Surgical Decision-Making for Cerebrovascular Disorders

Podcast Transcript

Neuro Pathways Podcast Series

Release Date: May 15, 2025
Expiration Date: May 14, 2026

Estimated Time of Completion: 30 minutes

Surgical Decision-Making for Neurovascular Disorders
Nina Moore, MD

Description
Each podcast in the Neurological Institute series provides a brief, review of management strategies related to the topic.

Learning Objectives

• Review up to date and clinically pertinent topics related to neurological disease
• Discuss advances in the field of neurological diseases
• Describe options for the treatment and care of various neurological disease

Target Audience
Physicians and Advanced Practice providers in Family Practice, Internal Medicine & Subspecialties, Neurology, Nursing, Pediatrics, Psychology/Psychiatry, Radiology as well as Professors, Researchers, and Students.

ACCREDITATION

In support of improving patient care, Cleveland Clinic Center for Continuing Education is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

CREDIT DESIGNATION

• American Medical Association (AMA)
  Cleveland Clinic Center for Continuing Education designates this enduring material for a maximum of 0.50 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
  
  Participants claiming CME credit from this activity may submit the credit hours to the American Osteopathic Association for Category 2 credit.

• American Nurses Credentialing Center (ANCC)
  Cleveland Clinic Center for Continuing Education designates this enduring material for a maximum of 0.50 ANCC contact hours.

• Certificate of Participation
  A certificate of participation will be provided to other health care professionals for requesting credits in accordance with their professional boards and/or associations.

• American Board of Surgery (ABS)
  Successful completion of this CME activity enables the learner to earn credit toward the CME requirements of the American Board of Surgery’s Continuous Certification program. It is the CME activity provider's responsibility to submit learner completion information to ACCME for the purpose of granting ABS credit.

Credit will be reported within 30 days of claiming credit.

Podcast Series Director
Andreas Alexopoulos, MD, MPH
Epilepsy Center

Additional Planner/Reviewer
Cindy Willis, DNP

Faculty
Nina Moore, MD
Cerebrovascular Center

Host
Glen Stevens, DO, PhD
Cleveland Clinic Brain Tumor and Neuro-Oncology Center

Agenda

Surgical Decision-Making for Neurovascular Disorders
Nina Moore, MD

Disclosures

In accordance with the Standards for Integrity and Independence issued by the Accreditation Council for Continuing Medical Education (ACCME), The Cleveland Clinic Center for Continuing Education mitigates all relevant conflicts of interest to ensure CME activities are free of commercial bias.

The following faculty have indicated that they may have a relationship, which in the context of their presentation(s), could be perceived as a potential conflict of interest:

Glen Stevens, DO, PhD

DynaMed Consulting

All other individuals have indicated no relationship which, in the context of their involvement, could be perceived as a potential conflict of interest.

CME Disclaimer

The information in this educational activity is provided for general medical education purposes only and is not meant to substitute for the independent medical judgment of a physician relative to diagnostic and treatment options of a specific patient's medical condition. The viewpoints expressed in this CME activity are those of the authors/faculty. They do not represent an endorsement by The Cleveland Clinic Foundation. In no event will The Cleveland Clinic Foundation be liable for any decision made or action taken in reliance upon the information provided through this CME activity.

HOW TO OBTAIN AMA PRA Category 1 Credits™, ANCC Contact Hours, OR CERTIFICATE OF PARTICIPATION:

Go to: Neuro Pathways Podcast May 15, 2025 to log into myCME and begin the activity evaluation and print your certificate If you need assistance, contact the CME office at myCME@ccf.org

Copyright © 2025 The Cleveland Clinic Foundation. All Rights Reserved.

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

Glen Stevens, DO, PhD: The variable pressures and flow rate of blood through vessels causes blood vessels walls to change shape, rebound, and move within the adjacent tissue. This rebounding movement in turn alters the flow pattern of blood in pathologies such as brain aneurysms or cerebral atrial venous malformations with unpredictable rupture profiles. These small interactions between blood flow and vessel distension may potentially explain the differences between a catastrophic hemorrhage and an entirely quiescent lesion and offer hope for better predictive modeling.

