Shunts and Normal Pressure Hydrocephalus: Pearls and Pitfalls

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- Colleagues and friends, thank you for joining us for another session of the Atlas Innovations. Our guest today is Dr. Jeff Chen from University of California at Irvine. He is Vice Chairman of Neurosurgery there, as well as the Director of Neurotrauma. He has significant expertise in complex clinical surgery, as well as NPH and shunting. And I'm very much appreciative of his time today to be able to tell us about NPH and troubleshooting the shunt. In fact, managing the shunt preoperative diagnosis and troubleshooting the shunt can be among the most difficult decision making processes in neurosurgery. Therefore, I think this is an exciting lecture that I think will be very much instructive to all of us, including myself. And therefore, Jeff, I wanna thank you and look forward to learning from you. Please go ahead.

- Thank you very much, Aaron. It's a pleasure and honor to be able to give this talk and to be part of The Neurosurgical Atlas, which touches many, many facets of neurosurgery. This topic is a topic I think that is quite pertinent because of our aging population and all the discoveries that we're making that NPH, although their controversies about its existence, is truly an entity and that shunting can help these patients.

- Well said. Very well said. I think neurosurgeons play an important role. And I think we should really emphasize that some of the biggest differences we have made in the lives of our patients has been by providing treatment for NPH and shunts, the quality of life that can be dramatically improved is a big blessing and is a big reward in neurosurgery that we should not take for granted. So with that, let's jump into your lecture, and looking forward to it.

