Evolution of Interventional Neurology

Podcast Transcript

Introduction: Neuro Pathways, a Cleveland Clinic podcast exploring the latest research discoveries and clinical advances in the fields of neurology, neurosurgery, neurorehab, and psychiatry.

Glen Stevens, DO, PhD: Interventional neurology has undergone a remarkable transformation from a field once considered stagnant to one now driving some of the most exciting innovations in neuroscience. Today, we're exploring the evolution and what lies ahead. I'm your host, Glenn Stephens, neurologist neuro-oncologist in Cleveland Clink's Neurological Institute, and joining me for today's conversation is Dr. Ashutosh Mahapatra. Dr. Mahapatra is an interventional neurologist in the Cerebrovascular Center at Cleveland Clinc's Neurological Institute. Ash, welcome to Neuro Pathways.

Ashutosh Mahapatra, MD: Thanks for having me, Glenn.

Glen Stevens, DO, PhD: So, let's start by having you introduce yourself to our listeners, what you did to train and what you do here at the Cleveland Clinic on a daily basis.

Ashutosh Mahapatra, MD: I'm one of the interventional neurologists and I trained in neurology at University of Miami in Jackson Memorial Hospital in Miami, Florida. Went on to do a critical care fellowship in neurocritical care at Washington University in St. Louis, followed by endovascular training here at the Cleveland Clinic. I practiced in the University of Texas in Houston for a couple of years before joining back as faculty very recently.

Glen Stevens, DO, PhD: Well, it's a pleasure having you and learning more about what you do. So, walk us through a little bit what interventional neurology is as an emerging specialty, applications, what you have to do to become an interventional person.

Ashutosh Mahapatra, MD: So interventional neurology, it goes by various names, interventional neuroradiology or endovascular neurosurgery. Basically, a specialty where we use minimally invasive catheter based techniques to treat all sorts of vascular disorders in the brain, neck, head, spine. So, our bread and butter is things like treating strokes, aneurysms. We also do tumor embolizations, and basically, anything blood vessel related.

Glen Stevens, DO, PhD: Back in the old days, and listeners who are familiar with the podcast, I always talk about the old days, but back in the old days, my recollection was all the interventional studies were done by the radiologist, were done by the neuroradiologist, but certainly now we have so many neurology trained folks. It's great to see. We would also, of course, have some of the cardiologists who are doing interventions also sneak in and do some cerebral type stuff, but I imagine that's probably less nowadays.

Ashutosh Mahapatra, MD: That's correct. We actually try to actively keep the cardiologists out. I feel like they have enough to do, but yes, neurologists have become more and more accepted in the field. Traditionally, it was a radiology-oriented field, and eventually with the advent of this interdisciplinary approach to treating neuroscience and neuroscientific diseases, especially things like strokes and aneurysm, the neurosurgeons and neurologists became involved, and now it's rather commonplace for it to be a shared ground amongst all three specialties.

Glen Stevens, DO, PhD: I won't go through the details, but I will tell you, I published one paper, interventional paper in the nineties, and it was on basilar artery reperfusion using a platelet inhibitor, and we published it. Dilated, we ballooned the constriction in the basilar artery, and then we gave a platelet inhibitor to try and open it, and we using some of the data from our cardiology friends, who for many years anyways, were well ahead of us in terms of what to do with vessels, but you're going to tell us today how we're catching up and moving forward as we go.

Ashutosh Mahapatra, MD: Absolutely.

Glen Stevens, DO, PhD: We'll talk a little bit about a diagnostic angiogram. Tell us what a diagnostic angiogram is.

Ashutosh Mahapatra, MD: Yeah, so diagnostic angiography is the cornerstone of what we do in interventional neuroradiology or interventional neurology and a vascular neurosurgery, whatever you want to call it. I'm going to call it neuro intervention moving forward just to keep things consistent. So diagnostic neuro angiography was actually invented by a Portuguese neurologist named Egas Moniz back in 1942. Interestingly enough, he suffered from horrible gout, so he recruited his friend who was a neurosurgeon to actually do all the procedures for him. And so he was the brains behind the operations, and they finally mastered the art of basically injecting sodium bromide directly into a carotid artery to highlight the blood vessels with using basically the old film style film on a plate x-ray, and took some time to get it right but they finally got it, and the initial application of this was actually to image brain tumors. There was no great way to really localize brain tumors prior to surgery, and so that's what the initial utilization of this was.

