Iatrogenic Instability of the Cervical Spine Overview
This is an example of what can happen when the spine becomes unstable after a simple laminectomy in the cervical spine. When normal, the cervical spine sits in a backwards curve called a lordosis. This curve allows gravity to “push” the vertebra backwards to align each vertebra properly. As the discs degenerate as these structures will to some degree in all of us, this curve can be lost and the spine “falls forward”.
This falling forwards puts pressure on the facets (the joints in the back of the spine) and can lead to a degenerative spondylolisthesis. This is a condition where the facets in the back of the neck wear out and allow the vertebra above to slip forward on the vertebra below. This slip can then create narrowing of the spinal canal called central stenosis. Of course, spinal canal narrowing can then lead to compression of the spinal cord and spinal cord dysfunction (called myelopathy).
In the example of this patient (who already had a fusion of the level below), she did develop a degenerative spondylolisthesis as noted in the first picture to the left (arrow points to the beginning of a slip). She did indeed also develop spinal cord compression and myelopathy. The surgeon decided to perform a laminectomy to open the canal and decompress the cord.
The second picture from the left has two arrows. The upper arrow points to the laminectomy (look at the missing spinous processes when compared to the first picture). The lower arrow points to the slip of C4 on C5 which is greater than the original slip. At this point, great care needs to be implemented to make sure the slip does not progress. Suggestion of an anterior fusion (ACDF) should be considered at this point.