- Thank you very much. And we'll go ahead and start. I have no disclosures. And just briefly just to ally what we're gonna talk about is just some of the challenges and difficulties with NPH and the diagnostic challenges that are out there. NPH has been around, and nearly a half a century ago was first identified. Yet still there's constant debate about the treatment, as well as the potential pitfalls and really where the patients should have shunts or not shunts. Now, talk a little bit about the shunt and how we can try to do this in such a way that we optimize the surgery so we optimize the outcome and minimize all of the potential problems and complications, and also talk about the follow-up, and how to monitor these patients, as well as very briefly, the future prospects and some of the future studies that are being done in NPH. Once again, as I had mentioned, NPH was first described in 1965 by the Harvard Group by Hakim and Adams. And they had a series of three patients. And back then, they did not have CAT scans, but were able to identify the dilatation of the ventricles and show that after draining off fluid that these patients improve with respect to some of these symptoms. The classic triad, which is called Hakim's Triad, is a gait problems, bladder problems, and cognitive problems. It's something we all learn about when we're in medical school about the patient who has the wobbly walk, and has bladder problems, and has trouble thinking. However, given that, even though we're all taught this early on in medical school, we oftentimes forget it. And many times, I have to remind primary care doctors and family doctors about this entity because it's not that common. If you look at all dementia as it represents about 5% of dementia, we talk about why is it called normal pressure hydrocephalus is because the pressure that the patient's experience is in the less than 20 range. We see a peak of this in patients who are over the age of 60, 70, and 80. And for some reason in my practice, I see a good number at these when the patients are 80. And looking back, you realize that they probably had many of this classic symptoms even five to 10 years before that. How bad a problem is this? Well, it's estimated to occur in about 1 over 200 patients over the age of 60 to 70. In the US, it's been estimated there are 500 to 700,000 patients who have this. And it's progressive and insidious in nature. Patients, oftentimes, don't even realize this. They just trip it everything to old age as do to their families. But looking back, they realize that this has been progressive and beginning worse, and that they have those classic symptoms of problems with the balanced gait, as well as memory and bladder control. If you look in several series where you look specifically in perhaps an at risk population, there seems to be higher incidence in patients who are in skilled nursing facilities and also patients who suffer ground level falls. At our incident, we've been looking at patients who have had ground level falls and go back and looking at them retrospectively. And significant number of those patients, if you look at their history as well as their CAT scans, have large ventricles and probably have NPH or components of them. This can be a probably a very big health problem, significant public health problem as we have more and more patients who are suffering ground level falls. If we look at the trauma data, which I see this as director neurotrauma, we see that there are more and more patients that have ground level falls that that seems to be where a lot of our head injuries are occurring. And if they're fallen because they have NPH, that is something that we could probably address or perhaps help with the problem. Worldwide estimate of dementia is about 35 million patients in 2010 and 65.7 million by the year 2030. If you think about how probably about 5% of all dementias is attributable to NPH, that's a pretty big number there. We're talking in the millions of patients who have potentially NPH in the world. There was, in the recent years, been a lot of debate about NPH. And our neurology colleagues have criticized neurosurgeons for over shunting patients. And in fact, there's been a call for randomized controlled trials for shunting or not shunting patients. And there are ongoing studies that are being done at this point to better clarify the patients with NPH. And I think what we're realizing is that NPH is not necessarily that clean an entity, and that it may be a spectrum of disorders and diseases of which the hallmark is the ventriculomegaly. But as we know, there are other reasons that patients can get ventriculomegaly. And we'll talk a bit about that. So as a neurosurgeon, the onus is upon us to be careful in the screening and selection of these patients, and also being careful so that when we do the surgeries, that patients have good outcomes, that we avoid the complications that often accompany shunts, and that even though this surgery is generally considered one of the less elegant and perhaps more simple surgeries, and even though oftentimes, in many institutes, it's relegated to the junior resident, I think we have opportunities to improve on our techniques and the way we do these, that we can use some of the neuro adjuncts, some of the neuropsych adjuncts that we have that can help us to improve the safety of these procedures. Part of what we want to do is also focus on the neurological exam, the review of systems, then we'll talk a bit of more about that. Okay. As far as the selection of the patients, the proper selection of the patients will help us to have better outcomes, meaning improved response, right? If we have the wrong diagnosis, that brings in the question of whether or not we should really be doing the shunt. Part of the preoperative preparation that I like to talk about is to remember that these patients are elderly patients and many of them have comorbidities. Many of the patients are anticoagulants for atrial fibrillation, for example, which is very common. And this increases the risks of the surgery and the difficulty of the surgery. Finally, I think it's very important to talk with the family, the patient about the expectations. I always tell them that you can't expect that it's just going to be like a light switch that you put a shunt in and magically they're better the next day. It's a process, and it takes time for that improvement to occur. So why does this happen? Well, one of the hallmarks is the large ventricles that occur. And over the last 50 years, there have been many hypotheses as to why this occurs. However, there is no unifying theme at this point other than the fact there is some problem with the CSF egress out of the ventricular system. Traditionally, it has been thought that there has been a compensatory dilatation of the ventricles as a patients age and that the cerebral atrophy occurs. Newer ideas is that this is part of a spectrum of degenerative processes that patients will lose brain tissue. And as a consequence, whether it be from Alzheimer's or whether it be from Parkinson's, there is loss of brain cells and brain tissues, which leads to the compensatory ventricular dilatation, which then leads to the associated symptoms. All right. This is a diagram showing the ventricles through a cutaway. And what we can see is the ventricles dilate out. And as it dilates out, for whatever reason, there's a stretching of the fiber tracts that are around this. Okay. These fiber tracts are many of the ones that control motor movement such as gait, as well as bladder and memory. As we are learning more about fiber tractography, this becomes a very much hotly debated topic. To make the diagnosis of normal pressure hydrocephalus, radiographically, these are some of the things that we find. And there are different findings that we see on CT scan. This shows the ventricular system. And we can see that this is the evidence ratio, which is the ratio of the frontal horns to the parietal diameter here. And if it is greater than 0.30, the patient is suspect. We also look at the colossal angle, which you can see here and also you see the on corona views. And an acute angle tends to be what we see with patients with normal pressure hydrocephalus. And also looking at the subarachnoid space. And if this is grossly enlarged, that is not favored normal pressure hydrocephalus. It favors another process such as Alzheimer's, which tends to lead to degeneration very specifically in the Sylvian fissure | region. So all this is pointing out is that there are these metrics that many people will use to look and characterize radiographically patients who have normal pressure hydrocephalus. There are also MRI studies that people will look at to try to find markers or neuroradiological markers to help predict whether the patient does have normal pressure hydrocephalus and to help with that diagnosis. Now, when we talk about normal pressure hydrocephalus, you realize that there are two major categories. There's the idiopathic, which are the majority of cases where we really don't know what caused the the problem. Then they have where we have the secondary or acquired group. These are patients who have had a traumatic brain injury, subarachnoid hemorrhage, stroke brain tumors or meningitis where there is some disruption of the CSF pathways. And this can occur at the level of arachnoid granulation where perhaps there's more protein, or perhaps it is because there's some webbing that occurs at the level of the aqueduct. So there's some impedance of flow through the aqueduct. What we find is these patients who have secondary or acquired hydrocephalus where the pressures are normal, these patients tend to respond better to a shunt. The idiopathic causes, again, it's more difficult because we don't know what is the underlying cause of the neuronal degeneration that led to the ventriculomegaly. Now, the classic symptoms, these are the classic symptoms that we see with normal pressure hydrocephalus, the classic triad that has been discussed for many years. And when you look at it, there are some subtleties to it. The gait with the classic gait is the patients feel as though they have trouble moving their feet, they have trouble lifting up their feet, and their feet seem to be glued to the floor or this magnetic gait that is described. However, there's subtleties to that. Sometimes the patients describe it as being imbalanced, that they feel that they're wobbling, that they sway side to side. And so this is not necessarily the classic presentation we see in all cases. So you need to be tuned in to what the patients are saying to you. Cognitive deficits. There is an overall slowing. The patients described to me that they have trouble finishing task. And when you talk to them, they'll say things like, "Well, I don't watch a movie anymore. I can't finish a book anymore 'cause I can't maintain my attention." And what's very interesting is that after surgery, they notice this really big difference that all of a sudden, they can think more clearly and they can complete tasks. And I've had patients who couldn't do crossword puzzles before surgery, then afterward are doing crossword puzzles just like they were 20 or 30 years ago. with urinary incontinence, it's a loss of bladder control that tends to appear later on in the disease. And patients can describe an urgency or frequency. With men, you have to be careful that it's not confused with prostate disease, whether the prostate disease is controlled. With respect to the dementias, once again I point out that there are a lot of causes of dementia. And our neurologists are very good at looking at these different dementias and having various tests to categorize them. Normal pressure hydrocephalus is 5% of all dementias. To look a little bit more specifically at the gaits, here are some examples of patients who have gait problems. And when you look at them and you stare at them, you can sort of see that this patient here, for example, is taking small steps and has trouble turning. Okay. Here is a patient, you watch him, he's got a rather fluid gait, but he's sliding with his gait. Even though you ask him to pick up his feet, his feet are sliding and he does not pick up his feet. Here is another example. And again, we spend a lot of time looking at the gates on these patients. Here on the right-hand side, you look at this walk, she does a shuffling type walk that the patient does right here just before making the turn. So a lot of focus looking at the feet. And over here, you see the patient has a wide base gait, and again is not picking up the feet, and the feet are sort of sliding here. So you spend a lot of time looking at the gait and following it. It's oftentimes nice to have videos of the gait so you can watch the progress of the patient and see whether they improve over time when they come back to clinic three months or six months later. And also, listening to what the patient says about their gait. They can tell you after surgery if they're improved because to walk and lift up their feet is a lot of work. And they'll tell you that they spend a lot of time or effort and they get tired quickly with walking. And that's one of the things I listen to when I listen to the patient when I listen to their history and the review of systems. Additional work-ups that we have to rule out other entities is key. And one of the mimickers of NPH is spinal stenosis, whether the cervical spine or lumbar spine, it can affect the patient's gait and movement. And patients can have a spastic or stiff gait from having cervical stenosis or having a herniated disc, for example, here. We'll talk a little bit about MRI scans with CSF flow studies, which can help us. But once again, the clinical exam and history cannot be underestimated. Once you've reached the decision for surgery, it's important to work up the medical issues. And I work very closely with our perioperative home team to ensure that that the patient is optimized for surgery. Whether we have our geriatrics team evaluate the patient for drug interactions, whether we have our anesthesia team evaluate to see whether the patient needs cardiac clearance or other clearance, don't forget these patients are in the seventies or eighties and have many comorbidities that we have to be aware of. PT/OT/ST can be used to help give us some baseline evaluations. Just briefly here, this is the CSF flows that I had mentioned. And when you can see here, the MRI scans are done. And you can see that if you look at the flow going through the region of the aqueduct, our radiologists or neuroradiologists are able to give us numbers to say whether the flow is hyperdynamic. And patients who have a bit of impedance of flow, a bit of impedance of flow through this region here tend to do better with a shunt. And that makes sense because if there's impedance of flow, whether it be a little bit of aqueduct stenosis, whether there's small webs that go through that area, the fluid is trying to be pushed through by the ventricular system. And as it pushes through, as puts more stress or stretch on the fiber tracts, so this is something that is a nice tool that can be used to help determine whether patients might be a good candidate for surgery. And and our radiologist can take a look at that, and they can put the cursor on the aqueduct, and actually give us a number to measure a measurement number which we can compare to normals. Other tests that can help you with a diagnosis, a high volume spinal tap that again simulates a shunt by draining some of the fluid and seeing where there's any change in the symptomatology. I always like to look for the opening pressure 'cause the opening pressure gives me a hint of whether the patient may improve. If the opening pressure is on the high side of normal, i.e. 15 to 20 centimeters, that is a good predictor. The patient would probably do better when we lower that pressure. A three-day lumbar drain test is also used to simulate the effects of a continuous drainage. This is difficult. And many of the patients complain about it because it is uncomfortable. The patient has to be in the hospital for three days for that. Other tests, our neurologists are very good at looking at other etiologies such as specific PET scans for Alzheimer's disease or Parkinson's disease, as well as additional complex neuropsychological tests that will help to see whether the patient may have a different reason for their cognitive issues. Some of the key points in this evaluation of the patient is that the diagnosis of NPH is oftentimes very difficult. And this makes sense because we're dealing with older patients who may have more than one neurodegenerative process going on. Although Alzheimer's, Parkinson's, vascular dementia and NPH are well-described, there are others that haven't been described or are currently being investigated further. There's no specific biomarker orogenic tests currently for NPH. There are a lot of other ancillary tests that we can do that can help us to try to predict whether the patient may be a good candidate or not for surgery. Oftentimes, it takes a multi-specialty evaluation, these patients. And this is where it's good for the neurosurgeon to team up with neurologists, neuropsychologists, geriatrics team to help identify these patients and to help sift through all their symptoms to see whether they are consistent with what we know about normal pressure hydrocephalus. Once the decision is made about a shunting procedure, there are basically three types of shunts that are used: the lumb-peritoneal shunt, ventriculo-atrial shunt, and ventriculo-peritoneal shunt. We will focus on this talk on the VP shunt as that is the one that is most commonly used and has some of the best results. And these are the ones that we have the most data for. At this time, we can stop to answer any questions.