Ultimately, that transformed more into endovascular procedural-based specialty where we could actually go in and start to fix things, and modeling after cardiology brought them up. A lot of interventional neuroscience is modeled after what the interventional cardiologist had done. They did the initial catheter work, Seldinger technique, coronary and cardiac catheterization, and then there's the real parallels between interventional neuroscience and interventional cardiology.

Glen Stevens, DO, PhD: We'll still at tumor board occasionally look at a lesion on a brain scan and the recommendation will be they should have an angiogram, and we're looking for a tumor blush. It probably happens more with some of the hemangioblastomas that are very vascular tumors. The vast majority we do not, but we still do today.

Ashutosh Mahapatra, MD: Absolutely.

Glen Stevens, DO, PhD: Nowadays, of course, we can do non-invasive vascular imaging with MRA, magnetic resonance angiography, CTA using a CT scan, do it. How do we decide, are we going to inject into the vessels themselves and do an angiogram versus an MRA or a CTA?

Ashutosh Mahapatra, MD: So, MR and CT technology has come leaps and bounds. Resolution is getting better and better every year and the sequence is getting better and better every year. I think now with even advent of 7T MRIs, it gets a little bit better. Then we'll get really, really good vascular. The thing that sets angiography aside for me is that it's not a static study. It's a dynamic study. So, in one study, although it's minimally invasive, in one study, you get a picture of the luminal caliber, the morphology of whatever you're looking at, but you also get this wonderful view of how things are flowing in real time. So instead of looking at a photograph, you're looking at a movie, and that temporal spatial relationship that you can make looking at angiography I think helps you understand a patient's physiology, their blood flow patterns in great detail, and it's a rather beautiful picture.

Glen Stevens, DO, PhD: Yeah, there's no question. Certainly, in the emergency department, someone comes in, you need to look at the vessels acutely, see if do they have a tear or an aneurysm? The non-invasive procedures work well, but there's clearly advantages, and the other big advantage is you can potentially do a procedure at the same time. And so talk to us a little bit about thrombectomy. What does that mean?

Ashutosh Mahapatra, MD: So thrombectomy is a scientific word for basically just taking a thrombus out from somewhere. Thrombectomy holds a special place in my heart as a neurologist. It's actually the first procedure that I saw when I was a medical student back in, and I still remember, it was May 20th, 2012. I had no idea what I was going to be doing. I was one of those students that loved everything and I had no direction. I actually saw a mechanical thrombectomy for the first time. A patient came in fully weak with a right MCA syndrome. We revascularized it. It took us a long time to do it back then. I was a student and I didn't participate too much except for flushing some syringes and wiping some wires at that time, but by the time that the procedure was over, in the brief moment that it took from the patient to be transferred from the angiography suite to the ICU, they made a full recovery.

And so this was in this very tumultuous time in interventional neurology or neuro intervention in general because there had just been multiple trials that had shown that maybe thrombectomy wasn't so great. The interventional management of stroke 3 trial had just shown that there was no significant benefit over medical management, but clearly and anecdotally speaking, these interventionalists were like, "There has to be a patient population this works for because we see it having such a dramatic effect." And so thrombectomy has been the saving grace, I think, of neuro intervention in many ways and driving a lot of the innovation in it, because shortly thereafter, we have so many trials now that have just had the pendulum swing in the opposite direction in terms of how effective of a therapy it is.

Glen Stevens, DO, PhD: And what you described is so exciting. I remember back, I'm a bit older than you are, but I remember back in the days, if a patient came in and they ended up having an angiogram and we saw a thrombus that was there, we didn't have a retriever. We could not go in and have somebody pull it out. So then you're left with is there a little bit of space they can maybe get a balloon in and try and just spread it out and squash it along the borders, or just poking at it and try and break it up. But of course, if you do that, where does everything go? It just keeps going distally, and at some point, the caliber of the vessels are going to get so small that it's going to stop and then you're going to have a stroke at the end of that. So it's exciting what can be done now. Other big moments, breakthroughs in intervention that you can talk about other than the thrombectomy?

Ashutosh Mahapatra, MD: Yeah, so certainly thrombectomy was one that got a lot of attention. Other things that moved the field forward, for example, in the late nineties, early two thousands, they had the advent of detachable coils. So we had these coils that could be electrolytically detached inside a patient. Of course, now it's a matter of seconds for the coils to detach. Then it was six to 12 minutes while you hooked the end of the coil onto basically a battery and watched that detachment point slowly melts away, but that really drove the field forward in terms of being able to treat intracranial aneurysms, whether ruptured or unruptured.

