Understanding and Treating Craniovertebral Junction Instability

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- Colleagues and friends, thank you for joining us for another session of the virtual operating room. My name is Aaron Cohen. Our guest today is Dr. Atul Goel from Lilavati Hospital in India. Atul does not require any introduction. He is an incredibly creative thinker in neurosurgery. He has had many different leadership positions in neurosurgery. He has been the reviewer and editor of many different sections of "Journal of Neurosurgery". Really, his disruptive and innovative thoughts have transformed different levels of neurosurgery, which I can't even summarize here. Today, he's going to talk to us about understanding and treating cranial vertebral instability. Atul, it's been truly an honor knowing you. I have followed your career and have learned so much from you, and today is not different. So, I'm very much looking your lecture. Please go ahead.

- Thank you, Aaron. Needless to say that, Aaron, I have given various lectures, various webinars and all those things, but this one is the prized. This is my biggest honors to say to the least. And I hope I do justice to your introduction to me and I hope I am in sync with what you wish that I should present.

- Thank you.

- So, let me go to the slides. So, I'm going to talk today on a very favorite subject of mine and that is craniovertebral junction. And I have been involved in the treatment of this craniovertebral junction issues for approximately four decades. And I will like to introduce to you some of my thoughts, and many of you know about my work. I must say that craniovertebral junction surgery is the most result-oriented surgery in our subject. It can give absolutely new life to our patient. It is highly anatomical, highly technical, highly philosophical, and you have to learn and know the subject, because if you treat properly, you give new life. On the other hand, if you are not doing a good operation, if you fail or you have a complication, that may be the most devastating complication that you will ever see in your lifetime. So, these kind of children and adults with neck deformities, neck deformities is one thing, but even without neck deformity, limb weakness, breathing issues, pain here, pain there, pain everywhere, these kind of things are completely devastating. And if you can treat them, you give new life and you give new life. This was the person who was on a wheelchair with this kind of neck, but this is not just the issue of deformity, pain, weakness, unable to do anything, and you treat it. Whether you can treat it or not, that is the issue. If you can treat it, you can get him back with the family, with the wife, with the child, and you can have a situation where you have given birth to a new family, not just the patient. On the other hand, any complication as I mentioned, can be completely, completely devastating. You can have a situation where the person is fully conscious, not able to breathe, not able to move limbs, on ventilator, that kind of situation you will never like to have in your whole career. So, it is important that we know and learn this subject. Absolutely, absolutely is the least word that I... So, you see these are the pillars and the upper part of the pillar is a V of the Y. This V of the Y is the craniovertebral junction. It hold the entire head. It has two joints, one is occipito-atlantal joint and one is atlanto-axial joint. Now, I want to say very clearly, atlanto-axial joint is the most mobile joint of the body and occipito-atlantal joint is the most stable joint of the body. So, stability and mobility are the hallmarks of craniovertebral junction. Craniovertebral junction instability means atlanto-axial instability in most of the cases. Atlanto-axial joint is the most mobile joint and is the most unstable joint of the body. Occipito-atlantal instability is an absolutely rare situation. So, when you treat craniovertebral junction instability, essentially you are treating atlanto-axial instability. Atlanto-axial joint is the most mobile joint. It contains two wonderful bones. You see this is the atlas, this is the axis. The spinous process of the axis is the biggest spinous process of the whole spine, Transverse process is the biggest. Transverse process of atlas is the biggest in the whole spine. These facets are the biggest facets of the whole spine facet of the atlas. And if you see the ruggedness on the rostral or the upper border of the atlas facet, which attaches to the conduct. So, it is huge and it is rugged. On the other hand, the inferior surface of the facet of atlas is round and flat like no other joint in the body, in the spine. Round and flat and has circumferential movements. And more the movements, more the possibility of abnormal movements and instability. So, atlanto-axial instability is the most unstable joint of the body. Atlanto-axial instability is misunderstood or under understood by all spine surgeons and I have no hesitation to say that atlanto-axial instability is the most undertreated instability of the whole spine. So, this is the technique that I described in 1988. And many of you know this technique. One, this is plate and screw technique of atlanto-axial stabilization, one screw in C1, one screw in C2, and this is the plate. 1988. Screws in the facets. You see facets, these are the largest facets, largest and strongest bones of the body. They are next to teeth, can you believe? Teeth and next is we call dens or odontoid process, but facets are the strongest. So, they take very, the purchase of the screw is fantastic in both atlas and axis. My technique since 1988, so more than approximately 32, 34 years old technique of mine, it involves opening of the joint, denuding of the cartilage, introducing bone graft inside the joint since 1988. And then, do one screw in C1, one screw in C2, and a plate. I use plate and I have been using plate, but of course you can use polyaxial screws and rods if you're more comfortable with those. I also used to do occipitocervical fixation like this. One screw in C2 and the wires on the occipital bone. We introduced for the first time in the literature, our articles were amongst the first when we talked of putting screws in the occipital bone and screws in C1 and C2s. So, occipital screws were introduced by us. But now over the years, if you ask me, is inclusion of the occipital bone necessary in craniovertebral junction stabilization? I am saying it is not necessary and it is countereffective. I should not say countereffective, but I will say it is a suboptimal form of fixation. And craniovertebral junction means atlanto-axial instability and it needs atlanto-axial stabilization. The other thing that I used to do on a very regular basis is transoral decompression. And this article I wrote in 1994 and I did this technique much earlier, one screws in the clivus and in the C2 after decompression. So, I was very happy and very familiar with transoral surgery once upon a time. And in 1992, I did this clivus to C2 after decompression. So, I used to do transoral surgery on a regular basis. So, you see this is iliac crest bone here, which I had put in 1992 or 1993 for this kind of decompression and stabilization. But if