- Great lecture in terms of diagnosis. As you very well mentioned, Jeff, it's very difficult to know if we're dealing with NPH for sure or not because is it because of atrophy and neurodegenerative diseases, or is it truly because of NPH? I tend to have a relatively low threshold to do the high volume tap. Obviously, you have to have certain measures, the triad, the signs of ventricle, megaly on imaging. And then I let someone get a large volume tap. And if you have the dramatic response, then I'm willing to offer them a shunt. Could you tell me, have there been instances that you did a large volume tap, the effect was relatively minimal? And then you did a three-day lumbar drainage, and you said you saw a dramatic improvement and therefore offered a shunt. Can you tell me if how often those rare cases happen?

- Oh, absolutely. Thank you, Aaron. That's a very good question, and it's something we're frequently asked. And I've found that there are certain patients who do not improve with a lumbar tap. And they just need a little more time that perhaps they need a little bit more decompression over time. And what the other thing is I emphasize also is if I find the opening pressure is high, i.e. 15 to 20, okay, I will probably bypass the lumbar drain test or the three-day lumbar drain test because if you face it, your ICP sitting here right now should be five or six, all right or less, okay? And so if a patient's walking around or existing with a pressure of 12, 13, 14, 15 in an older patient, that's just not normal. And I think that actually is what I've used a lot to guide me for doing shunts. And we shunt the patient, and actually they didn't improve. I have a good number of patients that do improve even though the spinal did not show a dramatic improvement in symptomatology.

- So the big question is, are we leaving some patients behind? In other words, are we being too conservative in terms of offering the shunt to some patients who could benefit? And I think that is the case. And so what you're telling me is that the initial pressure is important. And if they get some reasonable response by not dramatic, but the pressure was slightly elevated or within the normal range, but the higher end of it, you are still willing to offer them a shunt, Jeff?

- Yes, yes. A lot of it is the clinical symptomatology. Again, the walking, the gait, what the patients tell you, that is really a lot of the decision making. And I think that, unfortunately, because we as surgeons sometimes don't spend as much time with our patients, we don't listen as well and we miss it. And there are little key words that when you listen to the patient, they say certain things that key and that are very consistent with NPH. For example, if you just look at their fine motor movement that is grossly, that is very much affected by NPH, they may say my handwriting is just a little bit worse, or I can't button my shirt. These are little fine motor things that sometimes we don't pick up on.

