30
Speaker
And in terms of differentiating bacterial versus other types, obviously the white count is going to be very important, but anything in the differential important for encephalitis or viral causes?
00:44:42
Speaker
Yeah.
00:44:43
Speaker
So bacterial has like thousands of white blood cells.
00:44:47
Speaker
It's like they're neutrophilic predominant.
00:44:50
Speaker
There's a lot, a lot, a lot of cells.
00:44:52
Speaker
The protein is going to be super elevated.
00:44:54
Speaker
The glucose is going to be super low.
00:44:56
Speaker
Yeah.
00:44:57
Speaker
Often it's like less than 20, less than 10.
00:45:00
Speaker
I mean, it's usually not a subtle decrease in the glucose you're seeing.
00:45:05
Speaker
Viral can have this like, oh, there's like 10 WBCs and they're like lymphocytic predominant and the protein is like 60 and the glucose is pretty normal.
00:45:19
Speaker
Like viral meningitis doesn't have an impressive cell count.
00:45:24
Speaker
Yeah.
00:45:25
Speaker
Fungal meningitis, very elevated protein, also low glucose.
00:45:29
Speaker
So it's sort of, it looks sort of like a bacterial meningitis.
00:45:33
Speaker
Autoimmune and sort of neoplastic causes and other sort of etiologies can have all sorts of weird things going on.
00:45:40
Speaker
Very frequently, they don't have a elevated white count, but they'll have an elevated protein.
00:45:46
Speaker
That gets into the whole separate weeds and probably needs like a neuro consult to help you think through what those LPs look like.
00:45:55
Speaker
What about, so we talked about, and the protein's going to be elevated because of the inflammation.
00:45:58
Speaker
We talked about the glucose, the cell count.
00:46:01
Speaker
What about lactate, Casey?
00:46:04
Speaker
You know, lactate at my institution takes so long to come back that I don't use it.
00:46:09
Speaker
So I can't personally comment on it, although I know that people do, and there has been good evidence the last time I looked into this, which was, I think,
00:46:16
Speaker
like two years ago, that is actually pretty reliable for detecting CSF infections that are bacterial and helpful in terms of differentiating ventriculitis from just like sterile inflammation.
00:46:34
Speaker
So I personally can't comment in great detail just because everywhere I've practiced, it's always been a send out lab and therefore not very helpful and we never used it.
00:46:43
Speaker
Okay.
00:46:43
Speaker
But the idea would be that it would be elevated if it was bacterial.
00:46:46
Speaker
Okay, perfect.
00:46:48
Speaker
So you did mention, obviously, we would send this also for gram stain and culture.
00:46:52
Speaker
And then you did mention the BioFire film array.
00:46:56
Speaker
And just reading here from the Acute Neurology Survival Guide.
00:46:59
Speaker
Mm-hmm.
00:47:02
Speaker
Just to remind our listeners, that would check for bacterial pathogens that include E. coli, hemophilus, influenza, listeria, Neisseria meningititis, strep agalacta, and strep pneumonia.
00:47:16
Speaker
And viral pathogens that include CMV.
00:47:19
Speaker
enterovirus, HSV-1, HSV-2, human herpesvirus 6, human pericuvirus, and varicolusastrovirus, plus it also will check for cryptococcus.
00:47:32
Speaker
So really super, super useful.
00:47:34
Speaker
You cover, I mean, a tremendous amount of pathogens that you'll be worried about with that biofirofilm array.
00:47:40
Speaker
And like you said, it's PCR technology.
00:47:42
Speaker
So even if they receive the antibiotics, this would still be very valuable.
00:47:47
Speaker
Absolutely.
00:47:48
Speaker
One caveat to know is the cryptococcal screen in the biofire is not very accurate.
00:47:52
Speaker
You should use your typical cryptococcal detection.
00:47:55
Speaker
Perfect.
00:47:56
Speaker
And it's also very interesting.
00:47:58
Speaker
I mean, like I guess I'm going to I'm going to age myself, but I started internship in Chicago and we had a whole floor dedicated to HIV and we would do like a boatload of LPs.
00:48:11
Speaker
And by the time I finished, ACT was in place.
00:48:15
Speaker
And two years later, that floor had disappeared.
00:48:19
Speaker
So I guess, I mean, we don't do them as many as we did before for HIV, but still something that we should be considering in the multiple host of immunosuppressed patients that we might see.
00:48:29
Speaker
So for the BioFire, everything else is super specific, right?
00:48:34
Speaker
If it's positive, you should believe it.