In today's episode of Neuro Pathways, we're discussing the evolving understanding of the mechanical properties of blood vessels and the potential impact on cerebrovascular surgical decision-making. I'm your host, Glen Stevens, neurologist, neuro-oncologist in Cleveland Clinic's Neurological Institute. I'm very pleased to be joined by Dr. Nina Moore. Dr. Moore is a neurosurgeon and researcher in Cleveland Clinic Neurological Institute's Cerebrovascular Center. Nina, welcome to Neuro Pathways.

Nina Moore, MD: Thank you. Pleased to be here.

Glen Stevens, DO, PhD: So, Nina, tell our audience a little bit about yourself, how you made your way to Cleveland, why you decided you wanted to work in this area and what you do on a regular basis.

Nina Moore, MD: Well, I've been interested in the brain since I was a child, and I've done research through various means over time. So, I started with neuroscience research, looking at projection patterns of axons in the olfactory system in high school. And then in undergrad, I worked as a biomedical engineering student, where I did my bachelor's and master's over at Case Western and studied neuroprosthesis, which is quite interesting from a standing and walking systems for patients that are paralyzed.

When I went to medical school, I started doing more of a neurosurgery research because that was always the goal, and we were looking at different forms of MR imaging to stage tumors of various sorts. And, knowing that... Well, after seeing cerebral vascular cases, obviously I went down that pathway, fell in love with the neurovascular system. And so, I pivoted in my research and started looking more of the engineering applications within cerebral vascular. And so, I specialized in open and endovascular therapies for cerebral vascular diseases.

And my research lab actually was trying to solve some of the questions just using computers: “Can we figure out when an aneurysm or an AVM is going to rupture?” And realized that a lot of the data for those simulations isn't in the literature. And so, we started looking at how blood vessels respond to various pressures and are really trying to catalog that so that way other people also investigating this can use that as well.

Glen Stevens, DO, PhD: Well, you're very focused. I can say that. That's for sure. I needed to be more focused when I was younger, I guess.

So, to help our audience that's out there and just simply tell us what an aneurysm is.

Nina Moore, MD: So, in a blood vessel, there's a wall to a blood vessel, and that wall can sometimes weaken and form a weakened outpouching, or a bubble. And, we don't quite understand why certain people get aneurysms and others don't. There's a thought that potentially some of the layers in the blood vessel were inherently weak from birth and over time those kind of get stretched out. Or, there's other thoughts about the different layers of cells having irritation and changes in how they express their inflammatory properties, which can also potentially lead to an aneurysm.

Glen Stevens, DO, PhD: So, there's different types of aneurysm. The most common is the saccular berry aneurysm, which I always thought of it looks like a berry hanging on a... It's very descriptive. And then, you have fusiform, which look very different. And then, of course, you have mycotic, which is an infectious type of a process. But I always thought that the saccular and the fusiform, I mean, they look very differently. So is the mechanism, and maybe we'll get into this later, but is the mechanism of how they develop thought to be different or not necessarily?

Nina Moore, MD: Well, I don't know if anyone really knows the answer to this, but blood vessels themselves behave like silly putty. When they are stretched, if they get stretched beyond a certain point, they don't regain their normal shape. They keep stretching. And so, we see a lot of patients with chronic high blood pressure that have vessels that are much longer than what they probably started with.

And in a fusiform aneurysm, the wall itself starts getting dilated and stretching, and it could be a disruption to the layer wall through injury. If someone had a bad car accident, their blood vessel rubbed against a tough structure in the head, they can develop a fusiform aneurysm or a dissection. And other times it could just be that their blood vessel stretched too much over time and never regained its normal shape.

Glen Stevens, DO, PhD: And let's just pivot now to AVMs. What’s the difference between AVM and an aneurysm for the audience?

