New Types of Epilepsy Surgery - Prof. Sarat Chandra, All India Institute of Medical Sciences
What are some newer types of epilepsy surgery?! Today we hear about the new version called Robotic Thermocoagulative Hemispherotomy - for which you need a plaster! Also, what defines epilepsy surgery success? It isn't always just seizure reduction or freedom. Hear all about it from epilepsy surgeon Prof. Sarat Chandra. Watch/listen/read here 👇!
Episode Highlights
Different epilepsy surgery techniques - included minimally invasive
Endoscopic hemispherectomies - what are they?
Robotic Thermocoagulative Hemispherotomy technique - what is it?
Measuring success of epilepsy surgery
About Sarat Chandra
Sarat is a neurosurgeon who over the past three decades, he has established and led one of the largest epilepsy surgery programs in the world, with experience of more than 4,000 epilepsy surgeries encompassing the full spectrum of paediatric and adult epilepsy procedures, including hemispherotomy, hemispheric disconnection, corpus callosotomy, SEEG, robotic epilepsy surgery, neuromodulation, vagus nerve stimulation, and deep brain stimulation. He founded India’s first comprehensive Centre of Excellence for Epilepsy integrating advanced neuroimaging, MEG, neurobiology, genetics, artificial intelligence, and translational epilepsy research.
Full profile: Sarat-Chandra
Topics/terms mentioned
neurosurgery
robotic thermocoagulative hemispherotomy
laser interstitial thermocoagulation
endoscopic hemispherectomy
litt
radiofrequency ablation
hemispherectomy
hemispherotomy
craniotomy
cerebral hemosiderosis
rasmussen's syndrome
sturge-weber syndrome
hemispheric epilepsy
hemimegalencephaly
engel class
quality of life
neurostimulation
neuromodulation
vns
dbs
rns
anxiety
depression
mental health
radiofrequency ablation
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Trailer
00:00 Sarat Chandra
In the future we have laser for which we use it for doing the temporal lobe surgeries. So in US you find that using the laser interstitial thermocoagulation. Now the advantage of the laser is that you are able to control the heat map so you know exactly where the heat is spreading, which is kind of not very good with the radiofrequency ablation. But the advantage of radiofrequency ablation is you could create multiple trajectories, which is not possible with laser.
Intro
00:31 Torie Robinson
So last week, neurosurgeon Dr. Sarat Chandra explained to us many of the different types of epilepsy surgery that can be provided, the processes with tests and preperations, and the considerations when it comes to limitations and both other potential positive and negative effects! Today we are going to hear where the field of epilepsy surgery is heading; from minimally invasive procedures to pretty slick new techniques that can make surgery safer and more accessible in the future.
01:00 Torie Robinson
Thank you for joining us again this week, Sarat. So we were gonna go into…about the strategies for epilepsy. People generally think “Surgery, get a knife, scoop out the dodgy bit of brain.”. Tell us about the strategies you use to make things safer and more effective.
Different epilepsy surgery techniques
01:19 Sarat Chandra
So that's a wonderful question. So as I was saying in the previous episode, “epilepsy surgery” is an umbrella term, and you have multiple strategies over here. But till now, people have been mostly thinking about open techniques. The word “minimally access” or “minimally invasive” was slow to come in epilepsy surgery, even though it was coming in other parts of neurosurgical argumentorium. For instance, you know, whole of skull base has been converted into a minimally invasive endoscopic technique. So there have been many surgeries, for instance, laparoscopes. You know, you have lap surgeries which is done totally through small ports. But it was relatively very late to come for epilepsy surgery. So fortunately, as of today, we are finding that more and more minimally invasive surgeries are creeping into the almentorium of epilepsy surgery, the spectrum of epilepsy surgery. So if you look at the minimally invasive surgeries, you could… we mean that instead of making big flaps, we are going to make small holes and through small incisions and then perform surgery. So that the… technically you would be reducing the complications and hopefully the mortality (even the mortality itself is very less for epilepsy surgery). So the ways and strategies by which you can perform minimally invasive surgery could be by doing it with an endoscope. By endoscope we mean that it's a scope which has a rod length system by which you could visualise it on a monitor. So you do it by using smaller holes and smaller incisions. The other strategy is by doing it using the help of lasers or what we call as a LITT, laser interstitial thermocoagulation. And the third technique is by doing a radiofrequency ablation. Now, among the 3, we were among the first to introduce the technique of endoscope in epilepsy…
03:23 Torie Robinson
In the world?
03:24 Sarat Chandra
In the world.
03:25 Torie Robinson
Amazing.