you ask me today, transoral surgery is a completely historical operation for such instability. Now, we talk of facets. Facets are the key understanding of, facets can change not only craniovertebral junction, the whole spine, the entire spine surgery can be changed. And next, my next lecture will be on the subaxial facets. So, facets are the fulcrum or the point of attack of all muscles. It is not the disc, it is not the odontoid process, facets. Facets are the center of activity. Facetal fixation is the key. Facet is the point of movement and facet is the type, is the point of instability. So, this was my first case in 1988. One screw in C1-C2. This was the plate I used to use in 1988. Since then, I have done such fixation, C1-C2 fixation in easily more than 3,000 cases. So, these are the multiple cases that fixation. In children, of course in children where there is a bifid spine, C1. This is lateral facetal fixation is the only fixation. Midline fixation is difficult or not possible. This was a infant. This child was an infant less than one year old. This is another child you see with various deformity. Bifid spine, I did fixation. So, you can use this technique in children, in adults, and in all kinds of ages. So, screws, facets, and atlanto-axial instability were not very well known to neurosurgeons. At least screws we don't know, in neurosurgery, we didn't know in 1985, '86 what screws, even many neurosurgeons 'til date do not know what are screws and how are the facets used. But because of my association with my orthopedic senior doctor, Dr. Lahey, we develop and then progress further in craniovertebral junction and in rest of spine. If you see this C... This is C2 ganglion. C2 ganglion covers the atlanto-axial joint. So, for the first time in the literature, we describe that if you cut the C2 ganglion, you can expose the atlanto-axial articulation. And I think that opened the window for atlanto-axial joint. I do not cut the ganglion on a regular basis. No. Extremely rarely in absolutely complex cases, I may cut the ganglion. Generally, I do not cut the ganglion. Vertebral artery is the issue and vertebral artery is the key. We have to understand vertebral artery location. In this article, I described that vertebral artery has a dynamic relationship in this region. You turn the neck, the vertebral artery moves. So, this dynamic and when it is free, this space, I mean, is not completely occupied by vertebral artery, this space. And when it is not occupied, it is full of venous blood. Venous, it empties and opens and empties. So, vertebral artery is the issue. So, in 1988 we drew this kind of quadrangles and said this upper quadrangle, upper one, upper four are the best. This is what we said for the Vertebral artery. Obviously, you need to introduce screws in perfect direction to acquire this fixation. If you are not perfect, you can harm the person. So, it has to be medially directed towards the facet. This C2 is a problem. C1 is rather safe. You identify, you expose the atlas, you put the screw directly. But C2 is the issue, because vertebral artery is in a very close proximity in this region. So, we have treated, as I mentioned, several hundred cases of C1-C2. And when I say I have treated so many, it means I have given life to more than 3,000 patients with this technique. And I'm saying 3,000, but it is much more than 3,000 now over the years. So, these are the screws in C1 and C2 and you can see several cases I'm showing where there is dislocation, where there is reduction and fixation. So, this operation has to be learned by all neurosurgeons. As I have said, atlanto-axial instability is the most misunderstood and undertreated clinical entity in our subject. And there are several occasions where there is atlanto-axial instability. We do not know which are those situations. So, you see fracture odontoid. Trauma is one situation. Trauma is just a small part of craniovertebral junction instability. And you see odontoid fracture and you do fixation and you completely relieve the person of his symptoms and you give a new life. So, this is my position of surgery. I do with head elevated under traction. And this head elevation is very important. It reduces the venous congestion in this area. It gives a direct line of vision when you are operating and it gives a counter traction. And I expose this one, I expose iliac crest for the graft, always. I've never used any other graft. I'll just show you this video. And these are about five, seven-minute video. This is the spinous process. I am drilling in the lateral aspect of the lamina over the pedicle. This is the region of the pedicle I am drilling to make space for my plate. Now, you see more important thing in this operation is handling the venous bleeding in this area. It can be very heavily... The venous bleeding, you see I have introduced osteotome in the joint cavity. And then, I... This is the atlanto-axial articulation here. And I have distracted the joint. So, to do the fixation to introduce the implant, I will now expose the region better. And I have to tell you that this is not a difficult operation. I do simultaneously on three tables, three cases. I have done six cases in one day. So, it is not a difficult operation and it is such a highly rewarding operation in neurosurgery or spine surgery that there is no way we can say that we don't want to learn it. So, we have to learn two or three things. One is learn the art of opening the joint. Learning the opening of joint, I must say that it is easy, but it is not so easy. You have to learn it. You cannot say I will go and start doing on the first day. You have to learn it. So, now you see in the image, I have opened the articulation. I'm cutting the articular cartilage several locations. I drill the articular cartilage. Here is the vertebral artery. In this area is the vertical artery. I am putting a guide hole. And this operation can be done in one hour. You don't need 15 hours to do this operation. One hour maximum. See, time of course is never a consideration in our subject of neurosurgery. The consideration is that there can be huge venous bleeding. I'm now putting bone graft in the C1-C2 articulation. And I put extensive bone graft in the... This is my... Once you put the bone graft, you stabilize the joint by itself and it is absolutely important to give fusion. Ultimately, what we want is fusion and arthrodesis of the C1-C2. So, now, you see I'm putting more bone graft. And other thing that I want to tell you is, in my operation, I don't use coagulation. I don't think the need of coagulation in this operation is absolutely minimum. For that matter in any neurosurgery, coagulation it should be used absolutely minimum. Now, you see I'm using my construct. I have identified that hole. I have first... You see I'm just tightening the screw over the plate. Coagulation is the most overused instrument in our subject of neurosurgery. You can do majority of neurosurgery with absolutely minimum coagulation. This operation I am saying I do in half an hour or 45 minutes or 1 hour, I do because I... You know of course you have to coagulate. You cannot say there is a bleeding, I will not coagulate. But you have to minimize. You don't have to coagulate in this operation. There are