Assessing and Monitoring Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH), a condition of increased intracranial pressure (ICP), causes debilitating headaches and, in some, visual loss. The visual defects are often in the periphery and not appreciated by the patient until advanced; therefore, monitoring visual function with serial examinations and visual fields is essential.

In this episode, Kait Nevel, MD speaks with John J. Chen, MD, PhD, and Susan P. Mollan, MBChB, PhD, FRCOphth, authors of the article “Treatment and Monitoring of Idiopathic Intracranial Hypertension” in the Continuum® June 2025 Disorders of CSF Dynamics issue.

Dr. Nevel is a Continuum® Audio interviewer and a neurologist and neuro-oncologist at Indiana University School of Medicine in Indianapolis, Indiana.

Dr. Chen is a professor of ophthalmology and neurology at the Mayo Clinic in Rochester, Minnesota.

Dr. Mollan is an honorary professor of metabolism and systems science in the department of neuro-ophthalmology at University Hospitals Birmingham in Birmingham, United Kingdom.

Additional Resources

Read the article: Treatment and Monitoring of Idiopathic Intracranial Hypertension

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Host: @IUneurodocmom

Guests: @chenmayo, @DrMollan

Full episode transcript available here

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

Dr Nevel: Hello, this is Dr Kate Nevel. Today, I'm interviewing Drs John Chen and Susan Mollan about their article on treatment and monitoring of idiopathic intracranial hypertension, which appears in the June 2025 Continuum issue on disorders of CSF dynamics. Drs Chen and Mollan, welcome to the podcast. And please, could you introduce yourselves to the audience?

Dr Chen: Hello, everyone. I'm John Chen, one of the neuro-ophthalmologists at the Mayo Clinic. Thanks for having us here.

Dr Mollan: Yeah, it's great to be with you here. I'm Susan Mollan. I'm a consultant neuro-ophthalmologist in Birmingham, England.

Dr Nevel: Wonderful. So great to have you both here today, and our listeners. To start us off, talking about your article, can you share with us what you think is the most important takeaway from your article for the practicing neurologist out there?

Dr Chen: Yeah, so our article talked about the treatment and monitoring of IIH. And I think one takeaway point is, IIH is becoming much more prevalent now that there's this worldwide obesity epidemic with obesity having- essentially being the largest risk factor for IIH other than female. It's really important to monitor vision because vision loss is often peripheral vision loss at first, which the patient may be completely unaware of. And so, it's important to pair up with an ophthalmologist so you can monitor the papilledema of the visual fields and make sure they don't get permanent vision loss. And in the article, we also talk about- there's been changes in the treatment of severe IIH, where traditionally, we used VP shunts; but there's been a trend toward using more venous sinus stenting in addition to the traditional surgeries.

Dr Nevel: Great, thank you. I think probably most of our listeners or a lot of neurologists out there have a pretty good understanding of kind of the basics of the IIH. But can you kind of just go over a few key characteristics of IIH, and maybe some things that are less commonly known or things that are maybe just been kind of better understood over the past decade, perhaps?

Dr Mollan: Yes, certainly. I think, as Dr Chen said, it's because this condition is becoming more prevalent, people recognize it. I think it's- we like to go back to the diagnostic criteria so that we're making a very accurate diagnosis. So, the patients may come in to the emergency room with, say, papilledema that's been identified elsewhere or crashing headaches. And it's important to go through that sort of diagnostic pathway, taking a blood pressure, taking a full blood count to make sure the patient is anemic, and then moving forward with that confirmation of papilledema into urgent neuroimaging, whether it's CT or MRI, but including venography to exclude a venous sinus thrombosis. And then if you have no structural lesion that's causing the raised ICP, it's moving forward with your lumbar puncture and carefully checking those pressures. But the patients may not only have crashing headache, they often have pulsatile tinnitus and neck pain. I think some of the features that we're now recognizing is the systemic metabolic effects that are unique to IIH. And so, there's an increased risk of cardiometabolic disease that's over and above what is conferred by obesity. Also, our patients have a sort of maternal health burden where they get impaired fertility, gestational diabetes and preeclampsia. And there's also an associated mental health burden, amongst other things. So we're really starting to understand the spectrum of the disease a bit more.

