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Melanie Cole: Welcome to UF Health MedEd Cast with UF Health Shands Hospital. I'm Melanie Cole and I invite you to listen as we ask the question is your challenging epilepsy patient a candidate for stereoelectroencephalography?

Joining me is Dr. Giridhar Kalamangalam. He's a Wilder Family-endowed professor and Division Chief of Epilepsy at the UF College of Medicine and he practices at UF Health Shands Hospital. Doctor, it is a pleasure to have you join us today. So tell us a little bit about the prevalence of epilepsy in the general population and how really surgical indications have evolved over time to encompass a wider variety of epilepsy types and applying surgery to more patients that have medically refractory epilepsy.

Dr. Giridhar Kalamangalam: Good morning, Melanie. Yes, epilepsy affects about one in 200 people on the whole, all across the world. There are some changes depending on which part of the world you're exactly in, but that's a reasonably accurate figure. Now, while that proportion might not seem much, you just have to compute that percentage over, say, the population of the state of Florida. And then you realize the numbers of patients that are in this state. There are tens, in fact, hundreds of thousands of patients with epilepsy.

Over the years, treatments have evolved. The condition of epilepsy, of course, has been recognized since antiquity. This was a Hippocrates' sacred disease after all. And treatments have evolved such that, in today's day, we can treat most epilepsy patients satisfactorily after a good diagnosis, an accurate diagnosis, has been made in about 60%, maybe 70% of patients. That is a large proportion, but again, considering the numbers of epilepsy patients there are, even a small proportion, like 20%, 30%, 35% of patients who don't do that well with standard medications require more advanced treatments. And these are the patients that we call refractory patients, refractory because they don't respond satisfactorily or sufficiently to first-line medications.

And this population has been recognized also for a very long time. And indeed, the challenges of epilepsy management largely have to do with trying to help this 30%, 35%, 40% of patients on the whole. And a very important treatment for these patients is some kind of surgery.

Epilepsy surgery used to be thought of as some operation on the brain for epilepsy. And that in fact is true, but it's not the whole truth. These days, we have a large, really quite a menu of options available for patients who don't get satisfactory control of their seizures with medications. And those are the patients we deem surgical candidates. And in a center like ours, for instance, we see large numbers of such patients because these patients are referred in from the community.

And the options, the surgical options, for patients have really increased over the past couple of decades and especially in the past 10 years or so has really dramatically increased to include several novel options, all of which are available at our center. So these patients have always   but the options, the treatments that are available for them have become really expanded in recent years. And it's now more important than ever that, you know, a positive attitude is taken on behalf of these patients by all providers, such that these options can be presented and patients visit and get treated at specialized centers.

Melanie Cole: As we're talking about medically refractory epilepsy, tell us about the current indications for surgical intervention. And please tell us about SEEG and identify the patients who may benefit from this type of monitoring.

Dr. Giridhar Kalamangalam: Yes. That's actually a very relevant question in today's practice of tertiary epilepsy. Like I just mentioned, surgery for epilepsy can take many forms. The most important one and perhaps the most effective one are brain surgeries that operate on some part of the brain to disconnect or remove a portion of brain that is diseased and is causing epilepsy.

I should say, you know, while we're talking about brain surgery, there are many other surgical treatments. of them are not removal of brain, but perhaps more disconnective procedures. And those have been used for a long time, just like resective procedures for epilepsy in addition to other surgical treatments such as VNS, the vagal nerve stimulator. And in recent years, other stimulators that are implanted directly into the brain.

These are not strictly thought of as surgical treatments, but in a way they are because technically they involve a surgery, but they don't involve removing, disconnecting portions of brain, but rather stimulating parts of the brain or, in the case of VNS, one of the cranial nerves that enters the brainstem.

So those are neuromodulatory treatments that require a surgery, but let's just stick to brain surgery for epilepsy that, as I said, it remains really when successful the most effective frequent there is and the effectiveness can be pretty dramatic and, you know, in well-chosen patients, really long lasting.

The challenge, of course, of doing a surgery on the brain for a patient with epilepsy is to really do the right thing. And that might seem like an obvious statement, but many times this is a challenge. What exactly is the problem? Where exactly is the problem? What kind of surgery does the patient need?