Nina Moore, MD: Well, so AVMs can have aneurysms, but an AVM is an actual abnormal artery to vein connection. So, there's... Arteries typically branch into smaller and smaller branches, and then finally go to the cellular layer. And then those nutrients are taken away through blood vessels, called veins, and they get bigger and bigger, much like going towards a trunk of a tree. In this case, AVMs are actually the artery to vein plugging in abnormally early. So, it's skipping all those smaller and smaller processes. And so, you have high flow to low flow in this vascular malformation.

Glen Stevens, DO, PhD: And AVMs are congenital, or can you develop them later? Or they're all congenital?

Nina Moore, MD: Well, there's varying thoughts on this. Initially, everyone thought these were congenital only.

Glen Stevens, DO, PhD: That's what I thought.

Nina Moore, MD: But the natural history data may suggest that AVMs develop later in life for some people. And about 50% of these actually potentially have a KRAS mutation - 30 to 50%. So, there can be some genetic forms just within those cellular layers of the endothelial cells and the generational blood vessels that causes AVMs to grow and develop over time.

Glen Stevens, DO, PhD: Nina, you've just given me more things to worry about now.

Nina Moore, MD: Well, for the most part, they carry about a two to three percent risk of rupture per year. And a lot of people make it through their entire life even with some of these vascular malformations and will never know.

Glen Stevens, DO, PhD: So, we get aneurysms in other areas of the body. It doesn't have to be in the brain. Are they different in other areas, or do we have to reinvent the wheel based on the location of where it is?

Nina Moore, MD: Well, the blood vessels are different in different parts of the body. So, the aorta is a very thick blood vessel, has multiple elastic layers, a lot more vascular, smooth muscle cells. In the intracranial space, the tissue is significantly different. There's one layer of an internal elastic lamina, and we're talking about 600 micrometers of thickness. I mean, this is very small vessels and thickness. And so it's a different beast. And the valves of the veins are different. There's no valves in the intracranial space. So, a lot of the tissue... It's more specific in the brain.

Glen Stevens, DO, PhD: So risk factors, who gets these?

Nina Moore, MD: Well, there can be a family history...

Glen Stevens, DO, PhD: And stop staring at me [laughs].

Nina Moore, MD: [Laughs] Well, there can be a family history. So, if more than one immediate family member has an aneurysm, people should be screened.

Glen Stevens, DO, PhD: And screening means what?

Nina Moore, MD: Like an MRA brain... So an MR angiogram. It can be related to smoking. People that do cocaine or amphetamines can have a higher propensity towards getting an aneurysm. It can be familial, as I mentioned. There can also be congenital problems like polycystic kidney disease that can generate more aneurysms or narrowing of the aorta causes increased pressure towards the brain and can form aneurysms.

Glen Stevens, DO, PhD: Marfans?

Nina Moore, MD: Marfans? You know, we don’t see...

Glen Stevens, DO, PhD: Some of the connective disorders?

Nina Moore, MD: Connective tissue disease. We don't really have a full list of every risk. I mean, there's certain people that have blood vessel disorders and dissections and aneurysms that form that don't even have a diagnosed connective tissue disorder. But we assume that those people also probably have some form of a collagen-based disorder.

Glen Stevens, DO, PhD: So, as a neurosurgeon, you must hate people that smoke because it affects wound healing and all those types of things. What's the mechanism with smoking and aneurysm formation?

Nina Moore, MD: We don't quite understand because I can't necessarily tell a patient they should go to a vaping pen and just do nicotine-based only. I think there may be some factor in the elastin response to smoking. Could be a hypoxia event that triggers changes in the blood vessel.

We do know that the blood vessels start behaving differently. And people that smoke, if they do have an aneurysm, they have a higher rate of rupture or recurrence of their aneurysm. So, something is continually changing. If we coil an aneurysm, which is where we pack an aneurysm with metal, these small little pieces of wire that coil upon themselves, you know, the recurrence rate for aneurysms in people that smoke is much higher. And I think it's probably because their viscoelasticity changes in their blood vessel wall.

Glen Stevens, DO, PhD: So, males versus females. Who's more at risk, who's worse at risk?