Dr Nevel: Yeah, thank you for that. And that really struck me in your article, how important it is to be aware of those things so that we're making sure that we're managing our whole patient and connecting them with the appropriate providers for some of those other issues that may be associated. For the practicing neurologist out there without all the neuro-ophthalmology equipment, if you will, what should our bedside exam focus on to help us get maybe an early but accurate picture of the patient's visual function when we suspect IIH to be at play, perhaps before they can get in with the neuro-ophthalmologist?

Dr Chen: Yeah, I think at the bedside you can still check visual acuity and confrontational visual fields, you know, with finger counting. Of course, you have to know that those are, kind of, crude kind of ways of screening. With papilledema, oftentimes the visual acuity is intact. And the confrontational visual fields aren't as sensitive as automated perimetry. Another important thing will be to do your direct ophthalmoscope and look at the amount of papilledema. If it's grade one or two papilledema on the more mild side, it's actually not vision threatening. It's the higher degrees of papilledema that can cause rapid vision loss. And so, if you look in and you see grade one papilledema, obviously you need to do the full workup, the MRI, MRV, lumbar puncture. But in terms of rapidly getting to an ophthalmologist to screen for vision loss, it's not going to be as important because you're not going to have vision loss at that low grade. If you look in and you see this rip-roaring papilledema, grade five papilledema, that patient is going to be at very severe risk of vision loss. So, I think that exam, looking at the optic nerve can be very helpful. And of course, talking to the patient about symptoms; is there decreased vision Is there double vision from a sixth nerve palsy? Are there transient visual obscurations which would indicate at least a higher degree of papilledema? That'd be helpful as well.

Dr Nevel: Great, thank you. And when the patient does get in with a neuro-ophthalmologist, you talk in your article and, of course, in clinical practice, how OCT testing is important to monitor in this condition. Can you provide for the listeners the definition of OCT and how it plays a role in monitoring patients with IIH?

Dr Mollan: Sure. So, OCT is short for optical coherence tomography imaging, and really the eye has been at the forefront of OCT alone. Our sort of cardiology colleagues are catching up on the imaging of blood vessels. But what it allows us to do is give us really good cross-sectional, anatomical-level changes that we can see both in the retina and also at the optic nerve head. And it gives us some really good measurements. It's not so good at sort of saying, is this definitely papilledema or not? That sort of lower end of disc elevation. But it is very good at ruling out what we call the pseudopapilledema. So, things like drusens or these other little masses we find underneath the optic nerve head. But in terms of monitoring, because we can longitudinally take these images and the reproducibility is pretty good at the optic nerve head, it allows us to see whether there's direct changes: either the papilledema getting worse or the papilledema getting better at the optic nerve head. It also gives us some indication of what's going on in the ganglion cell layer complex. And that can be helpful when we're thinking about sort of looking at structure versus function. So, ophthalmologists in general, we love OCT; and we spend much more time nowadays looking at the OCT than we really do the back of the eye. And it's just become critical for patients with papilledema to be able to be very accurate from visit to visit to see what's changing.

Dr Nevel: How do you determine how frequently somebody needs to see the neuro-ophthalmologist with IIH and how often they need that OCT evaluation?

Dr Chen: Once the diagnosis of IIH is made, how often they need to be seen and how frequent they need to be seen depends on the degree of papilledema. And again, OCT is really nice. You can quantify it and then different providers can actually use the same OCT numbers, which is super helpful. But again, if it's grade three papilledema or higher, or article thickness of 200 or higher, I tend to follow them a little bit more closely, trying to treat them more aggressively. Try to get the papilledema down into a safer zone. If it's grade one or two papilledema, we see them less frequently. So, my first visit might be three months out. They come with grade five papilledema, I'm seeing them within a few days to make sure that's papilledema’s come down quickly because we're trying to decide, are they going to need surgery or not?

