Bob Underwood, MD (Host): Welcome to Peds Cast, a podcast brought to you by Children's of Alabama. I'm your host, Dr. Bob Underwood. Today we're talking to Dr. Curtis Rozzelle, Pediatric Neurosurgeon at Children's of Alabama, and we'll be discussing deep brain stimulation as a treatment for epilepsy. Dr. Rozzelle, welcome to Peds Cast.

Curtis Rozzelle, MD: Thanks, Bob. Glad to be here.

Host: Let's start by talking about drug resistant epilepsy in pediatric patients, because that's kind of your target patient population, right?

Curtis Rozzelle, MD: That's exactly right. I have fantastic colleagues on the neurology side, several of whom, do only epilepsy management all the time, and it's mostly evaluating patients for surgical consideration. And we only are considering for surgery, patients whose epilepsy is not adequately controlled medically, which generally, ends up being roughly one third of children who end up with a diagnosis of epilepsy, meaning that they've had more than one or two seizures, it's a recurrent problem and they're not having seizures because of some other disease process or laboratory abnormality or whatever.

Host: So that must be really hard for patients, for their families. You know, that's gotta be frustrating if it's not responding to medical treatment often.

Curtis Rozzelle, MD: Yes, it can be a tremendous burden for the obviously the child and their families as well, particularly if they are unfortunate enough to be in the group that, has a lot of, generalized tonic-clonic seizures or has a tendency to go into status epilepticus, meaning that they're coming to the emergency room frequently. Or another example of, of children that are really profoundly affected by their epilepsy are the very young patients who, develop epilepsy early in life, and are having seizures with such frequency, that it's impairing their neurologic development and their ability to learn.

Host: So with that in mind, you are offering a deep brain stimulation procedure or DBS. Tell us about this procedure.

Curtis Rozzelle, MD: When we talk about deep brain stimulation for epilepsy, that's going to be for the patient with medically refractory epilepsy, that either is not a candidate for a resective or ablative strategy targeting, an identified seizure onset zone. So that either could be because they have a generalized epilepsy, or it could be that they have failed previous either resective or ablative surgery because we thought we had identified the seizure onset zone and we treated that and they either didn't improve much or they improved for some period of time. Maybe they were seizure free for an interval of six months or a year or two, and then their seizures come back and, unfortunately we've sometimes run into the situation where we can resect what we believe the seizure focus to be, up to a certain point.

And then if we're looking at potentially having to resect eloquent cortex, which Cortex that's responsible for an important function, whether it be language, memory, motor function, then we have to think about these, these alternative strategies. So deep brain stimulation is one of those options.

Host: With this epilepsy treatment, you have a device called the NeuroPace Responsive Neurostimulation device. Tell us about that.

Curtis Rozzelle, MD: Certainly. Deep brain stimulation has been around for a long time, mostly for movement disorders and then in the past, oh, decade or two, been applied more and more often for the treatment of medical refractory epilepsy. The stimulators that drive a deep brain electrode array for a movement disorder, they stimulate on a schedule, but they don't respond to what's going on in the brain.

So the NeuroPace device is called a responsive neurostimulator system because it can record EEG from the electrodes wherever they are placed in the brain. The first phase when a patient receives one of these devices, is a recording phase and the device records whatever electrical activity is at the electrode contacts where they are implanted.

And on a daily basis, either the patient or the patient's caregiver, has to use a wand to download via Bluetooth, the EEG recording from the previous day. And then that gets uploaded to the company. And over a course of weeks to more likely a month or two, there'll be enough data recorded, that the epileptologist can recognize that a pattern of EEG activity that occurs just before the patient's clinical seizure starts.

So once that signature is identified and determined to be consistent and reliable, then the device can be transitioned to an active mode such that whenever the device sees this pattern, it will then apply a stimulus through the same electrodes, which most of the time, will then prevent the seizure from happening.

Host: That is absolutely fascinating.

Curtis Rozzelle, MD: Yeah, it's a little bit like the latest generation of cardiac pacemakers that sense what's going on in the heart and then respond to it. So it's a, it's a similar paradigm.

Host: That's exactly what I was thinking is, you know, an implantable defibrillator operates in much the same way. It's just picking up a different electrical signal.

Curtis Rozzelle, MD: Right. Yeah. Defibrillator that, that's probably an even better analogy than the modern pacemakers.

Host: Just amazing to me. So how do you determine where to put the electrodes?

Curtis Rozzelle, MD: From a simple surgical perspective, I put the electrodes where the epileptologist tells me to put them.

Host: That's fair enough.

Curtis Rozzelle, MD: From a more scientific perspective, for patients with generalized epilepsy in whom we're targeting a deep brain structure; there are two that are probably have the greatest combined experience with implanting, deep brain electrodes for epilepsy, whether they're connected to one of the older generators which were initially developed for movement disorder, or if they're connected to the NeuroPace responsive neurostimulator system.

And those are they're both in the thalamus. And the two sort of options are the central medial nuclei, or the anterior thalamic nuclei. Our experience thus far, I've not been asked to put any in the anterior thalamic nucleus, so I've, put, about a half a dozen in bilateral central medial nuclei of the thalamus. So, about six patients so far, bilateral implants each.

Host: And again, you know, to me that's, fascinating in terms of the technology and how we're able to apply the technology that we've got now, for the benefit of these patients. So how do you determine, when we kind of talked about drug refractory, or drug resistance, are there any other determinations of what makes a candidate a good candidate for this kind of therapy?