ways to handle venous bleeding. You see there are methods to run the operation quickly rather than going on coagulating. You cannot coagulate in extradural space. You cannot coagulate... Now, I am drilling the C2 screw. C2 screw, the direction is absolutely critical. I will discuss more about this issue, how the direction. You just see how I have put the C2 screw, this guide hole, and then I will turn the plate over that screw and tighten the screw. The other thing that is very important is once you have done both sides, you cut all the muscles attached to the C2 spinous process. My feeling is if you do not cut the muscles of C2 spinous process, they are so strong that they can move your implant. You just cannot leave these muscles of the C2, C2 spinous process and arch of atlas intact. You cut them. I will show you more images after my Brief my technique. It is nothing much in this, but you cannot imagine what results we can get. See, this is the region and this is the direction of my screw. Okay, next slide, please. You can use navigation. I used to use navigation to introduce and to be safe and I will not say don't use it. I will not say. But I don't use now, for a long time, I don't think I require it. But if you have some issues and if you are fresh and you are not conversant with this, you must use navigation. Other thing I was talking about these muscles on the arch of atlas and C2 spinous process, they are very strong muscles. They completely move the neck and head and you have to section them sharply at the end of your instrumentation. So, you can use double insurance, one screw in C1, one screw in C2. So, this is Magerl's technique transarticular, and you can use double insurance. I use it sometimes, rarely, not often. You see this is one screw in C1 one like Magerl's technique, and it gives additional... The issue, as I mentioned, is the vertebral artery. Vertebral artery can go very much medium. And that can, if you damage the vertebral artery, it is dangerous. It can be very harmful. But the world is not lost if you have damaged the vertebral artery. Well, I have damaged vertebral artery on several locations, but to have harm means you can ischemia related to vertebral artery is possible, and that is the danger. But it is not such a danger that you have to worry about it all the time. So, we introduce these three-dimensional models to identify the region properly to get to the screw and to identify the location of vertebral artery. You see these are the models. No. I can hold the model in my hand during surgery. You know exactly where is the vertebral artery and these models are very useful when you are going to do this operation. You see this is the vertebral artery. It is in an abnormal location. It does not normally stay here. So, you see this model can give you such a wonderful, wonderful image during the operation. So, this is the fixation that I used with the help of a model. I use model on a considerable number of cases, but not always. Nowadays, I don't use it often. You see this model. So, these are the pedicle and you see now exactly where you have to put the screw, where you have to put the screw in the C1, where you have to put in the C2, where is the vertebral artery. You can have this information very beautifully on the 3D model. So, this is another 3D model and then you do fixation. Now, I want to show you the beauty of this C2 vertebra. It is a different vertebra use... I told you the C2 spinous process is biggest and the largest of all the vertebra. There is odontoid process and we can talk about odontoid process all day. This is like a disc. There is no muscle attached, but it regulates the entire movements of the C1-C2. Another beautiful thing that you have to see is, this is the superior facet of C2. And this is the inferior facet of C2. They are not in one line. This is C... Superior facet is anterior and inferior facet is posterior. So, my screw goes in the superior facet like this. But if the vertebral artery is disturbing and it comes in the picture, then you can use inferior facet. You see you can use the inferior facet to introduce your screw, and that is in honors, on some occasions can be quite useful. So, this is the technique that we described of introducing the screw in the inferior facet. You see inferior facet. And this can be quite strong and that means the best is superior facet, obviously. But if it is not possible, you can use the inferior facet. So, you see here these pictures, there is the vertebral artery is quite high-riding here and introduction of the screw could have been difficult. So, I have put the screw in the inferior facet. So, this is a possibility. This is another case where we have put screw in the inferior facet, because of the problem of introduction into the superior facet. This is another case where the vertebral artery is in a very abnormal kind of situation, which happens lot of time when there are craniovertebral anomalies. I don't like to use anomalies. I like to use alterations, because I think, they are never anomalies. They are nature's protection. We will talk about it subsequently. So, this is inferior facet. The other thing that I have to show you is the vertebral artery can be quite medial. So, we introduce the technique of mobilization. You see this is the vertebral artery group and it is high-riding. You can actually mobilize the vertebral artery. And mobilization and then introduce this screw. So, I will like to show you a small video. You see this vertebral artery has been mobilized here, and then the screw has been introduced. Can you show the video, please? Little bit go ahead. I want you to go a little bit ahead. This is the position as I mentioned to you, head high. Yeah. Okay. So, I am now going to show you, I have not actually, I have skipped that vertebral artery high-riding. On the left side, the vertebral artery is here, but not so much head high-riding. This is the vertebral artery location. It is high-riding, but not so much. So, I am opening the joint and I will just like you to refresh the technique of C1-C2 fixation like a regular on the left side, it is not so high-riding. So, first, I introduce this osteotome, then I expose the C1 facet widely. You see the facet? And I have to tell you it is not difficult at all, but you have to learn the art of opening the facet articulation, atlanto-axial articulation, because if you do not open the C1-C2 articulation, I don't think you have done a good job of fixation. So, this drilling of the lateral part of the lamina to adjust my plate, which I use on a regular basis, as I mentioned to you, there is no need for using plate. You can use rod and screw, polyaxial screws. I describe plate and I like to use plate, because it gives me a very firm and stable fixation. So, one screw in C1 facet. This operation, neurosurgery is such a fascinating subject. Neurosurgery is the subject where you can give new life to the person. Neurosurgery is such a wonderful divine subject. On the other hand, if you do not do it properly, you can take the life of the person. So, it can give life, it can take life. So, it depends on us how we learn our subjects, how we develop our training, how we go further in our subject and give life. So, learning, as we all know, learn