Intro

Childhood-onset hydrocephalus encompasses a wide range of disorders with varying clinical implications. There are numerous causes of symptomatic hydrocephalus in neonates, infants, and children, and each predicts the typical clinical course across the lifespan. Etiology and age of onset impact the lifelong management of individuals living with childhood-onset hydrocephalus.

In this episode, Casey Albin, MD, speaks with Shenandoah Robinson, MD, FAANS, FAAP, FACS, author of the article “Childhood-onset Hydrocephalus” in the Continuum® June 2025 Disorders of CSF Dynamics issue.

Dr. Albin is a Continuum® Audio interviewer, associate editor of media engagement, and an assistant professor of neurology and neurosurgery at Emory University School of Medicine in Atlanta, Georgia.

Dr. Robinson is a professor of neurosurgery, neurology, and pediatrics at Johns Hopkins University School of Medicine in Baltimore, Maryland.

Additional Resources

Read the article: Childhood-onset Hydrocephalus

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Host: @caseyalbin

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 Albin: Hi, this is Dr Casey Albin. Today I'm interviewing Dr Shenandoah Robinson about her article on childhood onset hydrocephalus, which appears in the June 2025 Continuum issue on disorders of CSF dynamics. Dr Robinson, thank you so much for being here. Welcome to the podcast. I'd love to start by just having you briefly introduce yourself to our audience.

Dr Robinson: I'm a pediatric neurosurgeon at Johns Hopkins, and I'm very fortunate to care for kids and children from the neonatal intensive care unit all the way up through young adulthood. And I have a strong interest in developing better treatments for hydrocephalus.

Dr Albin: Absolutely. And this was a great article because I really do think that understanding how children with hydrocephalus are treated really does inform how we can care for them throughout the continuum of their lifespan. You know, I was shocked in reading your article about the scope of the problem for childhood onset hydrocephalus. Can you walk our listeners through what are the most common reasons why CSF diversion is needed in the pediatric population?

Dr Robinson: For the United States, and Canada too, the most common reasons are spina bifida---so, a baby that's born with a myelomeningocele and then develops associated hydrocephalus---and then about equally as common is posthemorrhagic hydrocephalus of prematurity, congenital causes such as from aquaductal stenosis, and other genetic causes are less common. And then we also have kids that develop hydrocephalus after trauma or meningitis or tumors or other sort of acquired problems during childhood.

Dr Albin: So, it's a really diverse and sort of heterogeneous causes that across sort of the, you know, the neonatal period all the way to, you know, young adulthood. And I'm sure that those etiologies really shift based on sort of the subgroup population that you're talking about.

Dr Robinson: Yes, they definitely shift over time. Fortunately for our kids that are born with problems that raise concerns, such as myelomeningocele or if they're born preterm, they sort of declare themselves by the time they're a year old. So, if you're an adult provider, they should have defined themselves and it's unlikely that they will suddenly develop hydrocephalus as a teenager or older adult.

Dr Albin: Totally makes sense. I think many of the listeners to this podcast are adult neurologists who are probably very familiar with external ventriculostomies for temporary CSF diversion, and with the more permanent ventricular peritoneal shines or ventricular atrial or plural shines that are needed when there's the need for permanent diversion. But you described in your article two procedures that provide temporary CSF diversion that I think many of our listeners are probably not as familiar with, which is the ventricular access devices and ventriculosubgaleal shunts. Can you briefly describe what those procedures provide? Who are the candidates for them? And then what complications neurologists may need to think about if they're consulted for comanagement in one of these complex patients?