- Very well said. I think that's an excellent point to emphasize the fact that we don't wanna be too strict and leave some patients behind that could benefit from the VP shunting. So I'm very excited to learn about the next stage of the talk. So Jeff, please go ahead and thank you.

- Thank you. Thank you. Why don't we go to the next step, which we'll be looking at the surgery itself? We'll talk a bit about the shunts and the placement of the shunt, as well as some of the nuances of surgery that could help to optimize the outcome. Here's a diagram, which is diagram that shows the surgery and schematize it for us. And what we can see here is the burr hole, the placement into the ventricle and the frontal horn. You have the shunt back here. It could be placed here. It could be anywhere along this pathway. You have access to it so that you can program the shunt. All right. And part of the key features of programmable shunt allows you to adjust the amount of fluid that is drained. And currently, all the shunts that are out there currently are pressure-driven shunts. And this just shows trajectory of where the shunt goes, goes from the brain down into the abdomen, or into the peritoneal space. This is a picture from the operating room. And this is where we have positioned the patient. And I've pointed out here with these blue arrows the trajectory that the shunt needs to travel so it's not quite as clear and clean as it was in the diagram because don't forget when we position the patient, returning the patient's head, returning the patient's neck. And the pathway that is taken is a little bit different. Now, I'll show you here the pathway here in blue. And we see it has to come over here over the clavicle and to this dip here in the neck and meet up here. And I use an intervening incision here between the frontal portion up here and the portion that comes up from the abdomen. So we meet here in the middle or somewhere behind the ear, the postauricular region. A postauricular incision here to continue this pathway through here. This is the frontal area here. And I like this frontal area here because you have much more access than over the occipital region. And plus the shunt will sit right here where you have access to it in the frontal region. Some people use a frontal burr hole, some people use occipital burr hole. The frontal gives you ease of access, the patient does not lay on it. And however, though, you have to require intervening incision. And if the patient is bald, it's sometimes hard to hide the surgery. The occipital burr hole, it avoids the intervening incision is hidden from view. It is hard to access when you'll try to program it or tap it. It sometimes is uncomfortable for the patient. And I've seen patients who are laying on it for a long time. For example, if they're in a nursing home, they're immobilized somewhat. And they can erode through that area because their head is laying on it. We make a semi-circle incision here and leave the . What we're going to do is develop a plane where the shunt will sit. So the shunt sits here between the galea and the pericranium. All right. And you can use any type of forceps. This is a a Bozeman forceps that you can use. You can use a Cushing forceps. They need to create a pocket here where the shunt will sit, the shunt will sit, or the reservoir will sit here and continue down this way. How much do room do you need? This is the size of the shunt. This is the implant here. And this is a Codman-Certas shunt, which is one of the very common shunts that is used. And this shunt has the capability of being programmed. It has the anti-siphon device here. All right. And also is antibiotic-impregnated. So it's antibiotic-impregnated shunt. It is unitized so that you don't have to put your ties in there. And there are various shunts that are out there and various manufacturers that have it. And everybody is working to create a better shunt ultimately so you have a better outcome. These are antibiotic-impregnated to help decrease the risk of infection. So this is a relatively small shunt. It's a very small profile and there are different sized shunts. I like this one here because it is small profile. And the reason is that one of the things to realize is that the skin that's overlying the shunt is under some tension. And what I have seen particularly in patients who are older is the shunt pushes on the skin over time, and skin is somewhat attenuated, and it can erode through. Therefore that is one of the reasons I use a smaller shunt. The other neurosurgery adjunct that I use is use of neuronavigation. Now, some people argue that the vectors are so big, that really you don't need neuronavigation, and you should be able to hit them. And that is true. However, what we like to do is try to place this as precisely as possible so that it sits here right above the frame in a row. So it's above the frame in a row but not too close to it because don't forget the choroid plexus passes right through that area. So you'd like to have it here. And I would've to say that having used this narrow navigation, we've had really good results that have not had any proximal failures. And with the navigation system, and this is the axiom system that we use, you can follow it. It is the electromagnetic so that you do not pin the patient. So you do not need to use pins. And it's electromagnetic so you have to minimize the amount of any metal that's in your field. So you're careful with your retractors. I tend to just use sutures to retract the skin. But you can follow it and watch where the ventricular catheter is deployed. Again, back to the opening pressure. And what I'd like to do is check the opening pressure of the patient in the operating room with the patient flat under anesthesia and with the CO2 as normal as possible. And immediately after placing the catheter, you check the opening pressure. And I find that in many patients, the opening pressure is, again, on the high side. It is greater than 10 and generally 15 to 20 centimeters of water. And this is helpful because it helps me to predict two things: One, those patients that tend to have a higher opening pressure tend to do better; also, those patients allow me to target, by knowing the opening pressure, allows me to target where I'm gonna program the shunt. Don't forget we're using a programmable shunt. And a little bit about the programmable shunt is that it is really revolutionized how we treat NPH. I think that before the programmable shunts came out, we were always worried that we would pick the wrong program. And we picked the wrong program, well, what happens is that you may be forced to change the shunt. And when I trained many years ago, we just had low, medium, high pressures. And if you have to pick the wrong pressure and the patients to get better, then you may have to come back and change out the shunt. So ever since, this is sort of a revolutionary change as to having this programmable shunt so that you don't drain too much, but you drain enough. This is a picture of at the time of surgery. And we drill a hole and pass the catheter. And you see that it bends around here, and you have this right angle attachment here that helps bend it over the bone. I like to cover this with a small burr hole cover. For the longest time, it did not do that. However, what I've found is that, again, with the older patients is that the patients would come back to me with divots there in the burr holes because again older patients' skin is a bit more pliable and fragile, it will dip in there. In extreme cases, it can erode through it, you can have opening of the incision there. But again, it's the burr holes that sometimes are a little bit unsightly. This is the final product here. And what we can see is the shunt here is visible, you can see the reservoir here. And that's good because sometimes we need to access it, we need to access it, we need to tap it, we need to program it. So this is easier to access than some way behind the occipital region. We see here the rather flush nature here that you want to have this stay flushed so that it doesn't sink in over time. One of the other adjuncts that is very helpful at the time of surgery is doing the catheter placement with our general surgeons. And I think there's been a general trend where people are using this more where you can work with your general surgeons and laparoscopically place the distal catheter. This improves visualization, you know exactly where that is, where the catheter is deployed. It's a smaller incision. And patients generally don't have much pain 'cause the laparoscopic techniques have gotten so good that they're frequently able to go home the next day. I would've to say in our series, I would say about probably 90% of my patients go home the next day after surgery. And they're able to eat right away and get up the pain from the laparoscopic procedure is very minimal. The other advantage of the laparoscopic approach is they have very nice visualization inside the abdomen. They're able to deploy the catheter where we want them and usually try to place it just above the liver, knowing that it will probably move and mobilize back down. If they're at adhesions, okay, and this is a patient who had adhesions in the abdomen that you can break them up. And our laparoscopic surgeons oftentimes will help break up the adhesions and free it up. Now, the problem with adhesions is that it's like scar. And that's an area where there's poor absorption of the CSF. And if there's poor absorption of the CSF, you can get a pseudocyst, poor absorption, and distal failure. So many times, our laparoscopic surgeons can break up that region and provide a good surface area that can subsequently be used for the shunt. A couple of other points is some of the other key pearls. Again, go back to the preparation of the patient. As we're dealing with older and patients who have many comorbidities, many of them are on anticoagulants. Frequently, for atrial fibrillation, we'd like to do is stop this several days beforehand and several days afterward. A discussion with the cardiologist, a discussion with their stroke neurologist is often important so they know the risk during this time are increased for a either cardiac or a neurovascular event. If the patient has had problems with abdominal surgery previously, that's good to know because then our laparoscopic surgeons can be tuned into it. And they can take measures to be a bit more careful and explore things a bit more. If they have a history of diverticulitis, that is also a red flag because if they have a flare up, okay, the general way they treat it is with antibiotics. However, they can also have perforations which can infect the shunt. So that is something I always ask to see if they've had problems with diverticulitis, or if it's active or it's quiescent. So some of the key points that I wanted to emphasize during this short segment is that good preoperative evaluation, medical clearance are key. And it's very important to work with our medicine colleagues or our geriatric colleagues to optimize these patients. Some of the nuances of the surgery using intraoperative neuronavigation, I think, helps to specifically place the catheters. And I point out once again that don't forget the patients oftentimes are not in the normal anatomical position, which we are used to when we place ventriculostomy. The navigation allows you to turn to head sometimes so you have to turn to head so you can get that catheter from the abdomen across the neck at clavicle up to the brain. So sometimes, you don't have your normal anatomy. And it's very easy when things are draped sometimes be off. I like to use the programmable shunts. This, again, has revolutionized the way we can take care of these patients. And we'll talk a bit more about that in the third session. Antibiotic-impregnated catheters are key, and they help us to truly decrease the risk of infection. Laparoscopic distal catheter helps with the patient's comfort. It really decreases any pain they have, and they're able to mobilize to get out of the hospital soon, which we know is very important in older patients. Most of my patients have very little pain. I try not to use any opiates because don't forget, older patients are very, very sensitive to opiates. So if you can just use Tylenol for the pain, that is really, really good. Get them up early, get them home, follow up the patients closely after surgery. And we'll talk a bit more about that in our third session.