00:48:36
Speaker
Yes.
00:48:37
Speaker
Okay, perfect.
00:48:39
Speaker
What about, as we move forward, we talked about imaging in terms of when you get a CT scan to begin with, but there's also some literature about getting MRIs in some situations, and that might be less diagnostic but more prognostic,
Imaging in CNS Infection Diagnosis
00:48:55
Speaker
I guess.
00:48:55
Speaker
What is your use of other imaging as you work with these patients?
00:49:00
Speaker
Yeah.
00:49:01
Speaker
So I think the, the helpful thing with the MRI, um, is that it's going to tell you whether or not there's brain inflammation.
00:49:08
Speaker
You'll see, um, you know, inflammation on the LP.
00:49:12
Speaker
So if they have a high white count, you, you've satisfied that inflammation criteria, but it tells you kind of how much of the meninges inflamed and how globally is it a problem?
00:49:23
Speaker
So with and without gadolinium should always be ordered.
00:49:25
Speaker
So these patients need gadolinium, um, um,
00:49:29
Speaker
I think what I find most helpful about the MRI is that if the patient also has encephalitis, you are getting a regional picture of where the brain tissue is most inflamed.
00:49:42
Speaker
So do you have limbic encephalitis?
00:49:44
Speaker
Do you have cerebrolitis?
00:49:45
Speaker
Do you have a rhomboencephalitis?
00:49:47
Speaker
All of those key characteristics are very helpful in narrowing the differential of what might be causing that inflammation.
00:49:57
Speaker
that inflammation.
00:49:58
Speaker
And then the acute survival guide, what I, we kind of broke down, you know, pathogens that are most likely to cause sort of these regional encephalitis, encephalitis.
00:50:08
Speaker
Um, so that's, that's what I, I find very helpful about the MRI.
00:50:12
Speaker
Again, if your patient's too unstable to go down and get MRI, um, this is not usually like
00:50:19
Speaker
make or break the differential, but it is really kind of crucial in the encephalitic patient who you think has a regional encephalitis.
00:50:30
Speaker
Perfect.
00:50:31
Speaker
And can you make any comments, Casey, on other testing, EEG?
00:50:34
Speaker
I mean, is there a role for brain biopsy or anything else?
00:50:38
Speaker
Yeah.
00:50:39
Speaker
So EEG, very helpful if the patient's altered, especially if they have fluctuating altered consciousness.
00:50:44
Speaker
Our patients with encephalitis, more so than meningitis, get seizures and can have non-convulsive status.
00:50:51
Speaker
So I, you know, for the patient that's altered, I have a very low threshold for using EEG.
00:50:58
Speaker
Brain biopsy, rarely needed in meningitis unless it's a very atypical sort of chronic picture.
00:51:02
Speaker
Yeah.
00:51:05
Speaker
We try not to need biopsy for our patients who are encephalopathic or have suspected encephalitis.
00:51:14
Speaker
This really becomes helpful in the patients who have like lesions in their brain and we don't really know if it's infectious.
00:51:22
Speaker
Maybe they're not super febrile.
00:51:25
Speaker
They're just altered and we have this weird lesion in the brain.
00:51:29
Speaker
And then we're trying to figure out, you know, is this a cancer?
00:51:32
Speaker
Is this autoimmune?
00:51:35
Speaker
Is this a very unusual demyelinating picture?
00:51:39
Speaker
So brain biopsy, not super commonly done.
00:51:44
Speaker
It's really more for the patient who's not acutely sick, but has sort of a more subacute presentation for which the differential is like much wider in terms of what it could be.
00:51:54
Speaker
Perfect.
00:51:55
Speaker
Let's talk about treatment.
00:51:57
Speaker
And as we mentioned, I think throughout the conversation is a time sensitive
Treatment Approaches for CNS Infections
00:52:02
Speaker
issue.
00:52:02
Speaker
And especially when we're thinking of acute bacterial meningitis and acute encephalitis due to herpes at type one, the sooner we get therapy on board, the better the outcomes will be.
00:52:14
Speaker
So why don't you, you mentioned a little bit before, but based on the etiology and if you're seeing this patient and you're trying to figure out if they have a meningitis or encephalitis, where do you start and why?
00:52:27
Speaker
Yeah.
00:52:27
Speaker
So again, I think one of the first things I think about is whether or not I really believe the patient has
00:52:33
Speaker
a bacterial meningitis.
00:52:35
Speaker
If I do, I want to give steroids like as the antibiotics are going in.