anatomy. Learn, go to cadaver lab, learn anatomy, get opportunity to do more cases, more cases, more and more cases. More the cases you do, more the confidence that you will get. And of course, you have to do it properly. We have to have confidence. We cannot have overconfidence. We have to be absolutely, we have to work with our heads down and feet firmly grounded. We cannot jump and operate. We cannot look up and operate. Patients are looking up on us and we have to not look down upon them. We have to be absolutely... This is beautiful subject. So, you have to tighten the screw. And now, I will want to show you the other side where I mobilize the vertebral artery. You see it is stable now. You can use even sometimes I have to, if I have some problem, I stabilize only on one side. And I have to tell you that several occasions, particularly these are the relatively simpler cases I'm showing you, but I will show you more difficult ones later in the... Now, you see here, this is the C2 spinous process here. And here is the vertebral artery in this area. Wait, here is the vertebral artery here. And vertebral artery is very high-riding. Unfortunately, I couldn't show you the image, but okay, see here is the vertebral artery here in this area. And this is the C1-C2 articulation. Then, you see first, I will putting a guide hole on the C1 facet. Learn the art of opening the joint. Learn the issues involved in arthrodesis. Bony fusion is mandatory. You cannot put a plate and screw and not put bone. We have to learn this principles of orthopedics. In neurosurgery, we never are taught, we are taught of course, but we try to avoid learning orthopedics. You see, when I started doing these cases in 1986, '87, at that time, screws were just introduced in the subject of spine. And lumbar spine, they were introduced. Nobody talked about C1-C2 screws and all. So, that screws we... Occipital screws, nobody knew about screws, no neurosurgeon at least knew about screws. So, these screws, we have to learn how to use the screws in difficult situation. Now, if you see here, I am trying to expose the vertebral artery here. It is a little bit... Normally, you don't need it, but I'm just showing you because I want to show you that this is possible. And this can be done on a rather easy note. This is not a such a technically complex situation. Of course, you have to learn the art of controlling bleeding. Learn the art of controlling venous bleeding, which is not easy in this situation. Venous bleeding can completely, can be quite difficult in C1-C2 fixation. Now, I'm not sure if you can see properly, but the vertebral artery, I have exposed quite elaborately in that region just using these kind of Rongeurs. You can use diamond burr and drill or at on... We have used on several locations, but here, I'm using these Rongeurs, which make things a little bit easier. Now, you see this vertebral artery right under my screw, it is pulsating. You see under the here, it is pulsating. Now, I will mobilize it, and then introduce the screw. You see I have mobilized it now with the dissector and I have got the facet. It is a little bit tricky, but not technically hugely difficult. But you have to have that kind of awareness that it is possible. And also, you have to have the feeling that I have to do it. I have to do C1-C2 fixation. I don't want to do C3 fixation or C4 fixation. You say oh, no, it is difficult. I use C3. You say C1 is difficult, I use occipital bone. Those are not good operation. Craniovertebral junction instability means C1-C2 instability. Craniovertebral junction stabilization means C1-C2 stabilization. If you are not able to do, of course then you have to do occipital fixation, subaxial fixation. I will not recommend them. But if you are not just able to do, then this is the only option that is remaining. You'll do C3 fixations, do C4 fixation. But more the segments you include in your construct, more the problem of instability of the construct becomes weaker. So, you see now I have mobilized the C2, mobilized the vertebral artery and input the C2 screw. So, can we just go further now to the next slide? Then, I drill the C2 bone. You see here the C2, the screw has gone. This is the high-riding vertebral artery here. And I have drill like that you see here. You can use sometimes, I describe spinous process screws and laminar screws and spinal laminar screws in 2004. This was the first article on the subject. When you cannot... I do not do use them at all now, but I have described, so I'm showing you. In case you are having problem, you can use spinous process. So, I have used screws in the occipital bone in the spinous process. If that is not possible, you can introduce intraarticular spaces, which we described as joint jamming technique. I have described them. I use it sometimes for basilar invagination, but in general, I don't use them. I use intraarticular bone. So, these spacers and technique we have discussed when we should use, when we should not use in this article of mine. So, you see here, you can use this as a stand-alone technique, and we have used it on several occasion. The other beautiful thing... You see, sometimes, the C1 screw can become difficult. You can use transcranial insertion of the atlas screws. Now, I want to show you this. You see here the insertion of C1 screw was difficult. So, I did a smallish craniectomy here around the suboccipital craniectomy. Extradural exposure of the C1 pedicle and facet is possible. And in difficult situation, I use C1 by doing a small craniectomy, but I don't use occipital bone. I used to use occipital bone on a regular basis, but of course now, I don't use. The other revolution in craniovertebral junction surgery was the introduction of the concept that there is nothing like fixed atlanto-axial instability. The whole... The craniovertebral junction was described as fixed atlanto-axial dislocation and mobile atlanto-axial dislocation. So, we introduced the concept that it is never fixed. It is never fixed and it can be reduced. It is pathologically mobile. So, this concept revolutionized craniovertebral junction surgery and we have got several patients, you see in flexion and extension, this odontoid process is not moving. As I mentioned, we were very good in transoral decompressions, but now, there is no need to do transoral decompression. You can open the joint, manipulate the facet, reduce that craniovertebral junctions. So, there is a possibility of reduction. This concept completely changed craniovertebral junction surgery. You see in flexion and extension, there is no change here. So, there is a possibility of opening the joint and reducing the dislocation, and giving new life instantly to the person, new life. I have no hesitation to say new life. The other revolution in craniovertebral junction was the art of manipulation of the facets, manipulation and reduction. So, if there is a disruption of the C1-C2 articulation, you can manipulate the facet and realign the craniovertebral junction. So, this completely, this is also a landmark situation in the history of craniovertebral junction surgery. So, you see the facets are disrupted. So, open the joint, manipulate the facet, and reduce the dislocation. So, by this concept, rotatory atlanto-axial