Dr. Ray Chu at the 2023 Cedars-Sinai Intracranial Hypotension Conference

Dr. Ray Chu, Associate Professor of Neurosurgery, Cedars-Sinai in Los Angeles, CA, presented a talk on shunting for idiopathic intracranial hypertension at the 2023 Cedars-Sinai Intracranial Hypotension Conference on July 9, 2023. The conference was hosted by Cedars-Sinai with generous support from the Spinal CSF Leak Foundation in Kohala Coast, Hawaii.

 

 

 

 

 

Transcript

[00:00:12] At first, I was worried when Dr. Schievink asked me to give a talk, it meant that my reputation was that I have caused a lot of brain and spinal fluid leaks. But a shunt is a type of CSF leak. It’s just hopefully a controlled CSF leak, and a CSF leak in a patient that needs it.

[00:00:26] So we’ll cover some things regarding different shunting procedures and talk about our decision making and complications. This is an audience that knows a lot about the incidence of IIH better than I do. Clearly there’s always a part where we talk about people who have had testing with Diamox and LPs and definitions with papilledema so that we know who we’re treating.

[00:00:46] There is this part where I will talk about lumboperitoneal shunts and just have this caveat in my head all the time that patients with a preexisting Chiari malformation are not great for LP shunts and we’ll talk about why. So, there’s always this part where medical options include things like weight loss, if that’s appropriate for the patient.

[00:01:02] And especially there seems to be something about truncal weight loss versus other weight loss. And even surgery can be an important way to address weight loss and prevent other procedures being necessary. We talk about different diuretics. There’s some talk about topiramate for this disorder, but it really is probably mostly addressing symptoms, not addressing the real pathophysiology of the disorder.

[00:01:23] And there are patients that have a more mild version that repeated LPs can get us by without needing the next treatment. So this is one of these examples of someone who has low lying tonsils, but does not have, you know, SIH type appearance and has small ventricles and things like that.

[00:01:39] So one of the treatments that’s still usable is optic nerve sheath fenestration. If you ignore the actual eye diagram on how to do it, it sounds great to a neurosurgeon, like anything you can do to avoid needing to have to do shunt surgery sounds fine to me. It’s great for people with papilledema. It’s taking advantage of the CSF pathway that’s expanded along the optic nerve.

[00:01:57] It’s not terrific for headache, but if it’s someone who has papilledema, a decrease in vision and headache, it could be helpful. There’s more that, ophthalmologists pursue this through a medial transconjunctival approach. The other approaches either through a superior or lateral pathway are a little bit more either difficult or cosmetically have issues.

[00:02:18] For times when that cannot be done, of course, we, there are some indications for surgery. Usually, we use some slightly different numbers for the opening pressure than for diagnosis of IIH. Clearly, we have a little bit of a different barrier for surgery. And also, there are a lot of patients that if their spinal fluid pressure is barely elevated, they may not require a shunt.

[00:02:39] Definitely, it’s good to consider. People have good symptom relief from a spinal fluid. spinal tap before we consider a brain surgery, even though it’s not a more minor type of brain surgery. And then when I was a resident, I don’t think we’d really talked about this a ton, but now I think most people would consider a lack of venous sinus stenosis that can be treated, right?

[00:02:58] That wasn’t always something in our mindset back then. Clearly, there are people we worry about for surgery, things like untreatable coagulopathies. Sometimes we have worries that. People have multiple prior abdominal surgeries, because that’s typically one of the places that we’ve placed the shunt is into the peritoneum.

[00:03:13] Although sometimes even with that, using our general surgery colleagues or laparoscopic placement, we can still get by. This is one of those diagrams that has laparoscopic placement, which can be helpful. Sometimes these patients tend to be a little bit on the larger size too. And it can be a little harder for surgical an open surgical approach for shunt placement.

[00:03:33] So one of the shunts that’s in some ways easier to place is a lumboperitoneal shunt, and it really kind of recapitulates what happens when a spinal tap is accessible for patients, so that you can place a catheter, a lumbar cistern, place it into the peritoneal space. One of the older valves that was used for this is an HV valve, a horizontal vertical valve that has a different opening pressure and drainage depending if a person is supine or if they’re vertical.

[00:03:58] But also now there are programmable valves that can do this. And so it’s just sometimes tricky to really place that programmable valve in a place that you can find it. And both for programming or even for aspiration. So sometimes we will tunnel with another small incision over like the Iliac crest.

[00:04:13] We can find that if it’s floating in space, it can be a little harder. Also it can be nice to suture it down. So it doesn’t flip over and inadvertently and things that’s harder to program backwards that way, but they have a special Some companies have a special lumbar shunt valve that’s a little bit larger, a little easier to find.