00:52:39
Speaker
So the evidence for steroids is really in patients with pneumococcal meningitis and
00:52:46
Speaker
to prevent hearing loss, but it gets generalized to basically preventing inflammation as the bacteria breaks down.
00:52:54
Speaker
So again, if I'm pretty convinced, like, this patient's sick, they look terrible, they have had a high fever, I have no other reason to suspect that they have some other, you know, other reason for their encephalopathy, then I'm probably just going to go ahead and give a slug of tenodecadron as I'm starting antibiotics.
00:53:13
Speaker
The empiric antibiotics you want to use, you want to make sure that you're covering broadly for, you know, gram negatives with ceftriaxone, usually two grams Q8.
00:53:25
Speaker
And then vancomycin in this case is actually covering resistant strains of strep, but you want that on as well.
00:53:32
Speaker
In the patients who are older than 60, starting ampicillin for listeria is also very important.
00:53:38
Speaker
And then you want to get acyclovir on board to cover, you know, possible HSV.
00:53:45
Speaker
So those are the ones that I'm thinking of starting right from the beginning.
00:53:49
Speaker
And those are CNS dosing is higher dosing than your other typical pathogens.
00:53:58
Speaker
Again, you still have some time, even like to the order of hours, maybe two to four hours to get your lumbar puncture without sterilizing the CSF.
00:54:07
Speaker
So, you know, start early, get the blood cultures and then just get those antibiotics as soon as you can get them from the pharmacy.
00:54:15
Speaker
And I think that one of the important aspects of the time-sensitive nature is encephalitis because I have seen or reviewed cases where really there was a delay in starting a Cyclovir, and that could be attributed then to leading to worse outcomes.
00:54:34
Speaker
And like you said, I mean, with encephalitis, a lot of times if we don't have the seizures or it's just altermental status, it might be a little bit more difficult to figure out.
00:54:42
Speaker
So having a very low threshold, I guess, for the acyclovir is very important.
00:54:47
Speaker
Absolutely.
00:54:47
Speaker
Especially with the biofire.
00:54:48
Speaker
Like you can start it, you know, it's nephrotoxic.
00:54:52
Speaker
We don't want to keep it on forever.
00:54:53
Speaker
Start the acyclovir, give them a dose.
00:54:56
Speaker
You're going to get an HSV test and the biofire, both of which can confirm that you don't have HSV.
00:55:02
Speaker
Um, very, very rarely the HSV PCR can be negative early in the course.
00:55:08
Speaker
Um,
00:55:10
Speaker
But it's truly rare that I keep the acyclovir going unless, like, it is a slam dunk.
00:55:17
Speaker
The patient has been altered for two days.
00:55:19
Speaker
They came in with a seizure.
00:55:21
Speaker
Now they've got a fever.
00:55:22
Speaker
That's a really good story for HSV encephalitis.
00:55:26
Speaker
I might keep the acyclovir on and get a second LP two days later to confirm the HSV PCR was negative.
00:55:33
Speaker
But otherwise, the HSV PCR is pretty reliable.
00:55:36
Speaker
Yeah.
00:55:37
Speaker
Excellent.
00:55:38
Speaker
The other question I had, Casey, is in terms of de-escalation or obviously as you get more information, if you grow a pathogen, you would go specific.
00:55:49
Speaker
But what about the steroids?
00:55:50
Speaker
What do you do with the steroids?
00:55:51
Speaker
You said, I mean, if you suspect bacterial, you give them 10 milligrams of DEXA.
00:55:57
Speaker
And then what do you do?
00:55:58
Speaker
Yeah, so I think it's 48 hours of steroids.
00:56:01
Speaker
And I think they give it 10 and then 4 Q6s.
00:56:07
Speaker
for 48 hours and then you stop them.
00:56:09
Speaker
So really not a lot of a downside for the patient there.
00:56:13
Speaker
Is there any role for steroids in non bacterial meningitis?
00:56:16
Speaker
Like if it's encephalitis or something else?
00:56:19
Speaker
like this, certainly not like as hard and fast evidence.
00:56:23
Speaker
I think they can be helpful for patients who are on treatment.
00:56:28
Speaker
So for patients who like for a TB patient, TB meningitis, there's actually some, some data to support that once the patient started on ripe, you actually want to keep them on some steroids while they are getting that initial tuberculosis treatment.
00:56:43
Speaker
For the rest of the time, it's really about brain inflammation.
00:56:46
Speaker
I don't think we have as much evidence for using this, certainly not for viral causes.