Dr Robinson: Well, the good thing is that if as an adult neurologist you encounter someone with, you know, residual tubing from one of these procedures, you are unlikely to need to do anything about it. So, we put in ventricular access device or ventriculosubgaleal shunts, usually in newborns or infants. And sometimes when they no longer need the device, we just leave it in because that saves them an extra surgery. So, if you encounter one later on, it's most likely you won't need to do anything. Often if the baby goes on to show that they need a permanent shunt, we go ahead and put in that permanent shunt. We may or may not go back and take out the reservoir or the subgaleal shunt. The reservoir and subgaleal shunts are often put in the frontal location. Sometimes we'll put the permanent shunt in the occipital location and just leave the residual tubing there. So, you're very unlikely to need to intervene with a reservoir or subgaleal shunt if you encounter an older child or adult with that left in. We use these in the small babies because the external ventricular drains that we're very familiar with have a very high complication rate in this population. In the adult ICU, you often see these, and maybe there's, you know, a few percent risk of infection. It actually heads into 20 to 25% in our preterm infants and other newborns that require one of these devices for drainage. So, we try not to use external ventricular drains like we use in older patients. We use the internalized device: either the ventricular reservoir with a little area for us to tap every day, every other day; or the ventriculosubgaleal shunt, which diverts the spinal fluid to a pocket in the scalp. So, we use these in preterm infants that are too tiny for a permanent shunt. And for some of our babies that are born, for example, with an omphalocele, that we can't use their peritoneal cavity and so we need some temporizing device to manage their CSF.

Dr Albin: Totally makes sense. And so just to clarify, I mean, this is a tube that's placed into the ventricles of the brain and then it's tunneled into the subgaleal space and the collection, the CSF, just builds up there, like?

Dr Robinson: Yeah.

Dr Albin: And over time either, you know, the baby will learn how to account for that extra CSF, and then I guess it's just reabsorbed?

Dr Robinson: Yeah. When it's present, though, it looks like maybe, I don't know if you're familiar with like a tissue expander. There is this bubble of fluid under the scalp, but it's prominent, it can be several centimeters in diameter.

Dr Albin: Wow, that's just absolutely fascinating. And I don't think I've ever had the opportunity to see this in clinical practice. I've really learned quite a bit about this. I assume that these children are going to go on to get some sort of permanent diversion. And then, you know, over time, those permanent shunts do create a lot of problems. And so, I was hoping you could kind of walk us through, you know, what are some of the things that you're seeing that you're concerned about? And then if you've just inherited a patient who had a shunt placed at, say, a different institution, how do you go about figuring out what kind of shunt it is and if they're still dependent on it?

Dr Robinson: There's a few things that, fortunately, technology is helping with. So, it is much easier now for patients to get their images uploaded to image-sharing software, and then we can download their images into our institutional software, which is very helpful. Another option is that we are strongly encouraging our families to use a app such as HydroAssist that's available from the Hydrocephalus Association. So that's an app that goes on your phone, and you can upload the images from an MRI or a CT scan or x-rays from a shunt series. And then that you can take if you're traveling and you have to go to emergency department or you're establishing care with a new provider, you can have your information right there and not be under stress to remember it. It also has areas so you can record the type of valve. And all of our valves have pluses and minuses, they all tend to malfunction a little bit. And they can be particularly helpful with different types of hydrocephalus. I really doubt that we're going to narrow down from the fifteen or so valves we have access to now. And so, recording your valve type, the manufacturer as well as the setting, is very helpful when you're transferring care or if you're traveling and then have to, unfortunately, stop in the emergency department.

Dr Albin: Yeah, I thought that was a really great pearl that, like, families now are empowered to sort of take control of understanding sort of the devices that they have, the settings that they're using. And what an incredible thing for providers who are going to care for these patients who, you know, unfortunately do end up in centers that are not their primary center. The other challenge that I find… I practice as a neurointensivist, and sometimes patients come in and they have a history of being shunt dependent and they present with a neurologic change. And I think that we as neurologists can be a little quick to blame the shunt and want the shunt to be tapped. And I was really struck in reading this article about the complexity of shunt taps. And I was hoping, you know, can you kind of walk us through what's involved and maybe why we should have a little bit of a higher threshold before just saying, ah, just have the neurosurgeons tap the shunt. Like, it's not that straightforward.