dislocation, rotatory. This kind of rotatory. This is were the only treatment was traction and all those things, open the joint, manipulate the facet, and give a new life to this patient, a new smile and a new neck to this patient is possible. And this has to be learned, this art of manipulating and realigning. So, this is vertical dislocation. It's like basilar invagination. So, basilar invagination, nobody knew. You see this is a article I think, in 1964. No craniovertebral junction anomalies was considered to be a curiosity, but in the last few decades, it has become a real thing, real treatable clinical entity. So, basilar invagination, I wrote this article in 1998, this is highly cited article where we said that basilar invagination is of two types. The concept was it is fixed dislocation. Odontoid goes up in group one and tonsil comes down in group two. So, the anomaly was fixed and the treatment was decompression, transoral decompression from this group and foramen magnum decompression for this group. So, transoral decompression in 1998, this is what we described. And the role of fixation was not convincing at that point of time, because we thought that the whole world thought that this is fixed dislocation and decompression is the treatment. At this time, we said, for Chiari malformation, there is no need to open the dura. This is what we said at this time. Another revolution in craniovertebral, journey of craniovertebral junction was in 2004 where we said that this group A is not fixed, atlanto-axial dislocation is not fixed. You can reduce the craniovertebral junction, basilar invagination, and we introduce for the first time in the literature this word realignment, realignment. So, over the years, we have got several hundred patients where we have done craniovertebral junction realignment. So, basilar invagination, the only treatment was transoral decompression for this. Transoral, but you can bring them in beautiful realignment, open the joint, distract the facet, distract and reduce and stabilize. So, there is bone in the joint, bone in the posterior elements. So, there are several beautiful cases I'm showing you. Basilar invagination, the treatment was transoral decompression. But you see the facetal articulation and you see the reduction, and you see the fixation. And as I have mentioned, this is radiologically looking very good, but radiological is not what we want. We want clinical. And clinical is dramatic. Patients not breathing, patients not moving, patients having pain, patient being fed, patient being... You have to take them for toilet to take for bathing. You can give new life and you can give new life beautifully and instantly. So, these are many cases which I'm showing you just to show you that many of these cases have assimilation of atlas. Many of these cases have complex anomalies. Many of these patients have vertebral artery anomalies. You have to know all these things. These are not easy operations. Basilar invagination in presence of assimilation of atlas like in this case, you can do C1-C2. There is no need for occipital fixation. Never, never. Of course, when you are not just able to do, that is a possibility. Then you accept that you are doing a suboptimal kind of fixation. So, C1-C2 fixation is the treatment for basilar invagination. Open the joint, give... You see within a few months, this boy I did in 2000, 22 years ago, I did this operation. He came on a wheelchair. You see how the father is holding, how the neck, and you see in two, three months, the boy is standing, still holding. I have no follow up of this guy, but he must be a completely normal human being doing work for the family. So, just see some beautiful cases and enjoy this beauty of basilar invagination and craniovertebral realignment. So, for basilar invagination, there was an era of decompression. Then, there came an era of decompression and fixation. And now, I have no hesitation to say that there is an era of only stabilization. Now, you see I have even removed this realignment. Realignment is a possibility and should be done, but what is important is stabilization is important. Another phenomenal concept which I want to talk to you about is chronic atlanto-axial instability. When there is a chronic instability, nature comes into play. Nature. And nature changes the whole dynamics of craniovertebral junction and of the neck. And I want to show how nature, how this nature comes in the picture. So, now, you see, carefully, I want you, my dear friends, see this slide. The situation of chronic atlanto-axial instability, chronic. There can be Chiari malformation, syringomyelia, external syringomyelia, syringobulbia, external syringobulbia, short head, short neck, basilar invagination, short body, Klippel-Feil anomaly, platybasia, and think so many anomalies, bifid C1, bone fusion, assimilation of atlas, and so many other things. My concept is absolutely clear that this chronic atlanto-axial instability is the father, and all these musculoskeletal, neural anomalies, I should not call them anomalies, alterations, are secondary. They're secondary to chronic instability. They are protective and they are reversible. So, they're three things, all these things. The other thing is all these anomalies or alterations which I'm showing can be present together like Chiari can be present with syringomyelia. Chiari can be present with Klippel-Feil, with bifid, with basilar invagination, with other things, or can be present discreetly. Like syringomyelia can be present discreetly. Short head can be present discreetly. Platybasia can be present discreetly. Whenever they are present, they indicate atlanto-axial instability and they indicate the need for atlanto-axial fixation. That is a revolution which I want to talk to you about. In 1999, we said that facetal instability, facetal listhesis. Facetal listhesis is the cause of basilar invagination. Like you treat listhesis, you treat basilar invagination. You see this is listhesis? You basilar invagination, you treat, open the joint, stabilize, and you realign the craniovertebral junction. There no need for decompression. Decompression is a negative. When there is instability, you need arthrodesis. We recently, about 15 years ago, introduced a concept of central or actual atlanto-axial instability. I have no hesitation to say that there is a complete change in craniovertebral junction. You read this between the lines. I'm not sure if you can read. There is... Central instability is present in Chiari, in syringomyelia. This is one. But I'm talking of spinal degeneration, spondylosis. I'm talking of deformities. I am talking of OPLL. I'm talking of Hirayama disease. All these disease can have central atlanto-axial instability. Mind it, my dear of friends, if you ignore instability you may have a complication at hand. You have to know that there can be central instability. I will talk about this in my subsequent lecture, not today. So, now, you carefully see this slide. There is listhesis of C1 over C2. There is compression of the neural structures by the odontoid process. The need is to realign the craniovertebral junction. That is type 1 instability. Can you go back please? Yeah. Now, you see here type 2. Type 2 is there is no neural compression. There is