Nina Moore, MD: Well, so females actually do have probably a higher risk of having an aneurysm. As far as risk of rupture, it depends on your risk factors. If there's an irregular aneurysm, meaning there's a secondary bubble on an aneurysm, we tend to be more aggressive in treating those even in smaller aneurysms. If there's family history and any sort of high-risk profile for those patients, we tend to treat those a little bit more aggressively, even if they're smaller aneurysms.

Glen Stevens, DO, PhD: Postmenopausal? Estrogen? I hear a bit about estrogen out there.

Nina Moore, MD: Well, so there's a discussion of whether or not estrogen's protective of aneurysm rupture. There's a researcher out of University of Florida who has been looking into estrogen. There's no current recommendations, and certainly the guidelines don't state that women should be on a low-dose estrogen for neuroprotection. But, certainly more to come on that I imagine once there's more randomized clinical trials.

Glen Stevens, DO, PhD: And I assume that's because the hemorrhage risk is greater postmenopausal?

Nina Moore, MD: Not necessarily. But, I would say that the majority of people that come in with an aneurysm rupture tend to be slightly later in life. But we do see kids come in with aneurysm ruptures too. Not as often, though.

Glen Stevens, DO, PhD: Size and location, I assume, also will factor into how old the person is, what's the size. How small, “small we leave it alone?” Or, if your dad had one and you have a small one, maybe you need to do something anyways. But I know these aren't always hard and fast, but what's the general?

Nina Moore, MD: Well, so the brain circulation's broken up into anterior versus posterior circulation, and we actually did a study looking at the effects of what the thicknesses of the different vessels are in the anterior and posterior circulation. If you look at natural history data, posterior circulation aneurysms are more likely to rupture, and that actually follows histology too and embryology. So, those two circulation areas actually develop differently.

And so, yeah, if posterior circulation... Seven millimeters in the anterior circulation is usually the cutoff for treatment, unless someone has higher risk features. In the posterior circulation, really having an aneurysm there is worrisome. And so we tend to treat those more aggressively.

Glen Stevens, DO, PhD: Let's go to flow then. So, they tend to... In the brain... They tend to occur at what location?

Nina Moore, MD: Well, branching points usually. So, typical berry aneurysms tend to happen at branching points. And it could be that there's an inherent weakness at that branching point and how the blood vessels developed or that the force and flow at that location causes greater pressure in those locations.

Glen Stevens, DO, PhD: So, I'm curious, are there preclinical models that are currently available?

Nina Moore, MD: Yes, there are some preclinical models. There's a couple of models being developed where they break down elastase to try to generate aneurysms, but it's kind of hard to compare. Since we're still in the investigative stages of figuring out why aneurysms form, it's hard to know if those models actually mirror what human aneurysm formation does. So, I think there's still more research to go as far as what's human natural mechanisms for aneurysm formation.

Glen Stevens, DO, PhD: What are you working on particularly?

Nina Moore, MD: So, we have a fluid structure model where we're actually measuring the mechanical profile of blood vessels to create what's normal, to find out what's a normal tissue behavior. And we've created a test rig really where we test how the blood vessels change in response to time. And we use that mechanical profile to incorporate it into a mathematical model where we basically apply those parameters to the same location on a blood vessel model of the brain.

And we've been taking fluid flow measurements both from transcranial Dopplers, as well as in vivo measurements using flow probes, to try to be able to create the inflow environment and the pulsatility environment that you would see for a normal blood vessel. So, the goal is to create a normal blood vessel. And then, we're also working on AVM mechanics and genetics to compare those biomechanics and create a model for arterial venous malformations.

Glen Stevens, DO, PhD: So, just to go back to the AVMs then. Since they're really mostly congenital-based, not much you can do, right? I mean, it's not a risk-factor-type thing. You're kind of born, you have it, unless there's something in utero that goes on that caused it. Do we know?

Nina Moore, MD: Well, we don't know. And so, those cells, the ones that have a genetic mutation, potentially down the road, there can be a potential treatment for that. There's certainly medications that are being used in the body AVMs to try to reduce the risk of formation. But I think right now, mainly it's a response thing that we do for these AVMs. It's if we find one, we tend to recommend treatment of a various sort for them.