- So beautiful presentation, Jeff, really nice point. I wanna reiterate a few things. Use of navigation, I think it's excellent in terms of assuring that we're in a good location. I think laparoscopic placement using our general surgeon colleagues is really important because we're not sure how many of our patients may not have the distal catheter in a good position if we're gonna just use the small linear incision and place it into the abdomen without using the laparoscope. And number three, the couple of things that is very important for me is that I wanna make sure that catheter is not kinked so I make sure there is good distal run from the tip of the distal catheter before we place it in the abdomen. So having that sort of a spontaneous drainage of the fluid or CSF distal is critical to make sure that this shunt is functional. And again, just having the ability to make sure there's no kinks at the site where the valve is sort of located in the pocket thing is another, I think, important point to remember. What are your thoughts about that?

- Absolutely, absolutely. Thank you very much for that. Those are very good points, and I agree with them a hundred percent. I think one of the things that I do, well, one of the tricks we do is when the general surgeons are in the abdomen, I actually have them hold up the tip of the catheter. And we look for distal spontaneous flow or pumped flow. And so we actually help them just visualize that at least it's patent, right? And again, a kink can... You're right, that could be why our shunts fail or why the patients don't get better so that's very important. If there's any question, I do a shunt series oftentimes on the table to make sure that that we have it nicely in attempt. I think that using this technique, we've had very actually probably no kinks. The navigation, I think, is key because we've all done shunts in the past or ventriculos where the catheters end up in embarrassing positions. And I think that this fragile population, taking them back for a shunt, a misplaced ventricular catheter is probably not what we want to do.

- I agree. Very well said, Jeff. Beautiful. Let's go ahead to the last section of the talk. Look forward to it.