[00:04:29] And on x ray, this is one of those shunts that has like a part of the lumbar cistern and coming around to the abdomen here and drainage into the peritoneal cavity. There’s oh, now I’m going to see. Okay. No. So there’s another patient who had IH and has had an LP shunt. These patients tend to be a little bit tougher in terms of complications rates of shunting.

[00:04:54] And this is one who had the lumbar cistern part pull out, had the abdominal part pull out, and eventually we converted her to a ventricular peritoneal shunt. And this too, you can use a programmable valve, which is helpful. But sometimes we have these different problems and intra abdominal pressure can be a problem either way with either type of shunt because sometimes they push the catheter out a little bit.

[00:05:15] So sometimes it helps to have extra suture to try to keep it in place. In terms of the complication rates of shunting that they’re not the same as other shunts when we have people for normal pressure, hydrocephalus, or someone who has post subarachnoid hemorrhage and needs a shunt, they tend to have a less complicated course.

[00:05:32] There’s a fair number of people who can get a need another surgery within a year that we hope that the program will valves help that rate a little bit. So in the old days of neurosurgery, we pick like a higher, a low pressure valve and. try to pick what is going to be a good valve pressure for the patient for a long term.

[00:05:48] But now we have ones that we can adjust a little bit. Sometimes before we would have people have to adjust their positions for a little bit until they accommodate to a pressure. But now we have a way to adjust that in the office. Also older programmable valves had this idea that it couldn’t be checked in the office easily.

[00:06:07] They have We checked out x ray and they’d be reset. Every time you get an MRI, we have better ones. Now, in terms of trying to control infection rate, there are now antibiotic and pregnant catheters, much might help the major downside for a lumbar peritoneal shunt is that it causes a secondary Chiari malformation in several patients.

[00:06:25] And some of these patients can even have, you know, SIH like symptoms because it’s essentially creating a spinal fluid. leak. Sometimes they leak around the catheter. It’s not even just the shunt itself, but they leak around the catheter. One example is a patient who was 23 but had a childhood glioma resected in hydrocephalus, multiple shunts, ended up developing a slit ventricle syndrome and had an LP shunt placed in an idea to try to adjust her cerebral compliance.

[00:06:51] And she had been Living horizontally mostly for a while only be able to get up for an hour or two has this LP shunt in place. And when we really studied it as these other. That’s funny again the audio thing that’s hilarious. I gotta stop doing these when my kids are in the room. You can see on the MRI these little cystic areas.

[00:07:15] And on our MR myelography, you can see an area where there’s leak fluid around and that was, we remove the shunt and repair that leak and help those symptoms. This is one of those class patients though, that had this kind of symptoms for years. And so while we improved her time that she can get vertical, she still had a fair amount of POTS related kind of symptoms and some deconditioning that she’s not totally vertical running around town, but she was better.

[00:07:43] So the other place that places shunt can be the ventricles of the brain. There are two lateral ventricles. And the most common place is a place, a ventricular peritoneal shunt. The shunt has a proximal catheter, a valve, which typically has a reservoir. It could be included. It could be separate that you can tap if you need to adjust the patency of the shunt and a distal catheter that goes different places.

[00:08:05] The most common is a ventricular peritoneal shunt. Your peritoneum has a wide surface and area for absorption, has fluid that you make and reabsorb every day. That sometimes when people have peritoneal dialysis, they do fluid exchange there. Although I’ve had that, I’ve had someone not really remember that someone had a VP shunt for hydrocephalus and They paired to know dialysis and all that fluid decreased flow in the shunt.

[00:08:27] They had a lot of symptoms and asked me if there’s a problem. They said, yes, there’s a problem. The another places they can place, we can place the catheters would be in the plural space. Sometimes the fluid volume can overload the absorptive capacity. And once a while people can have problem. And then atrial.

[00:08:42] The thing with atrial shunts is that you typically sacrifice an external jugular vein and plant the shunt there. And then also it’s because it’s in the bloodstream. There’s a little bit of worry that any transient bacteremia like a aggressive dental cleaning and stuff allows some seeding Potentially to the shunt in the older days of neurosurgery, people even shunted the bladder or the gallbladder that I’ve never seen that done.

[00:09:07] The shots can be placed either frontally or simply there’s a lot of personal preference for that. I think that one issue is that for frontally, you do have to shave a little bit more hair and you usually need a separate incision as your tunnel. And we try not to do that unless we have to. My hairline is not the same as when I started at Cedars, so I always want to consider that.

[00:09:25] The occipital shunts usually have to do a little bit less, but if people aren’t super familiar and don’t do them very often, they tend to be a little bit out of practice with that. Occipital shunts are not the easiest for IAH, though. There’s somewhere around 30, 000 shunt procedures performed in the U.

