Practical Surgical Anatomy of the CP Angle

SNI, Surgical Neurology International, an Internet Journal, and information resource with NCFCN as its editor-in-chief,

and SNI Digital, a new, editorially selected, neurosurgery and medical information multimedia platform, with operative videos, expert interviews, podcasts, and global interactive discussion for

the next-generation of clinicians with James Ousman as its editor-in-chief.

Are pleased to present in cooperation with the University of California at Irvine, Department of Neurosurgery and Interdisciplinary Scale-based Surgery Team, a lecture discussion by Denny Mocasian

on the embryological origins and surgical anatomy of the CP angle

Dr. Melkacian is also one of the few people around the world that SNI Digital is interviewed for its neuroscience leader.

His talk on the embryologic origins and surgical anatomy of the CP angle will be in three parts. Part one, the extracranial approaches. Part two, the detailed anatomy of the CP angle. And part

three, a future of neurosurgery in 2100.

Dr. Melchasian is a professor emeritus in the Department of Neurologic Surgery at the University of California at Irvine. He's the director of its neuroananomy and skull-based laboratory. He is an

accomplished molecular biologist

and a neurosurgeon

Alexander Hempstead is a PGY4 resident physician who is assisting Dr. Melchasian. He's in the Department of Neurologic Surgery at the University of California at Irvine. He graduated Alpha Omega

Alpha, had many other student awards, graduated from Chapman University, some will come out here, and has contributed his time and efforts in global health in Ghana and Panama.

Moderator is James Osmond, who's the creator, CEO of SNI and SNI Digital, and the former professor at the University of Minnesota, Michigan, and Illinois, and UCLA, and former head of

neurosurgery at Henry Ford Health Systems and UIC, University of Illinois at Chicago. He's a futurist entrepreneur in healthcare consultant.

Part one is on the extracranial approaches and Dr. Melchazian's talk on the embryologic origins of the end surgical anatomy of the CP angle.

Oh geez. Okay.

Okay, now we're recording. So, okay, please start.

First of all, Dr. Hampstead, I do thank you for including and asking us to participate in this series of operative challenges and

blending the clinical and anatomical aspects.

There was in our last presentation a far lateral procedure on a vascular lesion and to give this more perspective, Dr. Hampstead is going to try

to show a snapshot that will take a few minutes So the.

Okay,

you should be able to, Denny, I'll have to stop sharing screen so you can share it, Alex. Okay.

Let's go.

We're switching over now.

I think this will give a better flow

to the character of the challenges

There he goes. Okay. Oh terrific. Okay. Wonderful. Okay. So this is just kind of a couple of snapshots from the surgical video that we discussed in the last PowerPoint. So if you want the full

presentation, the full presentation would be in the last podcast. So please check that out.

Here we're looking at the surgical approach after the craniotomy. Has craniectomy

has been completed? Anterior is in the top left screen, posterior is in the bottom right, inferior is on the top right, and superior is in the bottom left. So just to orient. And then we're

looking at the dura over the cerebellum and the medulla. So that's kind of a good surgical approach. And you were approaching a CP angle tumor, right? We were approaching no. This one was a CPA

an aneurysm, right? CPA angle aneurysm, right?

kind of resecting and debulking the idurism. And again, for a full discussion of the case and then the high points

would refer you to the last podcast.

And just for those who were watching, they had the man who came in and presented with,

I think it was, was it a

right-sided lesion? Wasn't that right and by right about that, a right-sided lesion, some left-sided symptoms He had this very large mass that was a vascular mass part of the vertebral artery on

imaging. Are you going to show all this? 'Cause I won't say anything. So you can show, I can actually pull up

just a quick little summary here so the audience can understand it. And they went ahead and they

tried some intervention approaches which

Let's grab this one. OK, so here is some of the imaging just briefly. Here's the pre-op angiogram with

the fusiform vertebral artery aneurysm. Here's some pre-operative imaging. It was actually first treated with a stent - with a flow-diverring stent procedure, which helped eliminate the angioreysm

angiographically, but left us with symptomatic mass effect from brainstem compression.

And so this is kind of the pathology that we're doing. OK, and the question comes in. We think that you occluded the vascular supply to

this lesion. And now the question is, how do I approach this, right? Exactly. So are you going to

I selected to start from positioning and going through each layer of the opening. I think frequently we miss the anatomy of the opening, which can only create a problem in the surgery if we really

don't position the patient and have what I call the collateral anatomy to be mindful about it So one, the following dissections, illustrations and images are basically a collection of dissection

material that span over four decades of

my experience. This includes dissections, countless

dissections, my own surgeries, assisting on surgeries, giving second opinion on good results and results that were a bit discouraging

Two, the goal is to demonstrate the complexity of the region exposed of the cerebellopontine angle Let's face it, this arabella pontine. angle in totality is a challenge, but some areas are a

little bit more beneficial and lend themselves to some exposure to what I call getting proximal and distal views of the pathology, which you always want.

The neurosurgeon must, over a period of time, endeavor a learning curve that is very demanding and requires a defined commitment and dedication to develop his or her skills and to make him excellent.

Five, this is not meant to be a comprehensive review of every anatomical aspect of the so-called lateral far lateral approach. Why do I say so-called? Because it's so limited I'm not sure that is a

true exposure of the totality, but this is a

Pacific anatomical area from variable directions is the basis of developing a 3D understanding of the operative anatomy. You're not going to get this from reconstruction of CT scan.

I've always felt that doesn't show you all the nerves, all the veins, all the arteries. So it's kind of misleading. It's pretty. It gives some benefit. But I think we overstate it

Sometimes for show and tell purposes more than reality. Two, knowing collateral anatomy is the foundation of expanding one's comprehension of the surgical anatomy. To me, all three of these points

require understanding the collateral benefits and the collateral risks of the surrounding anatomy that you don't see frequently when you're dealing with the pathology and the surgery the surgery, but

you have to have it in mind. repetitive and continuous review of a regional anatomy consolidates knowledge. Revisiting it, the rest of one's career always has profit for the patient in the surgeon.

I'd like to just make a fast review of paraclival approaches and I made this very simple. I break up the CPA into the upper area and that's the

pre mesophilic and pontine area that's anterior to that. A mid portion that we're most familiar with because that's really the center of the cerebellal pontine angle and I'll define that more later.

And three, the lower mid portion. As far as the spinal medullary area, I do include that into the lower mid section. Okay, if you look at a paraclimal surgical approach commonly discussed, There

are some key words, look on your left side. Key words, they access. Well, there's a temporal patrol cell area, and if you look at the diagram, that's in red, and you're right next to the

medulla of the brainstem. And we can talk about jokes, the areas being upper pons and the diencephalon. I'm not gonna get into that.

But this is the apexectomy, some variation or the application of the so-called kawasi and its variations. The med CPA, I think is the most popular and we have the most experience with it. A

variety of approaches, there's retro-meatal, retro-sigmoid approaches and translabroids. Sometimes those two are really put together and we do both of them. So on the diagram, You see the

cross-section of the medulla. and that's in the red area. And that gives some exposure to taking the apex of the patrol cell bone down. And then we have the pons, for the cerebellia pontine angle,

you see that in blue. And in the lower one, which is a cross-section of the medulla, we've got the ventricular. And anatomy I'm

not gonna go into great detail here, but you have to appreciate the decosation and the pyramids of the cortical spinals. They're well-defined. And this particular lesion, no, not just this lesion,

any mass lesion that a far lateral procedure utilizes to deal with is in

that area. And

this, you can see, is lower down I put some MRIs. on the keywords of the brainstem on the right side. And for the midbrain, I really considered it an intertitorial kind of anatomy, then the pons

and the medullum, and the spinal medullary junction as you descend.

