Endoscopic Corpus Callosotomy: A Bright Future for Kids with Intractable Seizures
Neurosurgeon, Daniel Hansen, M.D. shines a light on this barrier breaking approach to epilepsy surgery. Using an endoscopic method to disconnect the left and right brain, this minimally invasive procedure has the same chance of seizure freedom post-surgery as traditional callosotomy, while reducing operating time and recovery time.
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Host: Hello and welcome to Cook Children's Doc Talk. Our guest for this episode is pediatric neurosurgeon Dr. Daniel Hansen. Dr. Hansen sees and treats children for the whole range of pediatric neurosurgical issues, and has special interest in minimally invasive surgery, endoscopic surgery, tumors and epilepsy. He works closely with the neuro-oncology and epileptology teams to provide cutting edge patient-centered treatment, using the most up to date information and treatment options. Dr. Hansen is the first neurosurgeon at Cook Children's and one of only two in the state of Texas to perform an endoscopic corpus callosotomy and endoscopic surgery on the corpus callosum that separates the right and left sides of the brain for children with certain types of intractable epilepsy or severe seizures. He's also one of the first pediatric surgeons in the nation to perform the endoscopic approach. Welcome, Dr. Hansen.
Dr. Hansen: Thank you.
Host: I want to start off with a little background about you. Initially, your career choice was between becoming an astrophysicist or a surgeon, clearly surgery won out. But why neurosurgery and in particular, pediatric neurosurgery?
Dr. Hansen: Well, you probably noticed, those are two pretty diverse career choices. But the link between them was a love of the unknown, of the unexplored. And I really can't see any better comparison than deep space, and the human brain, something that we live with every day, but is still vastly unknown to all of us practicing medicine. Going to college, I took some physics classes and very quickly realized that I wasn't going to be interacting, I wasn't going to be involved with people through much of my day. And I really craved that human interaction, that ability to have a meaningful impact in people's lives that I could see, I could tangibly touch. I wouldn't be working on esoteric theories, in a classroom writing out equations on whiteboards. But I'd be at the bedside, I'd be in the office next to people and next to families that were going through difficult times. Looking at the spectrum of adult neurosurgery and pediatric neurosurgery, adult neurosurgery is interesting. But to me, my heart has always been drawn to taking care of children, they are often a segment of our population that doesn't have a voice. They don't have someone who's advocating for them, they don't have someone who is supporting them in times of great struggle. And that really appeals to my heart. And the cognitive side of dealing with specific pediatric problems really appeals to my cognitive side.
Host: So callosotomies have been performed on adults and children for a while now. But the endoscopic approach is fairly new. Can you give us the background on the surgery, how it was originally done in adults, and why it's just now becoming available for children.
Host: So the goal of a callosotomy is to disconnect the left and right sides of the brain. For certain types of epilepsy, the electrical signals, going from the left to the right side or right to the left causes people to have a very specific type of seizure, as you might guess, and adults with a larger brain and larger anatomy, things that we do are a little bit easier, just from a space constraint standpoint. So many of the pioneering surgeries that we're doing and kids have actually had a basis in adult surgery for a number of years. So there was discovered several decades ago that disconnecting the right and left side would stop people from having something known as drop attacks, which is a very specific type of seizure where patients tense up or become floppy and fall to the ground causing pretty significant injury depending on when they fall. We also know that for people that have significant damage to either the left or the right side of the brain in a way that is causing abnormal electrical activity, sometimes disconnecting that portion of the brain makes a significant impact on their seizures. This was originally performed in adults and performed so well it was carried over into children. In the last decade or so our technology with very small video cameras, or endoscopes, has improved to a point where we are feeling more comfortable in other areas of the body, and in other areas of the brain performing surgeries guided by those video cameras. In the last couple of years, as more practitioners and more surgeons have gotten more used to endoscopic approaches, we've been pushing the boundaries of using those instruments for surgeries that they typically weren't used for. There were a couple of reports from other institutions from other hospitals in the country, about people using an endoscope to perform a callosotomy on adults or in cadavers. During my training, in residency, my medical training, I practiced using an endoscope quite extensively. And I wanted to put those skills to use and try to do a surgery for children that would otherwise be a very large surgery and turn it into something smaller that they could recover quicker from while still giving them the same outcomes.
Host: So do children have better outcomes with the surgery than adults?