Then further on, in terms of hemorrhagic stroke treatment, again in the late two thousands was the advent of a flow diverter, which is basically a specialized stent. When we think about stents, we think about these intraluminal constructs, but this is a semi-porous device that also allowed us to start treating aneurysms in locations that we couldn't easily get to, either endovascularly or surgically before, namely the ophthalmic aneurysms. The surgical approach for these was rather extensive. You'd have to do a clinoidectomy. Sometimes you have to displace the patient's eyeball and do a big dissection around the eye socket to go in and place a clip. That has certainly changed the way that we treat these types of aneurysms now where we could go in and place a stent across the aneurysm. It's a very low risk and technically not as challenging as doing a clinoidectomy for these types of procedures. And on top of that, the field just keeps advancing into various areas that we wouldn't normally think. Strokes and aneurysms are the bread and butter, but this field has really spread into so many different other aspects of clinical care.

Glen Stevens, DO, PhD: Okay, and we'll get into some of those in a little bit. So I was going to ask you that with the advent of TPA trying to dissolve clots, those types of things, what's the relationship with that and the intervention? Is that something, can you give a drug directly to the clot or it's still given intravenously? Can you give it intra-arterially?

Ashutosh Mahapatra, MD: Yeah, so with TPA and other even newer thrombolytic agents, and you mentioned antiplatelet agents earlier, there's a lot of soluble antiplatelet agents as well that we can give, and so we can really fine tune this technique to whatever the patient needs. At times, for example, you mentioned these distal vessels being blocked off. Thrombectomy, although it's very refined in the way that we do things now, is not without the potential for sending clots distally or having an incomplete result, and in many of those situations, we can go back in even through our small catheters and give lytic agents directly at the face of the clot.

And although by itself, it hasn't proved to be super effective, it's certainly a technique that we all reserve in our back pocket, and a lot of the early thrombectomy trials actually utilize these techniques rather extensively. Like you mentioned, we didn't have the advent of aspiration catheters or stent retrievers to be able to effectively pull clots out, so that was some of the initial techniques on how we did that. And there's actually some newer data that has come out recently that shows that even after you've had a successful thrombectomy, going in and infusing that area with local lytic agent and for arteriolytic agents has shown to benefit patients in terms of their recovery and reduce their burden of stroke, so it's rather interesting.

Glen Stevens, DO, PhD: So, with everything that's good, there's always a risk of bad. What are the risks of the angiogram?

Ashutosh Mahapatra, MD: Luckily, angiography, even though it's invasive, has become pretty safe with our newer catheter devices. The official risk, I'll quote, of doing diagnostic angiography is if you take everything, major and minor complications, is probably in the realm of about one to 2% at the most. Obviously, the most feared complication of angiography is damage to the blood vessel which can potentiate an ischemic stroke in itself or can go the other way. Depending on what you're doing, you can also cause a perforation of a blood vessel which can result in a hemorrhagic stroke. So these are the things I consistently tell my fellows that they have to become really good at balancing the ischemic and the thrombotic, the ischemic, the hemorrhagic concepts here, because the difference between those few complications is only a matter of millimeters.

Glen Stevens, DO, PhD: So, I'll just shift for a second to a fairly complicated thing to treat an AVM, arteriovenous malformation. My personal feeling is the field has changed quite a bit, but you can let me know, but I do a lot of gamma knife. I see a lot of AVMs being treated with radio surgery now, and in the old days, depending on the grading and the classifications, people would have resections, but what's the role with interventional procedures in AVMs these days?

Ashutosh Mahapatra, MD: I think it depends on who you'll ask. I think that the way that we do things here at Cleveland Clinic is we really utilize a multidisciplinary and individualized approach for the patient. So we take time to... So angiography has its role in, one, highlighting the morphological features of every AVM. You want to really understand the angioarchitecture of these complicated lesions before you tackle them with any sort of intervention. Our approach here has been a combination of embolization plus surgery for the appropriate patients. Usually, these are the ones that have, if you're going off by the Spetzler-Martin grading score, the lower scores on anywhere between one and three.

And then for the higher ones, that's typically, we think about those as more complex. Maybe they're really sitting in the middle of lots of eloquent territory. It's not easy for the surgeon to get to, lots of deep venous drainage, so in those scenarios, we actually employ a combination of embolization where it's feasible in combination with radiosurgery, and radiosurgery is actually really remarkable for AVMs. We see it takes a little bit longer for you to treat. Obviously, it takes some time, but we do see almost a 50% curative rate with combination therapy or sometimes even radio surgery alone. So it's really remarkable that we can offer these varied treatment modalities for patients, and I think with time, we'll get even better at selecting these patients.