Positioning of the cadaver or the patient in the muscular anatomy.

As I go through this, you'll wonder, you don't see this anatomy, and you're really adjacent to it for the most part, but you cut right through it. And this is the part that I think is part of the

surgery, but one should have in their memory, in their mind's eye, quote unquote, know where they are, because there are structures there, which I'll show you, can mislead you, and have some

overreaction too.

Now with the cadaver, you can do a little bit more. And to see anatomy, I always encourage people to do it there. But it's good also to practice.

You can keep the head flat and neutral and alignment and slightly flex. But if you have a big person and their shoulders come up, it makes it hard not to

have the head a little deviated off.

So in the real operative setup, it may require certain maneuvers that you can get away with ignoring in the cadaver preparation. Can you go back to that for just a minute? Yes. I would like to

point out to the audience that there's a signature on that picture, which is DEM, it's Dennis E. Malkasian Dennis is not only. and an animist, he isn't an exquisitely good artist. And so all the

pictures that you're gonna see, he's drawn, or most of them, I guess. And I just know that he's doing that. And because I think, I've never seen this view before, Denny. It's an excellent view.

Well, I appreciate the comment. It's been a lifelong journey, and I can only say that thank you for having,

giving me the opportunity to show some of that work. It's, there's a trail of it over the last 50 years, but it's always nice to share it with people because I think it shows things that you're not

gonna find in a textbook, at least right at this time.

One other point about that diagram. I hope I'm sorry to interrupt you. I'm really - Oh, I'm going to do that No, Dr. Osman.

your surgical target. You want to be okay.

And if you turn the table, you have to make sure that the patient is secured. If you do rotate it, you got to think about all those things ahead of time. Okay, I'm sorry. Pressure points. Yes.

All that. Yeah. That's a study in itself.

Okay. What we have here is on the far left part of the drawing, that's the back end of the sternocleidomastoid attached to the mastoid process. Up in the corner where there is a junction, an angle

between the screenous muscle and the semi-spinalis, capidus, attaches and that would say that's what makes up the superior nucle line, is that attachment? The screen

is, is at an angle and it attaches underneath the sternocleidomazoid as the second muscle that attaches out of the floor to the medial aspect of the mastoid. So, up in this angle, between the

semi-spinalis capidus muscle and the sphenius, we have classically, it's not always there, but when it's classically there, you'll have the

greater occipital nerve artery and vein, the classical van.

I find the vein is more unpredictable. These two are consistent. The artery, the occipital artery, and the greater occipital nerve are always at that angle. That angle is also with very, very

dense connective tissue, and you all know that when you try to put a shunt in as you try to pass over that area, it's always with resistance. Another thing in Marty Weiss and his group at USC about

10 years ago wrote an article, and I had noticed this and never thought much about it, but the ligamentum nuke, this is midline, had perforations in it and nerves came across from the opposite

side. I don't know other than their paper of anybody else describing that, but it makes you wonder if there's not cross midline extra spinal decosations in a sense. I have no idea what it means,

I've always cut through them without much thought beyond that. So we have semi-spinalist, capitalist, spleenous, capitalist, the ligamentum nuke and the sternocleidomacery. Now, I'm gonna cut

through these, I'm gonna cut through the spleenous

and flip it over.

to the attachment of both semi-spinalous cervicus. We detach capidus

and flipped it down. So this exposes the muscles that make up the triangle. This would be the inferior oblique, the superior oblique capidus, and the rectus capidus posterior major. The minor is

here Now, when you look at this,

you can pick out sometimes a connection between the nerve that's coming out here underneath the vertebral artery. There can be a communication. This is the dorsal reganglia to C2. There is no gross

anatomical dorsal reganglia to C1

And that curves. around the inferior margin of the inferior oblique. This is a lateral mass of C2, which we'll go into a little bit more, and I'll clean this up for you. Right now, it's busy.

What is the most important aspect here? Is this artery? We've frequently cut the greater occipital nerve. People don't seem to get an oralgia from it. Most people will recover and re-interbate

There may be some - what I would call a disaceted feeling that is not an allodangium. It

kind of reminds me, if this nerve had an occipital and oralgia and you cut it, you may get a lot of pain. Seems like when the nerve isn't working right, and then you cut it to stop the pain, you

get into more trouble. But cutting it normally, they seem to - patients don't complain about it Now, what? a neurosurgeon should understand is this artery right here that is the occipital artery,

which is one of the posterior branches of the external carotid. Learn your branches off the internal and external carotid. Let me say that again. Learn your branches, the anterior branches, the

ascending branches, the descending branches that posterior branches. Because if you remember, you make an incision here, it can be a sigmoid, an S-shaped incision, or a straight incision, as Dr.

Osman pointed out on the diagram. Well, this artery is variable in size. Sometimes it makes up not just the occipital artery, it makes up the posteriorerycular artery. And it can be

an artery that is like three millimeters or so. Don't forget, the vertebral artery is not much bigger some people that 5 to 6 millimeters. So it's not unusual to hit that. And at this point,

you're a little deep into

the suboxypical area. And that will bleed, it will bleed and let you know

that you've gotten into something. It's not a little loose, it's a vigorous bleed.

And an experienced surgeon worries that they got into the vertebral.

So always keep this in mind Don't be aggressive in cutting down, even following the squamma of the occipital bone. Now, this membrane here is the Elantoaxial membrane, which is a continuation of

the lateral aspect of the ligamentum flavor. I've kind of covered the area because all this pierces that membrane. But when you get deep to the muscles, and this is a sub-oxipital triangle, You

that I get down to the bone and then traveling here with a dissection outside of heat. I think that warning

can be appreciative. But I know people do it, they come along here and they stop maybe one and a half centimeters. You know, this is a month more than two centimeters And

there's your vertebral artery, and there's your occipital. You could say, well, Dr. Maokage, you must have some experience of getting into the occipital artery. Yes, I do. And if you do

enough of these, you're going to get into it. And you're going to get a little nervous for a little while.

OK, this is what Dr. Osman was very astute about. You see here the mastoid process on the left side So you want to look at the squamma?

or I'm a magnum posterior aspect, and the lateral mass of C1 on false. You want it to be perpendicular. Now we have the mastoid foramina. There's two here, and you see the lambdoy sutures split

up into a vermium bone for

the occipital temporal mastoid sutures.

These are not something to be concerned about. But the mastoid is here.

It has a groove for the posterior belly of the digastric that sits here. Then you have it ledge here, and another groove. That groove is for the occipital artery.

Now, when you flip over here, you see a bigger opening. We're gonna talk about that opening more, because that can become a critical management problem.

periroglique

rectus capidus posterior major and then we'll put in the vertebral artery. So that's where the corner starts to curve down. You notice something? You can't see the canal. They push your condler

canal anymore. That's what makes your incision dangerous and we'll go over here and I'll try to. I made this drawing. I know when you first look at it it's kind of confusing. So let me go through

it slowly. This is the mastoid on the left side. This is the mastoid on the left side. This is a posterior gastric groove medial to the left mastoid. And then the squamum curves up to encase and

caress the lateral cerebellar hemisphere Now, the artery comes. medial to the posterior belly of that gastric, that occipital artery comes through there. If you look at a man-made triangle, it's

right in here. We're going to go through that a little bit more. Now, this is very busy. So figure one, you go down to figure two, and this is an oblique view. This is a levator scapulae. This

is the

lateral rectus capidus, and it's very important. Let me say it again. It's very important because if

you get in trouble here, you got to stop the surgery. Why? Because right anterior to this lateral rectus capidus that goes from the front part of the lateral mass of C1. That

muscle is immediately and is adjacent to, there's no space there. You have to make the space of the internal jugular vein.