Dr. Hansen: In general, children usually do a little bit better after surgery than adults because they heal better and their brain is a little bit more adept at rewiring itself for lack of a better term. We also call it neural plasticity, meaning that their brain is able to adapt to changes a little bit better than adults. From a seizure standpoint, the seizures that adults have and that children have, often have very different onsets are different reasons for occurring in the first place. So their outcomes aren't directly comparable, but children are having excellent results from this type of surgery.
Host: Fantastic. So when did you first become interested in this particular surgery?
Dr. Hansen: One of my mentors in fellowship, Dr. Sandy Lam at Texas Children's, used the endoscope very extensively in her surgical practice. Although not initially for epilepsy. After I left fellowship, while I was no longer training there, she published a few case reports meaning single patient experiences on using the endoscope to do some epilepsy surgery. With my background in using the endoscope for other types of neurosurgical procedures. I thought that the corpus callosotomy made perfect sense, given its location in the body, the relative ease of getting at that structure, anatomically. And it's traditionally a surgery that has a very big opening in the skull, it traditionally puts a lot of tissue trauma to the brain. So I thought it was a perfect surgery to try and target something more minimally invasive.
Host: How many other epilepsy centers offer this type of surgery to children?
Dr. Hansen: That is a great question. And the simple answer is, I don't know. And the reason for that is that we can only have published reports from institutions to suggest that they're doing it. Otherwise, if they're offering it, they don't necessarily broadcast it or make it known. So I know that the University of Washington or Washington University in St. Louis, one of their epilepsy practitioners is doing this. And there are some small reports from Boston Children's, and also Dr. Lam in Texas Children's. But we're amongst a very, very small handful of places that are offering this sort of cutting edge procedure.
Host: Why do you think that is?
Dr. Hansen: It's technically very difficult, the feeling comfortable using an endoscope is not something that comes naturally. It is, uh, staring at a video screen, not looking at your surgical field, not directly staring at what you're operating on, but manipulating it through a screen in front of you. And through a rather small opening is a rather daunting task. And there's a pretty steep learning curve with an endoscope. I think a lot of practitioners don't have the time to invest in learning those techniques. And the traditional approach, although very invasive, works very well. So a lot of people don't see the need to try and make something better or reinvent the wheel.
Host: So who would be eligible for this surgery?
Dr. Hansen: Wonderful question. So we typically think of children with intractable epilepsy that have an underlying diagnosis of what's known as Lennox Gastaut syndrome, or children that have had damage extensive damage to specifically just one side of their brain. Those are the patients that we're focusing on currently, although if you ever have a child with epilepsy that has not been evaluated by our epileptology group here at Cook Children's, we would strongly recommend referring them so that they can be evaluated to see if this surgery, or any of the other surgery offerings that we have would be available to them.
Host: So what are the advantages or benefits for the patients?
Dr. Hansen: So with this specific procedure, we're taking a surgery that would have traditionally taken probably eight to 10 hours in the operating room, and we're now routinely doing them between five and six hours, so it's a shorter procedure. We're taking an incision that would have been 10 to 12 inches long on most children, and we've reduced it down to an incision, that's usually three or four inches. Instead. We're taking a bone flap or the size of what we call our craniotomy or the amount of bone we have to remove to do surgery. Although we do put it back, it's gone from the size of about your hand down to the size of about an inch by an inch and a half square. That means in the long term, that when kids are recovering from this surgery, they have less pain, they have less bleeding during the surgery, they're in the hospital, usually a fewer number of days just because they don't have ... their body didn't go through so much trauma. Now, the goal of surgery, severing the corpus callosum has some pretty significant neurologic impacts, at least temporarily. Those are not lessened through the surgery, because the goal is to do the same thing to the brain. We're just doing it through a smaller opening.
Host: If I understand correctly, you've performed this procedure on several patients here at Cook Children's. Can you talk a little about their backgrounds, the types of epilepsy or seizures, the severity of their condition and their ages?
Dr. Hansen: Absolutely. So in the last year, we've done about five of these procedures. We have children ranging from the age of five up to the age of 17. Two of those children had significant what we call perinatal injuries, meaning shortly after birth or at the time of birth, they had extensive damage to one side of their brain or the other. That damage resulted in debilitating seizures. And most of these children are having seizures every day, if not multiple times a day. Two of our other children have a syndrome called Lennox Gastaut syndrome, which it's not entirely clear what causes this, but it has a very specific epilepsy finding on EEG's or brainwave patterns of electrical activity. And it is notorious for causing drop attacks. Drop attacks are again where the child's muscles tense, and the patient falls to the ground. And, obviously, depending on where they are, when they fall, can have some pretty serious consequences from an injury standpoint. These children also are seizing multiple times a day, usually, even through multiple seizure medications.
