Understanding Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH) is characterized by symptoms and signs of unexplained elevated intracranial pressure (ICP) in an alert and awake patient. The condition has potentially devastating effects on vision, headache burden, increased cardiovascular disease risk, sleep disturbance, and depression. 

In this episode, Teshamae Monteith, MD, FAAN speaks with Aileen A. Antonio, MD, FAAN, author of the article “Clinical Features and Diagnosis of Idiopathic Intracranial Hypertension” in the Continuum® June 2025 Disorders of CSF Dynamics issue.

Dr. Monteith is the associate editor of Continuum® Audio and an associate professor of clinical neurology at the University of Miami Miller School of Medicine in Miami, Florida.

Dr. Antonio is an associate program director of the Hauenstein Neurosciences Residency Program at Trinity Health Grand Rapids and an assistant clinical professor at the Michigan State University College of Osteopathic Medicine in Lansang, Michigan.

Additional Resources

Read the article: Clinical Features and Diagnosis of Idiopathic Intracranial Hypertension

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Host: @headacheMD

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Full episode transcript available here

Dr Jones: This is Dr Lyell Jones, Editor-in-Chief of Continuum. Thank you for listening to Continuum Audio. Be sure to visit the links in the episode notes for information about earning CME, subscribing to the journal, and exclusive access to interviews not featured on the podcast.

Dr Monteith: Hi, this is Dr Teshamae Monteith. Today I'm interviewing Dr Aileen Antonio about her article on clinical features and diagnosis of idiopathic intracranial hypertension, which appears in the June 2025 Continuum issue on disorders of CSF dynamics.  Hi, how are you?

Dr Antonio: Hi, good afternoon.

Dr Monteith: Thank you for being on the podcast.

Dr Antonio: Thank you for inviting me, and it's such an honor to write for the Continuum.

Dr Monteith: So why don't you start off with introducing yourself?

Dr Antonio: So as mentioned, I'm Aileen Antonio. I am a neuro-ophthalmologist, dually trained in both ophthalmology and neurology. I'm practicing in Grand Rapids, Michigan Trinity Health, and I'm also the associate program director for our neurology residency program.

Dr Monteith: So, it sounds like the residents get a lot of neuro-ophthalmology by chance in your curriculum.

Dr Antonio: For sure. They do get fed that a lot.

Dr Monteith: So why don't you tell me what the objective of your article was?

Dr Antonio: Yes. So idiopathic intracranial hypertension, or IIH, is a condition where there's increased intracranial pressure, but without an obvious cause. And with this article, we want our readers---and our listeners right now---to recognize that the typical symptoms and learning about the IIH diagnostic criteria are key to avoiding errors, overdiagnosis, or sometimes even misdiagnosis or underdiagnosis. Thus, we help make the most of our healthcare resources. Early diagnosis and management are crucial to prevent disability from intractable headaches or even vision loss, and it's also important to know when to refer the patients to the appropriate specialists early on.

Dr Monteith: So, it sounds like your central points are really getting that diagnosis early and managing the patients and knowing how to triage patients to reduce morbidity and complications. Is that correct?

Dr Antonio: That is correct and very succinct, yes.

Dr Monteith: And so, are there any more recent advances in the diagnosis of IIH?

Dr Antonio: Yes. And one of the tools that we've been using is what we call the optical coherence tomography. A lot of people, neurologists, physicians, PCP, ER doctors; how many among those physicians are well-versed in doing an eye exam, looking at the optic disc? And this is a great tool because it is noninvasive, it is high resolution imaging technique that allows us to look at the optic nerve without even dilating the eye. And we can measure that retinal nerve fiber layer, or RNFL; and that helps us quantify the swelling that is visible or inherent in that optic nerve. And we can even follow that and monitor that over time. So, this gives us another way of looking at their vision and getting that insight as to how healthy is their vision still, along with the other formal visual tests that we do, including perimetry or visual field testing. And then all of these help in catching potentially early changes, early worsening, that may happen; and then we can intervene more easily.

Dr Monteith: Great. So, it sounds like there's a lot of benefits to this newer technology for our patients.

Dr Antonio: That is correct.

Dr Monteith: So, I read in the article about the increased incidence of IIH, and I have to say that I completely agree with you because I'm seeing so much of it in my clinic, even as a headache specialist. And I had a talk with a colleague who said that the incidence of SIH and IIH are similar. And I was like, there's no way. Because I see, I can see several people with IIH just in one day. That's not uncommon. So, tell me what your thoughts are on the incidence, the rising incidence of IIH; and we understand that it's the condition associated with obesity, but it sounds like you have some other underlying drivers of this problem.

Dr Antonio: Yes, that is correct. So, as you mentioned, IIH tends to affect women of childbearing age with obesity. And it's interesting because as you've seen that trend, we see more of these IIH cases recently, which seem to correlate with that rising rate of obesity. And the other thing, too, is that this trend can readily add to the burden of managing IIH, because not only are we dealing with the headaches or the potential loss of vision, but also it adds to the burden of healthcare costs because of the other potential comorbidities that may come with it, like cardiovascular risk factors, PCOS, and sleep apnea.