Now, you go back, I mean, back of that muscle, you've got the vertebral artery. So in the classical discussions of anatomy, we always say vertebral artery muscle, internal jugular. This is in

a 15 centimeter straight line

So figure 2B is where I played with this a little bit. And this is the vertebral artery coming through the transverse salus for amine. And you can see it curves around and there's a nerve there.

That's C1. And what I've done here is what you don't do in the operating room, but I lifted it up and that is the spinal nerve of C1. This is a posterior primary rheumus

This is the anterior primary rheumus. I'm sorry. That goes to this interface. suboxypical triangle. And this goes around the facet

and through a little opening there that we'll discuss a little bit over here. Now this is a classical view. What I've done here is I've taken this final cord out. Final cord is removed. This is

one of my models that this is not a model but a true specimen. Do you see how this curves down? You see that groove? Well the vertebral artery, once it's passed through its vertical segment,

comes through here, comes out here and caresses the base of the superior facet of C1 curves here and then goes in. You see the Adantoy process there. So what I've done here is I've taken the spinal

cord out and you see

joint, the occipital condyle, meat with a superior facet of C1.

This is the bottom of the clevis. This is the front of the foramen magnum. So,

one of the points I'm trying to make here is not only this anatomy, but this anatomy. You see how the vein has a, the artery, the vertebral artery has a common antise, a venous common antise

around it. I do have a theory why that is there, but I call it the cavernous sinus of the vertebral artery. And it's abundant. And with some people, it's all over the place, and you can get into

a lot of bleeding when you try to skeletonize a vertebral artery if a situation calls for that. But this is the artist's view of what that looks like. Now over here, we're going back to the

suboxypical triangle. And you can see that I brought some veins out. I put some fat in there in the nerves. C1 innervates the total muscular boundary of the suboxypical triangle.

Now you see the artery coming up here. Swings around,

and that's his position.

or other anti-platelet, platelet drugs, we didn't want to use heparin because we thought it would bleed and it failed. The other thing is I found that,

and other people tried it, they had the same experience. The other thing I thought about after we had done that for some time is that if I were to do that again, because

it's a way to do them, right now what they do is they put a stent up there and they can blow it up, blow up the artery, they just put a stent in it. I'm not sure that that's as very successful

either. But anyway, that was a story about that and it gets down to the vertebral venous plexus that you show there. And actually, you may not see the vertebral artery because it's what you said,

it's a cavernous sinus and it's very bloody And you've got to control that, because if you don't control that,

So it would not become stenotic, it never did that. But we spent a lot of time doing the anatomy of this area and trying to do a vertebral endoderectomy. And that was everything that came with it.

Okay, sorry. No, no, okay, good. Dr. Austin, when you would do those cases, did you open up the transverse remin to mobilize the vert so you could have a better control where it would be,

oh, trust me, you're muted.

Yeah, can we get a little closer to the microphone so we can hear you say that again? He asks if you expose it like this, drawing is exposing. Exactly. Yeah. Exactly like that. Exactly.

Exactly like that. My experience was, how did I get operative experience outside the cadaver? It's that the vascular surgeons wanted to do an in-art direct me on the vertebral artery. as Dr.

Osmond pointed out, the Atteroma. And they didn't know this anatomy, and they heard a lecture that I gave that was very boring on this topic, as I'm doing today. But I did that for them. And we

didn't do a lot. I don't really remember doing a lot, or remember doing the dissection, and taking it down There were some cases that I didn't find - I was all prepared for the vein, and there

wasn't much. But when the veins were there, they really are intimate - I don't want to say with the adventition of the artery. But it's not that easy to get a bipolar in. And a lot of times, you

just end up packing and moving on. That's true. That is true Other thing is

because you're fighting through blood to get to control and you should have it ahead of time. And so that's no matter where it is, if it's super-intentorial or infant-tentorial, I

want proximal and distal control.

They have that on this case because they impolize

the parent artery of the aneurysm. And

it's not - No, I remember I was only, I kept asking questions about, 'cause I had done that with removing coils from an aneurysms that had, where the coils got into the matrivessel and what is the

site of thrombosis. So yes, but I even doing any kind of an aneurysm, I get proximal and distal control. And so I even dissect down and you brought that out. Once you begin to do that in that

area, you're dissecting into this CP angle and you have to be very careful. because you can cause a deficit by trying to produce something that's gonna be protective, which is the point you made on

that video.

The, one of the things I learned, it's not just taking the back limb of the form of intransurceris. It's that

you have to disconnect these muscular, and this is the posterior meningial artery. If you don't, they hook you up, they hang you up. I never found that there was a problem in doing that, but

it's a technical point. Alex, you see the answer to your question, the reason why we expose the artery, just like Danny says here, is because if we're gonna do a vertebral endar direct to me, I

want control proximally and distally, And then I can open them and do an indirect to me. which we did and we could do the procedure very well. But we were flabbergasted because at the end, natural

stenosis occurred and we didn't have the biochemical help to prevent the thrombosis either at the time. This was in the early '80s. Do

you think with aspirin or like a dual antiplatelet type protocol that it could work? If you could aspirin what? No, if you gave aspirin or a dual antiplatelet if it would work. I don't remember

that. I think we did not have anything that would do it. We'd have used it. If we didn't use it, we were worried that it wouldn't be effective, there was no studies about this in this area. So

we were working at a time where we didn't have the kind of information we have now. I see. This is that I'm gonna orient you I initially said that sometimes the way you do it. the head you can get

very confused and you always have to remind yourself of the reference lines. And here the reference line is if you take this drawing on the right lower part the head wasn't

parallel with the floor it was angled a little bit. So this is left side down so this is left side down but there was an angle of maybe 25-30 degrees. So this is true midline

to orient you

and this is C2. This is the right semi-spinalis cervicus. This is

the left semi-spinalis cervicus.

This makes the inferior oblique. This makes is superior oblique.

So this is an example, not so much a name, the muscles, but your off orientation. And if you start naming these muscles uncorrectly without their reference points, I know Richter's Capitalist

posterior major has to attach the C2 and you have to find the right and left semi-spinalis cervicus. That will give you your true midline and then the minor should go to the post your arch midline of

the C1. And until you get

that, you can get lost. Okay, let me go back to that for a minute. I'm gonna make a comment 'cause what he said is absolutely right and it's true for for super-tentorial surgery because once you

reduce your operating field to something that's a hole in the drape, you're lost. And so what I used to do. is to put on the drapes. If the drape is, you see, that's the reason you study the

skull beforehand and you rotate it in the positions that you're gonna be. So you have this image in your brain before you do surgery of where it is. And if you change it on the table, you have to,

you change the computer model in your brain. But when I put the drapes on, I would put a drape on where the edge of the drape would outline the midline, or the

superior sinus, or something so that it would be some orientation landmark that would reorient to me to what I had learned beforehand. So your drapes can help you. It sounds stupid, but it's you.

But you can get lost. And what Danny says is absolutely right. And you don't want to get lost in this area There's too much, there's too much high price real estate here.

Yeah, it's expensive. You should see my bill when I send it. Oh, okay.

Is that helpful, Alex? Yes, absolutely. Now, this is a little cleaner.

Here,

you see the triangle again. I outlined it to the Boney Anatomy. C2 is a definite reference point. It's easy to find. It's the biggest spinous process, and it's the most bifid. It's very defined.

And the semi-spinalis sericus

attaches there, and so you can find a clean midline.

It's the end. It's a strong point of the ligamentum nucae attachment, inferior oblique to lateral mass of C1,

capine inferior superior oblique,

and then rectus capidus rectus here

and there's your triangle.

