 Good morning, everybody. My name is Jeff Nadel. I'm one of the neurosurgery interns. I'm here to give you grand rounds this morning about a topic that was relevant to me and that I saw a lot of in my time with you all on a neuro-octomology rotation last month, the surgical management of idiopathic intracranial hypertension. So I have no financial disclosures to report to you. I think most residents probably are absent of those. So in an overview for my talk, I'll give you a brief introduction into IIH, indications for surgical intervention and IIH, and then discuss a little bit about each of the surgical modalities that are in use for IIH and each of their supporting data, and then we'll conclude and have a moment for questions. So in order to talk a little bit about IIH, IIH is defined as an objectively measured increased ICP with no evidence of other source for the increased ICP, including mass lesion, evidence of hydrocephalus, as well as normal CSF studies. It's important too that the ICP is measured with somebody in the lateral decubitus position because the sitting position is not appropriate in order to actually get an accurate ICP rating. In terms of the etiology, it's still not super well understood exactly what is happening with IIH. It's a little bit of a chicken and an egg problem. Some suggest that there may be some sort of a cranial venous outflow pathology that results in a high ICP, which in turn the high ICP can worsen the venous outflow pathology by compressing veins, and this cycle just continues. On the other side, there may be some other reason that the ICP is elevated, which leads to what is often seen as venous outflow pathology, which then in turn worsens ICP. So it's a little bit hard to understand exactly what is going on with it. But why it matters, especially to ophthalmologists, is that the elevated ICP can result in papillodema, which can result in threatened vision, and that's often times when neurosurgery gets involved with these patients. And so in terms of the mainstay of therapy for IIH, I'm not gonna talk extensively about it, but medical management is how most patients with IIH are managed. The goals of treatment are alleviation of the symptoms, which includes the typical pressure headaches, as well as preservation of visual function for as long as possible, to try to prevent folks from having constricted fields and going blind. Standard medical therapies just briefly include carbonic anhydrase inhibitors, such as DIAMOX, the IIH treatment trial demonstrated benefit of the cytosolamide over placebo and improving visual outcomes. And so most folks are started on that standardly. There are other medications that are used if folks are not responding well to DIAMOX or have intolerable side effects. There are also other important adjuncts, including weight loss, other types of symptomatic headache control, and others. But if visual function continues to deteriorate despite optimized medical management, then surgical interventions become warranted, and that's where I'd like to focus on my talk today. So the first and type of surgical intervention that is often offered for idiopathic intracranial hypertension is optic nerve sheath fenestration. This is favored and is usually first-line surgical treatment, and it has been shown to prevent deterioration in vision and in some cases actually improve people's vision. Data shows that headaches also improve in about half of folks, which is an added benefit, and it's performed by ophthalmologists. And so I'm not gonna talk any further about that because the likelihood of me being able to teach you something about optic nerve sheath fenestration is exceedingly low. So we'll move on to something that I see a lot more of, which is CSF diversion and shunt placement. So there are multiple modalities for which folks can undergo CSF diversion. That includes ventricular perineal shunts and lumbo perineal shunts. Lumbo perineal shunts tended to be performed more commonly in the past, and I think folks are tending to favor ventricular perineal shunts at this point. This is just a diagram that shows a typical ventricular perineal shunt catheter, where you have a proximal catheter that's inserted into generally the lateral ventricle around the third ventricle, attached to a valve that controls the outflow of that CSF, and then a catheter that is tunneled underneath the neck, usually into the abdomen. So there are a number of complications, though, of folks undergoing shunt surgery. Shunt failure is a perpetual problem that we as neurosurgency all the time, most often from obstruction of the shunt, whether that's CSF debris or another cause. An additional problem is over-drainage and low pressure headaches that can actually result from shunting. VP shunts, you can place adjustable drainage valves. You can for lumbo perineal shunts, although it's not done quite as commonly, and lumbo perineal shunts are actually no longer favored quite as much because of a two-and-a-half fold increase in the need for revision compared to VP shunts. Often that happens because you can imagine folks, if that shunt is inserted