Glen Stevens, DO, PhD: So, I come see you. I've got a posterior circulation aneurysm, 6.7 millimeters.

Nina Moore, MD: Okay. Well, it depends on the anatomy of it. We have a lot of good treatment options these days.

Glen Stevens, DO, PhD: How do you decide if I should be treated or just followed?

Nina Moore, MD: For the most part in the posterior circulation, we'd probably recommend treatment. It depends on the shape. It depends on is it a fusiform basilar aneurysm? Is it below the anterior inferior cerebellar artery? If it's a saccular aneurysm, usually endovascular treatment's kind of where we go with that. However, if it's on the posterior inferior cerebellar artery, we might consider clipping.

Glen Stevens, DO, PhD: So endovascular, gluing, coiling, something else, flow diverters, what are we doing?

Nina Moore, MD: Well, so a lot of times for saccular aneurysms, it's an intrasaccular treatment. So coiling. We do have some newer devices where you can release a device into an aneurysm if it's the right shape. Flow diversion works well, but you have to... There's some nuances to it about what you can cover and what you can't cover. The stenting options, there's also stenosis coiling to try to hold coils in. And of course, clipping is still there. I think it just depends on its location, and we don't typically glue things right now.

Glen Stevens, DO, PhD: And when you coil, what happens to the aneurysm? It starts to fibros down and just close off, just like banding?

Nina Moore, MD: Kind of, yeah. If we do an open surgery after we've coiled someone for some other reason, the tissue actually shrinks into the coils. I think there's an endothelial layer that forms over the coils that are facing the normal blood vessel. And so, it kind of fibrosis over. If it doesn't secure it and the aneurysm continues to grow, putting a stent over it is usually a very durable treatment because then the endothelial layer will grow over the opening of the aneurysm and help it seal over.

Glen Stevens, DO, PhD: So, if you coil me, how long will it take for my risk to decrease for bleeding?

Nina Moore, MD: Pretty much immediately. I think if you get a decent enough packing job of the coils, you prevent inflow into the aneurysm. And really, we try to protect the dome of the aneurysm as much as possible. If there's some recurrence...

Glen Stevens, DO, PhD: What does that mean? That means you avoid putting something in the dome?

Nina Moore, MD: Oh, we try to fill it with metal.

Glen Stevens, DO, PhD: Or you fill the dome?

Nina Moore, MD: Fill the dome with metal. Yeah, we try to prevent inflow of blood flow into the aneurysm.

Glen Stevens, DO, PhD: Okay. And I thought I saw something recently that the percent of the aneurysm that actually gets filled with the coil is not that high. Is that right?

Nina Moore, MD: Well, people used to think that about 30% metal was enough to occlude the aneurysm. We try to fill the aneurysm here as much as possible just to try to reduce recurrence rates, where coils can compact over time from blood flow into the aneurysm. And at one point, we were seeing about an 80% recurrence rate of certain aneurysms in the front circulation at the one-year mark from aneurysm treatment. So, I think filling it more up front potentially reduces the risk of recurrence.

Glen Stevens, DO, PhD: And risk of injury to the vessel when you're coiling it?

Nina Moore, MD: Well, so usually not the vessel itself, the parent artery, but the aneurysm, you have to be cautious. Certainly too much can be too much. There's a sense for when you're pushing the coil, f you can't put a coil completely in, don't force it. At some point, the catheter backs out of the aneurysm so you know when to stop.

Glen Stevens, DO, PhD: Can the coils leave the aneurysm and float in the system?

Nina Moore, MD: They can. And so, part of the trick of coiling is that you try to get them to interlock, and so you gradually reduce the size of the coil. And then there's a limit. I usually try to not go beyond a certain smallness of the coil because I worry that that'll disengage and float down the vessel.

Glen Stevens, DO, PhD: What's a flow diverter?

Nina Moore, MD: A flow diverter is a special stent. It's kind of like a heavier mesh. A regular stent is more of like... I describe it to patients like chicken wire. There's more space in between the metal tines. A flow diverter is much higher density of mesh, like 33 to 60 some percent of metal. It covers the vessels, but it's enough that blood flow slows down within the aneurysm. But smaller branching vessels tend to stay open because there's enough flow through the stent into those vessels.