And when we say what kind, it means what would be the most effective surgery for this patient, but also extremely important, what is the surgery that will do or carry the least amount of with it? Not an intraoperative risk, but a risk of or risk of things getting worse or something occurring that the patient didn't have before, like a weakness or a problem with eyesight or some difficulty with speech.

These are all problems that we ponder. These are very important issues that we consider when we offer patients epilepsy surgery. And to do this correctly, to do this as effectively as possible, we use several techniques. And an emerging one in the United States over the past decade or so is the technique you just mentioned, which is SEEG or stereoelectroencephalography.

This is a method by which we explore the brain in a very targeted and precise way with electrodes that are implanted into the brain. In this way, we study the epilepsy at close quarters. We actually get right up to the face of epilepsy. We go right there knocking at its door, explore it where it starts, where it spreads to, how it involves various brain regions. We actually understand the epilepsy as it exists within the brain.

And based on that understanding, we come up with a plan for that patient, which we hope most of the time will involve removal or disconnection of part of the brain, because that remains the most effective treatment for epilepsy, surgical treatment for epilepsy.

But sometimes, the SEEG tells us that there is no such strategy available, and we wouldn't have known that unless we actually did that SEEG. And then we move on to other kinds of treatments, which also may be surgical, which may be stimulatory modulatory treatment for epilepsy.

So SEEG has become really good de facto method of exploring complex epilepsies. Not every patient needs it, but many patients do, especially in our practice where we get a relatively large proportion of complex, not just refractory patients, but refractory patients who are complex, where it's unclear where seizures start or which is the bad area and how the epilepsy is organized within the brain.

And so these are the patients that require this more in-depth exploration. I mean, in-depth is both literal and figurative. It's a depth electrode in the brain, but it also gives us a deeper look at the process of seizures that are occurring in that patient. So that, if you like, is a broad overview of what SEEG is.

Melanie Cole: So tell us a little bit about some of the limitations that you're seeing and really else might this be beneficial besides finding that location as you just described in the brain where these seizures occur. How else might intercranial monitoring, how else might SEEG be used during the evaluation for epilepsy?

Dr. Giridhar Kalamangalam: Right. The role of SEEG is really, there's only one role and now that role has different parts to it. So when you put electrodes into the head of something to the brain of somebody through the head, through the skull, your objective is to identify everything that you can with that data. That means understanding the epilepsy, like I just said, which is to understand, to recognize the primarily diseased areas, recognize secondarily diseased areas, which are areas where seizures propagate to. And therefore then obtain a map, if you like, or grade of disease. If you like. And then that maps out an area of brain that needs to be targeted for surgical removal or disconnection.

Equally, our job is to make sure that this procedure that we contemplate is safe for the patient, right? So I mentioned risks to normal brain areas, and we call that a risk of a deficit or the risk of incurring something that the patient didn't have before, such as, say, a weakness. And that can happen when the epilepsy area, the area to be operated on is very close to, say, an important area for strength, which we call motor eloquent areas. And so when we operate on the brain, we want to make sure that we stay away from those areas.

And this is our job as epileptologists, to provide this information to our epilepsy neurosurgeon, who then performs the procedure and performs the procedure in such a way that disease areas are maximally targeted and normal areas, where the patient might incur a deficit if they were encroached on, are minimally interfered with. So we have to maximize the yield of disease and we have to minimize really the risk. And if you like, those are the two things that we have to do with SEEG.

And if you do that successfully, then we have a plan and the electrodes are then taken out. And all of these data presented at our joint conference. Neurosurgery is a very important partner. But really the, epilepsy surgery as the name might indicate, you know, has two parts to it. It's got the epilepsy part of it and the surgery part of it. And so we have a team here which then considers all the data and, providing they're all convinced that we've identified the area accurately with SEEG and that area has also been identified, those areas that we think of operating on have been identified as not being a risk to that patient, if they are removed, we then have a plan. And that plan is then executed by our surgeon. So those are the two roles.

And when you talk about limitations, of course, every technique has limitations. First of all, I should say that most patients don't need SEEG, most patients require an accurate diagnosis. So we have a lot of patients who come to our outpatient clinic who will never need SEG or any kind of brain surgery. They do need an accurate diagnosis of what exactly that epilepsy problem is. They need good medications to be given to them, effective medications. We need to keep them free of side effects as much as possible and we need to reduce seizures to a minimum, hopefully no seizures.