right here around the flank, so with bending the shunts tend to kink, they tend to obstruct much more readily than a catheter that's coming down through the neck and going over the chest wall, which has a lot less mobility associated with it. Anytime we do surgery, there's a risk of infection, and certainly seeding an implant is a big problem, so shunt infections can cause big problems for patients. Bowel injury if we place the intraparentineal catheter in the wrong place. And importantly, there's a high failure rate due to the fact that these shunts are actually not designed for treatment of IIH, they're designed for treatment of hydrocephalus, and so it's important to consider that when thinking about CSF diversion. In aggregate, the data shows that the majority of folks who have IIH who do get CSF diversion through shunting do experience immediate headache reduction, although there's recurrence of those headaches over time. About 20% will recur, headaches will recur at 12 months, and then at three years, almost half of people will have return of headaches, usually not quite as severely, but that can happen. In addition, papillodema is improved and resolved in a lot of these patients. The amount of time that it takes for that papillodema to improve or resolve is variable based on the patient, and sometimes folks don't have any improvement in their papillodema. And in addition, visual fields were shown in several studies to return to normal or at least be improved in about two-thirds of patients, but a third remained stable from where they were previously. Here at the University of Utah, one of our neurosurgeons has actually begun to pioneer a new technique for the treatment of IIH with CSF diversion, this is Dr. Richard Schmidt, who's been putting in five ventricular shunts for folks with IIH. They are the proximal shunt catheters are actually tunneled outside of the head and connected to a single valve, so they're draining together at the same rate. And they recently published a paper actually in the Journal of Neurosurgery, which showed fewer shunt-related complications, and as well as those when compared to a unilateral VP shunt system, folks had better headache control, there was more subjective visual improvement in better papillodema resolution. So we're seeing increasing numbers of folks who are undergoing that. The last surgical intervention that I'd like to talk a little bit about is not favored, especially here, and is somewhat newer, and that's Dural-Venus sinus sensing. And so I talked a little bit about how the pathophysiology of IIH is thought to involve venous outflow in some capacity. And one of the findings that we oftentimes see in folks who have IIH is narrowing of the venous sinuses, especially at the transverse sigmoid junction. And in fact, now folks who have imaging that demonstrates that, those venous changes on imaging are recognized as nearly confirmatory of elevated ICP in these people. The method for Dural-Venus sinus sensing is endovascular, and so you tend to get access through the groin or through the wrist and snake a catheter up in to the, through the venous system rather than the arterial system up into the venous sinuses. You can measure the venous sinus pressure as well as deploy a stent and then measure the pressure after the stent. And the results, though, have been quite variable. Headaches only variably improve with this technique. Vision only variably improves. A lot of folks remain stable. There's actually a lot of complications that are associated with venous sinus stenting, including access site bleeding, intracranial bleeding, and probably most concerning stent occlusion. Folks will need to remain on antiplatelet therapy to prevent stent occlusion, and stent occlusion can be pretty drastic and have big time effects for folks. In terms of choosing to do something like this, people will need to have sinus stenosis, which not everybody does, and kind of getting back to the chicken and the egg problem, does it really work? We're not 100% sure at this point because the results have been so variable. And so in conclusion, for IIH that is not completely or appropriately managed with medical intervention, there's a number of surgical modalities that can be considered. Those include optic nerve sheath fenestration, which tends to be the first line that I've seen here, followed by CSF diversion with shunting. Fewer folks are interested in venous sinus stenting, but I think additional data will come out in the coming years about how it works and whether it works. So I'd just like to give a quick thank you actually to all of the neurophthalmology attendings, Dr. Warner for reviewing my presentation and Dr. Katz, Dr. C, Dr. Pram and Dr. DeGree who I learned from significantly over my month here. I was on rotation with Dr. Murray and Dr. Mamelis who were terrific and taught me a lot. I'm very grateful for them taking good care of me over the month. And then certainly to all of the technicians and staff who made me feel a little less lost while I was navigating the halls of the Moran. So these are my references. Thanks everybody. Thank you.