BACKGROUND Transdural disc herniation (TDH) is a rare event accounting for 0.3-1.5% of all disc herniation cases. Considering the risk of leakage of the cerebrospinal fluid from the dural defect after removal of TDH or incomplete removal, it is very important to recognize TDH before surgery. This study is a retrospective case analysis to analyze the imaging findings of seven cases and to construct a preoperative prediction model for TDH. METHODS Retrospective radiographic examination was performed among patients operated for TDH in two institutions from 2008 to 2018. The radiographic images were analyzed according to the following eight signs: including absence of dural tent, complete block of spinal canal, hawk-beak sign, double-layered lesion, increased distance between the dura and cauda equina, rim enhancement, dural tent enhancement, and epidural gas. To clarify the predictive ability of these radiographic signs, consecutive 131 surgically confirmed epidural disc herniation (EDH) patients for the last 2 years were set as a control group for TDH. The sum of radiographic findings was compared between TDH and EDH patients to determine the cutoff value. RESULTS There were 1 thoracic and 6 lumbar TDHs among 75 thoracic and 6674 lumbar disc herniation cases with an incidence of 1.33% and 0.09%, respectively. Dural tent (p = 0.000, odds ratio = 106.67), double-layered lesion (p = 0.000, odds ratio = 22.69), and distance between the dura and cauda equina (p = 0.007, odds ratio = 52.00) were statistically significantly different between TDH and EDH. According to the receiver operating characteristic curve, the cutoff value of 1.5 had 85.7% sensitivity and 90.8% specificity. CONCLUSION Preoperative imaging can be useful for TDH diagnosis. It is safe to consider the possibility of TDH in patients with more than two findings in the preoperative images.

中文翻译：

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硬膜外椎间盘突出症的术前影像学提示：可预测吗？

背景技术硬膜外椎间盘突出症（TDH）是一种罕见事件，占所有椎间盘突出症病例的0.3-1.5％。考虑到去除TDH或去除不完全后硬脑膜漏出脑脊液的风险，在手术前识别TDH非常重要。这项研究是一项回顾性病例分析，以分析7例病例的影像学表现并构建TDH的术前预测模型。方法对2008年至2018年在两家机构进行TDH手术的患者进行回顾性X线检查。根据以下8个体征分析X线影像：包括没有硬脑膜帐篷，完整的椎管阻塞，鹰嘴征，双鹰嘴征。分层病变，硬脑膜和马尾之间的距离增加，边缘增强，硬脑膜帐篷增强，和硬膜外气体。为了阐明这些影像学表现的预测能力，将最近两年连续经手术确认的硬膜外椎间盘突出症（EDH）的131例患者设置为TDH的对照组。比较TDH和EDH患者的影像学发现总和，以确定临界值。结果75例胸椎和6674例腰椎间盘突出症患者中，分别有1例胸椎TDH和6例腰椎TDH，发生率分别为1.33％和0.09％。硬膜帐篷（p = 0.000，优势比= 106.67），双层病变（p = 0.000，优势比= 22.69）和硬脑膜与马尾之间的距离（p = 0.007，优势比= 52.00）在统计学上显着不同在TDH和EDH之间。根据接收器的工作特性曲线，临界值为1.5，灵敏度为85.7％，特异性为90.8％。结论术前影像检查可用于TDH诊断。在术前影像中有两个以上发现的患者中考虑TDH的可能性是安全的。