00:56:51
Speaker
The vast majority of viral causes are going to be supportive care, and you don't want to tamper down the immune system without giving a drug to help the patient.
00:57:00
Speaker
So I usually limit steroids to bacterial or tuberculosis forms of meningitis.
00:57:09
Speaker
Okay, perfect.
00:57:11
Speaker
Any other ICU considerations that you might want to comment on in these acute meningitis and cephalitis patients?
00:57:18
Speaker
So a lot of them come to us because they're altered and they might be very, very sick.
00:57:21
Speaker
But any other thoughts?
00:57:23
Speaker
Yes.
00:57:24
Speaker
One of the main things that I think everyone should be aware of is the way that patients with bacterial meningitis die is often of acute communicating hydrocephalus.
00:57:35
Speaker
They get all this bacteria in the meninges.
00:57:38
Speaker
They cannot reabsorb their CSF.
00:57:40
Speaker
They develop this sort of global edema and they herniate and die.
00:57:46
Speaker
I am very, very, very aggressive about getting CSF diversion.
00:57:51
Speaker
I'm super lucky in the fact that I work with neurosurgeons who are willing to place an EVD for patients with meningitis.
00:58:00
Speaker
But I think that that's something I've advocated for more strongly since sort of being an intensivist and that I don't think I really appreciate it just as a neurology resident.
00:58:11
Speaker
CSF diversion can be life-saving for these patients.
00:58:14
Speaker
So if you have a patient who's really...
00:58:17
Speaker
altered, very, very sick, has evidence of global cerebral edema on their head CT, I would, you know, escalate quickly if you don't have neurosurgery where you're practicing.
00:58:32
Speaker
I think those are patients that it makes sense to transfer to your nearest neuro ICU hub.
00:58:38
Speaker
Because I think this is one of those things that they don't necessarily need a long time of CSF diversion.
00:58:43
Speaker
Three to five days, just while the antibiotics have a chance to work, can truly be life-saving for these patients.
00:58:49
Speaker
So again, I really think often and I think early about trying to get CSF diversion.
00:58:55
Speaker
That's an excellent point.
00:58:56
Speaker
And I think that also leads to the question, when would you repeat imaging or LP in a patient that you're treating for presumed or for confirmed meningitis or encephalitis?
00:59:09
Speaker
Um, so I think most of the time you don't really need a repeat LP.
00:59:13
Speaker
Um, if, if the patient, I think a lot of this goes clinically.
00:59:18
Speaker
How's the patient doing clinically?
00:59:20
Speaker
If the patient still looks terrible, uh, then repeating imaging, like the next day makes sense to me.
00:59:27
Speaker
Like we, we very frequently repeat head CTs like every day.
00:59:31
Speaker
Um, that patient also probably is the patient that really needs CSF diversion.
00:59:35
Speaker
And so hopefully they're in sort of a, a center that is, as norm is used to caring for these very complicated CNS infections.
00:59:43
Speaker
Um, repeat LPs though, you know, it depends a little bit on what, what the pathology is.
00:59:51
Speaker
Like we talked about those cryptococcal patients, like they have very high ICPs and they need to be temporized with an LP like every three days, maybe every two days.
01:00:00
Speaker
Um, you're right.
01:00:01
Speaker
There was a whole generation that was trained in LPs by that, that subset of patients.
01:00:06
Speaker
Um, and fortunately we don't see those patients as much anymore.
01:00:09
Speaker
Um, so again, a little bit is driven by what the pathogen is, what they're, what they look like.
01:00:16
Speaker
Um, the altered patient, I don't think a head CT hurts to understand, like, are they, are they developing more cerebral edema?
01:00:24
Speaker
Are they progressing to transitorial herniation?
01:00:29
Speaker
Otherwise, you know, mostly I'm just going by sort of what they look like at the bedside.
01:00:34
Speaker
Perfect.
01:00:35
Speaker
And then kind of like the last questions in terms of management, any considerations that you think intensively should be aware of on patients that are on their way out in terms of
Recovery and Long-term Considerations
01:00:46
Speaker
maybe follow-up?
01:00:46
Speaker
I think we're very focused on the ICU.
01:00:49
Speaker
The patient leaves the ICU and we all like high-five each other, but the patient might have a lot of other issues ongoing.
01:00:54
Speaker
Any suggestions of things that we should be aware of or maybe sharing with our patients and their families in terms of needed follow-up and potential complications?
01:01:03
Speaker
Yeah, this is a, for bacterial meningitis, this is a very long recovery process.