Glen Stevens, DO, PhD: AVM seems much, much more complicated. My recollection was in the old days, there was more coiling, stenting, whatever, clotting, blocking, but it seems there's less of that now. Am I right about that or wrong about that?

Nina Moore, MD: For arterial venous malformations, we do still block them. I think we've done a couple of studies here at The Clinic where we looked at our own data, and we do radiation for them, gamma knife or radio surgery for AVMs. We also do embolization where we glue off branches. You can also put coils in, but we tend to block those inflow vessels. And that's a careful process where you don't want to take too much down, you don't want to slow the vessels down too much until the whole AVM is cured. And then we do surgical resection for those still.

Glen Stevens, DO, PhD: Yeah. So blunt force trauma surgery, how much are we doing for aneurysms? How much are we doing for AVMs?

Nina Moore, MD: Aneurysms have gone down considerably for open surgery just because we have a lot of catheter-based treatments that are very, very good. There are still cases where we do need to do open surgery or they're better suited for open surgery. I would say the majority of cases, about 80 to 90%, of aneurysms are treated by catheters. And then AVM surgery, I'd still say 50/50, maybe 50% go to radio surgery and about 50% go to open surgery.

Glen Stevens, DO, PhD: And what happens if I have an aneurysm associated with my AVM?

Nina Moore, MD: Well, there's literature to say that if you treat the AVM, the aneurysm may go away. I'm not 100% convinced about that just because we haven't seen... I mean, there is data to say that they have involuted. But, I think we tend to treat those if they look like they have high-risk features or on their feeding artery of the AVM. And certainly in the posterior circulation, those AVMs tend to be found because the aneurysm is ruptured. If you see a PICA aneurysm, you should check to make sure they don't have an AVM, as well.

Glen Stevens, DO, PhD: And I don't want to divert things here, but mycotic aneurysms treatment is different?

Nina Moore, MD: So mycotic aneurysm or an infected blood vessel wall... We can still try antibiotics if they're not ruptured, six weeks of antibiotics and see if they go away on their own. If they are ruptured, we sometimes glue the vessel off. Or, if we can't get to it via catheter, then we go and surgically ligate it. There have been cases where it's been in an eloquent area, and so I've had to put coils in. The glue tends to be more bacteriostatic, so we tend to try to use those in infected blood vessels.

Glen Stevens, DO, PhD: I hear about giant aneurysms and that type of thing. Why does that develop or, is it a different process?

Nina Moore, MD: There could be a different process. Some of these aneurysms have clot in them, and it's an inflammatory response that occurs in the aneurysm dome. We don't quite understand why they initially started, potentially like a weakness in one of the layers of the vessel wall that keeps expanding. Oftentimes these giant aneurysms can go many years without being noticed. And then when we do find them, they have an inflammatory process of the dome that's happening as well. And that tends to make the wall actually much weaker.

Glen Stevens, DO, PhD: And my likelihood of having more than one aneurysm?

Nina Moore, MD: It's pretty low. But we do look... When we do an angiogram to look at someone's aneurysm, we do screen them for the entire location just to make sure we don't see any others.

Glen Stevens, DO, PhD: And other than you're screening me, how would I know I have an aneurysm?

Nina Moore, MD: Interestingly, there's rare scenarios when people have headaches that they find the aneurysm due to pressure. A lot of times they're incidentally found when people have some sort of accident and they get a scan for some other reason. Sometimes, they can grow and push on a nerve that causes a symptom. But for the most part, we find them incidentally.

Glen Stevens, DO, PhD: Bleeding. I come in with a thunderclap headache. The worst headache of my life. You see a little bit of subarachnoid blood on the scan. You do the test. I've got an aneurysm. Do you need to treat it right away, or do I need to cool down a little bit first?

Nina Moore, MD: It depends on what day you came in. So if you came in...

Glen Stevens, DO, PhD: I'm coming in right away [laughs].

Nina Moore, MD: Right away [laughs].