no atlantodental interval disturbance, but there is facet of C1 is behind the facet of C2. This is completely unstable. There is no need for decompression in this situation. There is a need for atlanto-axial stabilization. So, this is type 2. Type 3 is when there is Chiari and syrinx or basilar invagination. All the children that I talked about, platybasia, short head, short neck, torticollis, whenever they are present discreetly or in combination, like in this case, there is a simulation of atlas, there is basilar invagination, there is Chiari malformation, there is syringomyelia, they indicate atlanto-axial instability and they indicate the need for atlanto-axial stabilization. And the syrinx will go, the tonsil will go up. More important than that, the patient will dramatically improve. You have done decompressions for Chiari for ages. How many patients have dramatically improve? How many patients have got a new life in the evening of operation? So, basilar invagination. Instability is the cause and stabilization is the treatment. There is no place for any kind of decompression both in group A and group B. Inability is the problem and stabilization is the treatment. So, we have written several articles on this subject with several hundred patients where we have said that atlanto-axial instability for both group A and group B, and atlanto-axial stabilization is the treatment. Now, I take you further on this. Atlanto-axial instability is the cause of Chiari malformation. Atlanto-axial instability is the cause of basilar invagination, Chiari malformation, syringomyelia. As I mentioned that basilar invagination can be present with syringomyelia, with Chiari, or it can be present discreetly. So, we said in our article in 2013 that atlanto-axial instability is the cause of Chiari malformation and atlanto-axial actual fixation is the treatment. Even when there is no bone malformation, even when there is no basilar invagination, when there is Chiari, it indicates atlanto-axial instability. When there is syrinx, it indicates atlanto-axial instability. So, it needs atlanto-axial stabilization. So, you can see several cases here where we have done, you see there is some atlanto-axial instability. There is syringomyelia, there is Chiari malformation. I don't like Chiari malformation, that word malformation, because I say that Chiari is secondary to chronic instability. Syrinx is secondary to chronic instability. They are naturally protective. They are reversible after atlanto-axial fixation. Syrinx will go in hundred percent of patients if you do a scan after one year. And it will not go completely. It will reduce remarkably like in this patient. More important is that the patient will dramatically recover in the symptoms even when there is no atlantodental interval disturbance, even when there is no facetal malalignment. Presence of Chiari, presence of syrinx are indicators of unstable atlanto-axial joint. If you see this picture, there is no type posterior cranial fossa and there is no need for foramen magnum decompression. Atlanto-axial instability is the problem and atlanto-axial stabilization is the treatment. Now, over the last several years, we have got several hundred patients where patients with syrinx and Chiari of all kinds have been treated by only stabilization of C1-C2, not occipital bone, atlanto-axial joint stabilization. Syrinx will disappear, not disappear, but reduce remarkably in hundred percent of patients, and there is no question about it. So, we recently published, or not recently, about one or two years ago, my series of 388 cases of Chiari with only fixation, and I wish that you read this article. So, we said that Chiari is secondary to potential or manifest atlanto-axial instability and it is nature's protection or airbag. It is a formation, it is not a malformation. So, you see this another patient with Chiari and syrinx and some instability here, fixation, the syrinx disappears, no decompression, no decompression of any kind. Decompression in an unstable situation is a negative. So, I am saying that foramen magnum decompression for Chiari is a negative surgical procedure. You see the syrinx and Chiari, and only fixation and syrinx reduces, dislocation, stabilization, and magic. You see here, there is tonsillar herniation, there is facetal type 2 malalignment. I have done stabilization. The tonsil goes up. And more important than anything, the patient recovers dramatically. And I have to say that this kind of recovery that I'm talking about can never be even expected after foramen magnum decompression. So, you see syrinx and reduce only fixation, syringomyelia, reduce fixation. syringomyelia, atlanto-axial instability, basilar invagination in this case. Basilar invagination, Chiari malformation. Syringomyelia are not mother and daughter or granddaughter. They're brothers and sisters. Their father is atlanto-axial instability. They are children of this father. So, you see Chiari and syrinx and reduction and only stabilization. There is no facetal malalignment. Whether there is facetal malalignment or not, whether there is any kind of atlantodental interval disturbance or not, presence of Chiari, presence of syrinx, presence of basilar invagination, presence of bifid, presence of Klippel-Feil anomalies are indicators of unstable atlanto-axial joint and indicate the need for atlanto-axial stabilization. When you do foramen magnum decompression and it fails, then what? Now my main operation nowadays is treatment of failed foramen magnum decompression where I do atlanto-axial action stabilization. This patient had undergone foramen magnum decompression. I did fixation and you see the syrinx has reduced. Reduction of syrinx is not our aim. Reduction of tonsil is not our aim. Aim is the patient, and I have said that patient will dramatically improve in the evening of operation, a thing which you have never imagined. So, there is no need to undergo stabilization and this and that. I will say if you have some in issue, you please come and we will have together we will see cases, but you don't lose this opportunity to give new life to this patient. This patient was operated 13 times. You see there is a shunt here and decompression and ventriculoperitoneal shunt, theco-peritoneal shunts. Then, I did this fixation, very educated and top graduate from a technology institute, and he got back into life. He had come with tracheostomy with to me and various kinds of things and new life. When we wrote this article, there was a big hue and cry from the Pediatric Society of North American Neurosurgeons. They said it does not work in pediatric neurosurgery. They said it does not work in cases where there is no bone abnormality. They said that it works only for Indian patient, may not be for American patient. These kind of things are not such great. You see these pediatric patients or no pediatric patients, Chiari is an indicator of unstable atlanto-axial joint, whether there is facetal malalignment or not, whether there is atlantodental interval disturbance or not. Presence of Chiari, presence of syrinx indicate the need for atlanto-axial stabilization. Then, I said that cervical fusions like Klippel-Feil abnormality, C1 assimilation, C2-3 fusion are all secondary to chronic instability