01:01:07
Speaker
I mean, the patient will be altered for encephalitis.
01:01:11
Speaker
That patient had brain parenchymal damage done, and they're going to be altered for a really long time.
01:01:16
Speaker
Some of these patients leave the ICU, but they need longer time in LTAC to kind of have a mental status that their airway is protected and they can be safely transitioned off a ventilator.
01:01:26
Speaker
And, you know, I think many of these patients have a have an uncertain sort of what their final recovery is going to be.
01:01:34
Speaker
So just being sensitive to the fact that, you know, families are still even if they're out of the critical care phase, you know, that does not mean that they have recovered to baseline and that recovery to baseline could take a really long time.
01:01:49
Speaker
So I guess one last question that I forgot to ask you, and we did mention encephalitis can be associated with seizures.
01:01:57
Speaker
Obviously, if you identify seizures, you would do an EEG and you would treat that appropriately.
01:02:00
Speaker
But is there any role for prophylactic seizures, Casey?
01:02:03
Speaker
Seizures treatment, sorry.
01:02:05
Speaker
We don't, I mean, we don't have enough evidence to really say, but right now there's no guideline association or like no guideline recommendation for prophylactic in these patients.
01:02:15
Speaker
Again, go by what the patient looks like.
01:02:17
Speaker
If they're altered, get an EEG.
01:02:19
Speaker
If you find seizures, treat the seizures.
01:02:21
Speaker
I don't empirically start them on anti-seizure treatment.
01:02:24
Speaker
Excellent.
01:02:26
Speaker
So I gather the message really is to have a high level of suspicion and a low threshold to start treatment as we figure out what's going
Empiric Treatment Summary
01:02:34
Speaker
on.
01:02:34
Speaker
And the good news is that the things that we can treat
01:02:38
Speaker
and are time sensitive is not a long list.
01:02:41
Speaker
So appropriate empiric antibiotic regimen plus a cyclovir when we suspect encephalitis while we figure things out could probably give the patient the best chance for having a good outcome.
01:02:52
Speaker
As we close the episode, we tend to ask our guests a couple of questions unrelated to the clinical
Personal Insights and Conclusion
01:02:59
Speaker
topic.
01:02:59
Speaker
Would that be okay, Casey?
01:03:01
Speaker
Absolutely.
01:03:02
Speaker
So the first question relates to books.
01:03:04
Speaker
And are there any books that have influenced you significantly or books that you have gifted other people?
01:03:10
Speaker
Can I say my own?
01:03:12
Speaker
Of course.
01:03:12
Speaker
And we'll link that in the podcast.
01:03:14
Speaker
Yes.
01:03:14
Speaker
Yeah.
01:03:15
Speaker
Yeah.
01:03:15
Speaker
No, I, I, this, um, so I, I wrote and edited, I mostly wrote, and then some people contributed other chapters.
01:03:21
Speaker
And so then I became an editor with, um, Sahar Zafar, uh, the acute neurology survival guide.
01:03:29
Speaker
Um, I started the project when I was a resident and then kind of completed it as a fellow.
01:03:33
Speaker
And I truly believe it was like written for like,
01:03:36
Speaker
what do you know if you're just sort of not an expert neurointensivist?
01:03:40
Speaker
And so I've spent an embarrassingly long amount of time in my life working on this book.
01:03:46
Speaker
But I'm really proud of how it turned out.
01:03:48
Speaker
And I think it's a very helpful bedside guide.
01:03:50
Speaker
And it's like really, really, really practical.
01:03:53
Speaker
So it's definitely the book I've gifted most to others because I give it to all the neurology residents.
01:03:57
Speaker
And, you know, we I think it's I think it's really helpful.
01:04:02
Speaker
Yeah, absolutely.
01:04:03
Speaker
And I I have it and I can testify that it's very practical.
01:04:08
Speaker
And I can imagine that people who are dealing with acute neuro patients in the ICU and outside the ICU will find it as a very, very useful resource.
01:04:18
Speaker
Perfect.
01:04:19
Speaker
The second question relates to something you believe to be true in medicine or in life that most other people don't believe or at least don't act like they believe.
01:04:29
Speaker
So I struggle thinking about this.
01:04:32
Speaker
And I think one of the things that I think that people in medicine don't do the best job at is getting enough sleep.
01:04:41
Speaker
I'm actually a very, very big believer in eight hours of sleep.
01:04:46
Speaker
like religiously so.