Endoscopic hemispherectomy
03:26 Sarat Chandra
And we were the first to introduce the concept of endoscopic hemispherectomy. And this was a paper which was published in Neurosurgery, I think, more than 15 years back. So we brought in a concept of doing the whole hemispheric disconnection using an endoscope. And once we did it, you know, it was picked up rapidly. It was picked up by other people as well, so there have been other papers published from US particularly on endoscopic technique. Doing… using an endoscope for hemispherectomy came to us because if you see hemispherectomy, it's the surgery which has… which I can say is maximally invasive. You're thinking of removing one half of hemisphere or disconnecting one half of hemisphere of the brain. And this traditionally has been done using a large craniotomy. So the ways you could do a hemispheric disconnection is either through a lateral approach or through a midline approach. And earlier they would remove the whole hemisphere. So it was called as a hemispherectomies. So you would remove one half of the brain.
04:25 Torie Robinson
And it would just literally fill up with cerebral spinal fluid.
04:28 Sarat Chandra
So it would be just be empty. But these group of patients started having a strange and a peculiar complication called as hemosiderosis. Cerebral hemosiderosis, which was progressively fatal. They would become cognitively declined, bedridden. And that's where they started thinking of strategies where instead of removing the hemisphere, you could disconnect the hemisphere. So, it's very much has its own blood supply, but it's still active but it's disconnected. It's like you have to switchboxes and one of them is short circuiting and you just cut off the wires.
05:02 Torie Robinson
Just explain that to us, because I've always wondered with this surgery, if you… say we identified that the seizures start in one half of the brain, right, and you snip it, often people still don't have the seizures in that area where the seizures originally started. Why is that? Because the tissue is still there.
05:23 Sarat Chandra
That's because the connection to rest of the brain is gone. So the brain can be supplied by blood supply, which makes it alive. But for it to be functional, it has to be connected to the rest of the brain. And these are the connections which we divide. So even though that area of the brain is alive… but it's not connected to the rest of the brain anymore. And the pathologies in which we do this kind of surgery, the hemispheric surgeries, are the extreme form of epilepsies where the whole… where the epilepsies are arising from the whole half of the hemisphere. So some of these pathological substrates include typically a Rasmussen's syndrome.
06:01 Torie Robinson
Yep.
06:01 Sarat Chandra
Or there could be a more severe form of hemispheric pathology which we call as a hemimeglencephaly, —-- AARGHGHGhghgh! I SPELT THIS WRONG IT’S: hemimegalencephaly —------ which is a very severe form of cortical dysplasia involving the whole hemisphere. Or there could be something like a Sturge-Weber syndrome, you know, it's a kind of a disease where the whole brain, again, is abnormal and whole hemisphere is involved. Or it could be sometimes even following an infarction, following an infarct, whereby, post-infarct the person could develop you know hemispheric epilepsy. And these are the conditions where the hemisphere has to be disconnected because the hemisphere is not serving any normal function; all it's doing is producing abnormal electricity, which is disrupting the patients. And we have to understand, even though these surgeries are very, very major surgeries, if you do a craniotomy, but the outcomes are exceptionally good. For instance, if you do it for a post-infarct, your outcomes could be as high as 80-90%, and for Rasmussen’s, the average is about 70%, and of course for pathologists like hemimegalencephaly they're substantially lower, but still they're good, you know, about 60% of the patients could be seizure-free.
Measuring the success of epilepsy surgery
07:11 Torie Robinson
And how else do you assess the effectiveness or the success of a surgery though? Disregarding the seizures, how else would you… you know, we often talk about Engel class. Personally, I think that that's not enough because quality of life includes things other than seizures.
07:29 Sarat Chandra
That's an excellent question, Torie. So, firstly, you have to understand that children with hemispheric epilepsy are often very highly disabled. They have as many as 100 or 200 seizures a day. And if you don't do the surgery, they're going to die very soon. And about 10% of the seizures whom we operate do in hemispheric surgery are very, very ill. So we are looking at a complete seizure, you know, seizure-free outcome. But we also need to understand that Engel score doesn't give you a good justice for assessing the entire outcome of seizures. A significant portion of patients, I would say maybe 10 or 20% of the patients, could have seizure freedom by more than 90%. And they have significantly improved quality of life. But in terms of Engel scoring, they are much below, so that's the reason, you know, we need to develop scoring systems which reflect more better on the outcomes. For instance, most of the neuromodulatory procedures like vagal nerve stimulation or the deep brain stimulation or even the later responsive neurostimulation, at an average these neuromodulatory procedures can make 50% of the patients seizure-free by 50%. It's 50-50. But still a lot of these patients have greatly enhanced quality of life following surgery.
08:58 Torie Robinson
Yeah.