Dr Nevel: Yeah, great. And that's a nice segue into talking a little bit about how we treat patients with IIH after the diagnosis is confirmed. And I'd like to just point out you have a very lovely figure in your article---Figure 5-6,---that I'd like to direct our listeners to read your article and check out that figure, which is kind of an algorithm on how we think about the various treatment options for patients who have IIH, which seems to rely a lot on the degree of presence of papilledema and the presence of vision disturbance. Could you maybe walk us through a little bit about how you think about the different treatment options for patients with IIH and when more urgent surgical intervention might be indicated?

Dr Mollan: Yeah, sure. We always find it quite hard in any medical specialty to write these kind of flow diagrams because it's really an individual we're looking at. But these are kind of what we’d say is “broad brushstrokes” into those patients that we worry about, sort of, red disease in those patients, more amber disease. Now obviously, even those patients that may not have severe papilledema, they may have crashing headaches. So, they may be an urgent referral themselves because of that. And so, it's nice to try and work out which end of the spectrum you're working with. If we think of the papilledema, Dr Chen's already laid out the sort of lower end of the prison's scale---our grades one, our grades two---that we're less anxious about. And those patients, we would definitely be having discussions about medical management, which includes acetazolamide therapy; but also thinking about weight management. And it may well be that we talk a little bit further about weight management, but I think it's helpful to sort of coach those conversations after you've made a definite diagnosis. And then laying out the risk that's caused, potentially, the IIH in an individual. And then having a sort of open conversation with them about what changes they can have in their lifestyle alongside thinking about medical therapy. There’s some patients with very low levels of papilledema that we decide not to put on medicines initially.

As patients progress up that papilledema grade, we're definitely thinking about medical therapy. And our first line from the IIH treatment trial would be using acetazolamide, but we need to be thinking about using appropriate dosing. So, a lot of the patients that I see can be sent to me with very low doses that may be inappropriate for that person. In the IIHTT they used up to four grams daily in a divided dose. And you do need to counsel your patients when you're putting them on acetazolamide because of the side effects. You've got quite a nice table in this article about the side effects. I think if you get the patient on board, that they understand that they will experience side effects, that is helpful because they will expect it, and then possibly tolerate it a bit better. Moving through to that area where we're more anxious, that visual-threatening papilledema. As Dr Chen said, it's sort of like you look in and it's sort of “blood and thunder” in there. And you need to be getting on and encouraging the ophthalmologist to get a formal assessment of the visual field. It's very difficult to determine exactly the level at which- and we talk about the mean deviation in a lot of our research studies. But in general, it's a combination of things: the patient's journey to get to you, their symptoms, what's going on with the visual field, but what's also happening at the OCT. So, we look in and we see that fluid is seeping towards the fovea. We get very anxious, and those patients may not even have enough time for a rapid escalation of acetazolamide. It may well be at the first presentation, which we would term, like, fulminant; that we'd be thinking about surgical intervention. And I think before I stop, the other thing to say is, the surgical landscape is really changing. So, we're having some good studies coming out in terms of stenting. And so, there is a sort of bracket where it may well be that we are thinking about neuroradiological intervention in an earlier case. They may not quite be at that visual-threatening stage, but they may be resistant to medical treatments.

Dr Nevel: Thank you for that. What do you think is a potential pitfall or a mistake to avoid, if you will, in the management of patients with IIH?

Dr Chen: I think it's- in terms of pitfalls, I think the potential pitfalls I've seen are essentially patients where we don't necessarily create a good patient physician relationship. Where they don't have buy-ins on the treatment, they don't have buy-ins to come back, and they're lost to follow-up. And these patients can be dangerous, because they could have vision threatening papilledema and if not getting the appropriate treatment---and if they're not monitoring the vision---this can lead to poor outcomes. So, I've definitely seen that happen. As Dr Mollan said, you really have to tell them about the side effects from the medications. If you just take acetazolamide, letting them know the paresthesias and the changes in taste and some of these other side effects, they're going to immediately stop the medication. Again, and these medications do work, proven in the IIH treatment trial. So again, I think that patient-physician relationship is very important to make sure they have appropriate follow up.