Host: So how are the kids doing now?
Dr. Hansen: Well, I'm happy to say fantastically, so the very first child that we performed a surgery on has been seizure free now for over a year since the day of surgery. And he was seizing multiple times a day prior to that. The other kids have also had wonderful results, although one other is now seizure free and has had no seizures since about six months ago, the others have had over a 90% reduction in their frequency of seizures, but also, more importantly, the severity of the seizure. So instead of seizures that are lasting for minutes, and causing significant cognitive impairment after the seizure is done, many of these seizures now are brief seconds, and the child goes back to their baseline immediately afterwards.
Host: One of the things that I would be curious about, I know for kids who have these multiple seizures, that a lot of times it can cause long term developmental and cognitive issues. So does this surgery, help repair or at least reduce those future conditions or long term conditions?
Dr. Hansen: Yeah, that's a wonderful question. I don't think we have enough evidence yet to know if performing the surgery will reverse some of the effects, that long term anti seizure medications cause or that just long term exposure to repetitive seizures cause but I can tell you, as we have lots of data, that the earlier we can treat children, the earlier we can intervene in them surgically, if appropriate, the quicker we can get them off anti epileptic drugs, and very often reduce their seizure frequency that does have a significant impact on their long term cognitive development.
Host: Fantastic. So when you disconnect the left and right brain, what impact does this have on brain functionality and or cognition?
Dr. Hansen: So it's kind of a funny thing, the left and right brain like to talk for some very, very specific instances that we can set up in a lab to show that when we disconnect them, they're no longer doing that. But in day to day life, it's really actually very difficult to know that the left and right side are not talking. And in fact, for many of the children, because they were seizing so frequently, and that has such a significant negative impact on cognition, the children actually appear to be better off after surgery than worse. One of the really funny sort of things that you can test just as an example of what you get with split brain syndrome, which is one of the names for this is if you place an object in a patient's left visual field, so not in their left eye, but in their left visual field, so the left side, and they aren't allowed to see it with their right visual field. So you have to put up blinders. And this is why it's all very simulated, but the left visual field connects to the right side of the brain, the right side of the brain, for most people is not very responsible for language. So that image on the left side, going to the right brain is recognized as an object. But if you ask the patient to describe what it is, they're unable to come up with the word for because of the language or identifying that object comes from the left side of the brain. And because the left and right side aren't talking, the right side knows there's something there, and the left side would know what it is, if it could tell that there was something there. But in day to day life, there's very few things that just show up on the left side of our vision, or just the right side of a vision or just in our left hand. So again, these are very simulated tests to show how the left and the right side of the brain talk, but in practicality rarely come up.
Host: Fascinating. So how does this compare to loss of cognition or functions without treatment?
Dr. Hansen: If we didn't think it had enormous benefit, we wouldn't offer it. So again, we know that children who have repetitive seizures over years of life and are on antiepileptic medications which have significant brain chemistry and neurocognitive developmental side effects, we know that stopping the seizures even when it involves severing the left and right sides of the brain from one another or removing parts of the brain for other types of seizures, surgery, their outcomes, the children's outcomes are significantly improved by stopping the seizures even with loss of brain tissue.
Host: So as you've mentioned, this procedure is appropriate for treating kids with certain types of epilepsy or seizures. But what surgeries are currently available in pediatric surgery for other types of severe epilepsy or seizures, or for that matter, tumors or any other anomalies that may occur in the brain?