Glen Stevens, DO, PhD: I'm a male, so probably three days later [laughs].

Nina Moore, MD: [Laughs] Oh, well, okay. So, if it's the third day, the vasospasm window, which is where the blood starts irritating the lining of the normal blood vessels starts happening around... Really starts around day seven. But if the vessels look like they have spasm already, we tend not to do any open surgery treatment on the vessels that are currently spasmed. You can get away with more doing the catheter-based treatments for people that are in spasm. However, it does make the vessels a lot more friable.

We tend to treat the aneurysms within 24 hours of rupture if we can, just because there is an increased risk of re-rupture in the first 24 hours and then a 50% chance of re-rupture in the first six months. So, we definitely want to treat the aneurysm when we know it's ruptured.

Glen Stevens, DO, PhD: And the morbidity and mortality high?

Nina Moore, MD: Very high. A third of patients don't actually make it to the hospital after an aneurysm rupture. A third have deficits afterwards, and about a third make it out without too much of a problem.

Glen Stevens, DO, PhD: Which are scary things to hear, right? Which is always sort of a, “hey, I have one and we're just following it.” I'm sure is difficult for patients.

Nina Moore, MD: It can be. And so I think that's part of the reason that we're motivated to try to figure out who and when someone would potentially rupture. And the more data we can get for patient specific information, the better. Right now, we base these decisions off natural history studies. But everybody's circulation is a little different. Everyone's family history is a little different. And so, really tailoring it to the patient I think is going to be critical over the next couple of decades.

Glen Stevens, DO, PhD: And for the most part, if you follow these, do you see them change much, or it's uncommon that they actually change a lot?

Nina Moore, MD: Well, in gross imaging, you would say they look stable. But, based on what we know about the blood vessel biomechanics, I think all of them are probably changing slowly. We're trying to get more sensitive with our studies of imaging studies to know the comparison between the two. I think if we see any major growth, meaning we see growth and actually can visually detect it, then we tend to treat those if they're changing.

Glen Stevens, DO, PhD: Yeah, I think we all get tricked into it a little bit. We're not doing true good volume measurements and we're just doing a two-dimensional measurement. We go, "Ahhh." But when you start doing a volume, it starts to be a shocking increase in size in these things over time.

Nina Moore, MD: Yeah, I think as we get more sensitive with our imaging studies, I think we might be treating a lot more aneurysms just because we'll be realizing that they're actually changing over time.

And then the question will be, is it a significant change? And eventually we'll probably have to answer that question.

Glen Stevens, DO, PhD: Okay. Anything else flow wise I need to know, you need to tell me?

Nina Moore, MD: Well, hopefully we'll be a lot more specific as we get more information. I think we're still behind the cardiovascular world and certainly behind the aerospace and the mechanical engineering world and being able to understand how things respond to internal pressures. So, as we get further along, I think we'll have a lot more data for people to make good decisions for themselves.

Glen Stevens, DO, PhD: Well, my college roommate, my best friend growing up, is a hydrogeologist, so he does water flow. Should have him here giving the talk today [laughs].

Nina Moore, MD: Yeah, no kidding [laughs].

Glen Stevens, DO, PhD: He'll be very excited. They do some math formulas with you [laughs].

Nina Moore, MD: That'd be fun [laughs].

Glen Stevens, DO, PhD: And figure all that out as it goes through [laughs].

So anything that we haven't touched on that you think is important for the audience to know?

Nina Moore, MD: I think we're in an exciting time and we're slowly moving the knowledge forward. So, I think hopefully everyone's out there working on their own area.

Glen Stevens, DO, PhD: Well, Nina, I really appreciate your taking the time to educate us. I'm always amazed at the things that you guys are doing, especially interventionally now with patients, and appreciate all your efforts. And excited to have you come back in the future and tell us all the great things you've figured out.

Nina Moore, MD: Well, thanks. I appreciate you guys having me on here.

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 don't forget, you can access real-time updates from experts in Cleveland Clinic's Neurological Institute on our Consult QD website. That's @CleClinicMD, all one word. And thank you for listening.