- One of the big questions after doing the shunt is, is the shunt working? And this is asked both by the patient, the family, as well as the the neurologist. And the question is, does the shunt really help? Okay, that is one of the questions that is always asked there. Here's an example of a patient before surgery here on the left. And you can see that typical slow walking, swaying side to side, not picking up the feet, going very slowly, being very careful and tentative. And you look at the turns here. That turn breaks or turn up into four or five segments. That's something I look at too is how fast or how well they're able to turn. And asking the patient to pick up the feet, just telling to try to get them to pick up the feet, and they have that difficulty. Now, here's the patient about a week after. Okay. You can see the dressing is still on her head. And she's able to walk quite well. And this patient, long term, did really, really well with the surgery and even a year or two out. This is from about 10 years ago. The patient did very well. So yes, it can work very well. The shunt does work, and it can work. Now, do all patients get this dramatic result? No. In fact, it is rare that the patient gets that dramatic result. And that's the common query we get from the patient's family. Is it really working? Are you sure you put it in properly? That's one of the things that they ask us, okay? And what I tell the patients and their family is that early on, I don't expect them to get better right away. If they come into the hospital and leave in the same condition they did when they came in, that is actually an accomplishment. But what I wanna do is get a shunt in there, and get it in there safely with no problems, with bleeding, or infection. Down the line, we will start to tighter the shunt and turn it down to the appropriate level. I always start to shunt off sort of at the mid-level at about 150 millimeters or 15 centimeters setting. And the reason I do that is that I want it to be too high; I want it to be too low. Now, even that setting of 150 millimeters, all right, the patient is still getting benefit. Now, don't forget that every time the patient coughs, every time the patient has a bowel movement, every pain the patient sneezes, the pressure will transiently go up to 30 or 40 or 50. And that happens to everybody. So during that time period, the patient will get a bit of drainage. So they will get drainage even though we may not set at their equilibrium level. Now, the other question I get is, after a year or so, the patient may plateau and not get any better. And that may be because of the nature of the underlying problem. The patient may have this underlying neurodegenerative problem. And we're treating the NPH component, but that other underlying problem may be continuing, and we may not be treating that. Finally, patients can frequently have worsening because they have a systemic problem going on. If they had a urinary tract infection, upper respiratory infection, if they get COVID, that will we know affects the neurological system and affects the brain. And these patients are much more sensitive to than the average bear. So if they get a fever, a cough, chill, that can cause all of their symptoms to get worse. Now, how do we assess the patient? We assess them by talking to them, hearing the family story. Sometimes, they'll keep a diary of how far they're able to walk, how fast they were to walk, how many times they get up to go to the bathroom at nighttime. These are all things that we factor in. And also by physical examination, seeing the patient looking at how they walk, how fast do they get up, how fast do they turn. Those are all measures that we use to see whether or not the patient is having some improvement. Now, if there's a question, we will always assess the patency of the shunt and determine whether, structurally, we have a problem. One of the fastest ways is just to pump and fill the shunt. So you pump the reservoir and see where the pumps and fills. That tells you that the proximal portion is working well. And one would expect you if you're careful, put it in using navigation that you're sitting right in the middle of the ventricle, it should not fill with with debris or choroid plexus. So that's one of the first things that I check. The other is doing a shunt series. And with a shunt series, that can give you a lot of information about the patency or whether there's any kinks or breakages. A CT and MRI scan can be done to look for brain structural problems. However, if you're trying to see whether the ventricles decrease in size, that usually doesn't happen because the ventricles are not compliant. Don't forget they've been stretched out for many years from NPH, and they don't decrease in size. There are new fancier computers using AI technology that are being used to try to calculate whether there's changes in the volume. We'll have to wait and see how that works out. If you do the aqueduct CSF flow study, like we mentioned with MRI scan, those numbers should change because the fluid going through there should be decreased if the shunt is working. So you shouldn't have that hyperdynamic appearance. All right. This is example of a shunt series. And here, I'm focusing on the chest portion here where we can see here is there's a break right here in the shunt, right? And that can happen as you're assessing the patient. It is rare that we see it in a fresh shunt. And it's usually odor shunts that you see that. Additionally, additional information you can get from a shunt is here. You can see this is the shunt valve, okay? This is a Codman-Hakim right here. Over here, This is a Codman-Certas. And the information you get from this is, if you look at the shunt, you can sort of see how it is programmed. This will give you the actual number that is set at. A lot of times, we get patients who come to emergency room from another hospital, or somebody else did a surgery. We don't know what kind of shunt they had, or what is programmed it. This is important information. As it can tell you, it's a shunt inadvertently set at two-way, high level example for common services eight, which would be the virtual off physician. You're not gonna expect any drainage or any benefit. If it's set way too low at a Level 1, you could be overdraining the patient, it can cause them headaches, it can cause them subdural hematomas, or subdural flu collections. This is a picture here. And you can see there's a different appearance to the Codman-Hakim versus the Codman-Certas. I think all the manufacturers at this point in time have designed or shunts have a specific x-ray appearance. And you can look online. And there have been papers where you can look up the pictures, they can tell you the type of shunt and what it's set at. Here is example of one of the structural problems that you can see in a patient after a shunt. And this is a patient who had a VP shunt done maybe a week or two beforehand. And the patient actually did very well, was getting better and was a little bit too active. So he had a slight fall and bumped his head and developed this subdural flu collection here. Now, when I see the subdural flu collection, you wanna be fairly aggressive with it. And the way to be aggressive with it is to program the shunt to a level where it's not draining as much because don't forget, as the shunt drains, there is this vector force pulling the ventricles down a bit. It pulls the brain away from the skull and increases this potential space here. This potential space can fill with blood. This patient is what we did. We increase this shunt from a Level 5 to Level 7 and asked him to be careful and to come back. He came back a couple weeks later. And we see there that there now is a little bit of blood here in this, right? It's maybe a little bit smaller, but it appears that there's a little bit of an acute component. So he is developing with a chronic subdural hematoma. And I think our mistake was not emphasizing enough to the patient to stop his non-steroidal. It turns out he has knee problems and back problems, and takes a bit of non-steroidal for that. So that's another point where the history discussed with the patients is important. Usually, just adjusting shunt will do it. And here, we just adjust the shunt further to the virtual off position, which is the 8th position on the Codman-Certas, which then decreases even further chance of drainage. Now, one of the caveats with the virtual off is that its pressure is equivalent to 40 millimeters. We talked earlier, if you cough, or sneeze, or bowel movement, your pressure can get close to that. So that is one of the caveats that perhaps you can still get a little bit of drainage, but clearly it's much less. This is long term. What you worry about is that the patient develops a chronic subdural fluid collection, which can become a chronic subdural hematoma. What you see here, right here is a chronic subdural membrane that's evolving, which you also see here. If that continues, it can evolve in the chronic subdural hematoma where you have this inner membrane here, okay? You have the outer membrane and the fluid underneath there. These can become very problematic. And the reason they become problematic is you just get a little bit of blood in there, and you can start an inflammatory reaction which causes this formation of these membranes. These membranes come about because of that scarring that occurs in inflammatory processes. A diagram that one of my colleagues, Dr. Mackenzie Drew for me. And here's the inner membrane here, what's you're lifting up, this is the part up against the brain. The outer membrane is already outside by the dura. And you can lift this up and you dissect underneath here. And frequently, there's blood and inflammatory products in here, which once you clear them out, it improves. So that is one of the reasons we try to avoid having to do this in a patient who has had a shunt. So adjusting a shunt and dialing the shunt can really obviate this. And that's one of the important advents with the programmable shunt. I think before the program was shunt, we're