Dr. Hansen: Well that's a pretty big question, but we'll focus on the seizures. So we have several different seizure surgeries that are available, if after a thorough evaluation with our epilepsy group it's deemed appropriate. So the most common seizure surgery that people may be aware of, is something called an anterior temporal lobectomy. And you may be familiar with that because it's one of the most common surgeries for seizures in adults. So the anterior temporal lobe is an area that is commonly a focus of seizures. And a lobectomy simply means we take that portion of the brain out, we can do that to other areas of the brain as well, if we determine that they are a focus of seizures. That's among the more common surgeries, we also have surgeries that sound super cool. Laser ablations, where we put a small fiber optic cable into the brain into an area where we think seizures are coming from, and we can actually burn that area, or thermally coagulate that area, destroying the tissue that's the origin of the seizures. We also have the ability to implant multiple electrodes into the brain itself. So people may be familiar with with what are known as scalp EEGs, where you see children or adults with all the dots scattered on their heads connected to a bunch of wires connected up to machine with all the squiggly lines. We have the ability to move those electrodes from the scalp where the readings are good, but not very accurate, actually down into the brain tissue itself, where the readings are incredibly accurate, and allows us to more accurately diagnose where seizures are coming from letting us know better whether or not a child is a surgical candidate or not. We have a couple more technologies that we don't use very frequently that are available in really difficult to treat cases. One is known as a vagus nerve stimulator, which is a small device that we place onto the nerve in the neck that sends small electrical impulses back up to the brain, and is thought to help certain types of seizures for certain kids who are otherwise difficult to treat. We also have something very new, that is being not used very much in pediatrics yet, but is being more used in adults called an RNS. And that is a device very much like a vagal nerve stimulator. However, instead of stimulating a nerve in the neck, we're stimulating the surface of the brain directly using a special computer and a special electrical impulses to try and help modulate seizure frequency as well.
Host: So are there any innovative and minimally invasive surgeries on the horizon for kids with severe forms of epilepsy and what advantages do they bring? Or do we hope they'll bring?
Dr. Hansen: Yeah, so from myself personally and from the other providers I know throughout the country who are really trying to push the boundaries of endoscopic work, I think we will continue to try and refine our use of the endoscope and apply it to other traditional forms of epilepsy being it lobectomies of the temporal lobe or the frontal lobe or a procedure called a hemispherotomy or hemispherectomy. Things that are again, traditionally done through a very large surgery trying to make them performed through a smaller, less invasive opening. But there's also something that is very new on the horizon is not being used that I know of yet in pediatrics, but something called focused ultrasound. So much like our laser ablation is looking to heat up tissue to destroy an area of seizure focus, that still requires us to put a fiber optic cable into the brain which is invasive, even if minimally so. Focused ultrasound is very much almost like stereotactic radiosurgery, which is radiation. But this is using focused ultrasound beams to try and destroy or heat up a small area of tissue in the brain to get the same effect as we would with using a fiber optic cable. So truly non invasive.
Host: Absolutely amazing. So overall, what does the future look like for these patients?
Dr. Hansen: You know, unfortunately for epilepsy, a lot of children, they are not surgical candidates. And so they have a very difficult life. They are treated with usually multiple medications, and they continue to have seizures throughout their life. But that's not everyone. And it's difficult to tell those children from the children who are true surgical candidates, which is why we would always recommend referring any children that you might know that have failed as a seizure medicine so that we can evaluate them more in depth. For those children that are surgical candidates, surgery outcomes vary based on the area of the brain that the seizures originate from. But we can have seizure freedom upwards of 50% in some areas of the brain 70% in some areas of the brain and over 90% in other areas of the brain. So it can be substantial impact on the child's life in a positive way if we can perform surgery on them.
Host: So for pediatricians or other primary care providers, as well as specialists who have patients they think maybe candidates for this or any of the neurosurgeries at Cook Children's, how would they refer them? At what ages? And how early in their care?
Dr. Hansen: Sure. So if you think that you have a child with a standard neurosurgical issue, refer them immediately. Call up our clinic. Call up, one of the physicians on call will be happy to chat with you. Cook actually has a direct connect line to be able to connect to a specialist of choice within a very small amount of time if you've got something that you're worried about, and we're always happy to see the children if it's something that you're not comfortable managing or diagnosing. From a surgery standpoint for epilepsy specifically, those children should be referred to our epilepsy group. And that is our neurology colleagues first. They really spearhead the effort to diagnose children with seizures, and to determine whether or not they're surgical candidates. We typically think of children who have failed two seizure medications as being medically intractable epilepsy or medically intractable seizures. Those children no matter what their age are, or no matter how long you've been treating them, would be appropriate candidates to be referred to our program for evaluation.
Host: So it's been really great talking with you today. Dr. Hansen, thanks for taking the time to share about endoscopic corpus callosotomy and the fantastic work you and your team are doing here at Cook Children's. It's truly amazing and so important to the future of these kiddos.
Dr. Hansen: It's been my pleasure to be here today. Thank you so much. I'm always happy to talk to anyone in our organization or without about these procedures and how they might be able to impact the children that you're caring for.
Host: Fantastic, thank you. We're so glad you could join us today. If you'd like to learn more about this program or any program at Cook Children's, please visit us at Cook Children's dot org