C1-C2 fusion is all the rage among patients with CCI. So what is it and what are the side effects? Should you get a C1-C2 fusion? Let’s dig in.
What is Craniocervical Instability (CCI)?
Craniocervical instability (CCI) is when the upper neck levels of the spine are unstable (1). This is usually C1-C2, but can also be C0-C1. There are a number of strong ligaments that hold this area together which can be injured or loose and there are a slew of measurements used to determine if CCI is present. Common symptoms can include headaches, dizziness, imbalance, upper neck pain, visual disturbances, rapid heart rate, and various pains elsewhere, just to name a few.
What is C1-C2 Fusion? Why Is It Done? Are there Different types?
C1-C2 fusion means using screws, rods, or bone to make sure that the C1-C2 joint doesn’t move. While the most common reason this rare procedure was performed used to be because of an upper neck fracture or severe ligament rupture, these days more of these procedures are performed in patients with ligament laxity leading to upper cervical instability. This is where this review of C1-C2 fusion will focus.
C1-C2 Fusion Risks
Now that these procedures are being performed for non-life threatening injuries like ligament laxity, the risk-benefit ratio is different. For example, when a patient with an upper neck fracture may die or become a high quadriplegic if the fracture isn’t stabilized, the risks allowed for the surgery can be quite severe and the risk versus benefit equation still makes sense. However, now that these invasive procedures are being performed for patients with loose upper neck ligaments due to damage or congenital problems like EDS, the risk-benefit bargain can be a bit off. Let me show you what I mean.
Nonunion
One of the big risks of any fusion surgery is that the joint being fused never actually grows together. For these procedures, accurate information that applies to adults is hard to find, as many of these surgeries are performed on children with congenital abnormalities. However, at least one author states that nonunion rates can be high with these techniques (5). However, there’s nothing like a good case report to make complications personal. Katie is a twenty-something I treated several years ago. She had a C1-C2 screw fixation performed for CCI after a DMX showed too much movement at C1-C2 and nothing else was helping. Regrettably, the joint never fused, leaving her with new strange movements of the C1-C2 joint as it now pivoted around the screw going through it. The joint was also damaged by the screw and still moving, making her headaches worse and not better (pain from the C1-C2 joint refers to the head). She was also not a good candidate for our PICL injection procedure due to the surgery. Through injections of PRP into the C1-C2 joint, we were able to get the joint to fuse, but she also had damage to the nerves and extra force across the C0-C1 joint leading to new pain there. These areas were treated with platelets and stem cells with some improvement.
Misguided Screws
A big issue we’re seeing in the clinic is the fact that these screws placed into bone are hard to guide. Hence, they can inadvertently reach places that can damage structures. For example, the screw can hit the vertebral artery and damage it, end up hitting and damaging nerves, and even destroy the C0-C1 joint. Since these screws are large, what they hit is usually obliterated. The vertebral artery runs through the neck bones and this upper neck area. It supplies blood to the back of the brain.
The good news is that most people have one on each side, so losing one vertebral artery can often be compensated for by the other. Realize though, that destroying one of these arteries with a big screw is still a very bad thing. For example, in an older patient, this could lead to a stroke (blood clot or other debris floating into the blood supply of the brain). This happens 4-10% of the time with upper cervical fusion (2,4).
Damage to the upper spinal nerves can also happen (3). The most common nerve injury is to the C2 spinal nerve (3). This supplies the back of the head, so damaging it can lead to chronic headaches. As discussed above, the C2 spinal nerve is also sometimes sacrificed in the surgery itself. That means it’s taken out by the surgeon because it’s in the way of the desired screw placement. This can also lead to chronic head pain about 1/3 of the time.
The destruction of the C0-C1 joint is also possible and frankly, one of the most common complications I have seen. Here the screw is placed too high and travels through the C0-C1 joint, which destroys the joint. This means that the screw causes arthritis in the joint, which is bone and cartilage damage. So the C0-C1 joint becomes a new source of pain. This joint also causes headaches at the back of the head.
C0-C1 Joint Damage Case Reports
The most common complication I see with these C1-C2 fusion surgeries is that the screw goes into the C0-C1 joint. This is a BIG problem. Why? This destroys the cartilage and bone in the joint and leads to instant arthritis. Since this joint commonly refers pain to the head, it can cause instant and new pain at the base of the skull. Let’s go over two patients that were sent to me after this happened.
Th
Adjacent Segment Disease
Adjacent segment disease (ASD) is the bane of every fusion, making the biggest hit to its success rate. ASD happens because all spinal levels are built to move just a little bit. When that movement is stopped due to fusion, the levels above and below take too much force and can develop degenerative arthritis and breakdown. Here the C1-C2 joint is responsible for half of all of the rotation of the head on the neck, so fusing it dramatically increases force both on the C0-C1 and C2-C3 joints above and below. Meaning that over time, you can expect these levels to break down in most patients.
The Other Side of the Argument
There are patients who really need this surgery. In fact, I can remember one patient from more than a decade ago who had life-changing results. Having said that, I’m seeing much higher complications and side effects than have been reported by surgeons in the literature. Hence, trying less invasive procedures, such as our non-surgical treatment for craniocervical instability, first just makes common sense. The upshot? Upper cervical fusion is not a routine spinal surgery. It’s much higher risk than the average procedure due to the vertebral artery as well as the other problems I’ve shown. In addition, I’ve seen far too many screws inadvertently placed into the C0-C1 joint which destroys it and often causes new pain. So while there are a handful of patients that really need this surgery, it’s always a good idea to try less invasive procedures first before fusion.
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References: (1) Mathers KS1, Schneider M, Timko M. Occult hypermobility of the craniocervical junction: a case report and review. J Orthop Sports Phys Ther. 2011 Jun;41(6):444-57. doi: 10.2519/jospt.2011.3305.
(2) Gluf, W. M., & Brockmeyer, D. L. (2005). Atlantoaxial transarticular screw fixation: a review of surgical indications, fusion rate, complications, and lessons learned in 67 pediatric patients, Journal of Neurosurgery: Spine, 2(2), 164-169. Retrieved Jan 8, 2020, from https://thejns.org/spine/view/journals/j-neurosurg-spine/2/2/article-p164.xml
(3) Myers KD, Lindley EM, Burger EL, Patel VV. C1-C2 fusion: postoperative C2 nerve impingement-is it a problem?. Evid Based Spine Care J. 2012;3(1):53–56. doi: 10.1055/s-0031-1298601
(4) Schroeder GD, Hsu WK. Vertebral artery injuries in cervical spine surgery. Surg Neurol Int. 2013;4(Suppl 5):S362–S367. Published 2013 Oct 29. doi:10.4103/2152-7806.120777
(5) Ghostine SS, Kaloostian PE, Ordookhanian C, et al. Improving C1-C2 Complex Fusion Rates: An Alternate Approach. Cureus. 2017;9(11):e1887. Published 2017 Nov 29. doi: 10.7759/cureus.1887