Curtis Rozzelle, MD: So again, if they have a generalized epilepsy where there's not a, a seizure focus then they're not going to be a candidate for any resective surgery. so those are pretty straightforward patients that you would consider for this. And then for patients who even if they aren't truly generalized, but if they have multifocal seizure onset, they're sort of in the same ballpark as the generalized epilepsy patients, in terms of consideration for this therapy.

And then the patients for whom we have done previous procedures, either open resection or laser ablation of a seizure focus, and, and it didn't turn out, you know, as well as we had hoped; then this is kind of a fallback strategy. For context, the NeuroPace device can be used for electrodes that are placed elsewhere in the brain. It's not exclusive to deep brain stimulation.

And we've done a couple of those so far in our early experience with the NeuroPace system. So examples there are patients who have an identified seizure focus, but it's in, or, too close of proximity to eloquent cortex such that we don't want to risk a resection there. So, the best example was, one we did, late last year, someone with temporal lobe epilepsy, and it was their dominant temporal lobe.

Um, so rather than resecting that and giving them prohibitive deficits, we put one depth electrode in their hippocampus, and then we put a subdural electrode on the surface, the under surface of their temporal lobe and connected those to the RNS system. And so it works the same way, whether the electrodes are in the thalamus or around a seizure focus that's been identified.

Host: It's amazing and great case examples as well. So what kind of results are you seeing from these patients post procedurally?

Curtis Rozzelle, MD: Well, knock on wood, we haven't lost any of the devices to infection.

Host: Nice.

Curtis Rozzelle, MD: We did have one patient who developed an epidural hematoma underneath the device after it was implanted, which we took out the next day. And then that device is still in place and, and working well for that patient. Our experiences, it is still fairly early. But the early reports that I'm getting back from our epileptologists and from patients and their parents when I cross paths with them are very favorable.

I don't have enough numbers to give you anything that would be statistically significant or anything like that.

Host: What a relief for them if they've got drug resistant epilepsy, they've had it for years, and to suddenly have something that will intervene for them. Because it's debilitating in terms of the seizure activity, but also, and the kind of the psyche of the patient and the family because that's the thing with seizures. You don't know when they're going to happen and it's never at a good time. So it's gotta be great for them.

Curtis Rozzelle, MD: We had a great example just, recently. Most patients go home the day after this operation. But we had someone last month who had a flurry of seizures the night after we implanted the device. So they ended up staying in the hospital for a couple of days. The nice thing about them having the flurry of seizures was the epileptologist was able to go ahead and start the therapeutic mode much earlier than what we typically do. And when I saw them for their post-op check a couple of weeks later, the family already had noticed a difference decreased seizure frequency, and the patient was more alert andinteractive and so forth.

Host: That's amazing and that's just wonderful benefit for the patient. So, along those lines, the recovery time post procedure, you already said that they generally go home next day, so, I'm guessing that's makes it a fairly, no procedure is minor if it's happening on you. But in the overall scheme of things, you know, it's pretty quick to get home post-procedural and afterwards?

Curtis Rozzelle, MD: Right, so we haven't really talked about sort of the nuts and bolts of how we put these things in. The device, it's roughly the size of a key fob for a car. So if you were to put that on somebody's head, like outside the skull and try to close the scalp over it, it would be difficult to get a good closure and, and it would be really prominent.

So the way that the pulse generator is implanted is we actually do a craniectomy, in the sort of posterior parietal region. And we take that piece of skull out of the same size as, what the device is. And then we put the device in its place. There's a little metal tray that the device sits on and that's attached to the skull with some screws, at the four corners.

And then the device sits on that tray so that it ends up being only very slightly more prominent than the normal cranial contour. There's no struggle to get the scalp closed over it. So that's probably the biggest inconvenience for the patient and amount of postoperative discomfort just relates to the size of the scalp incision.

And the thing that the patients and families tend to focus on more than anything else is how much hair will I have to cut to put this thing in?

Host: Yeah. That's a, a good thing that that's what they're worried about, in the overall scheme of things. That's awesome. So for parents, primary care providers who were interested in exploring this option, what should they do?

Curtis Rozzelle, MD: Anybody whose seizures are not controlled, after trials of two medications, that's the generally accepted definition of medically refractory, should be referred to an epilepsy center to see whether or not they would be a candidate for, some sort of surgical intervention. The places that are equipped and have all the right people and diagnostic studies available and so forth are the level three and level four epilepsy centers.

And we are a level four epilepsy center here at Children'sof Alabama as is the big adult hospital nearby, UAB hospital. But each, both the adult hospital and the children's hospital are independently level four epilepsy centers.

Host: That's awesome. Dr. Rozzelle. Thanks for being on today. I'm sure everybody listening learned a lot because I know I did.

Curtis Rozzelle, MD: Thank you, Bob. Nice talking with you.

Host: Nice talking to you too. And for our listeners who want to learn more, or if you'd like to refer a patient to Children's of Alabama visit insidepeds.org. That's insidepeds.org and click on neurology and neurosurgery. And if you found this podcast helpful, please share it on your social channels and check out the entire podcast library for topics that might be of interest to you.

And don't forget to subscribe, rate and review this podcast. Thanks for listening to this episode of Children's of Alabama Peds Cast.