Glen Stevens, DO, PhD: So, we've concentrated on cranial. What about spinal? What's the role of neuro intervention with spinal abnormalities?

Ashutosh Mahapatra, MD: Anywhere there's a vascular lesion, you can find an interventionalist trying to make their way in, and so the spinal AVMs and fistulas, although rare conditions, are not infrequent in our practice. The other area where we really get involved here is spine tumors, especially the vascular tumors, renal cell metastasis to the vertebral bodies and things like that. I feel like we can do a really good job of helping our surgeons not only do preoperative embolization to help make their surgeries easier, less bloody, but also to help them with their planning purposes for that.

Glen Stevens, DO, PhD: This may or may not be controversial, but timing of the embolization relative to the surgery, any thoughts on that?

Ashutosh Mahapatra, MD: Sometimes it depends on the technique that you use. A lot of times, for these spinal tumors for example, we'll use a lot of PVA particles. It's tiny micro particles that we use to occlude the artery, as opposed to some of the other embolic agents. We use liquid embolics which act like super glue or lava, coat the vessels and harden and form a cast. So, it depends on which technique we employ. Regardless, and the reason that is is because anytime you embolize something like a tumor, this really live vascular reactive structure, it's going to cause necrosis and edema, and depending on the location, we usually don't like that to have more space occupying stuff in the brain or spine. And so for us, the timing is really, the ideal time point in my opinion would be somewhere between 24 or 72 hours from the embolization is when we encourage our surgeons to operate, although sometimes it can be delayed a little bit longer, up to a week. I think the data shows that probably about a week is about as long as you want to wait in terms of the interval between embolization and resection.

Glen Stevens, DO, PhD: So, you hinted at this a little bit, but beyond stroke and aneurysms, where is the field going?

Ashutosh Mahapatra, MD: Where is it not going? So I'll start with the low hanging fruit, which is the venous standpoint. So we focus a lot on arterial interventions. Now there's a big focus also on the venous side of things, and where this really shines is things like pulsatile tinnitus and idiopathic intracranial hypertension. These are, I think, the two biggest areas where there's a lot of excitement about doing venous work, and we've noticed either venous sinus stenosis or some venous abnormality, venous structural issues can typically cause these patients to have these types of conditions and symptoms. And so venous sinus stenting for IIH has become a really robust alternative to shunting or optic nerve sheath fenestration for patients with IIH pulsatile tinnitus, which really didn't have a lot of cures before. If it's attributed to, for example, a high riding jugular bulb or a big venous dehiscence, these things can be treated relatively easily with either coiling or stenting or a combination of, and really reduces the morbidity of some of these patients that suffer from these conditions that didn't have any treatments before.

Moving forward from that, we've also expanded what we can do on the hemorrhagic stroke side. Chronic subdural hematomas, something of real concern in our aging population that's on a lot more blood thinners for the risk factors, this has come in vogue as well. There's been several trials that show a reduction in the risk of expansion or the risk of need for future surgery with middle meningeal artery embolization for these subdural hematomas, so I know my practice has seen a huge growth in the amount of subdural hematomas I treat.

Glen Stevens, DO, PhD: Yeah, I've seen that as well. How long have we been doing that?

Ashutosh Mahapatra, MD: We've been doing it for probably about two to three years now. It was first described once again in the early two thousands, but the techniques have really become refined and the patient selection, which I think is the most important part, is more refined. I think there are still some kinks to work out on who benefits the most, but at this point in time, we do a lot of MMA embolizations. The volume of chronic subdural hematomas is expected to outpace the volume of even ischemic strokes. I think that there's a real opportunity to help patients there.

Glen Stevens, DO, PhD: So, if you do the procedure, can you avoid draining the subdural in some patients, or you're doing it in patients, just that you're planning on doing surgery?

Ashutosh Mahapatra, MD: The data shows that there's benefit in both subsets of populations, even the ones that are deemed non-surgical, so the way I like to think about it is I really dichotomize them as, hey, these are patients that for sure need surgery. Big hematomas, they have focal neurological weakness. Maybe they have midline shift or mass effect. They're going to need some surgery to help decompress their brain, and we can use that as an adjunct to surgical treatment, MMA embolization as an adjunct to help decrease the risk of recurrence and the risk of repeat surgeries. Because I think that's one of the biggest concerns that neurosurgeons have is once they go in there, they don't want to have to go back because taking the skull off, doing a craniectomy is a big deal. So if we can reduce the risk of that, I think that's really important.