Dr Monteith: So why don't we just talk about the diagnosis of IIH?

Dr Antonio: IIH, idiopathic intracranial hypertension, is also called pseudotumor cerebri.  It’s essentially a condition where a person experiences increased intracranial pressure, but without any obvious cause. And the tricky part is that the patients, they're usually fully awake and alert. So, there's no obvious tumor, brain tumor or injury that causes the increased ICP. It's really, really important to rule out other conditions that might cause these similar symptoms; again, like brain tumors or even the cerebral venous sinus thrombosis. Many patients will have headaches or visual disturbances like transient visual obscurations---we call them TVOs---or double vision or diplopia. The diplopia is usually related to a sixth nerve palsy or an abducens palsy. Some may also experience some back pain or what we call pulsatile tinnitus, which is that pulse synchronous ringing in their ears. The biggest sign that we see in the clinic would be that papilledema; and papilledema is a term that we only use, specifically use, for those optic nerve edema changes that is only associated with increased intracranial pressure. So, performing of endoscopy and good eye exam is crucial in these patients. We usually use the modified Dandy criteria to diagnose IIH. And again, I cannot emphasize too much that it's really important to rule out other secondary causes to that increased intracranial pressure. So, after that thorough neurologic and eye evaluation with neuroimaging, we do a lumbar puncture to measure the opening pressure and to analyze the cerebrospinal fluid.

Dr Monteith: One thing I learned from your article, really just kind of seeing all of the symptoms that you mentioned, the radicular pain, but also- and I think I've seen some papers on this, the cognitive dysfunction associated with IIH. So, it's a broader symptom complex I think than people realize.

Dr Antonio: That is correct.

Dr Monteith: So, you mentioned TVOs. Tell me, you know, if I was a patient, how would you try and elicit that from me?

Dr Antonio: So, I would usually just ask the patient, while you're sitting down just watching TV---some of my patients are even driving as this happens---they would suddenly have these episodes of blacking out of vision, graying out of vision, vision loss, or blurred vision that would just happen, from seconds to less than a minute, usually. And they can happen in one eye or the other eye or both eyes, and even multiple times a day. I had a patient, it was happening 50 times a day for her. It's important to note that there is no pain associated with it most of the time. The other thing too is that it's different from the aura that patients with migraines would have, because those auras are usually scintillating and would have what we call the positive phenomena: the flashing lights, the iridescence, and even the fortification that they see in their vision. So definitely TVOs are not the migraine auras. Sometimes the TVOs can also be triggered by sudden changes in head positions or even a change in posture, like standing up quickly. The difference, though, between that and, like, the graying out of vision or the tunneling vision associated with orthostatic hypotension, is that the orthostatic hypotension would also have that feeling of lightheadedness and dizziness that would come with it.

Dr Monteith: Great. So, if someone feels lightheaded, less likely to be a TVO if they're bending down and they have that grain of vision.

Dr Antonio: That is correct.

Dr Monteith: Definitely see patients like that in clinic. And if they have fluoride IIH, I'm like, I'll call it a TVO; if they don't, I’m like, it's probably more likely to be dizziness-related. And then we also have patient migraines that have blurriness that's nonspecific, not necessarily associated with aura. But I think in those patients, it's usually not seconds long, it's usually probably longer episodes of blurriness. Would you agree there, or…?

Dr Antonio: I would agree there, and usually the visual aura would precede the headache that is very characteristic of their migraine, very stereotypical for their migraines. And then it would dissipate slowly over time as well. With TVOs, they're brisk and would not last, usually, more than a minute.

Dr Monteith: So, why don't we talk about routine imaging? Obviously, ordering an MRI, and I read also getting an MRV is important.

Dr Antonio: It is very important because, one: I would say IIH is also a diagnosis of exclusion. We need to make sure that the increased ICP is not because of a brain tumor or not because of cerebral venous sinus thrombosis. So, it's important to get the MRI of the brain as well as the MRV of the head.

Dr Monteith: Do you do that for all patients’ MRV, and how often do you add on an orbital study?

Dr Antonio: I usually do not add on an orbital study because it's not really going to change my management at that point. I really get that MRI of the brain. Now the MRV, for most of my patients, I would order it already just because the population that I see, I don't want to lose them. And sometimes it's that follow-up, and that is the difficult part; and it's an easy add on to the study that I'm going to order. Again, it depends with the patient population that you have as well, and of course the other symptoms that may come with it.

Dr Monteith: So, why don't we talk a little bit about CSF reading and how these set values, because we get people that have readings of 250 millimeters of water quite frequently and very nonspecific, questionable IIH. And so, talk to me about the set value.

