A pinched nerve causing neck and/or arm pain is one thing. But when the spinal cord in the neck area gets pinched or compressed, that’s more serious. Permanent paralysis can develop if the problem isn’t corrected. One of the most popular surgical procedures to decompress the spinal cord is called an open-door laminoplasty. This study takes a look at why the procedure fails for about 10 per cent of patients and what to do about it.
The lamina is a ring of bone around the spinal cord to protect it. And it works very well in doing so until outside forces create a stenosis or narrowing of the spinal canal. And then suddenly, that protection becomes a problem. Aging and the degenerative changes associated with getting older are the most common reasons for spinal stenosis. For example, disc degeneration brings vertebral bones and spinal joints closer together. Closer proximity of the bone and joint surfaces without a healthy disc to hold them apart can cause bone spurs and other bony changes to develop.
The posterior longitudinal ligament (PLL) along the back of the spine thickens and takes up additional space inside the canal. Disc degeneration and arthritic changes cause the vertebral bones to shift or collapse slightly. Even a minor shift in the vertebral bone alignment can put pressure on the spinal cord.
A laminoplasty involves cutting through the lamina on one side and swinging the bone away from the spinal cord. It’s much like swinging a door open, which is why it’s called an open-door laminoplasty. The surgeon places a laminoplasty plate on the opposite side to help hold the door open. It’s a popular procedure because patients get pain relief without causing harm or injury to any of the soft tissues or spinal structures. Recovery from neurologic symptoms following an open-door procedure is as high as 72 per cent.
But sometimes the procedure fails. That’s where this study comes in. The surgeons wanted to take a look at why failures occurred and figure out what to do about it. They reviewed the medical records of 130 patients who had a cervical laminoplasty over a 10-year period of time. An after-the-fact review of this type is called a retrospective study. The authors believe this is the first and only study to report on what happens after a failed open-door laminoplasty.
By carefully analyzing the data available on these patients, it was clear that there were three major reasons why the procedure failed. Surgical technique was the most common cause of failure affecting 25 per cent of the cases. In particular, the use of the suture anchors used at that time to hold the door open was not successful. In other cases, it was a matter of the underlying problem (arthritis, degenerative changes) continued to get worse, causing more stenosis. This cause is referred to as disease progression. And in a few cases, there just wasn’t enough decompression to relieve the spinal cord compression.
In all three cases, symptoms got worse and a revision surgery was needed. The type of revision procedures that were done varied. For some patients, the surgeon just removed the lamina. This procedure is called a laminectomy. If enough of the lamina bone was removed, then the spinal segments were fused together to provide stability. Fusion procedures can be done in a variety of different ways depending on where the surgeon enters the spine (anterior from the front, posterior from the back, or circumferential around two or more sides). To highlight what can happen, the authors presented four individual cases and showed MRIs and X-rays to illustrate the various problems.
The authors now use laminoplasty plates instead of suture anchors to keep the lamina door open. This is especially important for anyone who has poor head control, which was the case in two of their failed cases. One patient had excess head and neck movement due to cerebral palsy and the other had low muscle tone and poor head control because of Down syndrome.
They conclude that open-door laminoplasty is still a good surgical procedure to use when there is spinal cord compression in the cervical (neck) region. It is a motion-preserving technique that usually works quite well. But patients should be advised that the procedure isn’t always 100 per cent successful. There is a slight chance that they could end up with only partial relief from their symptoms. Or the symptoms can get worse over time when there is disease progression.
A second (revision) surgery (usually a fusion) may be necessary. The type of fusion performed depends on the underlying cause of the failure. The authors use posterior fusion when the lamina door has closed, anterior fusion when symptom relief isn’t enough, and a circumferential approach when there are spinal deformities present or when the door hinge breaks and doesn’t heal (nonunion). More studies are needed to find out how successful are revision surgeries and when it is best to use each type of approach (anterior, posterior, circumferential).