And the reason that I bring that up is I see a lot of surgery done with a lot of bleeding. And I saw one from a very prestigious institution. I think they couldn't see what they were doing. I

couldn't possibly understand how they saw what they were doing. They were operating in the cell on the pituitary, which is vascular.

And the answer is, that's why you have to have absolutely a hemostatic

meticulous

dissection, and so you don't have bleeding. So you can see the anatomy.

And people just say, well, they put a bag on the end of the bed and they lead a bleed. And they do the sucker out of there. Lots of irrigation, which helps prevent infection And lots of

meticulous, meticulous coagulation. And that maintains your ability to see the anatomy I don't feel great, Kenny, but that, to me, my story. I'm an advocate of a

bloodless field within reason. Sometimes we can't exactly get it, but when it's accomplishable, you shouldn't be swirling with a lot of red blood. No. That is not a way to do a surgery.

This is C1, one of his branches into the muscle And you saw my drawings for it. But this is rectus capidus posterior major. This is inferior oblique. And this is superior oblique over in this

corner. And again, you can see there's a lot of venous vascularity. Right. And that's going to bleed. And if you don't stop it, it's in your way. The other thing is the split and the spinous

process of C2 is always in a very important localizing factor. You put your finger down there. you know, reorient you. True. Now this, I'm gonna explain to you.

There's more to come.

This is the posterior arch of C1. And again, what do I show that curve coming down? So if you take a dissector, and you're stripping this, stripping it, stripping it, as you get down to here,

year of vertebral land And this definitely is in vertebral land. Now, this is C1

and, sorry. This. This area suboxipital the is is the

occipital lanto membrane here. And this

is that membrane, the same membrane and as a whole in it for passage to the vertebral artery segment four. Now, what is the purpose of this drawing? This is to show the superior C1 facet joining

the joint capsule and instrument within

separating C1 occipital condyle in

the joint space. This is occipital condyle

This is the joint capsule that for illustrative purposes I showed and removed. This is the vertebral artery coming out of the transversus foramen,

curving around and going intracranially through the membrane. This is a sympathetic nerve and this instrument is in canal. Now, this is to orient you to this drawing, to this fact This is this

squamous.

And I have an instrument in the capsule. You see the joint space here? This is the occipital condyle and This is

a sphere for set of C1 so the vertebral artery is running right next to the base of that See the base of that there and this hugs it

Now I said I'm showing you something else too. This is C1

That comes from the bottoms You see it there That's C1 Post your primary Rhemus again. You see a lot of Venus structure Then we get down here and running on the inferior for set of C1 and the

superior for set of C2 You see a dorsal root ganglion and you see that's sitting on the joint. You see the capsule around the joint

Now we don't get that far down when you do a far lateral. So this is in your mind's eye. This is a one centimeter away.

Now, this is another difference. You see the dorsal root and the ventral root, this is the dura.

This is the dorsal root is sensory. This is the motor root, the ventral root. And I don't think people appreciate that there is a continuation of separation there by the dura. So the dura,

see all those venous structures,

dorsal root, ventral root, and dorsal root ganglion. Okay, the question you could ask yourself here is where is that sitting? It's sitting on the joint between C1 and C2. So if you get an

inflamed joint there, you get an osteovlyte formation You get cytokines with inflammation. It won't surprise me that that creates, it's one of the origins, I think, of greater occipital neuralgia.

And generally, if you just treat it medically, you'll be fine. I think there are some people that want to inject it. I'm not so much for percutaneous injection. I'm not saying it doesn't work. I

just don't like to get an infection or bleeding in those areas. Okay, location, signs of craniectomy

Busy. Whenever you got a busy drawing, you lose people. So let's go to the far left and forget about everything on the right. This is the hard palate. This is the bone marrow. This is the front

of the clivis. This is the base occipital bone. This is the occipital condyle on the specimen's right side and this is the condyle on the left side. This is the foramen magnum

now. This is the posterior condular triangle that I'm gonna demonstrate to you with the foramen and canal of the same name. This is an extracranial view. So here's the condyle. Oops. Hmm. This

is the foramen magnum lateral wall. If you draw a line across here, over here and back, there should be somewhere along here for foramen. There isn't Oh, there's a little one right here. That

may have been a Venus one. Wouldn't do too much. Okay, let's go extracranial to another skull. You got midline, you got base occipital, you got occipital condyle. Oh, see that hole?

Interesting. And that's within the triangle

Now.

where this enters, where this enters.

There's a groove in the bone because the vein is large. The vein is very large on this. So let's, let's do a tilting of the head for a far lateral craniality.

No posterior condler foramen of any significance here. Styloid process, mastoid, external auditory meadis.

Coming down here, the left occipital condyle, posterior midline margin of a foramen magnum, anterior margin, opposite occipital condyle. See how rough it is? There's a reason for that. There's

a reason for the roughness. Roughness means attachment Attachment of what? Well, that's where the alar ligament attaches. They check ligament. Okay, let's go over here to another.

Because in this position, it can do either one. But if you don't see bleeding, be very careful if you realize that you've gotten into a canal now. If the anesthesiologist says to you, we've got a

problem here. I'm hearing problems on my - there's an air embolist going on. Well, if this is elevated, then it's going to suck an ear. Nothing's going to collapse here This is a vein that was

coming in that was a large size. It's going through the bone. It's got a terrific channel to the jugular. You don't want to start putting in a little gel foam because it's going to embolize,

probably not hurt the patient, but you put it up and it will hurt the patient. And so this is a problem. If there's an air embolist and you don't see anything, I'm going to share something with

you. My experience is that if you get an air embolist, And I've been exposed to that maybe five times six. Most of the time there wasn't one, but there were some that really were there. I didn't

see bleeding and we say, Well, did you wax the bone? I don't think that's where you get it. You get it through a big opening.

There has to be, you know, the deploy space of a bone unless there's a big venous lake in it.

It's not going to suck in that much air. It's like through a radiator Now, if it's very, very venous lake within the deploy space, that's different. So,

air embolus. It feels real dry and you got something like this going on where there's a drop in blood pressure, and the anesthesiologist was worried about it. You worry about it and you look for

that, drop the head and you want to see some bleeding Now, let's go back and this is my drawing and this is nature

left occipital condyle.

Condeller for Eman.

So now, this is my drawing

and here's your triangle. I put it with a star.

You connect it that way.

And in the middle of that, Condeller Triangle, which the base usually runs through the flat part, this is the flat part, the flanks,

the condyle that's consistent.

The Condeller Canal, in my experience,

can be here, can be here, can be here. It's not consistent. I've never found it always to be in one place. I have found it to be in that span.

That is not necessarily a problem, because if it's big, you're going to see it. Now, what I'm going to show you is a technical point that requires knowledge of anatomy point that requires

knowledge of anatomy.

Tistle or whatever, a gel foam film. And you wanna use it in combination, that's up to you. But make it big. When I say big, twice as big as a stamp, if not larger. And put it there, and this

is what neurosurgeons, we all have trouble doing this, but you must do it. You put it there, you put a ray checks on it, you put a little gentle pressure, and you wait five minutes When five

minutes is there, wait another minute.

Take it off, the bleeding should have stopped if it hasn't, then we can give more time to it. And now, in figure three, I would do an immediate

duroplasty and cut into the dura,

flip it over,

He said, Wait, pack it off and wait, wait five minutes. And I've seen this happen time and time again, where people are holding a rush there, worried about the fact that they got all this blood

in the field, pack it off, wait, let it coagulate. And then if you got it, you do what you did, which is to reinforce it. And you put some muscle or some tissue in there to do that And then you

put a flap over there to hold it in, and to make sure it seals off,

you don't have to go after it, go after it. I've seen people do that. And they get in all kinds of trouble. So there is a place for waiting. And it's with Venus, Venus bleeding. You had

something else on the previous slide, you reminded me of that. Could you just show me that a minute? 'cause we're coming up to break time here for a minute.

