Morphological characteristics of diffuse idiopathic skeletal hyperostosis in the cervical spine

Objectives
Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by anterior ossification of the spine and can lead to dysphagia and airway obstruction. The morphology of the newly formed bone in the cervical spine is different compared to the thoracic spine, possibly due to dissimilarities in local vascular anatomy. In this study the spatial relationship of the new bone with the arterial system, trachea and esophagus was analyzed and compared between subjects with and without DISH.
Methods
Cervical computed tomography (CT) scans were obtained from five patients with dysphagia and DISH and ten control subjects. The location of the vertebral and carotid arteries, surface area of the hyperostosis and distance between the vertebral body and the trachea and esophagus was assessed in the axial view.
Results
The surface area of the newly formed bone was located symmetrically anterior to the vertebral body. The ossifications were non-flowing in the sagittal view and no segmental vessels were observed. Substantial displacement of the trachea/esophagus was present in the group with DISH compared to the controls.
Conclusions
The hyperostosis at the cervical level was symmetrically distributed anterior to the vertebral bodies without a flowing pattern, in contrast to the asymmetrical flowing pattern typically found in the thoracic spine. The hypothesis that the vascular system acts as a natural barrier against new bone formation in DISH could be further supported with these findings. The significant ventral displacement of the trachea and esophagus may explain the mechanism of dysphagia and airway obstruction in DISH.

研究目的
弥漫性特发性骨肥厚（Diffuse idiopathic skeletal hyperostosis, DISH）以脊柱前方骨化为特征，可引发吞咽困难（dysphagia）与气道梗阻（airway obstruction）。颈椎（cervical spine）新生骨的形态与胸椎（thoracic spine）存在差异，这可能与局部血管解剖结构的差异有关。本研究旨在分析新生骨与动脉系统、气管（trachea）及食管（esophagus）的空间位置关系，并对比DISH患者与健康对照者的相关差异。

研究方法
本研究纳入5例伴吞咽困难（dysphagia）的DISH患者及10名健康对照者，收集其颈椎计算机断层扫描（computed tomography, CT）影像。在轴位（axial view）影像中评估椎动脉（vertebral arteries）与颈动脉（carotid arteries）的位置、骨肥厚（hyperostosis）灶的表面积，以及椎体（vertebral body）与气管（trachea）、食管（esophagus）之间的距离。

研究结果
新生骨的表面积对称分布于椎体前方；矢状位（sagittal view）观察可见骨化灶不呈连续性走行，未观察到节段血管（segmental vessels）。与对照组相比，DISH组患者的气管/食管存在显著移位。

研究结论
颈椎（cervical spine）部位的骨肥厚（hyperostosis）灶对称分布于椎体前方，无连续性走行模式，这与胸椎（thoracic spine）典型的不对称连续性骨化模式存在显著差异。本研究结果进一步支持“血管系统可作为DISH新生骨形成的天然屏障”这一假说。气管（trachea）与食管（esophagus）的显著腹侧移位（ventral displacement），或可解释DISH患者出现吞咽困难（dysphagia）及气道梗阻（airway obstruction）的病理机制。