Cervical Laminoplasty

INTRODUCTION

My name is Doctor Louis Jenis. I'm an orthopedic spine surgeon at the Boston Spine Group here at Newton-Wellesley Hospital. I'm going to describe a cervical laminaplasty in one of my patients. In general, the overview is that we bring the patient into the operating room, and after induction of general anesthesia, we place the Mayfield tongs onto the skull for prone positioning. After the patient is positioned, we then carefully perform an exposure of the posterior cervical spine and identify the appropriate levels for the laminaplasty to be performed. We create the laminaplasty defect and then hinge it open. The next step is to keep the hinge open by placing laminaplasty plates or instrumentation. The last part of the procedure is closure, and after the patient is returned to the supine position, the Mayfield tongs are removed and then - he is then excavated.

CHAPTER 1

So what we'll do is just mark out some landmarks here. This is the base of the skull. Midline. C2 spinous process should be right around here and C7 in this general area. So soon as - we'll just make an incision here.

Okay, so we'll - we'll start. So midline incision. So we just kind of slowly dissect down to the ligamentum nuchae, and the more midline we stay, the less bleeding will occur. C2 right here - and we'll just try to stay midline. The more midline you stay, the less muscle dissection there is. A little deeper. So we dissect right down to the tip of the spinous process. So after we get down to the midline, we'll start dissecting the paraspinal muscles off the spinous process and the lamina, and we try to stay subperiosteal as much as possible.

And then we start to come down on the lamina on each - at each level. C2 spinous process is right here. The - the muscle attachment, see, coming onto the C2 spinous process is very important to maintain, and if they are detached, at the closure we'll often try to reattach them for stability of the upper cervical spine. So we try to maintain them as much as possible. The other muscles are all stripped pretty easily though. So as we do the exposure, the sponges, which helps retract the muscle - and it also helps to control bleeding - and we will often just alternate side to side with the exposure until we get up to the junction of the lateral mass and lamina. So now we'll just dissect the other side. Okay? You see? I think that's too risky. You'll see that the tips of the spinous process are bifid. So you can see the spinous process here with both sides of it are almost bifid, which means when we're dissecting along the lamina, we often have to come around the spinous process to get to the lamina. And the Cobb retractor - the Cobb elevator allows us to pull the muscle away from the side.

Then we'll just take a localizing x-ray - just confirm the level of our dissection. Alright, two Kochers. So to mark the level, we'll put a Kocher clamp on the spinous process. Dental. The other way to mark the level, we could put something into the facet joint to mark, and we'll take a quick picture.

Okay, so C3 is right here. This is the lamina. This is the lateral mass on this side. So what we don't want to do is dissect too far onto the lateral mass capsule, which could potentially cause some instability postoperatively, so we try to stay a little bit superficial - preserve the facet joint capsule as much as possible. And the important landmark that we want to find is that junction of the lateral mass and lamina. That'll be the site of our laminaplasty - osteotomy will be right there. So that is as far as lateral as we typically need to get. Alright, so 3, 4, 5, 6, and 7 - great. So the first step of the procedure is the exposure. We have our levels marked. This is C3, C4, C5, C6, and C7. We can see the lamina and the lateral mass. The important anatomic landmark here is the junction of the lateral mass and lamina. Basically it's a small valley right here between the two. That's the site of the osteotomy. So we're going to hinge it open. The hinge on the right side will open it on the left side. So we're going to osteotomies the outer and inner cortex on this side, and on the right side, we'll just osteotomies the outer cortex and greenstick fracture the lamina open.

CHAPTER 2

So we'll start at each level, and then we'll go to the other side. 10-4. As we go through the outer cortex, we feel for the inner cortex, and the softness that we'll feel next will be the ligamentum flavum. Suction at 5. There we go. Good - that's nice and soft.

Okay. So typically, when do we do the osteotomy, the bleeding is going to occur from some epidural vessels. And sometimes we just take some bone wax, and we can use that to kind of tamponade the - the epidural. Give me some FloSeal. Let's actually use that in a sponge. Okay.

Let's - let's try working on your side now. So after the left side is osteotomized, now we'll make the hinge on the right side. Tell me when you're going.

Ready? On. Put that retractor back in.