No, I don't think that doesn't come back to me, but anyway, so we can go on. But anyway, that's an excellent point and an excellent point in how to be patient and how to handle us. And figure

five, you notice I made a big thing about acting of

a, that should be tacking stitch. Tacking stitch, yeah. And just to make a tout and make it make it a tout and keep the emotion And I don't want the, I don't want the muscle. I never, I always

worried that there was some part of physiology, I may not understand that even a muscle that starts to shrink up over a period of time can't be sucked in. I don't think that would happen, but I

would, would attacking stitch, not just around here, but I would go through deep and grab the muscle. So the muscle couldn't be pulled in was probably an overkill, but anybody that knows me knows

I would do something like that. One of the comments you made about ERM was, and I was doing a case at a VA hospital, and

this is a man who had a serious pain problem. He was a veteran. He had

serious pain problem, and at that time we were doing a spinal cord section of the pain pathways. And I was obviously not experienced during that, so I asked one of our professors to come over and

do this. And so we could learn the patient was up in the sitting position. So you could do the laminectomy and you get down there and you went ahead

and you cut the spinal cord where it was, never was. And it turned out the patient didn't wake up. They came and took a picture of the patient's ventricular system. And the patient's brain, he

had a massive or embolus. And so,

in a, like a trauma, like that's a trauma. And you have to be careful that you're not putting pressure on due pressure on a peripheral nerve. But yeah, I still have questions about that. But

this, I wanted to share this because this requires knowledge of anatomy and how you repair things. But let's look, we're gonna move on to in part two of the embryologic origins and surgical anatomy

of the CP angle. Dr. Malkagian addresses the details of anatomy of the CP angle. What's helpful about this? I think it's just great to see the

operative anatomy from so many different angles and to really appreciate the, as Dr. Malkagian says, the collateral anatomy It makes, at least it will make me think when I'm. observing or

participating in these cases, a lot harder about what is going on, what we're cutting through, what we're looking at, and then kind of understanding when it's safe and when you should be careful.

That's great, I appreciate that. You know, you can go to an anatomy course or a lab or a skull-based lab. You guys have done this, I haven't, but you may not or you go into some other operative

course, you're getting here not only surgical pearls from a neurosurgeon, but anatomical pearls that are gonna help you reduce your complications, reduce your complications. And this is important

for people doing cervical spine surgery or surgery to, if they've got C1, C2 dislocations, you gotta be in the same area. Obviously, if you're gonna do a sub-occipital, Exposure and you're going

to go to the CP angle. This becomes extremely important also. So it has a wider audience Singing to listen learning. Is this helpful or not? Absolutely Did you pay him to say that Dennis? You bet

you I did Trump You know what is back. I'll rub your back you

see yeah

Okay, Danny you want to start part two? Okay

But

We're moving into basically part two. This is a base view of the medial extension of The far lateral approach Let's look on the MRI Some things are a bit subtle here, but this is Going through the

Condolered canal so that's part of

I doubt it. I think most people know that it's a lateral check ligament, that you cannot take down because you run the risk of destabilizing.

So I've asked this question to neurosurgeons. It's unfair to ask it to one that doesn't really do this higher level of dangerous neurosurgery, and they're not going to know. But I've been surprised

that a lot of people that are skull-based surgeons, it was about

40-60 of the answers that I got, and there are three or four things that people mentioned. But the two things you have to be aware of is, yes, the hypoglossal, and most importantly, the lateral

check ligament of the alar ligament of the odontoid, and I'm going to get into that a bit. But, Here is generally the areas that we open to get to a far lateral. Sometimes we have to go in the

back because of the size of the lesion and staging it. And here is two thirds.

And our opening will drill that off. Now, this is very important, the importance of collateral netting If

those of you, and we recommend you go back and look at it, Dr. Seuss's far lateral approach on the aneurysm. He does a very good job in drilling out the posterior aspect of the condyle,

occipital condyle. You have to do that to get, not only a view, but to get your instruments down there.

It's a bit dangerous to drill off, I think, my opinion,

the superior facet of C1. I think there's a risk there, but what is that risk? I think you could weaken the transverse ligament.

But

if we look at the key things, occipital condyles, the anterior condler, hypoglossal foramen canal.

Importance of the occipital condyle is sparing the anterior one third. Avoid injury to the alar ligament of the odontoid process. And what is that? That's right here. This is a cruciate ligament.

The broad area

is where the weight of stress is going to occur in osteodegenerative disease and the panace. that comes with autoimmune disease. So this is the transverse ligament. These are the ALAR ligaments.

We're in the back of the canal looking forward with this final cord removed. And so that's what these diagrams are trying to show. Now let's go up here. Here's the condyle. This is approximately,

if you're gonna view it, the angle, which is 45 degrees with the misageral line Let me say that again, it's 45 degrees. It looks right at the

sphenoid spinous process by the foramen spinoesum. And

this is true. What isn't true about this is to go down to this illustration that that's pretty high and it's well above where the collateral ligament attaches So the concern is this. that if you

take out the condyle and you start getting into that anterior one third, you run the risk of weakening that ligament. And you know, if the patient's older and that includes everybody, anybody past

ages 65 is starting to get degenerative changes to these ligaments. They're becoming calcified. They've had inflammation, God knows what enzymes and cytokines and things we don't even know about

yet But are affected by that. So this is a transverse ligament that attaches to what? Well, that is the anterior part of the C1 ring that is off the superior facet. So you want to stay away from

these areas. You may be playing with the ligament. OK, repeat our drawing again.

idea of that.

Now, this is a mid-sadual cut. You see the teeth. You see what here? This is the clivis. This is the squamen, the posterior margin of the 4M-A-magnum, anterior margin of the 4M-A-magnum. I've

drawn a line. Why? Because the roughness on the medial aspect of what? The occipital conduct. It's rough. Why? It's not involved with articulation, where that part is smooth because of synovial

and the hyaline cartilage that's there. This is where the checked ligament attaches. So if you drill one third of the distance here, I don't think you had to worry about the hypoglossal nerve

because that's up here. You can see the canal and this is the jugular foramen with the spinous process.

The posterior view orients you. It may not be what you see during surgery. But again, in your mind's eye, you've got to see that. That's critical.

So let's take the posterior view of the spinal medullary junction. The spinal medullary junction, I like to say technically, I like to believe from soft tissue standpoint, is the first end-tate

But remember I said the lateral rectus

capidus off a C1 has certain relations.

The most anterior is the jugular vein, the muscle, and the vertebral artery. But we got a similar kind of thing here. We have a dentate. In back of the dentate, there are two structures - the

dorsal roots of C1 that can be very flimsy.

You see the ascending accessory, spinal accessory, go down and attach to these lower rootlets. We're gonna talk more about that. What I'd like to point out that a key anatomical point here is,

see, is the

all the very tubical You'll see that that is a very important landmark for nine, ten, and the bull bar of 11.

You'll see that that's critical because below that all the very tubical is where you get the take off of the rootlets for the Gauss-O-Pheron-Geo the Glazo parent, Geo,

his intimate, with the turn of the vertebral artery before it gets midline. It's right at that turn. And it's a very interesting thing. I've never seen a surgery or on a cadaver, there wasn't a

little tension on that. So I ask the listeners of this conference, not a final opinion or to say and think that I have a final opinion But I have never heard of a hypogosyl paralysis intracranially

that didn't come from a tumor mask or something that was obviously injuring it. But yet we have a cranial nerve that has been pulsated on constantly at least 1400 times a day, if not more.