01:04:48
Speaker
Obviously, as a neurointensivist, I take call, and so sometimes that's not feasible.
01:04:53
Speaker
But I am like rigorously devoted to getting a good night's sleep, and I do think that it makes you more productive and a nicer person.
01:05:00
Speaker
And like I feel that I was so sleep-deprived during training and obviously on the nights that I'm on call that I really do believe that we can feel better if we get a good night's sleep.
01:05:14
Speaker
That is music to my ears.
01:05:16
Speaker
I'm a big believer in sleep as well.
01:05:19
Speaker
And it's very interesting that this is something that I learned later in life and appreciate it.
01:05:24
Speaker
There's a book by Matt Walker, Why We Sleep, that really blew my mind in terms of all the research that associates health issues related to chronic lack of sleep.
01:05:35
Speaker
But most important, I think, Casey, when we're in the ICU, whether it be the neuro ICU or surgical ICU or medical ICU,
01:05:44
Speaker
I see intensivists as high-performing professionals.
01:05:48
Speaker
And every other high-performing professional, whether it be an athlete or other areas, they take their sleep very, very seriously and make it intentional and deliberate to have proper sleep.
01:06:03
Speaker
Yet as clinicians, we have ignored this for a long, long time.
01:06:07
Speaker
And I think it can not only have consequences on our own health, but had an impact on our patients.
01:06:13
Speaker
Absolutely.
01:06:14
Speaker
Co-signed.
01:06:15
Speaker
I believe this too.
01:06:16
Speaker
Excellent.
01:06:17
Speaker
So the last question is, what would you want every intensivist to know?
01:06:20
Speaker
It could be a quote, a fact, or just a thought as we close.
01:06:24
Speaker
Yeah, I think especially for our neuro patients, spending time at the bedside, really doing a thoughtful neurologic exam, checking pupils, pinching their extremities to see how they move.
01:06:35
Speaker
We get a lot of information at the bedside.
01:06:37
Speaker
And it's one of the things that I emphasize to our fellows is like, let's go see the patient.
01:06:41
Speaker
Let's go back to the bedside.
01:06:42
Speaker
You know, it was emphasized to me when I was a trainee and I was sort of like, but like, don't you understand?
01:06:48
Speaker
I also have to go like,
01:06:49
Speaker
look at the EMR and I look, I need to look at the MRI and I need to look at the cell count and I have discharge paperwork to do.
01:06:54
Speaker
And I, I could spend all day sitting behind a computer, but the most important information is almost always at the bedside.
01:07:02
Speaker
I agree, and I think it's something that we tend to do almost like by default and not without a lot of thought and intention.
01:07:10
Speaker
Yet, like you said, there's a lot of findings, especially in the neuro exam, that can be telling to a change in the course of our patient and could actually have an impact on how we treat them.
01:07:21
Speaker
So 100%, I think that's a great place to stop.
01:07:25
Speaker
Casey, thank you so much for sharing your time and expertise with us.
01:07:29
Speaker
I hope to have you back on the podcast to discuss other neurocritical care topics.
01:07:34
Speaker
Thanks for all you do to promote free open access education in medicine.
01:07:39
Speaker
And one last thing is where can people find you on social media?
01:07:45
Speaker
Yes, I'm on Twitter.
01:07:48
Speaker
The name is Casey Albin.
01:07:50
Speaker
It's pretty easy to find.
01:07:52
Speaker
I post still frequently, even in Twitter's demise.
01:07:57
Speaker
So especially posting on behalf of the Continuum Journal, which for those of you who are not in neurology, is this incredible just...
01:08:05
Speaker
Beautiful teaching CME journal that the American Academy of Neurology produces.
01:08:09
Speaker
And so I've done a lot of work with them recently and publicizing some of the cases from those articles.
01:08:16
Speaker
Really great teaching cases.
01:08:17
Speaker
They come with a lot of linked studies and studies.
01:08:21
Speaker
I would highly suggest people check it out.
01:08:23
Speaker
And Sergio, thank you so much for having me.
01:08:25
Speaker
This has been just a delight to talk about a rare but just critically important topic that all ICU providers need to have some level of awareness of.
01:08:35
Speaker
So thank you for having me.
01:08:37
Speaker
Thank you.
01:08:38
Speaker
Take care.
01:08:40
Speaker
Thank you for listening to Critical Matters, a sound podcast.
01:08:44
Speaker
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01:08:50
Speaker
Sound's transforming the way critical care is provided in hospitals across the country.
01:08:54
Speaker
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