Dr Robinson: And it may depend on the population you're caring for. So, when I was at a different institution, we actually published that there's about a 5% complication rate from shunt taps. And that may be- that was in pediatric patients. And again, that may be population dependent, but you can introduce infection to a perfectly clean shunt by doing a shunt tap. You can also cause an acute shunt malfunction. So that's why we tend to prefer that only neurosurgeons are doing shunt taps for evaluation of a shunt malfunction. There are times that, for example, our patients who are getting intrathecal chemotherapy or something have a CSF access device like an Ommaya reservoir, and other providers may tap that reservoir to instill medicine. But that's different than an evaluation, like, you're talking about somebody with a neurological change. And so, it is possible that if somebody has small ventricles or something, if you tap that shunt, you can take a marginally functioning shunt and turn it into an acute proximal malfunction, which is an emergency.

Dr Albin: Absolutely. I think that's a fantastic pearl for us to take away from this. It's just that heightened level. And kind of on the flip side of that, you know, and I really- I do feel for us when we're trying to kind of, you know, make a case that it's, it's not the shunt. Many of our shunted patients also have a lot of neurologic complexity, which I think you really talked upon in this article. I mean, these are patients who have developmental cognitive delays and that they have epilepsy and that they're at risk for, you know, complications from prematurity, since that's a very common reason that patients are getting shunts. But from your experience as a neurosurgeon, what are some of the features that make you particularly concerned about shnut malfunction? And how do you sort of evaluate these patients when they come in with that altered mental status?

Dr Robinson: It is challenging, especially for our patients that have, you know, some intellectual delay or other difficulties that make it hard for them to give an accurate history. Problem is, if they're sick and lethargic, they may not remember the symptoms that they had when they were sick. But sometimes there's hopefully there's a family member present that does remember and can say, oh, no, this is what they look like when they have a viral illness. And this is different from when they have the shot malfunction, which was projectile emesis, not associated with a fever. It's rare to have a fever with a shunt malfunction, although shunt infection often presents with malfunction. So, it's not completely exclusionary. We often look at the imaging, but it's taking the whole picture together. Some of the common other diagnoses we see are severe constipation that can decrease the drainage from the shunt and even cause papilledema in some people. So, we look at that as well on the shunt series. It's very important to have the shunt series if you're concerned about shunt malfunction or- the shunt tubing is good. It tends to last maybe 20to 25 years before it starts to degrade. And so, you may have had a functioning shunt for decades and it worked well and you're very dependent on it, and then it breaks and you become ill. But on the flip side, we have patients that have had a broken shunt for years, they just didn't know about it. And we don't want to jump in and operate on them and then cause complexities. And so, it is a challenge to sort out. The simplest thing is obviously if they come in and their ventricles are significantly larger, and that goes along with a several-hour or a couple-day deterioration, that's a little more clear-cut.

Dr Albin: Absolutely. And you talked about this shunt series. What other imaging- and, sort of maybe walk us through, what's involved in a shunt series, what are you looking at? And then what other imaging is sort of your preferred method for evaluating these patients?

Dr Robinson: In adult patients, the shunt series is the x-ray from the entire shunt. And so, if they have an atrial shunt, that would be skull x-ray plus a chest x-ray; or the shunt ends in the perineal cavity, it goes to the perineum. And we're looking for continuity. We're looking for the- sometimes as people grow and age, the ventricular catheter can pull out of the ventricle. So, we're looking to make sure that the ventricular catheter is in an optimal position relative to the skull. We can also look at the valve setting to see the type of valve. So, that can also be helpful as well. And then in terms of additional imaging, a CT scan or an MRI is helpful. If you don't know what type of valve they have, they should not, ideally, go in the MRI scanner. We like to know what their setting is before they go in the MRI because we're going to have to reset the valve after they come out of the MRI if it's a programmable valve.

Dr Albin: This is fantastic. I've heard several pearls. So, one is that with the shunt series, which, am I correct in understanding those are just plain X-rays?

Dr Robinson: Yes.

Dr Albin: Right. Then we can look for constipation, and that might be actually something really serious in a pediatric patient that could clue us in that they could actually be developing hydrocephalus or increased ICP just because of the abdominal pressure. And then that we need to be mindful of what are the stunt settings before we expose anyone to the MRI machine. Is that two good takeaways from all of this?