[00:09:39] S. annually. It’s an example of a frontal shunt in a patient with IH with a catheter in that ventricle. You often see this phenomenon with hydrocephalus or IH that’s shunted, that the ipsilateral ventricle is a little bit smaller because it decreases these pressure waves for CSF. And this is what that programmable valve looks like.

[00:09:58] And this is an occipital shunt, but it says someone in pH, because it’s easier to hit the ventricles, the normal pressure hydrocephalus, but then you kind of hide all this incision and thing. And even if someone’s mostly bald, you’re not talking to people and looking at the back of their head very often.

[00:10:12] So you hide things a little bit. This is a view of some of these at programmable valves. Now we have programmable valves that are smart enough that you can read a pressure in the office, and you can adjust it, and you can have an MRI that these often have a locking mechanism now so they don’t have to be reset every time you have an MRI, even though Dr.

[00:10:33] Maya’s techs always call us, they’re usually pretty safe. So one thing that helps the complication rate of shunting for IH is navigation. So we can have a brain MRI or CT scan with these fiducials, these stickers we put on the scalp and we put a mark there too, in case a couple of stickers fall off also, really, we can also map the skull and use this for navigation.

[00:10:54] And so with a 3d interoperative computer, we can navigate and help us find things in the brain. As an Asian, sometimes I need a GPS. So we wish the machine were to move around like this. It’s really moved by people, but now we actually have a device that allows us to do this with an electromagnetic field and without the head frame that we use to clamp on people as much for this.

[00:11:14] So now we can electromagnetically put a couple of trackers and there’s a. Probe with the flexible tip where you can actually track the tip. So many times in the past, we would just have a point or an Amber trajectory and hope whether we’re good, but now this more. trackable tip, we can actually see whether it is relatively, it’s not real time imaging, but see where that is relatively as we place the catheter.

[00:11:38] The other thing that can add to this success rate would be using an endoscope, and so this endoscope can show you the lovely cells of the corte plexus that make spinal fluid and show you blood vessels you’re trying to avoid. It is a little bit pixelated. It’s a fiber. It’s very thin. It could fit down a catheter.

[00:11:53] So it’s not like the world’s best picture that really could help. And part of what we want to do is not only navigate the brain to make sure we’re in the ventricle, but try to put it in a part of the ventricle that will give us the longest life. Less for this disorder, really for other disorders, you might find a cyst or some other obstruction that you want to clear.

[00:12:11] If you have bleeding, you can irrigate and try to stop that. This is more of a picture. That was an example. This is more a picture from the frontal horn. There is a little bit like you’re operating using a moving keyhole looking for other parts of the ventricle, but it’s also very good for a resident expertise to see the intraventricular anatomy plus.

[00:12:29] It’s beautiful. So complications of VP shunting are not small. Again, we talked about things like programmable valves and neuroendoscopy to try and decrease that rate. There are people who report rates as high as 50 percent revision at 12 months. Some of that is the idea of whether catheters pull out one direction or the other.

[00:12:50] And it’s just very different. I mean, it seems more common for subarachnoid hemorrhage or for normal pressure hydrocephalus who might have a shunt that can last someone’s whole life. For outcomes, there’s a report from rural neurosurgery on 160 patients were a few different states that report a very strong improvement in papillodema and transient visual obscurations.

[00:13:11] Again, it’s not the greatest treatment for headache, it can help some headache, but there’s always that idea of multiple causes and right we know this is an audience that knows that the CSF diversion only is treating part of what’s going on with IH is not really treating the pathophysiology as much as the cycle of pressure.

[00:13:28] And clearly when patients have symptoms for less than a month, we tend to do a little bit better for headache relief. This too, people can have different types of headaches after shunting. So sometimes this or hydrocephalus patients, we’ll talk about knowing what high and low pressure headaches are like.

[00:13:42] They won’t have typically the full sequelae of SAH, but they may have some positional headaches that need some adjustment for that. And so that’s why programmable valves can be really helpful in this population. So, there are definitely medical issues for IIH. I think a lot of them are better. They’re really more addressing the pathophysiology, but there’s nothing to stent in venous sinus and there’s a way that a neurosurgeon can help with a good shunt.

[00:14:06] We tend to use more ventricular peritoneal shunts in the United States for this disorder and try to avoid the secondary QR malformation and programmable valves and navigation are clearly very helpful. So thank you very much for allowing me to do this talk and encouraging me to come to Hawaii and see this over the Kīlauea the other day.

[00:14:25] And thank you very much.

[00:14:31] Thank you very much, Dr. Chu. Our last speaker for this session needs no introduction. It is the good Dr. Marcus Studley from Macquarie, and he’ll be speaking.