and they are protective and they are potentially reversible. So, this patient, there is no compression at the craniovertebral junction, but presence of fused subaxial bones is an indicator of atlanto-axial instability. This girl was not even able to breathe properly, got a brand new life after surgery and completely new life. This was a daughter of a press. So, it was heavily introduced in the press, this patient. C2-3 fusion, C3-4 cord compression. The problem is C1-C2 instability. You see there is a multisegmental here. But there are problem of central instability and you have to treat atlanto-axial instability for this. Is C2-3 fusion an evidence of atlanto-axial instability? Absolutely yes. You see there is compression here. There is C2-3 fusion here. Compression is here, but instability is here. You have to do atlanto-axial stabilization. Don't mess around in this area. This may be a negative form. You do stabilization and you see the magic. Bifid is secondary to chronic atlanto-axial instability. Bifid is protective, bifid is dynamic, bifid is indicator of C1-C2 instability. Bifid is an indicator of atlanto-axial stabilization. So, there is bone fusion here, there is bifid here, there is no compression here. There is a need for atlanto-axial stabilization and there is no question of the beautiful outcome. Os odontoideum is secondary to chronic atlanto-axial instability. When you see os odontoideum, it means it is unstable atlanto-axial joint. There is no need for any kind of decompression. There is a need for stabilization and there is a need for realignment. Even we have discussed in our article, this cyst is secondary protective, natural phenomena. Syringomyelia is secondary, protective, natural, and helpful, and not harmful. You see this is such a diversion of concept and I have no hesitation to say that the whole world of syringomyelia probably, probably has changed after this concept. Otherwise, syringopleural shunts and syringo shunts and all those shunts were very commonly done. Nowadays, I don't think many people do this. Now, you see this case. I mentioned when syrinx can be present with Chiari, without Chiari, with basilar, without basilar, with fusion, without fusion. Syringomyelia without Chiari or idiopathic syrinx as we have learned to label these patients is an indicator of unstable atlanto-axial joint. Stabilize and see the magic. Absolutely idiopathic syrinx on several occasions can be due to C1-C2 instability. Musculoskeletal changes in basilar invagination like short neck, torticollis, are not primary phenomena. They are secondary to chronic instability. You do atlanto-axial stabilization, the neck will become long, the neck will become straight, and there will be a beautiful smile after surgery. Atlanto-axial instability is primary and these musculoskeletal anomalies are secondary. You can give beautiful smile, not so beautiful in this case, but neck is straight and long in very early post-operative period. Atlanto-axial instability is the cause and stabilization is the treatment. So, we have treated several, several patients like this. We introduce the term externals syringomyelia. This is external syringomyelia, external syringobulbia. Presence of fluid inside the cord, presence of fluid outside the cord are not a problem. They are solutions and they indicate chronic instability and they indicate the need for stabilization. Syrinx can be present inside the cord, outside the cord. There can be fluid inside the medulla. There can be excessive fluid outside the medullas. External syringobulbia, these things are very important even in chronic tumors, we introduced that there can be external syringomyelia. You see there is a chronic small I don't know what the tumor is, but you see there is excessive fluid here. Excessive fluid here. These are naturally protective phenomena. Water is life. Water can never go wrong. In basilar invagination, there can be short neck, short head. You see short head. Short neck is associated with torticollis. Short spine is associated with kyphoscoliosis. You see and these are indicators of these basilar invagination, indicators of atlanto-axial instability, and give the need for atlanto-axial stabilization. So, these kind of patients with torticollis, you can make them straight, you can give them beautiful smile, you can make them kings and wonderful. Only thing is you have to learn the technique of C1-C2 fixation. I said short neck is associated with torticollis. Short spine is associated with kyphoscoliosis. In this age group, my feeling is at least 80% of patients in this age group have central or actual atlanto-axial instability. And atlanto-axial stabilization is the treatment. And you see this curvature and this curvature in the very early post-operative period, the curvature has gone more important than these curvatures. The whole system, whole body becomes new and magically new life. And intra disc motor-evoked potentials can reverse during the fixation. This patient was with syringomyelia and Chiari. You fix, there was some 40% improvement in motor-evoked potential. So, central or actual atlanto-axial instability can be cause of cervical myelopathy. This is a very novel kind of phenomena and you have to understand, and if you realize this can change the treatment. So, in this patient, there is bifid, which indicates atlanto-axial instability. When there is bifid, you don't even have to see the joint. It is unstable. There is syringomyelia. It indicates the presence of unstable atlanto-axial joint, the treatment is atlanto-axial stabilization and the result is absolutely fantastic. These kind of kyphoscoliosis can be due to degenerative spine. I will like to talk on this subject in my next lecture with Aaron, and I want to talk about atlanto-axial instability in such a situation. You see the shoulder is not proper. In the immediate post-operative period, the shoulder is up, the shoulder was down here, the shoulder is up in the immediate postoperative period. So, you can have the potential of doing differently. So, I am saying transoral surgery is completely and historical operation for such issues, not for throat tumors and all those things. I am now saying that foramen magnum decompression surgery can become absolutely historical. The problem is, and the issue is that you have to learn the art of doing this operation. So, I'm going to show you one case where there is a simulation of atlas. This is a operation I had done for a workshop and it was recorded. The issue is I don't have the possibility of going further and fast in this situation. Identify the C2 spinous process. Identify the lamina of the C2. Subperiosteal dissection. You see this is the C2 lamina. Then, go... This is the patient with assimilation of atlas. This is almost unedited tape, maybe a little bit here and there editing, but not much. You see here the C2 ganglion width articulation is flattened over the C1-C2 articulation. Now, I'm opening the articulation. You see this C1-C2 articulation I am opening. I will introduce an osteotome in the C1-C2 articulation, then expose the articulation widely. Wide exposure is the key. And if you have to cut the ganglion, you have to cut the ganglion. But as I mentioned to you nowadays, I don't cut the ganglion very