Dr Antonio: Right. So, the modified Dandy criteria has shown that, again, we consider intracranial pressure to be elevated for adults if it's above 250 millimeters water; and then for kids if it's above 280 millimeters of water. Knowing that these are taken in the left lateral decubitus position, and assuming also that the patients were awake and not sedated during the measurement of the CSF pressure. The important thing to know about that is, sometimes when we get LPs under fluoroscopy or under sedation, then these can cause false elevation because of the hypercapnia that elevated carbon dioxide, and then the hypoventilation that happens when a patient is under sedation.

Dr Monteith: You know, sometimes you see people with opening pressures a little bit higher than 25 and they're asymptomatic. Well, the problem with these opening pressure values is that they can vary somewhat even across the day. People around 25, you can be normal, have no symptoms, and have opening pressure around 25- or 250; and so, I'm just asking about your approach to the CSF values.

Dr Antonio: So again, at the end of the day, what's important is putting everything together. It's the gestalt of how we look at the patient. I actually had an attending tell me that there is no patient that read the medical textbook. So, the, the important thing, again, is putting everything together. And what I've also seen is that some patients would tell me, oh, I had an opening pressure of 50. Does that mean I'm in a dire situation? And they're so worried and they just attach to numbers. And for me, what's important would be, what are your symptoms? Is your headache, right, really bad, intractable? Number two: are you losing vision, or are you at that cusp where your optic nerve swelling or papilledema is so severe that it may soon lead to vision loss? So, putting all of these together and then getting the neuroimaging, getting the LP. I tell my residents it's like icing on the cake. We know already what we're dealing with, but then when we get that confirmation of that number… and sometimes it's borderline, but this is the art of neurology. This is the art of medicine and putting everything together and making sure that we care and manage it accordingly.

Dr Monteith: Let's talk a little bit about IIH without papilledema.

Dr Antonio: So, let's backtrack. So, when a patient will fit most of the modified Dandy criteria for IIH, but they don't have the papilledema or they don't have abducens palsy, the diagnosis then becomes tricky. And in these kinds of cases, Dr Friedman and her colleagues, when they did research on this, suggested that we might consider the diagnosis of IIH. And she calls this idiopathic intracranial hypertension without papilledema, IIHWOP. They say that if they meet the other criteria for modified Dandy but show at least three typical findings on MRI---so that flattening of the posterior globe, the tortuosity of the optic nerves, the empty sella or the partially empty sella, and even the narrowing of the transverse venous sinuses---so if you have three of these, then potentially you can call these cases as idiopathic intracranial hypertension without papilledema.

Dr Monteith: Plus, the opening pressure elevation. I think that's key, right? Getting that as well.

Dr Antonio: Yes. Sometimes IIHWOP may still be a gray area. It's a debate even among neuro-ophthalmologists, and I bet even among the headache specialists.

Dr Monteith: Well, I know that I've had some of these conversations, and it's clear that people think this is very much overdiagnosed. So, that's why I wanted to plug in the LP with that as well.

Dr Antonio: Right. And again, we have not seen yet whether is, this a spectrum, right? Of that same disease just manifesting differently, or are they just sharing a same pathway and then diverging? But what I want to emphasize also is that the treatment trials that we've had for IIH do not include IIHWOP patients.

Dr Monteith: That is an important one. So why don't you wrap this up and tell our listeners what you want them to know? Now's the time.

Dr Antonio: So, the- again, with IIH, with idiopathic intracranial hypertension, what is important is that we diagnose these patients early. And I think that some of the issues that come into play in dealing with these patients with IIH is that, one: we may have anchoring bias. Just because we see a female with obesity, of reproductive age, with intractable headaches, it does not always mean that what we're dealing with is IIH. The other thing, too, is that your tools are already available to you in your clinic in diagnosing IIH, short of the opening pressure when you get the lumbar puncture. And I need to emphasize the importance of doing your own fundoscopy and looking for that papilledema in these patients who present to you with intractable headaches or abducens palsy. What I want people to remember is that idiopathic intracranial hypertension is not optic nerve sheath distension. So, these are the stuff that you see on neuroimaging incidentally, not because you sent them, because they have papilledema, or because they have new headaches and other symptoms like that. And the important thing is doing your exam and looking at your patients.

Dr Monteith: Today, I've been interviewing Dr Aileen Antonio about her article on clinical features and diagnosis of idiopathic intracranial hypertension, which appears in the most recent issue of Continuum on disorders of CSF dynamics. Be sure to check out Continuum Audio episodes from this and other issues, and thank you to our listeners for joining today. Thank you again.

Dr Antonio: Thank you.

Dr Monteith: This is Dr Teshamae Monteith, Associate Editor of Continuum Audio. If you've enjoyed this episode, you'll love the journal, which is full of in-depth and clinically relevant information important for neurology practitioners. Use the link in the episode notes to learn more and subscribe. AAN members, you can get CME for listening to this interview by completing the evaluation at continpub.com/audioCME. Thank you for listening to Continuum Audio.