Why is knit shutting down with motor dysfunction? Well, it's a query. I don't have an answer to that And I'm sure some would. Now, you notice I put dorsal roots here, and dorsal root is

here

for C1. Then we get the vertebral artery in front of the dentate, posterior to the dentate, I expanded this opening so you can see that, that it is 12. And then the inferior olivary nucleus, as

a reference point, that we'll get a better view when we do the oblique And then the 10th cranial nerve rootlets are here joining up the ascending spinal accessory. And then here we got the ninth

cranial nerve. I'm going to make a big thing about that because

there's a definition for it. I'll show a dissection momentarily on that. Now, the vertebral artery is going to give off one major vessel that we will see, posterior that supposed to improve

cerebellar artery. We're not going to see the anterior spinal artery. That is midline, and there's no way from this angle, we're gonna see it. But you have to have this in mind, not only for

collateral anatomy, but your pathology may extend there. The pathologies that exist here from meningioma, not so much a

schwannoma, but meningiomas, dermoids, epidermoids, malignancies, can be very encasing and

spread, and wherever there's no resistance. Okay.

Now, this is more - That past picture you just had was an outstanding view. I've never seen that view pictured anatomically. That's just terrific picture. Yes, what I've done, that I didn't talk

about, that there's a fissure here. A Rotten talked a lot about this fissure.

And this is tight. This is not much more than 15 centimeters on some people far less. Some people, you can't even see it.

Now notice this is the

olivary tubercle. The olivary nucleus is deep to that. And the covering is white matter that we call the immiculum Notice on top of

the boundaries here

that we see the nerve roots of 9 and 10 and below we see 12.

We've already discussed in a introduction 11. Now look at this. This is the jugular spine and a sligament. It separates those two. You never have to worry about identifying 9

anatomically.

Now, above nine, you're going to get an anterior inferior cerebellar artery, and I cut it off here. But it's usually

underneath the flocculer nodular lobe. If you pick up the flocculer nodular lobe in the posterior extension of the cerebellar pontine fissure, you'll see it And that covers

the vestibular cochlear complex with the nervous intermedius major portion of the motor of 7. If you pick up the cori plexus, it will reveal the lower 9, 10, and 11 cranial nerves. These are

landmarks. Sometimes the cori plexus goes all the way out, and you have to pick it up, and it's safe, and you'll find that So

again, vertebral artery comes in. it goes underneath the first dentate.

The ascending spinal accessory is over the dentate, vertebral artery is ventral to the dentate, and

then you get the lower cranial nerves here. Just to give it a dimension in real life, the 12 cranial nerve is hiding in here, somewhere between here and here. Now, the posterior fear of

cerebellar artery not infrequently goes between those two, but anything that you could make up, anything that you could create of the loops, where they go through for the pecan, pecan. I have

found. I know that they give percentages. I've looked at all that. I've tried to work out my own percentages There's so much variation.

with a superior facet of C1, and that is a drill taking the facet, the occipital condom and a little bit of the facet off, that actually, if you go back to Dr. Seuss presentation that

we did, you'll see that. Now, in figure two, as you come across, I try to point out those same structures that we talked about. I think it's very interesting that a sending branch of the spinal

accessory comes up in his dorsal, yet it's all motored. There's no sensory part to spinal accessory, yet our motor units are underneath the dentate. In fact, we use that as a landmark. And then

here,

the reason why I was drawing this to get a better idea to show the principle of what Dr. Sue did with the aneurysm. And so here's a vertebral artery. Here's 12. Here's the ascending branch. And

here's the first dentate. So, and the aneurysm is here, as Dr. Hem said, showed you. And what was done, this is the basal artery, this is the vertebral artery Here's the aneurysm. And for

some reason, it got a little larger even after they imbalanced. And my guess is this, is that they included the vessel, it looked fine, it leaked afterwards, got a little larger than it included,

so on the second angiogram, following that, it didn't show it. Now, here is 12.

When you come over here, this is a seven, this is looking from above. This is seven and eight, this is nine, 10,

and

this is questionably 12.

And it's going on top of the vertebral, and this is clearly 11

So here, this is a relatively nice model of this is 12, and this is nine and 10, because it's separated

by, it doesn't make a very good cut, but these are the bottom branches of 12 and 10 So this is just the tubercle, all the very tubercle is here. So this is kind of too expensive. something.

There's not much room here and I made a point at the very beginning of this lecture that to me this is the most challenging route to do any type of definitive pathology. If you have an epidermoid or

a dermoid, a lot of times they just suck out. There may be some metastatic lesions that do the same thing.

A meningioma is not going to just suck out, not in the base of a skull. It's not a neutral that they can be very fibrous and we use the ultrasonic aspirator with a lot of frustration. Now

it was debated a lot how to manage this neurological decline from the brainstem and I think you could flip the coin as the weight or to proceed with the surgery. Now here is something that kind of

gives you that collateral anatomy.

I've tried to get this to

You see the 10th and 11th, this is the 9th, let's see if I can get that a little bit better

This is the ninth,

this is ten and eleven, and this right here is the jugular ligament. Sometimes it's calcified, so the pars

nervosa separates

the pars vascularis There are two terms for misnomers, aren't they? Because there are nerves and venous drainage in both. So it's just the jugular foramen that's separated into an anterior and a

posterior aspect. On some other animals, like rabbits, there are two different openings. Some of the animals have just calcification On humans, sometimes the ligament is calcified too. So then

we'll come over here. Let's see if we can

It's that

Pawns and medulla, fourth ventricle, and this is the super-olivary facet, the

Cp angle in blue and the cerebellum hemisphere. Now, where is the super-olivary facet? It's the dibbit, this dibbit that is deepest in the most medial aspect of the CpA This is the

pontine middle, pontine pedicle. This is

the rest of the form body, the inferior cerebellia of the ankle. And some people would say all of this is that area. To me, this is the only area that should be considered. But I'm not gonna

debate about this This was named by out of NYU and Cornell in 1965 by some excellent neuroadiologists of

the time, and they did venous arterial studies, but they brought out the historic name of the super-olivary facet. Super-olivary because it's right above the olive. That's why I don't like to go

around it But in fairness, you have the

7th and 8th, sorry about that. That should be 7th and 8th complex here. You have 4A menolusca, and up here you have 9, and back here you have 10 in spinal accessory, and down here you have 12.

So, the definition is that, you know, if you want to accept all this as a complex, that's fine. And, The things that I pointed out, landmarks for 9, 10, and 11 is the choroid plexus coming

out.

And for 7 and 8, it's the flocular nodular lobe. And

for the cranial nerves here, you could see the aneurysm was here And these filaments on the video

and the views that you saw

initially doesn't leave much room to work on.

Now, this is without any vascular elements. I just want to put it in perspective.

Now we're putting vascular elements And now we put a few arteries in there. The arteries are not the problem.

or they can be a problem. Here, I did posterior cerebellar artery and brought it around and swed it around. I'm not saying that they all look that way. Now, for here,

this is busy, because you have superior patrol cell vein. Some consider it very important. Superior inferior patrol cell vein is sinus.

Here, what drains into that? A major drainage is the vein of the lateral recess. No, most neurosurgeons never think much of that vein or even know it anymore. But that vein is critical to the

fissures of the horizontal and posterior lateral fissures. It's a major draining area. And if that blees, I've seen where it looks like a stab wound was put into the cerebellum, it's not. It's

the posterior lateral recess and the vein terrors for whatever reason, it can leave that. That's well tolerated, most patients recover. I think we've seen that of recent. And it was unexplained.

It's just the vein of lateral recess. Why was it so important to neuroradiology? Because it was deviated, depending on if it was extrinsic or intrinsic, because it was very intimate with the brain.