often. If I have to cut, I cut little bit of ganglion here and there, but not the entire thing. But if possibly, if it is necessary for the exposure, you have to do it. Now, you see I've introduced the osteotome in the articulation. You see here the whole C1-C2 articulation. This is a little bit tricky case, but you see even in this situation, I don't like to do any other kind of treatment other than C1-C2 fixation. This is the articular cartilage of the articulation capsule of the joint. I am elevating the C2 ganglia. This is a little bit oblique my direction. As this is almost an unedited version, you please bear with me. See now, I have opened the C1-C2 articulation widely. Then, I am drilling the region where my plate will come, so that it can be right in the region of pars and pedicle. So, my dear of friends, I hope you have enjoyed this journey of C1-C2. This is a journey of C1-C2. This is not the journey, craniovertebral junction is occipital C1 and C1-C2. My craniovertebral is just C1-C2. Occipital C1 incivility is extremely rare. If I am saying I have done 3,000 cases of C1-C2, I have not done a single case of occipital condyle C1 instability. Absolutely rare. Sometimes in pediatric age group in syndromic children. Otherwise, an extreme highest degree of trauma, you might just get C1, condyle C1 instability. Otherwise, it is always C1-C2. In Chiari and syrinx, always C1-C2. Never include occipital bone in your fixation construct. So, lot of bone in the joint. Learn the art of opening the joint. That is the bottom line of the C1-C2 operation. Minimum or no coagulation. You see coagulation of all these tissues can introduce not only burning of tissues, can introduce infection in the region. When there is an implant, we have to avoid all kind of... I have to tell you that never in my career I have reoperated or reopen a C1-C2 fixation, which I have done, never. And I related to minimum or no coagulation and quick operation. So, in my next lecture, I want to go further on the issue of craniovertebral junction, craniovertebral junction degeneration, the issue in rheumatoid craniovertebral junction, the issues in tuberculosis craniovertebral junction, the issue in degenerative spine, the issue in OPLL, the issue in deformities of cervical spine and craniovertebral junction, the issues in Hirayama disease, and several other situations I will like to discuss with you in my next lecture on this platform. See, as I mentioned to you, you can use rods, but you see this is such a... You can tighten the screw on the plate and this is on the facets. So, that is the advantage. The rod is a little bit away from the facet. I'm not saying that is wrong technique or a bad technique. I use it sometimes, but I like to show you this one, because this is my basic stronghold, this is my technique, which I described in 1988. And this is the technique that I like to show and use. This is a solid technique, beautiful technique, quick and fast and sure. Maybe I like to stop here. Is it okay? Most important thing which I want to tell you is, that after you are done with the plate and screws, you have to remove all the muscles attached to C2 spinous process, drill the C2 spinous process, drill the arch of atlas. You have to when you are introducing the screw in C2. You have to feel the pedicle. You have to identify the Vertebral artery region, and then you have to introduce the screw. I think that is very critical and very important. So, both the size, the screws are tightened, and this patient is cured. Bone is inside the joint and it will eventually stabilize. I have mentioned to you, instability is the issue and stabilization is the treatment. Even if your odontoid process has not come back to complete normalcy, it doesn't mean anything. You just, if it is stable, it is finished. That is the operation. Instability is the issue and stabilization is the treatment. Arthrodesis is the aim of operation. Arthrodesis will occur if you are able to provide a zero movement situation. Arthrodesis will occur if you have provided the opportunity, you have introduced a lot of bone graft in the region, and you have prepared the host bone and you have prepared the region properly. So, some of these issues, which you have to learn from orthopedics where how to make the environment suitable for bone fusion. That is absolutely important. You see you can tighten the screw over the facets. That is the advantage of plate and screw method of treatment. Now, I want to show you one important thing which cannot be neglected. This operation, here you see this is the C2 spinous process. You see the muscles attached to the C2 spinous process, huge muscles. You have to cut those muscles sharply. You see now here, motor-evoked potentials have been... I don't normally use this is stimulation. Nothing will move now. You see these muscles have to be cut over the C2 spinous process. You have to cut these muscles. They are so strong. If you don't cut, they can demolish the implant. That is why I say anterior surgery cannot be a viable option, because these muscles are not cut during anterior fixation. And if you are not cutting these muscles, these muscles will break any implant that you have put from front. That is why I'm saying the entire body, the whole muscles, the entire body musculature is extensively predominant, because of standing human position. There is nothing in front. There is no muscle in front in the vertebral bodies, in the region of the disc, in the region of a very thin, flimsy, longus colli is there. That is not the muscle, which is... These are the muscles. They are the powerhouses of our body. You have to drill this area nicely. Prepare the host bone beautifully. That is what I wanted to show you, because this is one critical part of the operation. You do this, you intro... Now, you see so much bone graft I'm introducing here. And this bone graft will fix in 15 days. You will find the whole thing fused. You see this bone graft? So, my dear of friends, my dear Aaron, thank you very much. I am sure, I hope, that you enjoyed this presentation and I hope many of the audience will love, enjoy craniovertebral junction, because it's such a great operation, such as rewarding operation, gratifying surgery. You must learn it. Thank you very much.

- Atul, thanks for a very, very intriguing lecture. Incredible contributions. It's just the innovative spirit of yours has been a model for so many of us. I think, the concepts you presented for craniovertebral instability is so important for overall understanding of this disease and how we're gonna treat it in the future. So, I wanna congratulate you for being such a role model for so many of us, and importantly, I look forward to the next lecture series where you're gonna talk about other aspects of spine instability. So, thank you again.

- Thank you, my dear Aaron. It has been a pleasure. I have been waiting for your invitation for a long time, I must tell you, because your forum is one of the most, I must not say glamorous, but it is most wonderful and important and very widely seen. Thank you very much for inviting me, Aaron. I look forward to my next one.

- Thank you. It was honor to have you. Coming from you, it means a lot.

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