always worried that there could be over drainage and the patient could develop a chronic subdural hematoma. Additionally, one of the things to always keep in mind is that a patient can overdrain and have headaches. They can get a spinal headache. So one of the key complaints, if the patient tells you, "I have headaches when I'm sitting up, or standing up, or walking," that's sign your over draining. So again, with a programmable shunt, you can adjust it by decreasing the amount of drainage by decreasing the flow by increasing the amount of resistance. Now, there are many shunts out there at this time of many different companies. All right. This is just a table showing the different shunts and whether or not they're MRI sensitive. This becomes important because in this day and age, many patients are getting MRI scans for other reasons. They get MRI scans for their knees, their backs, their shoulders for stroke workup. And it's good to know whether this shunt is MRI sensitive or not. Now Codman-Hakim is the older shunt, which I showed you a picture of. And that has up to about 20 different programs settings. But it is MRI-sensitive and these reprogramming after that,. The new one, the Codman-Certas, which is the one I showed in my talk, is not MRI sensitive and does not need reprogramming. Although most MRI centers would tell the patient to make sure they check in with their neurosurgeon shortly after because they're always worried that it might change. The same with the Sophysa-Polaris, as well as the Aesculap, those are also FDA-approved for MRI compatibility. The Medtronic-Strata is MRI-sensitive and does need reprogramming. What does this reprogram mean? How is it done? Well, there are a plethora of programmable machines out there and each specific for its particular shunt. This is the older Codman-Hakim that I showed earlier. And this has all the different settings that can be accomplished. This gives you very fine degree of setting. You can go from a pressure of 15 to pressure of 16 centimeters. So it's on one centimeter increments. And this can be used, it's a rather bulky device. This shows the size of the shunts. You wanna localize right over one of these shunts and its little clicking mechanism that the programmer can hear and detect the number of clicks it is from a neutral or start position. Also, these can be verified by checking an x-ray. And remember this is sensitive to MRI scans. There are other shun programmers out there. This is these Sophysa-Polaris. This is the Metronic-Strata and this is the Codman-Certas. These work on similar principle that it floats like a compass over the shunt valve. And those are the metal settings we see on the x-rays. It can line up in such a way that it gives you a reading. Also, this can be used to program the shunt. This is a large magnet here that can be used to dial the shunt as is this a magnet. And this is a magnet here that is put over the shunt as it's lined up. And then you can dial it to a five, to a six, or to seven, for example. The other way, a technique that is used is to check the flow through the shunt. And this is called the shunt check device. And basically, it's a nice device where you noninvasively check the shut. You put these strips on the patient. And what it does, it measures the difference in the skin temperature. So if there's flow going through, it makes it cooler. So the sensor, and there are three sensors. One here, one here, and one here. The three sensors over that can detect differences in the temperature cooling of the skin. And what we see is it can detect the flow, and it reports to flow here, that if there is flow, you can detect an appropriate decrease in the temperature. Here's some examples of some of our patients. And this is an example of the effect of gravity. So this is a patient who had a carbon shut in place for NPH. And you see there's not much flow, which is which you expect when the patient is supine. Once the patient sits up here at 90 degrees or even 45 degrees, you see this drop in flow, or this increase in flow, and this drop in temperature that occurs. And this shows that this is a threshold line here so you're clearly below the threshold line, so you're getting very good flow. This shows another patient who has a very nice flow. And then you break it into components here. You sort of see the blue, which is right over the middle, which drops on the most. And these are the flanking sensors on the side, which slow down at a lower rate. All right. And so this is a very nice way to check a shunt if you're worried about it or you're concerned about it. And it's very assuring for the patients and their families when you can do this in the clinic. These are very nicely mobile. We've mounted them onto mobile units in our hospitals. So we carry them around, we move them around the hospital in the clinic to the emergency room. And for NPH specifically, it's very nice to have a set of baseline that you can give to the patient or show the patient to say, "Yes, we have a working shunt." So if they come back a year from now, you can repeat it, determine whether that has changed. This is just a paper that we recently published showing how we use this in our emergency room for patients with possible shunt failure and a question of whether the shunt is working. So it works in those situations that are not NPH as well. But specifically with NPH, it's very useful because we done in elective fashion. And families frequently, I have found, are very worried about whether the shunt is working or whether it's optimized. So one of the things to discuss is sort of where are the future of NPH is going. There is a lot of interest in NPH. There are randomized controlled trials that are being done now to determine what are the facets or what are the things we should be looking for to determine whether the patient will be responding to a shunt. And when I say responding to a shunt, I'm not just limiting it to the short term; they're looking more for the long term, whether the patient will respond long term, two years, three years, five years out. One of the criticisms with NPH shunting is that many patients plateau out after about two years. And the theory or the hypothesis is maybe it's because the NPH portion is being treated adequately. And it's the neuro degenerative process that continues. Most cases of NPH are idiopathic. And those are the ones that we've been focusing on. All right. Those that are secondary tend to respond better to a shunt. Finally, point out that the detection is often delayed because people don't really know, or many people don't really know the symptoms, or that there is etiology, and they just attributed just to old age. Recent studies have to look at whether NPH might be related to head injuries, ground level falls, chronic subdural hematomas. There are studies being done looking at the genetics whether or not there may be gene mutations that may be involved with NPH. And finally, studies have been looked at the whole CSF flow issues, looking at the glymphatics inside the brain or the dural lymphatics, and seeing where those are apparent in NPH. We're also involved in many of these studies. And I think this area is an area of great research and hopefully some very nice discoveries. What does it take to have an NPH program? Frequently, it's a multidisciplinary approach. And a lot of education for the family. Looking at patients using the latest neuroradiological techniques, spinal taps. We tend to do these with our radiology colleagues under interventional guidance because it is much more comfortable for the patients. Pre-op, PT/OT/ST and geriatric evaluation using clinical pathways and working with our medicine teams to ensure that we've optimized the patient, so to minimize their comorbidities and the effect of those comorbidities at the time of surgery. Post-operative, following the patients closely, adjusting the shunt to optimize it for the patient. Again, depending on the patient's study, the patient's neurological status, their degree of improvement or lack of it, as well as radiographic findings. ShuntCheck is a newer designed device that can be used to help assess where the shunt is functioning. There is some quantitative amounts in there. We have found that if you have the patient sit up, you can augment the flow. We also have done studies where you can adjust the patient from a Level 5 down to Level 2, for example, and show the changes. Finally, outreach is important to get the word out there so that this entity of normal pressure hydrocephalus is better recognized both by patients, their families, as well as their primary care physicians. Here's a PubMed study it did. Recently, did a search to look at NPH or normal pressure hydrocephalus. And if you plug in the words for normal pressure hydrocephalus, you can see that there is this upward trend of publications. So there clearly is interest that continues in NPH. So to summarize, so the key points for all three talks or three segments of our talks, NPH is a clinically important entity that is becoming better defined. There are a large number of patients that it affects worldwide. Improved diagnosis is gonna be a key. And with the newer diagnostic techniques, both radiology as well as genetic or looking for biomarkers, I think this is gonna be key. It seems that there's a fundamental problem with CSF and interstitial fluid flow. And hopefully, further studies will be done to help us out with that. The current neurosurgeon techniques that we've talked about, i.e. VP shunt have efficacy and are safe. There have been many advents that have been done so that shunts are much better tolerated by the patient, and much more efficacious, and less prone to failure. We're looking for new technology that is on the horizon. I'm sure that it will involve some shunts. And there will also be endovascular techniques that may come to play. And ultimately, I think we have to realize that NPH is not as simple as just one entity. And it may be combination of multiple different neurogenerative disorders. I thank you for your attention and be happy to answer further questions.