So if it was intrinsic in the brain prancoma, it would distort it in a lateral direction. If it was from the outside, like a schwannoma. So you have to recall that we always didn't have CT scan

and MRs. We do it by pneumo, encephalograms, and cerebral angiograms. No longer is that important to talk about the position of the brain based on the distortion of the blood vest. those because

of the CT scan and MRI. But what hasn't changed is that these veins are very intimate and you cannot pull them off of their PIA attachment.

And so I leave you with this,

that there are a lot of structures here and hardly any movement. So at the very beginning of this talk, I made some comments They may have looked discouraging. I hope they are.

The surgeons that do this kind of work are not for beginners. This is a decade of experience that people should have before they get involved with it. And they should have very good judgment of how

aggressive they should be because you can't control anything in there. And a lot of it is blind. You may not even be able to see the basilar artery, no matter how far lateral you think you are.

Am I understanding you're saying, if a tumor is larger, it actually makes it a little bit easier because it creates space for you. I'm glad you picked that up. Yes, because they'll push the

brainstem and the spinal medullary back. And a lot of times if that is slow growing and it takes two or three decades, there may be neuro defects, but there's been a lot of adjustment to it And so

if you come and do a lateral, take the arch of C1 off,

do a wide

squamous cerebellar craniectomy, I think you can get that off just fine without forming around with the facets. And the brain relaxes. And if it's not relaxed, you just put a cottonoid there let

it sit there and work.

even a Cordoma

or a Condroma or a Condrosarcoma. If it doesn't violate

the Dura and the Arachnoid,

membrane is intact and there's CSF

in between, at that stage you may be able to free things up without thrombosing the

veins here. But once you start violating the Arachnoid and get intimate with the Pia, then you run the risk that already the patient is very vulnerable and you can get particular hemorrhages, even

if it's not there, by violating the vein and maybe even thrombosing it

And this is finishing up, this is if you went ventral. So we have the dural opening, We have posterior cerebrals off the brainstem, a basilar. The vertebral artery,

the basilar artery, the posterior cerebellar

artery. And we open up and get into the dura

and rachnoid, and we get in the subarachnoid space here. This is about, on a far lateral, this is about what you're gonna see It's just about like this, not much more than that. And if I put

some variations here, one variation is that the six abducens cranial nerve can be ventral,

can be ventral to ayaka, or

it can

be dorsal.

A lot of people think this gives entrapment and a stretching injury. That's why a six nerve pericis occurs. I don't, I think it's attachment at the brainstem. I don't think it has anything to do

with the blood vessels. But it is an important feature if you're taking out a mask because you will see the six nerves on a lateral, far lateral, but you can't do much with it. So you wanna be

careful and keep in mind this relationship

of the nerve being more superficial here is deeper to the artery. And then a variation for the, you're not gonna be this high up, but there can be two or three, superior cerebellar arteries. Now,

the last thing I wanna talk about is what you're not interested in. If you say that this is a schematic, semi schematic view. of the internal jugular canal. And this is nine and this is 10 and 11

in spinal accessory. I have a problem. One problem is they say there's a superior and inferior ganglion. Well, they're right, but sometimes there's no superior because the superior is part of the

inferior and it can separate or you can't tell. And that's one thing and some people call this inferior patrosal for nine and no docile for 10. But my argument isn't so much with who names what and

where they are is this part. Spinal accessory has no sensory unit and has no sympathetic units. Yet we say that the lower part of 10 is really cranial spinal cerebellum. I mean,

spinal accessory I don't know why they've done that.

That does it. We're not gonna get into the appendix. Dr. Oswin, you add a question or an observation. I get you to go back to the basilar artery that we saw in FOS. That's one, right? I just

wanted to make about five to three for five minutes comments about this. We were, as you know, we were interested in vertebral basilar insufficiency We had a man come to us who had a basilar artery

thrombosis. This is before the time where you could go ahead and I'll remove an embolus. You could put people, put stents up at a wasn't. It was not very successful. It was really nothing to do.

He was having continued symptoms. And there was nothing to do for him, basically. Couldn't put him in a coagulants because he's still gonna thrombosis or eventually will. So we talked to his wife

we'd been working on this in the laboratory. And we said, We'd like to go transclivallybecause we think that what this man hasis an atheroma that's led to the thrombosis.

We talked to her about her. We may lose him during surgery. We have nothing else to offer him. This is the first case that we ever knew had been done. And she said, If it's if it can help him,

let's do it. So we went and did it So we went transorally. And we went transorally and drilled off the clavus. They split the clavus. And what we then did is find the basilar artery. We didn't

find it out as wide as you did. We opened the dura. And one of the problems with going through this is if you close the dura, then they get meningitis 'cause they get leeks. If we had to go

through all kinds of ways, we're gonna close it so that wouldn't happen.

well after surgery died. We did this, we never reported it, we probably should have, but I was just an attempt to do something, to save somebody's life and hopefully it would work and it didn't

work. Thankfully the wife was very accommodating, we explained everything to her. But what we learned is that the textbooks had not described it in detail. We went back and looked through all the

previous techniques. They're all textbooks, they're all

end arteries. So when I saw this picture it was a reminder to me about

we don't know everything.

I think

what you just said there is the truth. And the arteries is a redundant statement based on prior readings. There haven't been a lot of studies that I'm aware of.

to see, is there a read-of-myopoly that exists at the Pia

level or at a level that you really wouldn't be able to see by standard ways. You really have to refine it and do it with electron microscopy. I don't know if that's been done. That's exactly right.

And we were studying actually the lacunar infarction, which you know, the female that Fisher studied anatomically, just incredible paper

And those are supposedly end arteries. And we injected specimens, autopsy specimens, and actually it turns out that they're collaterally connected. And so I would imagine that the brain, I can't

imagine the brain being constructed or it wouldn't be collaterally connected. That makes no sense. Well,

there's another question that you could ask This opens up.

What happened is this man had slow progressive occlusion of vessels, developed collateral channels in the heart. In the heart. So that actually when one became much more occluded, he had other

collateral channels already developing. He did not develop a massive baccalaureate on fortune. So I think, again, there's things we don't know, and we will know with seven Tesla MR and some other

things, 'cause that shows these small vessels in the anatomical detail. I wanted to ask you one question before we close, if I could. Okay? Yeah. If we project ourselves to Alex Future,

which is in the next year and a half, and I'm kidding you. Now, it's the next 50 years, okay? And we have all the technology that can show us how we can navigate to the CP angle. Why don't we.

Alex, let's get out of this view. Stop sharing.

And in part three, Dr. Malkasian and the discussants talk about the future of neurosurgery by 2100.

Yeah, and let's say 50 years from now, and we see this coming now. We have all this neuro navigation developing. We have imaging that's incredible. You can see it in the microscope, and you can

see it in 3D. You can see it in the other sides and so forth. And we have to understand what we went through. We have very detailed angiography. You and I grew up at a time where you did carotid

injections to do angiography. And there was nothing before that. And we do ventriculography. So to think that nothing is going to change would be kind of a stupid thing to say Bye!

to much of the pathologies that we face. I think that's why a lot of people go into spying. And I think they're gonna be disappointed that they too are not gonna be able to make people better. They

think they will be. But in the long run, they're gonna be relapses. These are not structural alterations have a very limited calling, trauma, removing a mass that's not malignant, that's not

gonna return. But the rest of it is going to have to be dealt with at a very sophisticated, advanced biological level. And so I think we will have to fit into that. You've heard me say this before,

so I know it's old news to you. And we

can't do much better with the glioma than we're doing from their surgical standpoint. 'cause it's a disease, most likely the whole cereroom. And so you take out what you think is tumor, people

tell you, yeah, the margins and all that. No, no, no, there are molecular genetic changes, epigenetic changes on and on. There are already kicked into motion, it's just when that gate is

gonna open. So I do think there's gonna be a major requirement. And I try to share that with the residents Then be careful what you choose, even things like DPS. They're not gonna be the answers

to people that are getting fat. Nobody wants an electrode in their head, that has to be changed and the battery has to be changed. It's gonna have to be understanding the molecular aspects of it

and treating those. But does that remove the need for neurosurgery? I don't know, it does. It may remove the need for neurosurgeons because other surgeons will do the more. technical work like

remove a clot, some tumors will be benign that is better. You remove them that play with them. So is this a pessimistic view? No, things move on. And we'll just have to see. I'm not sure in Dr.