We've also shown that even the patients that receive it as a standalone therapy that don't have the emergent need for surgery, that this reduces the risk of them having repeat surgery or requiring surgery in the future dramatically, which in itself, obviously speaking, has some great benefits in terms of reducing patient morbidity, healthcare costs, so many different things.

Glen Stevens, DO, PhD: Yeah, I think for the listeners out there, this is really a growth area and something that people are not familiar with it, and they're seeing a lot of these types of patients, and certainly time to get educated on it, right?

Ashutosh Mahapatra, MD: Absolutely.

Glen Stevens, DO, PhD: So, you do a lot of stenting and you talked about arterial and venous. How different is it putting a stent in an artery versus a vein? One a lot more complicated, the risk different. How do you find it? Obviously, you do artery a lot more than vein historically.

Ashutosh Mahapatra, MD: Right. There are some technical nuances. The arteries that we operate in are pretty small and fragile, except for maybe the carotid arteries which are rather robust, but intracranial stenting obviously is a very delicate procedure. To be honest with you, in the periphery, even the coronaries and in the peripheral vessels, we have so many different types of stents and things that are really indicated for those types of procedures and designed for specifically accessing those vessels. In the brain, we've utilized these devices, for example, coronary stents and peripheral stents are the ones that we typically use to stent the arteries in the brain or the veins in the brain.

In terms of differences, I think the neurosurgeons will maybe cringe at this a little bit, but I feel a lot safer mucking around in the venous system than I do in the arterial system with stents. They're protected by bone and especially the dural venous sinuses, so we're well protected from that standpoint, and we think, at least I feel safer doing that. To be honest with you, I think that there's a lot of room for improvement in the technology to make both of those procedures, either arterial or venous, safer.

Glen Stevens, DO, PhD: So, in terms of things people wouldn't necessarily think of when they're thinking of interventional neurology, treating migraines, do you guys have a role there?

Ashutosh Mahapatra, MD: Yes. This is something that's been around for a little while in small circles, but with some recent publications and some recent look at things, we found that once again, going back to the middle meningeal artery, which seems to be our playground these days, we found that patients that had either embolization of the middle meningeal artery had a history of headaches. They would come in for other pathologies like a fistula or chronic subdural hematoma and they would get embolization, or during the embolization, they would get some anesthetic infusion like lidocaine into these arteries, and what we started noticing over time is that these patients were reported less and less chronic headaches. So there's a recent study that was done by Dr. Fiorella and Dr. Arthur that showed that infusing lidocaine into the middle meningeal arteries can help reduce the frequency, the number of headache days that patients have with refractory migraines.

I think this is very much a new thing and there's a lot of selection criteria that we have to figure out on how to appropriately select these patients, but I think there's going to be a real role in this. Here at Cleveland Clinic, we've started to do these procedures as well. We've done probably about 10 or 15 patients now. What I'll say is that there is definitely some immediate reduction in the pain that we've seen pretty much all across the board, but we don't know a lot about how long the effect lasts. Is this going to be something like Botox where they have to come back every three months to get repeat infusions, or is this something that we can potentially just take down the artery and decrease that meningeal supply and reduce some of the activity in the meninges that may be triggering migraines?

Glen Stevens, DO, PhD: I remember Dr. Fiorella when he was here many years ago.

Ashutosh Mahapatra, MD: A very, very smart guy.

Glen Stevens, DO, PhD: So always glad to hear what he's doing. Our time's starting to run out here, but hydrocephalus in the role of intervention?

Ashutosh Mahapatra, MD: Also, very new. We're going to be starting our own enrollment for a clinical trial here at Cleveland Clinic, but yes, so endovascular shunting, what this basically involves is us drilling a small hole in the inferior petrosal sinus and placing a little valve inside, basically embedding a valve in the wall of the vein which allows drainage in a one-way system into the cisterns. And so basically, you're creating this venous to CSF channel to help with drainage. Compared to VP shunting or external ventricular drainage, this may pose a very interesting alternative, especially in patients that have other pathologies like normal pressure hydrocephalus or even subarachnoid hemorrhage related hydrocephalus. It's very early to say how things are going to pan out, but we're pretty hopeful that this is going to be something that's very exciting,

Glen Stevens, DO, PhD: Artificial intelligence in your field?

