van Biervliet J, Scrivani P V, Divers T J, Erb H N, de Lahunta A, Nixon A
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
Equine Vet J. 2004 Jan;36(1):14-20. doi: 10.2746/0425164044864642.
Different criteria have been described based on height reduction of the total myelographic contrast column and components of it as tests for compression of the spinal cord due to cervical stenotic myelopathy (CSM). Fifty percent height reduction of the dorsal myelographic column (DMC), <2 mm empiric height of the DMC and a 40% reduction of the ratio of stenosis calculated based on the height reduction of the entire dural diameter (DD) have been described as decision criteria for considering the test result positive. The reasons for selecting these decision criteria or their accuracies have rarely been reported.
To evaluate the accuracy of diagnostic criteria based on reduced height of the total myelographic column and components of it for diagnosing extradural spinal cord compression using different decision criteria, and make recommendations for consistent myelographic interpretation in horses suspected of having CSM.
Four measurements were obtained by 2 readers in a retrospective sample population of 38 horses in which both cervical myelography and histopathological examination of the cervical spinal cord were performed. The prevalence of CSM in the sample was 50%. At intervertebral sites, the minimum heights of the DD and DMC were measured. At intravertebral sites, the maximum heights of the entire DD and DMC were obtained. Percent height reductions of the DMC and DD were determined as the ratio of minimum intervertebral height to maximum intravertebral height within the next cranial vertebra. Histological examination was used as the gold standard for determining the actual site of spinal cord compression. Sensitivity and specificity for the diagnostic criteria were estimated at each site in neutral and flexed neck positions using several different decision criteria.
At C6-C7, in neutral or flexed neck position and using 20% reduction of DD, the test was highly sensitive and specific for CSM. At other sites, reduced height of the myelographic column generally was not accurate for diagnosing extradural spinal cord compression. Using 20% reduction of DD in neutral position at the mid-cervical sites, the test had only low sensitivity and high specificity. Flexion of the neck appeared to increase detection of spinal cord compression in the mid-cervical region, but also substantially increased the frequency of false-positive diagnoses.
By using the reported sensitivity and specificity estimates, readers may decide on a decision criterion for diagnosis of extradural spinal cord compression due to CSM. However, in planning a surgical correction, it is difficult to define a decision criterion that combines acceptable sensitivity and specificity, especially at the mid-cervical sites.
基于脊髓造影对比柱总高度的降低及其组成部分，已经描述了不同的标准，作为诊断颈椎管狭窄性脊髓病（CSM）导致脊髓受压的检查方法。脊髓造影背侧柱（DMC）高度降低50%、DMC经验性高度<2mm以及基于整个硬脊膜直径（DD）高度降低计算的狭窄率降低40%，已被描述为判断检查结果为阳性的标准。选择这些判断标准的原因或其准确性很少有报道。
使用不同的判断标准，评估基于脊髓造影柱总高度及其组成部分降低的诊断标准在诊断硬膜外脊髓受压方面的准确性，并为疑似患有CSM的马匹的脊髓造影解释一致性提出建议。
在38匹马的回顾性样本群体中，由2名读者进行四项测量，这些马匹均进行了颈椎脊髓造影和颈段脊髓组织病理学检查。样本中CSM的患病率为50%。在椎间部位，测量DD和DMC的最小高度。在椎体内部位，获取整个DD和DMC的最大高度。DMC和DD的高度降低百分比确定为下一个头侧椎体椎间最小高度与椎体内最大高度的比值。组织学检查用作确定脊髓受压实际部位的金标准。使用几种不同的判断标准，在中立位和屈颈位的每个部位估计诊断标准的敏感性和特异性。
在C6 - C7节段，处于中立位或屈颈位且使用DD降低20%的标准时，该检查对CSM具有高度敏感性和特异性。在其他部位，脊髓造影柱高度降低通常对诊断硬膜外脊髓受压不准确。在颈中部部位中立位使用DD降低20%的标准时，该检查仅具有低敏感性和高特异性。颈部屈曲似乎增加了颈中部区域脊髓受压的检测，但也大幅增加了假阳性诊断的频率。
通过使用报告的敏感性和特异性估计值，读者可以决定用于诊断CSM所致硬膜外脊髓受压的判断标准。然而，在规划手术矫正时，很难定义一个兼具可接受的敏感性和特异性的判断标准，尤其是在颈中部部位。