M. Sid's career that it will change so much. That will require a number of

changes that we can't even imagine.

Let me venture into the changes we can't imagine territory. We've got a series of, and this is all conjecture, Alex. So it may be worth less information. Somebody will show this information at

20 years or 30 years from now be laughing at it and see how crazy these guys are Um. But we're going through a series of lectures now on SI digital, given by a professor, he used to, he used to,

he used to follow who's in France. And what he's doing is going in and taking a medium to low grade gliomas out. And he's, and he's doing this with incredibly long survivals that we don't see in,

in places around the world. And he, and the basic thing is, he says, you've got to think not about the tumor. You've got to think about the brain. And so his surgery is functionally based. And

he says, I can't rely on imaging because the brain has got plasticity and what, what the imaging may show may be different the next day. Or if I come back and operate on somebody, some months

later, the speech area has been shifted already to the other side of the brain or someplace else. And he said, the only thing that matters is to make sure you see.

order to understand what you're operating on. The machine, well, the machine be able to integrate all of Denny's knowledge using imaging, ABC and 4, ABC and D, to get that information. Well, I

remind you what Dafoe has found. He said no matter what the imaging shows, it's not reliable And the brain shift may alter things. So that doesn't help you either.

Will they have fixes for that? I think they're probably working on it desperately. That's a hard problem to solve. Because are you going to ever have imaging that's accurate? And will it take into

account neuroplasticity? So I'm thinking of,

we're going to this, going to one of the bio. my biomedical companies and to construct something so I can get to the CP angle, just like Danny said. And it would tell me all these, it would just

put arrows showing all these things that are going on. Is that gonna make me a better surgeon and I'm gonna have a better result? Or the answer is it could. But in the end, there still has to be

something that Frank Hsu had at the end of the conversation in presenting his patient It is the judgment to know when to stop.

And the computer won't tell you that. And you have to know that. And the other thing that will happen is what Dennis said, is you're gonna have to have very sophisticated neurosurgeons to do this

kind of work and that means they're gonna have to be in centers to do that. And right now we don't have enough vascular surgeons who know what to do. They can't even do aneurysm surgery well. So I

think that's another thing. And the third thing, Danny, is something you talk about. Are we gonna be treating tumors instead of what Dr. Defoe is gonna do? And what

else we've talked about?

Is cancer gonna turn out to be a metabolic disease? And we have papers on S and I digital about that. And are we gonna find biochemical answers to that? And there's no question that what the answer

to that? Yes, the answer to that, yes.

Of course, cancer is, it's got major metabolic effects. And a cell is metabolically dependent, the mitochondria, all of it, we'll get

there. But we're not there now because we don't even think that way.

I think there are some people that do, but the pragmatism in the business that runs

that's chewing up a lot of money for people that should just live with what they have. They haven't got such bad problems. I agree. So this is for another time, but I thought I'd ask you

particularly after you, you just did a fabulous job going into this and it's very humbling, listening and seeing what you've said, your pictures are outstanding. And if anybody just didn't want to

put aside two hours and listen about this, they would learn an enormous amount about medicine, neurosurgery, humility, and what you can do and what you can't do and what you have to know to

prepare, to operate on a patient with zero complications, right? Well, I wish I

could ask to be given credit for most of this, but I have to tell you,

this two-hour series.

The question is, should the average resident, regular everybody going through here, this two-hour symposium basically on anatomy, biologic anatomy and surgery and management?

That's a kind of a loaded question. I think

that a lot of residents who are not interested in skull-based surgery or complex cranial surgery would think that it's not helpful to them. It's wasting time. But I don't know that that means that

they shouldn't watch it because I think that the principles discussed in how to think about a problem, how to think about an approach and have a think about the relevant anatomy when you're going in

and performing operation on somebody is valuable to everybody. Well, I think that's an excellent answer. I appreciate the confidence and I know you're telling me an honest answer. But the question

is, if you're chairman of a department,

would you have all the residents watch this?

Probably the ones that are interested in school-based and vascular, I'd say. Do you think that spine surgery eventually is going to come to a point where you're going to need something like this in

detail? There's going to be biochemical treatments for osteoarthritis.

Nobody's done an ant, does routine angiograms on the spine? So we don't know if there's vascular occlusions and the reason is because it's too hard to do where we had that, like, how many Denny?

That was almost a hundred years ago.

And yet we don't have no idea. We wanna know about the vasculature in the brain. We know nothing about the vascular of this spinal cord. Can you imagine, do you think that we're gonna, somebody

did this, Dr. DeKiro did this in the 1960s, in 10 cases of spinal cord trauma, found all kinds of lesions.

And the answer is, do we not wanna know or is it too hard to find out or too complicated? Yeah, I think those things are probably true Not a lot of people are skilled enough to do that. But so

we're getting to a point where you gotta be open to the fact that they're gonna be lots of changes and lots of new things and you're gonna evaluate what's new is good and what's not good and so forth.

And so the others are gonna get to this detail. Does it make sense for pituitary tumors to grow and have to radiate them and do something else? Don't you think I'm one of the most accessible lesions

in the body that we ought to know biochemically what's going on and treat it. I mean, it makes no sense.

You know, a lot of the

opinions

that we have developed because of a journey in life. And this is what makes different aliquats of

people defined by their age and what stage of life they're

in. We're at a stage of life, Jim, that we reflect a lot on the mistakes that we made and other people made. And that kind of skews us in a certain mental state. And I think we're right. But

there won't be advancements without the enthusiasm, without the

We hope you enjoyed the presentation. A legal disclaimer is that the views and opinions expressed in this program are those of the author or interviewee and do not necessarily reflect the official

policy or position of SNI Digital or its management. And the information in this program should not be considered to be medical advice. Patients should consult their own physicians for their

specific medical needs

This session is recorded on SNIdigitalorg.

Click the blue icon at the lower right-hand corner of the home page at the bottom right. And if you have any questions, suggestions, comments, or requests for CME credit.

SNI Surgical Neurology International

is viewed in 239 countries and territories It's the third largest neurosurgery journal in readership.

on podcasts on Apple Amazon and Spotify. Look for us and I digital.

And the foundation also brings truthful medical and science news to the world through its medical news network. It's medical news that you can depend upon.

This program is copyrighted in 2026 by the James I. and Carolyn Ousman Educational Foundation All rights are reserved. Contact Dr. Ousman at the email address below if you want further information.

And we want to thank you for watching the program. Hope you found it valuable.

Practical Surgical Anatomy of the CP Angle; Dennis Malkasian

James I. Ausman, MD, MA, PhD

Dennis Malkasian, MD, PhD

Alexander Himstead, MD

SNI Digital®, the Global, Interactive, Peer-reviewed, New Video Journal of Neurosurgery and Neuroscience-2024 Edition; "Innovations in Learning" for the 21st century

VIDEO EDITORIAL

NEW SNI Digital® Version 4.2

Search