Dr Robinson: Yes. And it's very rare that there'll be an MRI tech that will allow a patient with a valve in the MRI without knowing what it is. So, they have their job security that way. But yeah, if you're not sure, just go ahead and get the CT. Obviously, in our younger kids, we're trying to avoid CT scans. But if you're weighing off trying to decide if somebody has a shunt malfunction versus, you know, waiting 12 or 24 hours for an MRI, go ahead and get the CT.

Dr Albin: Absolutely. I love it. Those are things I'm going to take with me for this. I have one more question about these shunts. So, every now and then, and I think you started to touch on this, we will get a shunt series and we'll see that the catheter is fractured. Do the patients develop little- like, a tract that continues to allow diversion even though the catheter is fractured?

Dr Robinson: Yes. So, they can develop scar tissue around, and some people have more scar tissue than others. You'll even see that sometimes, say, the catheter has fractured and we'll take out that old fractured tubing and put in new tubing on the other side. But if you go and palpate their neck or chest, you'll still feel that tract is there because it calcifies along the tract. Some patients drain through that calcified tract for weeks or months without symptoms, and then it can occlude off. So, we don't consider it a reliable pathway. It's also not a reliable pathway if you're positioned prone in the OR. So some of our orthopedic colleagues, for example, if they go to do a spine fusion, we like to confirm that the shunt is working before you undergo that long anesthesia, but also that you're going to be positioned prone and you could potentially- you know, the pressure could occlude that track that normally is open.

Dr Albin: This is fantastic. I feel like I've gotten everything I've ever wanted to know about shunts and all of their complications in this, which is, you know, this is really difficult. And I think that because we are not trained to put these in, sometimes we see them and we just say, oh, it's fractured that must be a malfunction. But it's good to know that sometimes those patients can drain through, you know, a sort of scarred-down tract, but that it may not be nearly as reliable as when they have the tubing in place. Another really good thing that I'm going to put in my back pocket for the next time I see a patient with a potential shunt malfunction.

Dr Robinson: And we do have some patients that the tubing is fractured years ago and they don't need it repaired, and that totally can be challenging when they then transfer to your practice for follow-up care. We tend to follow those patients very closely, both our clinic visits as well as having them seen by ophthalmology. So, there are teenagers and young adults out there that have… their own system has recovered and they are no longer shunt-dependent; and they may have a broken shunt and not actually be using that track, but they usually have had fairly intensive follow up to prove that they're not shunt-dependent. And we still have a healthy respect there that, you know, if they start to get a headache, we're going to take that quite seriously as opposed to, you know, some of our shunt patients, about 10 to 20%, have chronic headaches that are not shunt-related. So, not everybody who has a headache and has a shunt has a shunt malfunction. It's tough.

Dr Albin: This is really tough. That actually brings me to sort of the last clinical scenario that I was hoping we could get your perspective on. And I think this would be of great interest to neurologists, especially in the context that these children may develop headaches that have nothing to do with the shunt. I'd like to sort of give you this hypothetical case that I'm a neurologist seeing a patient in clinic and it’s a teenager, maybe a young adult, and they had a shunt placed early in childhood. They've done really well. And they've come to me for management of a new headache. And, you know, as part of this workup, their primary care provider had ordered an MRI. And, you know, I look at the MRI, and I don't think that the ventricles look really enlarged. They don't look overdrained. Is having an MRI that looks pretty okay, is that enough to exonerate the shunt in this situation?

Dr Robinson: In most cases it is. The one time that we don't see a substantial change in the ventricles is if we have a pseudocyst in the abdomen. The ventricles cannot enlarge initially, and then later on they might enlarge. So, we see that sometimes that somebody will come in and their ventricles will be stable in size, but we're still a little bit suspicious. They’ve got this persistent headache. They may have, you know, some emesis or loss of appetite, loss of activity, and a slower presentation than you would get with an acute proximal malfunction. We can check an abdominal ultrasound for them. And sometimes, even though the ventricles haven't changed in size, they still have a malfunction because they have that distal pseudocyst.