Ashutosh Mahapatra, MD: We do have some artificial intelligence overlap. We're not to the point where robots and AIs are doing our procedures for us or taking stroke call for us, but certainly there's a lot of work in AI and robotics that are happening, mostly in an assistive fashion. But when I was early in my training, I had to carry my laptop around with me everywhere when I was on call. Now, we have these phone and mobile apps that alert you using AI software, that, oh, hey, there's a CTA that has some detection of a large vessel occlusion, and so they help us filter some of that stuff and it makes it easier for diagnosis, and I think we're going to see that as AI becomes a bit more sophisticated.

Glen Stevens, DO, PhD: Our interaction with the cardiology folks, because obviously they're doing a lot of this type of stuff. Are we playing together in the sandbox or we're still a little apart?

Ashutosh Mahapatra, MD: Well, I think that the interventional cardiologists have done a great job of setting a roadmap in so many different ways, including systems of care. How do you triage a patient effectively? And we get so much of this from the PCI and STEMI culture that we've adopted into the interventional stroke culture. I think that the heart and the brain are two separate organs, and the cardiologists, not to get too political here, but they have their own playground, we have our own. Everything from the neck up I strongly believe is interventionist territory. That's just something that we do day in and day out, whether it be diagnostic angiography, and we're well suited to treat the complications of catheterizing anything that goes towards the brain because that's our bread and butter.

With that being said, I think there's so much to learn from the way that the cardiologists have organized themselves as a field and the way that they've delivered care, and even the way that they conduct their clinical trials. Their patient volumes, their data is so immense and robust that it's nothing short. It would be hard to say that I'm not envious of all the stuff that they do.

Glen Stevens, DO, PhD: So, as we're closing out, what's on the horizon?

Ashutosh Mahapatra, MD: Lots of exciting things on the horizon. I think the pendulum will continue to swing. We've had some recent negative trials in chasing the very small distal vessels and seeing if there's a benefit, so we're going to see a lot more attention towards refining the technique for chasing these distal occlusions. There's going to be overlap with brain computer interfaces in a different subset, which I quote unquote, "functional endovascular neuro intervention," where we're going to be implementing the use of brain computer interfaces such as stentrodes and electrodes planted in the brain to either gather data or to help patients with communications, things like locked-in syndrome.

There's some research being done on infusing stem cells to allow for brain recovery in devastated patients after strokes, so there's many different aspects. So one other thing I'll mention that should be close to your line of work is Y-90 infusions for glioblastoma as well, and there's some clinical trials coming out that are showing that maybe there'll be some efficacy with that as well.

Glen Stevens, DO, PhD: Yeah. Just as a quick aside, back in the day, we used to run an intra-arterial chemotherapy program, so we were utilizing the interventional folks quite a bit and infusing chemo directly into the cerebral vasculature. If somebody wants to send a patient here, how do they do it?

Ashutosh Mahapatra, MD: You can send them directly to any of the CV Center staff, but there is a CV Center triage pool that you can easily look up on Epic, and if you send it to the triage pool, they'll make it happen.

Glen Stevens, DO, PhD: Great. Any final thoughts?

Ashutosh Mahapatra, MD: This field, I've been obsessed with it. I'm very passionate about it. For all the trainees out there, especially the neurology trainees, that are considering something a little bit off their traditional path, it's a great field that marries the concepts from the high-tech nature of radiology, the procedural aspects of surgery and the cerebral aspect of being a neurologist together, so it's a wonderful training field. It's certainly been rewarding for me to pursue. It's just a field that just keeps expanding its horizons, and I think that the practice of neurointervention, when I first started and got exposed to it and where it is now is dramatically different, and we're going to continue to see the shift over the years. So I'm very excited to be a part of it and very excited to utilize our skillset to help as many patients as possible.

Glen Stevens, DO, PhD: Well, Ash, thank you very much for joining me today. I hope I never need you, but I'm glad you're there if I do, and look forward to the great things you guys are doing.

Ashutosh Mahapatra, MD: Excellent. Thank you so much for having me, Glenn.

Glen Stevens, DO, PhD: Thank you.

Closing: This concludes this episode of Neuro Pathways. You can find additional podcast episodes on our website, clevelandclinic.org/neuropodcast, or subscribe to the podcast on iTunes, Google Play, Spotify, or wherever you get your podcasts. And for further learning, you can access real-time updates from experts in Cleveland Clinic's Neurological Institute on our Consult QD website, that's consultqd.clevelandclinic.org/neuro, or follow the Cleveland Clinic Neurological Institute on LinkedIn. And thank you for listening.