So the next part of the procedure after we make the osteotomy on both sides is to start releasing the lamina and creating that greenstick fracture. Basically, what I like to do is put a Cobb in and in turn, very gently, you can start to see some give of the lamina. And we'll just kind of work each level as we go here, so we'll go to the next set. Ready? Go. Close up higher. And same thing - we just got to give it a little twist. Start releasing it. That's getting there - you can go just high. Tell me when. And it's been opened. I'm going to move this down a little bit. And it's going to open. Let's see - can you see there? Do want to move this down more or less? Could be my side to if you must. Just score it a little deeper in yours - then we'll go back to mine. There we go. Yeah, I think I can see my top end and my bottom end here.

CHAPTER 3

Small Cobb. So at this point the - the - the laminaplasty, the greenstick, has taken place. We are now ready to create that hinge, and what we're going to do is take this small instrument that's going to allow us to retract the lamina open. This is the time in the case that you just want to be patient and allow that lamina to just - to retract. The amount of retraction is variable. I tend to go for about 8 mm and that allows enough central canal decompression in for the spinal cord to migrate posteriorly. So what we'll do is just kind of grab the - grab the edge a little bit and just slowly start working that. Semos, if you could just reach around and hold that.

Two ways to do it. You could certainly use a retractor such as this. The other way is just with your thumb and pushing on the spinous process to create that - that gap. So the sucker is on the ligamentum flavum and right underneath that is the spinal cord. Here you can see the ligamentum flavum, and sometimes that ligamentum flavum will prevent the laminaplasty from opening, so we can release it with a curette that allows a little bit more play. There we go. I'll take the plate please. I could just suck that in one area right over there. So the laminaplasty plate - there's a lot of different types. This particular type that I use: the edge will sit over the lamina and the lateral edge on the lateral mass here. The width of this is 8 mm, which will allow us to do open up this defect by about 8 mm. Come off of that. Good. So we we retract and try to get the edge under the lamina. Think I'm stuck on the muscle here. Let that go down. Surgicel. Okay another plate. Try to come under. Okay, let that come down. So as the lamina is a - is released, the edge of the plate will sit right on the lateral mass, and that'll help maintain the opening here. It's not necessary to have instrumentation at every level. Go out there.

Go up to that four. Go up to this one over here when you're ready. Okay, can we have the screws now? So once the plates are in place, then we'll use a starting-all, and then we'll drill each one. Typically one screw into the - into the lamina and two screws into the lateral mass. Like that looks done. That's - no - it's kinda up too high, huh? Nice and easy. I think you got it, no? All. And then another screw. Bring your hand towards me a little Semos. All and an 8. Try to medialize a little - I'm not sure how much we are at the lateral edge here. Cobb. Cobb.

CHAPTER 4

So the instrumentation is in. We have a little bit better hemostasis on the epidurals, which we're going for a little bit.

At this point, what I like to do is resect the spinous process. Resecting the spinous process allows for closure of the fascial layers a little bit easier. Otherwise, they tend to be very prominent to the other side. So we'll - we'll take this bone off of several of these. So you... It's important when you take off the spinous processes at this point of the surgery not to twist and not to disrupt your instrumentation. We'll take each of the bifid at each level. We'll also use this bone to place along the hinge for extra healing of the - the hinge side, the greenstick side, of the laminaplasty.

CHAPTER 5

He's really harmless, but he's just painful. Are you going to put a gown over it? I am. It's going to go into this lightbox here. Is that what you're talking about? Yes so it's just hooking up to here.

DISCUSSION

So this patient has progressive neurological symptoms. He has the diagnosis of cervical spinal stenosis and is developing progressive numbness in his hands as well as weakness and clumsiness. So on this examination, he had a couple of findings that are very consistent with cervical spinal stenosis. One being hyperreflexia in both his upper and lower extremities and also pathological signs such as Hoffman signs.

So a Hoffman sign is when patients will have hyperreflexia in their upper extremities. And it is manifested by flicking of their middle finger, and you'll see concomitant flexion of their thumb at the same time. It's not fair to me a sign of upper motor neuron dysfunction. So the problem of Hoffman sign in particular is that it can be present in asymptomatic patients. So that's why it's very important to do a complete physical examination and correlate any examination findings with their MRI.