Dr Nevel: The topic of weight loss in this patient population can be tricky, and I know I talked with Susie in a prior interview about how to approach this topic with our patients in a sensitive and compassionate manner. Once this topic is broached, I find many patients are looking for advice on strategies for weight loss, or potentially medications or other interventions. How do you prioritize or think about the different weight loss strategies or treatments with your patients, and how do you think about the way that you recommend these different treatments or not?

Dr Mollan: Yeah. I think that's a really great question because we sort of stray here into a specialty that we have not been trained in. One thing I definitely ask my patients: if they've been on a weight loss journey before, and what's worked for them and what's not worked for them. And within our different healthcare systems, we have access to different tiers of weight management approaches. But for the person sitting in front of me, that possibly there may be a long journey to access more professional care, it's about understanding. iIs there things that are free, such as, we have some apps in the National Health Service which are weight management applications where they can actually just start putting in their calories, their daily calorie intake. And those apps can be quite helpful and guiding in terms of targeting areas, but also informing the patient of what types of foods to avoid in their diet and what types of foods to include in their diet. And with some of the programs that are completely complementary, they also sometimes add on things about exercise. But I think it is a really difficult thing to manage as, say, an ophthalmologist or a neurologist, mainly because it's not our area of expertise. And I think we've all got to find, in our local hospitals and healthcare systems, those pathways where the patients may be able to access nutritional support, and sort of behavioral lifestyle therapy support, all the way through to the new medications for weight loss; and also for some people, bariatric surgery pathways. It's a tricky topic.

Dr Nevel: So how should we counsel our patients about what to expect in the future in terms of visual outcomes?

Dr Chen: I think a lot of that depends on the degree of papilledema when they present. If a patient comes in with grade five papilledema, that fulminant IIH that Dr Mollan had mentioned, these patients can have very severe vision loss. And even if we treat them very aggressively with high-dose medications and urgent surgical interventions, sometimes they can have permanent vision loss. And so, we counsel them that, you know, there's a strong chance that they're going to have a good amount of vision loss. But some patients, we're very surprised and we get a lot of vision back. So, we kind of set expectations, but we're cautiously optimistic that we can get vision back. If a patient presents with more mild papilledema like grade one or two papilledema, they're most likely not going to have any permanent vision loss as long as we're treating them, we're monitoring their vision, they're coming to their follow-ups. They tend to do very well from a vision perspective.

Dr Nevel: That's great, thank you. And you know, ties into what you said earlier about really making sure that, you know, we create good- as with any patient, but good physician-patient relationships so that they, you know, trust us and they come to follow up so we can really monitor their vision appropriately. What do you think is going on in research in this area that's exciting? What do you think one of the next breakthroughs or thing that we need to understand the most about treatment and monitoring of IIH?

Dr Chen: I think surgically, venous sinus stenting is going to probably take over the bulk of surgeries. We still need that randomized clinical trial, but we have some amazing outcomes with venous sinus stenting. And there's many efforts on randomized clinical trials for venous sinus stenting. So we'll have those results soon. From a medical standpoint, Dr Mollan can actually say, actually, more about this.

Dr Mollan: I completely agree. The GLP-1 receptor agonists, the twofold prong approach: one is the weight loss where these patients, you know, have significant weight loss to put their disease into remission; and the other side of it is whether certain GLP-1s have the ability to reduce intracranial pressure. So, a phase 2 study that we undertook here in Birmingham did show that we were able to reduce intracranial pressure, but we don't think it's a class effect. So, I think the sort of big breakthrough will be looking at novel therapies like xenotide and other drugs that, say, work on the proximal kidney tubule. Are they able to reduce intracranial pressure directly? And I think we are on the cusp of a real breakthrough for this disease.

Dr Nevel: Great. Thank you so much for chatting with me today. And I really learned a lot, appreciated the opportunity. I hope our listeners learned something today, too. So again, today I've been interviewing Drs John Chen and Susan Mollan about their article on treatment and monitoring 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 us today.

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.