Abstract
Adjacent segment disease (ASDI) is a well-described complication of spinal fusion surgery that may ultimately lead to spinal stenosis and repeated surgical intervention. Although congenital block vertebrae also present with degenerative changes in the adjacent segments, this has not yet been systematically investigated. The aim of this study was to assess the presence and degree of ASDI in congenital cervical block vertebrae. Methods: A total of 51 patients with congenital vertebral fusion in one cervical segment were analysed in this IRB-approved retrospective cross-sectional study using available CT/MR imaging. Exclusion criteria were prior spinal surgery and the presence of additional hereditary abnormalities. We assessed the severity of degenerative changes using a sum score. The sum score for adjacent and non-adjacent segments was then divided by the highest possible degeneration score, which resulted in a ratio of severity for adjacent and remaining segments (ranging from 0 to 1). Results: Overall, 35 of 51 patients (68.6%) showed evidence of ASDI, and 34 of 51 patients (66.7%) also showed degenerative changes in the remaining segments. The severity score was significantly higher (p = 0.025) in the segments adjacent to the congenital block vertebrae (mean value 0.307) compared to the non-adjacent segments (mean value 0.188). Conclusions: Our results suggest that ASDI is also caused by congenital block vertebrae of the cervical spine.
Highlights
Accepted: 18 November 2021Congenital block vertebrae are the result of a segmentation disorder in which the chorda dorsalis fails to form the nucleus pulposus, resulting in a rudimentary fibrous intervertebral junction or the complete absence of any disk-like structure [1]
The search interval included the years 2000–2015. These radiological reports were subsequently screened for potential congenital block vertebrae, which resulted in 165 patients
Osteophyte formation, herniation of intervertebral disks, spinal canal stenosis, and luxation in neighboring facet joints are hallmarks of spinal degeneration, which lead to an increase in the biomechanical loading of adjacent spinal segments and consecutively to malalignment and degeneration of neighboring segments [12]
Summary
Congenital block vertebrae are the result of a segmentation disorder in which the chorda dorsalis fails to form the nucleus pulposus, resulting in a rudimentary fibrous intervertebral junction or the complete absence of any disk-like structure [1]. Most congenital block vertebrae present in the cervical spine. Congenital block vertebrae can be differentiated from acquired vertebral fusion. Rudimentary intervertebral disk material (chorda remnants) may be seen around the zone of fusion, if not a smooth trabecular structure with no signs of scarring. The height of the block vertebra usually equals the combined height of two vertebral bodies plus one intervertebral disk [4], whereas the anteroposterior diameter and the intervertebral foramen is reported to be Published: 31 December 2021
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