- Beautiful lecture. Very well done. Really nice way to troubleshoot the shunt. It's very intriguing. Why do these patients get better, Jeff? And they're good for a few years, maybe two years, maybe four years, maybe five years, and then they start getting worse. And you troubleshoot the shunt, you tap it, you drain hollow volume fluid off their shunt, and they still don't get better. And I agree there is a combined processes that were able to fix one, but then other processes progress and lead to the patient worsening. Do you warn the patients ahead of time when you do this shunt, that the miraculous effect may not be permanent?

- Yes, absolutely, absolutely. I tell the patients, their family, that there's a lot that we don't know about the brain. And we all know that it is evolving, our knowledge is evolving, and that although we can fix the NPH component or we can treat that, there are other things that are going on. And frequently, I have patients who then after three years, their Parkinson's takes off, and now they're heading down the Parkinson pathway. So I think that we have to be sensitive to that. We have to work closely with our neurology colleagues and have that constant dialogue, that it's not just one thing. And ultimately down the line, perhaps the shunt may help with some of these other processes that are going on.

- Yeah, very well said. Really thankful to you. Thankful to Codman. I think they have their new shunt valve systems, CERTAS Plus, as a number of advantages including number one, it's much less prone to magnetic interference from iPads, iPhones, airport devices, and something that is so prevalent among us. So CERTUS Plus has advantage there. It also comes in lower profiles for older individuals, smaller valves, and therefore can be very useful when the skin is very thin and be able to avoid any skin breakdown. And I think there are also other advantages in terms of very flexible levels in also a virtual off if you need to turn off the shunt completely. CERTAS Plus provides an opportunity for us to do that. So I really wanna, again, thank Codman for sponsoring this presentation. And also, wanna sincerely thank you for huge expertise you have, Jeff, in many levels, including NPH and shunts. And thank you for being with us today.

- Thank you for having me. Once again, been honor and a pleasure.

- Thank you, Jeff.

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