08:58 Sarat Chandra
Which goes to show, you know, you cannot have the Engels grading for apply to all the all the all the patients here.
Improvements in mood
09:04 Torie Robinson
Because these treatments can also improve mood, can't they?
09:07 Sarat Chandra
Absolutely.
09:07 Torie Robinson
So whether that's down to reduced…it's not even always down to reduce seizure frequency or severity, it's other “stuff” happening that can improve mood, like decrease anxiety, decrease depression, which of course affects quality of life.
09:23 Sarat Chandra
Absolutely. And the other advantage of a neuromodulation is that you have improvement which goes on improving year after year. So your improvement at year 3 is much better than year 2, year 4 is much better than year 3. And these are the things which are not taken into account when you use a scoring system like an Engel grade.
Managing expectations
09:44 Torie Robinson
And also, in addition, think - and this is just my personal experience - If you… I was told very clearly that I had 60% chance of seizure freedom. And so my hopes for complete seizure freedom were not in the sky. They were not really high. And then therefore, even though I still have some seizures today, I consider the surgery a complete success. And so, do you find… that managing expectations, do you find, as a neurosurgeon, is very important?
10:12 Sarat Chandra
Yes, it's very important. We don't expect the patient to become seizure-free, but we expect the patient to have significant reduction of seizures. And that's when the caregiver or the patient are a bit doubtful whether they should undergo surgery at all. Because they think that “If I'm not going to become seizure free, why should I undergo surgery?”. And that's the time we usually make them speak to the people who have had significant seizure reduction, but they may not be seizure-free and when they speak to them they find that over earlier they would have 30-40 seizures a day, but now I have a minor episode once in 3 months or once in 6 months and I'm able to do all the activities. And that is where they understand that it's okay, even if you have a seizure maybe in 6 months or 1 year, technically, even though it's not a type 1 Engel, but still it's going to make a significant impact on the quality of life.
Robotic Thermocoagulative Hemispherotomy
11:03 Torie Robinson
Indeed. So can you tell us about ROTCH? I don't know if I'm butchering the acronym, but R-O-T-C-H and you'll work in that. What is it? What do you do?
11:13 Sarat Chandra
So, thank you so much for asking this question. So, ROTCH, in other words, stands for Robotic Thermocoagulative Hemispherotomy. So, this is a minimally invasive strategy which we developed, and the preliminary work of this has been published in the Journal of Neurosurgery Pediatrics. And you have the picture on the cover page as well. And I would consider this to be one of the greatest contributions from our team. The reason is that it's totally bloodless and it's converted a very major surgery like hemispherotomy into a totally bloodless surgery. So technically, what we do, is we use a robotic system whereby we drill holes in certain strategic areas and we pass electrodes through that, and we burn the connection of the hemisphere to the opposite side, the abnormal hemisphere to the opposite side, rather than cutting them surgically. And this has to be done by very good planning, which has to be done pre-op. The best part of this procedure is it's totally bloodless. And earlier, the surgery was taking about 8 or 9 hours or 10 hours, but then we modified our techniques. So we brought in techniques like “X technique” and we improved the radiofrequency ablation, and now it is we are able to complete the surgery almost on an equivalent time of open hemisphereotomy, which is about 3-4 hours we are able to complete the surgery. The best part is as soon as we finish the surgery there is absolutely no blood loss. We could extirpate the patient on the table. He doesn't need to be provided any kind of ventilatory support or anything (which is usually the case for open hemispherotomies). And that is very important because hemispherotomies are usually performed in kids.
12:56 Torie Robinson
Yes.
12:56 Sarat Chandra
And in kids the 2 major challenges are blood loss and hypothermia. And by using this minimally invasive technique, we are able to bypass this. We are able to avoid both the complications.
13:08 Torie Robinson
And so, and so how do you do it?
13:09 Sarat Chandra
So the whole thing is done using a robotic system. So the surgery is actually planning. So we had a full team come from Israel, you know, they wanted to learn it. And they were there with us for 1 week and they learned the planning. And I'm very happy to say - they're from Tel Aviv University - I'm very happy to say that they have done about 5 procedures and they're finding it very useful. So that's a procedure which we created. Now the way we do it is that we have a robotic system where we do the planning, we plan everything. So the robot moves to the area, and it has a hole through which you can put in a 2mm drill which is attached to a motor, and we drill a hole in the brain, and then through that we pass an electrode which is passed through a predetermined length, and then we produce a burn, and then we go on producing serial burns. So, with this, we are able to now use the radiofrequency ablation in order to disconnect the abnormal hemisphere to the opposite side. So we are not cutting it, we are actually burning it. The reason why we call it as ROTCH is if you look up onto the website, ROTCH also stands for a very small Arctic bird.