So the imaging work-up on this patient included plane X-rays and an MRI scan. The plane X-rays showed well-maintained lordosis of the cervical spine and no instability or significant degeneration on his flexion-extension views. The MRI was particularly impressive because of the multiple level spinal stenosis. There was also evidence of an intrinsic cord change behind the C4 vertebral body, which is called myelomalacia - a - again a very common sign we see with a spinal stenosis.

So the goal of a laminaplasty procedure is to decompress the spinal cord. In effect, we're trying to halt any further progression of neurological symptoms. So the reasonable outcome in the - in this situation is to halt any progression of numbness or weakness or lack of coordination. Typically, the - this type of procedure as well as a laminectomy infusion are very successful in doing that. There's very uncommon instances where patients will continue to have neurological decline, but the vast majority of them do experience some improvement. That improvement can take weeks to months at times, and some people will not peak in the neurological recovery up until a year after their surgery. So we follow these patients very closely. Decline after that period of time is very unusual unless there's an adjacent level problem that may be contributing to new onset of neurological symptoms.

So there are several surgical alternatives here, and we basically think about this as an anterior approach versus a posterior approach. So posterior cervical approaches are typically broken down into laminaplasty or a laminectomy or a laminectomy infusion. I think laminaplasty has some significant advantages though because effusion is not - is not performed. Theoretically at least, that patient is allowed to move a lot quicker, and they're not immobilized for a long period of time. And typically in the younger patients, we find that their range of motion is well preserved. Patients who have a laminectomy infusion well obviously we will lose some motion there, and I think this is a big advantage for a laminaplasty.

Certainly with a laminaplasty or a laminectomy infusion, there are some risks associated with them. One of the problems that we all see with laminectomy infusion is that the instrumentation certainly could loosen. If the fusion does take well, that does place the adjacent levels at risk for breaking down in the future also.

So cervical laminaplasty has been performed for the last several decades. It originated in the Far East, specifically in Japan. Patients there - a very high preponderance of what's called ossification of the posterior longitudinal ligament, or OPLL - basically spinal stenosis due to formation of bone. Cervical laminaplasty has gone through several iterations of techniques, and over the last decade or so, it's really been incorporated into a lot of United States spine surgeons' practices. It has significant advantages like, we said, of allowing early mobility, but there are some contraindications too that we should think about. And patients do need to have really good lumb - cervical lordosis - so maintain lordosis because that's how decompression is achieved, allowing the spinal cord to migrate posteriorly.

There are several types of laminaplasty procedures available to us today. Some are - really approach from the midline, and we'd call that a French door laminaplasty where the cut is raid - made right down the midline, and both hinges are then opened. The procedure that we're going to do today is called an open door. It's an asymmetric opening where one side is hinged open, and we keep the opening with instrumentation on that side. There's a lot of forms of instrumentation that have been used over the years, and sometimes we place just bone graft, suturing it in. And really the evolution has gone to very rigid laminaplasty plates, and that's what we're going to use with this patient.

So the real perils of this procedure - beyond positioning, beyond marking the levels - is to really be careful with placement of the trough. It has to be at the junction of the lateral mass and the lamina. If the trough is made a little bit too laterally into the lateral mass, you - more bone is removed, and it's very hard to open up the lamina. If the trough is made to mediately you're not going to get as much of a decompression. So really attention to landmarks and really looking for that junction where the lateral mass and lamina connect is really where you want to start the trough. So that junction where the lateral mass and lamina meet is the thinnest part of the cortical part of the bone, and that allows for much easier ability to open up the spinal canal.

So the patient needs to play a big role in the recovery in these procedures. Years ago, we used to immobilize them with a very rigid external collar. We thought that was the case because we wanted to get those hinges to heal, but we also found at that time that patients lost a lot of range of motion. So today, these - our patients are placed into a soft collar for comfort for - for a week or two, but then they're really encouraged to get moving. The advantage of instrumentation and the lateral mass plates is that we can start pushing them quicker. So we start an active range of motion pro - program with their neck and shoulders very quickly after surgery. So when they come back and see me after 4 weeks for their first visit, I want to hear that they're walking, they're carrying some light weights, and they're moving pretty well with their neck. Each patient is different in terms of getting back to their life. I would expect that at that first visit - at 4 weeks - most patients are pretty comfortable. We would likely place them into a gym at that time for some slight exercises with the typical recovery about three months, having them back to their life and doing most activities. We would probably restrict them from contact activities for some time until we're really assured of some adequate healing in their neck.