So, SEEG is used for the more complex patients. There is a limit to what it can achieve. In some patients, we have the risk, it's not really a risk, but, if you like, the fundamental difficulty of the epilepsy is such that you do an SEEG thinking that you would confirm something that you are thinking as the cause of the patient's seizures or the areas of the brain regions that are causing seizures. And we go in and we find it's actually much more complicated than we thought and that no clear area emerges from that data, that is, if you like, no clarity. That can happen. And that is a limitation and that limitation arises because the disease itself is very complicated.

Obviously, if an SEEG is not done with the care that it really should be done with, then of course one can get data that isn't helpful, but that is because the technique hasn't been carried out, if you feel like, optimally. But with the optimal technique, with the optimal thinking behind an implant, one might still have a situation where the data is too complicated to be, if you like, parsed or, put into a classification so that we clearly have a distinction between abnormal areas and normal areas. So that's the limitation and that comes from the fundamental complexity of disease in some patients.

Obviously, you know, there's a number, there's a limit to how many electrodes one can put into the brain, too. And so some epilepsies cannot be, if you like, explored sufficiently. So that can be a problem too where, you know, you're just unable to explore everything you want because there's a limit to, the number of electrodes that can be put in safely.

So those are some limitations. There's a set of other limitations that have to do with the technique itself and I won't go into those necessarily. Those are interpretive challenges and that takes us kind of deep into the field of SEEG data analysis, which I think would be inappropriate to talk too much about.

But there are certain challenges at, if you like, the data interpretive level that we deal with. And it's an evolving field. We don't know everything about it. Not at all. We are learning about it. We're discovering things about it. We're learning from our patients, from our experience and from other people. And so that remains a challenge too.

I won't talk about the technical challenges. I'm not a neurosurgeon, but a neurosurgeon would tell you what challenges there are in actually implanting these electrodes, the actual procedure itself and what the risks are and where things can go wrong, and so forth. So there are those challenges too, but on the whole, it's a safe technique. It's being increasingly recognized as the de facto method, the best single method for exploring the brain for patients with refractory epilepsy.

So it's seen very wide acceptance very quickly in this country, I should say, in the same breadth that it's been known about for decades. It's been practiced in other parts of the world for decades, but it has recently taken off in North America for many reasons. But it's now here to stay. Everybody wants to do it. A lot of tertiary centers, over a hundred centers in this country do it. And all of this has happened literally in the past five years.

So it's an emerging, rapidly exploding field of knowledge and something that is on the whole safe for patients as far as surgery on the brain goes and extremely a dramatic impact on the treatment of epilepsy in a very short time. And, it's our job to be able to provide that kind of knowledge out to the community so that people know, patients know and providers know that they have options.

Melanie Cole: As a final thought and a wrap up for this episode, where do you think SEEG is going in the future? Give us a little blueprint. Or really what's exciting? And why do you feel it's important that providers refer?

Dr. Giridhar Kalamangalam: The answer to that actually is in two parts. And I will tell you the more important part first, which is I think where SEEG is going, is it's going in the direction of greater visibility. That is perhaps the single most important thing. I think everyone who deals with epilepsy patients should know that there are options available for refractory patients. There are options available that are less invasive than in years gone by, and that, at experienced centers, a patient can get a thorough evaluation, an intracranial evaluation with SEEG that will really lead to an advanced understanding of their epilepsy and give them options that they didn't have. I think that is the single most important thing about the future of SEEG.

There are of course scientific and medical advances that we have to make. We have to understand the data better. We have to understand how to do the technique better and so forth. And that's incremental. And that will go on, I guess, for decades. But a greater awareness, I think, can make a dramatic impact on the treatment of epilepsy in a very short time. And it's our job to be able to provide that kind of knowledge out to the community so that people know, patients know and providers know that they have options.

Melanie Cole: Wow. Thank you so much for joining us and sharing your incredible expertise. What a fascinating topic. Thank you again.

To refer your patient or to listen to more podcasts from our experts, please visit ufhealth.org/medmatters for more information and to get connected with one of our providers.

That concludes today's episode of UF Health MedEd Cast with UF Health Shands Hospital. Please remember to subscribe, rate and review this podcast and all the other UF Health Shands Hospital podcasts. I'm Melanie Cole.