One of the questions that we ask our patients when we're establishing care, in addition to what valve type they have and what sort of their shunt history or other interventions such as endoscopic third ventriculostomy, is to ask if their ventricles enlarge when they have a shunt malfunction. There is a small fraction where they do not. They kind of have a stiff brain, if you will. And so, it's good to know that. That's one of the key factors is asking somebody, do the ventricles enlarge when they have a malfunction? If they have enlarged in the past, they're likely to enlarge again if they have a malfunction. But again, it's not 100%. So, in peds, 20% of the time the ventricles don't enlarge. So, in adults, I'm not that- you know, I don't know what percentage it is, but it's something to consider that you can have a stable ventricular size and still have a shunt malfunction. So, if your clinical judgment, you're just kind of, like, still uneasy, you know, respect that and maybe do a little more workup. That's why we so much want patients to establish care with somebody, whether it's a neurologist or a neurosurgeon or other provider in some areas that have fewer neurospecialists, but to establish care so that you all know what a change is for that patient. That's really important.

Dr Albin: That's fantastic. So, to summarize that, it's really important to understand the patient's baseline and how they presented with prior shunt complications, if they've had some. That if they're coming in with a new headache that we don't have a baseline, so, we should just have a heightened level of awareness that, like, the shunt has a start and it has an end. And even if the start of the shunt in the brain looks okay, there still could be the potential for complications in the abdomen. And maybe the third thing I heard from that is that we should look for GI symptoms and sort of be aware of when there could be a complication in the abdomen as well. Does that all sound about right?

Dr Robinson: And especially for our kids with spina bifida and for posthemorrhagic hydrocephalus are now adults, because the preterm infants are prone to necrotizing enterocolitis. And they may not have had surgery for it, but they still may have adhesions and other things that predispose them to develop pseudocysts over time. And then our individuals with spina bifida often have various abdominal surgeries and other procedures to help them manage their bowel and bladder function. And so that can also create adhesions that then predisposes to pseudocysts. So, we do have a healthy respect for that. In addition, it used to be---because we have gotten a little better with shunts over time---it used to be, like, when I was in training that you heard, you know, if you haven't had a shunt malfunction for 10 or 15 years, you must- you may no longer be dependent. And that's not really true. There are some people who outgrow their need for shunt dependence, but not everyone does outgrow it. And so, you can be 15, 20 years without a shunt revision and still be shunt-dependent.

Dr Albin: Those are fantastic pearls. I think most of them, walking away with this, like, a very healthy respect for the fact that these are complex patients, which the shunt is one component of sort of the things that can go wrong and that we have to have a really healthy respect and really detailed investigation and sort of take the big picture. I really like that.

Dr Robinson: Yeah, I know. I think it's- there's a very strong push amongst pediatric neurosurgery and a lot of the related, our colleagues in other areas, to develop multidisciplinary transition clinics and lifespan programs for these patients to help keep everything else optimized so that they're not coming in, for example, with seizures. But then you have to figure out if this is a seizure or a shunt; you know, if we can keep them on track, if we can keep them healthy in all their other dimensions, it makes it safer for them in terms of their shunt malfunction.

Dr Albin: Absolutely. I love that, and just the multidisciplinary preventative aspect of trying to keep these patients well. So important. Dr Robinson, I really would like to thank you for your time. We're getting towards the end of our time together. Are there any other points about the article that you just are anxious that leave the readers with, or should I just direct them back to the fantastic review that you've put together on this topic?

Dr Robinson: No, I think that we covered a lot of the high points. I think one of the really exciting things for hydrocephalus is that there's a lot of investigations into other options besides shunts for certain populations. We are seeing less hydrocephalus now with the fetal repair of the myelomeningocele, which is great. And we're trying to make inroads into posthemorrhagic hydrocephalus as well. So, there are a lot of great things on the horizon and, you know, hopefully someday we won't have the need to have these discussions so much for shunts.

Dr Albin: I love it. I think that's really important. And all of those points were touched on the article. And so, I really invite our listeners to go and check out the article, where you can see sort of, like, how this is evolving in real time. Thank you, Dr Robinson. Please go and check out the childhood-onset hydrocephalus article, which appears in the most recent issue of Continuum on the disorders of CSF dynamics. And be sure to check out Continuum Audio episodes from this and other issues. Thank you again to our listeners for joining us today. And thank you, Dr Robinson.

Dr Robinson: Thanks for having me.

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.