14:19 Torie Robinson
Oh! Haha!
14:19 Sarat Chandra
It's a very gentle and a small Arctic bird.
And we thought that it gels well with the metaphor because it's a technique which is very gentle on kids. You're not losing any blood, you're not producing any hypothermia, there are no variations. Normally, if you have to operate a on a kid who is 1 year or 2 years, it could be extremely challenging. Surgery could go on for 10 hours, and even the best of surgeons could lose a lot of blood. But now you could do all those procedures without losing even a single drop of blood. And in the end, we are just putting a single suture for every… so we can now… so for any hemispherotomy to be done, we use 5... 4 or 5 trajectories to first divide the corpus callosum. So nowadays we are doing corpus callosotomy as a standalone procedure using radio robotic guided radiofrequency ablation, and we are yet to publish it. We have done it in about 10 cases or so, and we are kind of analysing the serial data as of now. But we use about 4 or 5 trajectories first to do a corpus callosum disconnection. And then for the hemispheric disconnection, we have a single trajectory here and using a technique called as X-knife. So it kind of swishes, goes like an X and disconnects the whole middle part of the brain. And then we have another opening in the front and maybe one more opening for the posterior disconnection. So with a with about 7 or 8 holes, which require 7 or 8 stitches. We are able to disconnect the whole hemisphere and at the end we just put some banded and that's it.
15:57 Torie Robinson
Haha! You put a plaster on it and that's it.
15:58 Sarat Chandra
So we just put a plaster [on it], and you know the moms are very happy. So they see that you know the child doesn't have a big bandage on the head, they don't have a big incision…
16:09 Torie Robinson
A big swelling or...
16:10 Sarat Chandra
So I believe, firmly, that this is going to be the technology of the future. It takes about 3 or 4 hours because our robotic technology is not so much developed to take care of this technique, and even the radio frequency technique has been there for many decades, but there has been no improvement on it because people have become more interested in laser. So I'm sure this would kind of push the technology, and if it does, it could bring down the surgical duration for less than an hour. So it could become a procedure which is less than an hour. And I firmly believe that this is the future we're looking at it.
16:49 Torie Robinson
And do think it will be able to be used in multiple different types of epilepsies, this technology?
16:54 Sarat Chandra
This is something we are currently using it for hemispheric disconnection and for corpus callosum disconnection. That's it.
17:01 Torie Robinson
But in the future?
Future use of lasers and radiofrequency
17:02 Sarat Chandra
In the future we have laser for which we use it for doing the temporal lobe surgeries. So in US you find that using the laser interstitial thermocoagulation. Now the advantage of the laser is that you are able to control the heat map so you know exactly where the heat is spreading, which is kind of not very good with the radiofrequency ablation. But the advantage of radiofrequency ablation is you could create multiple trajectories, which is not possible with laser. So, using a laser you can do something like a hippocampal lesioning. But if you want to do a hemispherotomy with a laser, it would be very challenging because every time you need to do it, patient has to be shifted into an MRI suite and then you need to produce a lesion. Whereas in radiofrequency, it just takes a couple of minutes for you to change the trajectory. So you could use multiple trajectories in the same setting.
17:56 Torie Robinson
This is a great example, just from what little you've been able to tell us in this few minutes, how there are so many different types of surgery. so people needn't think, there's only one type and everyone gets the same and it's dangerous, far from it.
The monetary price of Robotic Thermocoagulative Hemispherotomies
18:14 Sarat Chandra
Thank you. Yeah, it's been lovely. I think I reiterate the same. As we are developing, we are moving to safer technologies. And just to add a last word, this procedure, you know, in our institute costs just about £15-16 (GBP).
18:32 Torie Robinson
Hahaha!
18:32 Sarat Chandra
I don't usually say that aloud because the cost is not the main point here. The main point here is the technology on how we have been able to convert a maximally invasive procedure into a minimally invasive procedure without losing any blood. But yes, we've been able to do it. So not only is it technologically the most advanced procedure for hemispherotomy, I think it's the most inexpensive procedure on the planet.
18:59 Torie Robinson
Well, watch out, you're going to have a load of people traveling over to New Delhi at this rate. Thank you so much, Sarat. Okay.
19:05 Sarat Chandra
Thank you.
Closing thoughts and thanks
19:06 Torie Robinson
Thank you again to Sarat! I wish I’d known all of this prior to epilepsy surgery. If this episode made you more interested or less nervous about epilepsy surgery - whether you be somebody with an epilepsy, a carer, or a cinician - let us know why in the comments below! And also, please do subscribe to support our channel - if you haven’t already(!) - and see you next time.